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Sample records for welded trapezoidal joints

  1. Acute Dislocation of the Metacarpal-Trapezoid Joint.

    Science.gov (United States)

    Cardozo, Diego Fernando Rincón; Plata, Guillermo Varón; Casas, Jairo Antonio Camacho; Rodríguez, Natalia Sauza

    2016-06-01

    The trapezoid metacarpal dislocation is a rare event. In the literature, it is found in case reports. This injury is caused by direct or indirect high energy trauma. In most cases, the dislocation is dorsal and is difficult to reproduce because the joint is not very mobile. Given the low incidence and little evidence supported in the literature regarding the management, this injury can be treated by open or closed reduction; however, it has been published that most authors use Kirschner wire fixation with good results. Here we present our experience in the management of a male patient with acute trapezoid metacarpal dislocation handled with a splint with good functional results at 6 weeks.

  2. Studies of welded joints

    Directory of Open Access Journals (Sweden)

    J. M. Krupa

    2010-07-01

    Full Text Available Studies of a welded joint were described. The joint was made as a result of the reconstruction of a truss and one of the possible means to make a repair. The studies were of a simulation character and were targeted at the detection of welding defects and imperfections thatshould be eliminated in a real structure. A model was designed and on this model the tests and examinations were carried out. The modelwas made under the same conditions as the conditions adopted for repair. It corresponded to the real object in shape and dimensions, and in the proposed technique of welding and welding parameters. The model was composed of five plates joined together with twelve beads.The destructive and non-destructive tests were carried out; the whole structure and the respective welds were also examined visually. Thedefects and imperfections in welds were detected by surface methods of inspection, penetration tests and magnetic particle flaw detection.The model of the welded joint was prepared by destructive methods, a technique that would never be permitted in the case of a realstructure. For the investigations it was necessary to cut out the specimens from the welded joint in direction transverse to the weld run. The specimens were subjected to metallographic examinations and hardness measurements. Additionally, the joint cross-section was examined by destructive testing methods to enable precise determination of the internal defects and imperfections. The surface methods were applied again, this time to determine the severity of welding defects. The analysis has proved that, fabricated under proper conditions and with parameters of the welding process duly observed, the welded joint has good properties and repairs of this type are possible in practice.

  3. Thermal treatment of dissimilar steels' welded joints

    Science.gov (United States)

    Nikulina, A. A.; Denisova, A. S.; Gradusov, I. N.; Ryabinkina, P. A.; Rushkovets, M. V.

    2016-04-01

    In this paper combinations of chrome-nickel steel and high-carbon steel, produced by flash butt welding after heat treatment, are investigated. Light and electron microscopic studies show that the welded joints after heat treatment have a complex structure consisting of several phases as initial welded joints. A martensite structure in welded joints after thermal treatment at 300... 800 °C has been found.

  4. Total carpometacarpal joint dislocation combined with trapezium fracture, trapezoid dislocation and hamate fracture.

    Science.gov (United States)

    Gvozdenovic, R; Soelberg Vadstrup, L

    2015-10-01

    Multiple metacarpal dislocations combined with carpal fracture - dislocations are rare injuries. We report a new combination of these injuries where fracture-dislocation of the base of the 1st metacarpal bone occurred simultaneously with a comminuted fracture of the trapezium, dislocation of the trapezoid and metacarpal joints (2nd to 5th) and an avulsion fracture of the hamate. This specific carpal injury has not been previously described and our description will contribute to understanding the mechanism of these complex injuries. The injury pattern in the case featured here was multifaceted and resulted from rupture of both transverse and longitudinal carpal columns. According to the Garcia-Elias classification of axial carpal disruptions, this particular injury mechanism was a combined axial-radial-ulnar type injury. These injuries are extremely rare and are only sporadically described in the literature. Trapeziectomy, followed by open, partial, low-profile screw fixation of the fracture of the first metacarpal and open reduction and pinning of the carpometacarpal joints and the trapezoid injury yielded a good result at the 1-year follow-up. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  5. Materials participation in welded joints manufacturing

    Science.gov (United States)

    Ghenghea, L. D.

    2016-08-01

    Management of materials dilution to form a joint with higher features asked by complex metallic structures is a problem that took attention and efforts of welding processes researchers and this communication will give a little contribution presenting some scientific and experimental results of dilution processes studied by Welding Research Group from Iasi, Romania, TCM Department. Liquid state welding processes have a strong dependence related to dilution of base and filler materials, the most important are for automatic joining using welding. The paper presents a review of some scientific works already published and their contributions, results of dilution coefficient evaluation using weighing, graphics and software applied for shielded metal arc welding process. Paper results could be used for welders’ qualification, welding procedure specification and other welding processes researchers’ activities. The results of Welding Research Group from Iasi, Romania, TCM Department, show dilution coefficient values between 20-30 % of base material and 70-80 % of filler material for studied welding process.

  6. Yield load solutions of heterogeneous welded joints

    Energy Technology Data Exchange (ETDEWEB)

    Kozak, D., E-mail: dkozak@sfsb.h [Mechanical Engineering Faculty in Slavonski Brod, Josip Juraj Strossmayer University of Osijek, Trg Ivane Brlic-Mazuranic 2, Hr-35000 Slavonski Brod (Croatia); Gubeljak, N. [Faculty of Mechanical Engineering, University of Maribor, Smetanova 17, SI-2000 Maribor (Slovenia); Konjatic, P.; Sertic, J. [Mechanical Engineering Faculty in Slavonski Brod, Josip Juraj Strossmayer University of Osijek, Trg Ivane Brlic-Mazuranic 2, Hr-35000 Slavonski Brod (Croatia)

    2009-12-15

    The aim of this paper is to establish yield load solutions when the materials inhomogeneity within the weld is present, which is usually the case in repair welding. The effect of yield strength mismatch of welded joints performed with different geometry on the yield load value has been investigated in the context of single edge notched fracture toughness specimen subjected to bending SE(B) using the finite element method. The crack was located in the center of the weld and the two most important geometrical parameters were identified as: crack length ratio a/W as well as slenderness of the welded joint, which were systematically varied. One practical and four additional combinations of filler materials, with the same portion of overmatched part and undermatched part of the weld, were analyzed, and plane strain FE solutions for the case when the crack is located in the overmatched half of the heterogeneous weld were obtained.

  7. 46 CFR 56.30-5 - Welded joints.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Welded joints. 56.30-5 Section 56.30-5 Shipping COAST... Selection and Limitations of Piping Joints § 56.30-5 Welded joints. (a) General. Welded joints may be used..., then: (1) The backing rings shall be removed and the inside of the joint ground smooth, or (2) The...

  8. STRUCTURAL DEGRADATION OF HETEROGENEOUS WELDED JOINTS

    Directory of Open Access Journals (Sweden)

    Eva Schmidová

    2012-10-01

    Full Text Available Developing the techniques of welding materials with higher dynamic strength onto the rolling surfaces of rails is one of the options for increasing their operational endurance. The subject of this paper is an analysis of heterogeneous weld joints experimentally manufactured by welding medium-carbon austenitic steels onto high-carbon unalloyed pearlitic steels. The analyses focus on examinations of the marginal mixing of the materials at the fusion line and the circumstances under which intercrystalline cracks form in the weld deposit layers. Structural analyses, chemical microanalyses and a hardness assessment were performed in order to identify the corresponding structural changes. The proportion of zonal vs. interdendritic segregation of the alloying elements in the degradation of the welded joint was distinguished. We described the nature of the structural heterogeneities produced, locally connected with the martensitic transformation. The chemical heterogeneity leading to the formation of martensite at grain boundaries was identified as the limiting effect.

  9. Structural degradation of heterogeneous welded joints

    Directory of Open Access Journals (Sweden)

    Eva Schmidová

    2012-09-01

    Full Text Available Developing the techniques of welding materials with higher dynamic strength onto the rolling surfaces of rails is one of the options for increasing their operational endurance. The subject of this paper is an analyses of heterogeneous weld interfaces experimentally manufactured by welding medium-carbon austenitic steels onto high-carbon unalloyed pearlitic steels. The analyses focus on examinations of the marginal mixing of the materials at the weld interface and the circumstances under which intercrystalline cracks form in the weld deposit layers. Structural analyses, chemical microanalyses and a hardness assessment were performed in order to identify the corresponding structural changes. The proportion of zonal vs. interdendritic segregation of the alloying elements in the degradation of the welded joint was distinguished. We described the nature of the structural heterogeneities produced, locally connected with the martensitic transformation. The chemical heterogeneity leading to the formation of martensite at grain boundaries was identified as the limiting effect.

  10. Condition and problems of ultrasonic inspection of austenitic weld joints

    Energy Technology Data Exchange (ETDEWEB)

    Grebennikov, V.V.; Gurvich, A.K.

    1986-05-01

    A review is presented of methods and means of ultrasonic inspection of austenitic weld joints. The basic structural factors influencing the propagation of ultrasonic vibrations in austenitic weld joints are considered. The influence of the ultrasonic inspection parameters on the ratio of the useful signal to the average level of structural interferences is shown. Acoustic models of austenitic weld joints are presented. The basic methods of increasing the interference resistance and apparatus for inspection of acoustic weld joints are described.

  11. The technology and welding joint properties of hybrid laser-tig welding on thick plate

    Science.gov (United States)

    Shenghai, Zhang; Yifu, Shen; Huijuan, Qiu

    2013-06-01

    The technologies of autogenous laser welding and hybrid laser-TIG welding are used on thick plate of high strength lower alloy structural steel 10CrNiMnMoV in this article. The unique advantages of hybrid laser-TIG welding is summarized by comparing and analyzing the process parameters and welding joints of autogenous laser welding laser welding and hybrid laser-TIG welding. With the optimal process parameters of hybrid welding, the good welding joint without visible flaws can be obtained and its mechanical properties are tested according to industry standards. The results show that the hybrid welding technology has certain advantages and possibility in welding thick plates. It can reduce the demands of laser power, and it is significant for lowering the aspect ratio of weld during hybrid welding, so the gas in the molten pool can rise and escape easily while welding thick plates. Therefore, the pores forming tendency decreases. At the same time, hybrid welding enhances welding speed, and optimizes the energy input. The transition and grain size of the microstructure of hybrid welding joint is better and its hardness is higher than base material. Furthermore, its tensile strength and impact toughness is as good as base material. Consequently, the hybrid welding joint can meet the industry needs completely.

  12. STUDY AND ANALYSIS OF THE EFFECT OF WELDING PROCESS ON DISTORTION WITH 304L STAINLESS STEEL WELD JOINTS

    OpenAIRE

    Dhananjay Kumar*, Dharamvir mangal

    2017-01-01

    The effect of welding process on the distortion with 304L stainless steel 12thk weld joints made by TIG (tungsten inert gas) and SMAW (Shielded metal arc welding) welding process involving different type joint configuration have been studied. The joint configurations employed were double V-groove edge preparation for double side SMAW welding and square – butt preparation for double side TIG welding. All weld joints passed by radiographic. Distortion measurements were carried out using height ...

  13. The characteristics of welded joints for air conditioning application

    Science.gov (United States)

    Weglowski, M. St.; Weglowska, A.; Miara, D.; Kwiecinski, K.; Błacha, S.; Dworak, J.; Rykala, J.; Pikula, J.; Ziobro, G.; Szafron, A.; Zimierska-Nowak, P.; Richert, M.; Noga, P.

    2017-10-01

    In the paper the results of metallographic examination of welded joints for air-conditioning elements are presented. The European directives 2006/40/EC on the greenhouse gasses elimination demand to stop using traditional refrigerant and to change it to R744 (CO2) medium in air conditioning installation. The R744 refrigerant is environmental friendly medium if compared with standard solution such as R12, R134a or R1234yf and safer for passengers than R1234yf. The non-standard thermodynamic parameters of the R744 which translate into high pressure and high temperature require specific materials to develop the shape and to specify the technology of manufacturing for the particular elements of the conduits and moreover the technologies of joining for the whole structure, which would meet the exploitation requirements of the new air-conditioning system. To produce the test welded joints of stainless steels four different joining technologies were applied: laser welding, plasma welding, electron beam welding as well as high speed rotation welding. This paper describes the influence of the selected welding process on the macrostructure and microstructure of welded joints of AISI 304 and AISI 316L steels. The results indicated that plasma welding laser welding and electron beam welding technologies guaranty the proper quality of welded joints and can be used for the air conditioning application in automotive industry. However, high speed rotation welding not guarantee the good quality of welded joints and cannot be used for above application.

  14. A Neural Network Approach for GMA Butt Joint Welding

    DEFF Research Database (Denmark)

    Christensen, Kim Hardam; Sørensen, Torben

    2003-01-01

    This paper describes the application of the neural network technology for gas metal arc welding (GMAW) control. A system has been developed for modeling and online adjustment of welding parameters, appropriate to guarantee a certain degree of quality in the field of butt joint welding with full...... penetration, when the gap width is varying during the welding process. The process modeling to facilitate the mapping from joint geometry and reference weld quality to significant welding parameters has been based on a multi-layer feed-forward network. The Levenberg-Marquardt algorithm for non-linear least...

  15. 49 CFR 195.216 - Welding: Miter joints.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Welding: Miter joints. 195.216 Section 195.216 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... PIPELINE Construction § 195.216 Welding: Miter joints. A miter joint is not permitted (not including...

  16. Virtual Welded - Joint Design Integrating Advanced Materials and Processing Technology

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhishang; Ludewig, Howard W.; Babu, S. Suresh

    2005-06-30

    Virtual Welede-Joint Design, a systematic modeling approach, has been developed in this project to predict the relationship of welding process, microstructure, properties, residual stress, and the ultimate weld fatique strength. This systematic modeling approach was applied in the welding of high strength steel. A special welding wire was developed in this project to introduce compressive residual stress at weld toe. The results from both modeling and experiments demonstrated that more than 10x fatique life improvement can be acheived in high strength steel welds by the combination of compressive residual stress from the special welding wire and the desired weld bead shape from a unique welding process. The results indicate a technology breakthrough in the design of lightweight and high fatique performance welded structures using high strength steels.

  17. Impact Tests of Welded Joints

    Science.gov (United States)

    1936-04-01

    La Soci&i des Ingenieurs Soudeurs and ITn- stitut de Soudure Autogene drawn up for adoption in January 1936.3 The specimens adopted. Fig. 3, are...Specification of the Joint Commission of Society des Ingenieurs Soudeurs and Institut de Soudure Autogene, 1935. Rev. Solid. Anlog., J7, (257), 2-10 July...34, 1413-1422 and 1521-1525 (1925). " Kleiner, H., and Bossen, K., Autog. Melallb.,37, 131-139 (1934). ’» Keel, C F., J’l. de la Soudure . 22, 12-13

  18. The impact of welding wire on the mechanical properties of welded joints

    Directory of Open Access Journals (Sweden)

    Magdalena Mazur

    2014-06-01

    Full Text Available This paper presents results of the mechanical properties of Hardox 450 steel welded joints. These welded joints were made in accordance with welding procedure specifications (WPS, which was prepared and  applied in the Wielton company. Fillers were provided by welding wires with two different diameters. The welding wire was G4Sil with diameter of 1.0 mm and 1.2 mm. The aim of this study was to examine whether the thickness of the welding wire has a direct effect on the properties of welded joints. Test specimens were made in similar parameters of the welding process. Then they were subjected to macroscopic research, tensile strength, impact strength and hardness

  19. Welded joints integrity analysis and optimization for fiber laser welding of dissimilar materials

    Science.gov (United States)

    Ai, Yuewei; Shao, Xinyu; Jiang, Ping; Li, Peigen; Liu, Yang; Liu, Wei

    2016-11-01

    Dissimilar materials welded joints provide many advantages in power, automotive, chemical, and spacecraft industries. The weld bead integrity which is determined by process parameters plays a significant role in the welding quality during the fiber laser welding (FLW) of dissimilar materials. In this paper, an optimization method by taking the integrity of the weld bead and weld area into consideration is proposed for FLW of dissimilar materials, the low carbon steel and stainless steel. The relationships between the weld bead integrity and process parameters are developed by the genetic algorithm optimized back propagation neural network (GA-BPNN). The particle swarm optimization (PSO) algorithm is taken for optimizing the predicted outputs from GA-BPNN for the objective. Through the optimization process, the desired weld bead with good integrity and minimum weld area are obtained and the corresponding microstructure and microhardness are excellent. The mechanical properties of the optimized joints are greatly improved compared with that of the un-optimized welded joints. Moreover, the effects of significant factors are analyzed based on the statistical approach and the laser power (LP) is identified as the most significant factor on the weld bead integrity and weld area. The results indicate that the proposed method is effective for improving the reliability and stability of welded joints in the practical production.

  20. A Neural Network Approach for GMA Butt Joint Welding

    DEFF Research Database (Denmark)

    Christensen, Kim Hardam; Sørensen, Torben

    2003-01-01

    This paper describes the application of the neural network technology for gas metal arc welding (GMAW) control. A system has been developed for modeling and online adjustment of welding parameters, appropriate to guarantee a certain degree of quality in the field of butt joint welding with full...

  1. Effect of weld spacing on microstructure and mechanical properties of CLAM electron beam welding joints

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Yutao; Huang, Bo, E-mail: aufa0007@163.com; Zhang, Junyu; Zhang, Baoren; Liu, Shaojun; Huang, Qunying

    2016-11-15

    Highlights: • The welded joints of CLAM steel with different weld spacings have been fabricated with electron beam welding, and a simplified model of CLAM sheet was proposed. • The microstructure and mechanical properties such as microhardness, impact and tensile were investigated at different welding spacing for both conditions of as-welded and post weld heat treatment (PWHT). • The effect of the welding thermal cycle was significantly when the weld spacings were smaller than 4 mm. • When the weld spacing was small enough, the original microstructures would be fragmented with the high heat input. - Abstract: China low activation martensitic (CLAM) steel has been chosen as the primary structural material in the designs of dual function lithium-lead (DFLL) blanket for fusion reactors, China helium cooled ceramic breeder (HCCB) test blanket module (TBM) for ITER and China fusion engineering test reactor (CFETR) blanket. The cooling components of the blankets are designed with high density cooling channels (HDCCs) to remove the high nuclear thermal effectively. Hence, the welding spacing among the channels are small. In this paper, the welded joints of CLAM steel with different weld spacings have been fabricated with electron beam welding (EBW). The weld spacing was designed to be 2 mm, 3 mm, 4 mm, 6 mm and 8 mm. The microstructure and mechanical properties such as microhardness, impact and tensile were investigated at different welding spacing for both conditions of as-welded and post weld heat treatment (PWHT). The PWHT is tempering at 740 °C for 120 min. The results showed that the grain size in the heat affected zone (HAZ) increased with the increasing weld spacing, and the joint with small weld spacing had a better performance after PWHT. This work would give useful guidance to improve the preparation of the cooling components of blanket.

  2. Research on Fracture Failure of the Underwater Welding Joint

    Science.gov (United States)

    Kong, Xiangfeng; Qiu, Feng; Zhang, Jing; Zou, Yan; Chu, Dongzhi

    2017-12-01

    In this paper, by testing welding joints of their metallography and hardness, we analyze the metal structure. And then, the microstructure characteristics, macro and micro fracture morphology of underwater welding joint were investigated by means of metallographical examination and SEM. The fracture failure of the underwater welding joint is discussed here. The cracks are the major factors to fracture failure. The cracks spread along with the crack of the welding line, and this expand process generates dimple. The crack continues to expand under the action of tensile and the fracture fails eventually.

  3. Forming Completely Penetrated Welded T-joints when Pulsed Arc Welding

    Science.gov (United States)

    Krampit, N. Yu; Krampit, M. A.; Sapozhkov, A. S.

    2016-04-01

    The paper is focused on revealing the influence of welding parameters on weld formation when pulsed arc welding. As an experimental sample a T-joint over 10 mm was selected. Welding was carried out in flat position, which required no edge preparation but provided mono-directional guaranteed root penetration. The following parameters of welding were subjected to investigation: gap in the joint, wire feed rate and incline angles of the torch along and across the weld axis. Technological recommendations have been made with respect to pulsed arc welding; the cost price of product manufacturing can be reduced on their basis due to reduction of labor input required by machining, lowering consumption of welding materials and electric power.

  4. Models for selecting GMA Welding Parameters for Improving Mechanical Properties of Weld Joints

    Science.gov (United States)

    Srinivasa Rao, P.; Ramachandran, Pragash; Jebaraj, S.

    2016-02-01

    During the process of Gas Metal Arc (GMAW) welding, the weld joints mechanical properties are influenced by the welding parameters such as welding current and arc voltage. These parameters directly will influence the quality of the weld in terms of mechanical properties. Even small variation in any of the cited parameters may have an important effect on depth of penetration and on joint strength. In this study, S45C Constructional Steel is taken as the base metal to be tested using the parameters wire feed rate, voltage and type of shielding gas. Physical properties considered in the present study are tensile strength and hardness. The testing of weld specimen is carried out as per ASTM Standards. Mathematical models to predict the tensile strength and depth of penetration of weld joint have been developed by regression analysis using the experimental results.

  5. Influence of the Gap Width on the Geometry of the Welded Joint in Hybrid Laser-Arc Welding

    Science.gov (United States)

    Turichin, G.; Tsibulskiy, I.; Kuznetsov, M.; Akhmetov, A.; Mildebrath, M.; Hassel, T.

    The aim of this research was the experimental investigation of the influence of the gap width and speed of the welding wire on the changes of the geometry in the welded joint in the hybrid laser-arc welding of shipbuilding steel RS E36. The research was divided into three parts. First, in order to understand the influence of the gap width on the welded joint geometry, experimental research was done using continuous wave fiber laser IPG YLS-15000 with arc rectifier VDU-1500DC. The second part involved study of the geometry of the welded joint and hardness test results. Three macrosections from each welded joint were obtained. Influence of the gap width and welding wire speed on the welded joint geometry was researched in the three lines: in the right side of the plates, middle welded joint and in the root welded joint.

  6. Tracking on the joint during the electron beam welding

    Science.gov (United States)

    Braverman, V.; Bogdanov, V.; Belozertsev, V.; Uspenskiy, N.

    2016-11-01

    In the article the description of device, which provides automatic positioning of electron beam relative to joint of welded parts during welding, is given. Extremum seeking based on synchronous detection of sensor signal (X-ray or secondary emission) is realized in the device. Measurements are made when beam goes out of the channel following the welding direction. The application of synchronous detection is possible due to the fact that during joint scanning with electron beam harmonics, carrying data about beam position relative to the joint appear in the joint sensor signal spectrum.

  7. Microstructure development of welding joints in high Cr ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Kubushiro, Keiji; Takahashi, Satoshi; Morishima, Keiko [IHI Corporation (Japan). Research Lab.

    2010-07-01

    Creep failure in high Cr ferritic steels welding joints are Type IV failure. Type IV-failure was ruptured in fine grained region of heat affected zone, microstructure and phase transformation process at welding in fine grained region were very important to clarify. Microstructure difference of heat affected zone was investigated in Gr.91, Gr.92, Gr.122 welding joint. The fraction of 60 degree block boundary, packet boundary, random boundary (including prior gamma boundary) length was compared in three ferritic steels by EBSP(Electron Backscatter Diffraction Pattern) analysis. HAZ was almost fully martensite phase in Gr.122 weld joint. On the other hand, HAZ in Gr.91 welding joint were some equiaxial grain and martensite structure. (orig.)

  8. Weld bead profile of laser welding dissimilar joints stainless steel

    Science.gov (United States)

    Mohammed, Ghusoon R.; Ishak, M.; Aqida, S. N.; Abdulhadi, Hassan A.

    2017-10-01

    During the process of laser welding, the material consecutively melts and solidifies by a laser beam with a peak high power. Several parameters such as the laser energy, pulse frequency, pulse duration, welding power and welding speed govern the mode of the welding process. The aim of this paper is to investigate the effect of peak power, incident angle, and welding speed on the weld bead geometry. The first investigation in this context was conducted using 2205-316L stainless steel plates through the varying of the welding speed from 1.3 mm/s to 2.1 mm/s. The second investigation was conducted by varying the peak power from 1100 W to 1500 W. From the results of the experiments, the welding speed and laser power had a significant effect on the geometry of the weld bead, and the variation in the diameter of the bead pulse-size. Due to the decrease in the heat input, welding speed affected penetration depth more than bead width, and a narrow width of heat affected zone was achieved ranging from 0.2 to 0.5 mm. Conclusively, weld bead geometry dimensions increase as a function of peak power; at over 1350 W peak power, the dimensions lie within 30 μm.

  9. Corrosion resistance of «tube – tubesheet» weld joint obtained by friction welding

    Directory of Open Access Journals (Sweden)

    RIZVANOV Rif Garifovich

    2017-08-01

    Full Text Available Shell-and-tube heat exchangers are widely applied for implementation of various processes at ventures of fuel and energy complex. Cost of production and reliability of heat exchangers of this type is to a wide extent determined by corresponding characteristics of tube bundle, «tube – tubesheet» is its typical joint in particular when welding operations are used in order to attach tubes to tubesheet in addition to expansion. When manufacturing such equipment of heat-resistant chrome-bearing or chromium-molybdenum steels including steel 15H5M, the process of fixed joint manufacturing gets significantly more complicated and costly due to the necessity to use thermal treatment before, during and after welding (this problem is particularly applicable for manufacturing of large-size equipment. One of the options to exclude thermal treatment from manufacturing process is to use «non-arc» welding methods – laser welding, explosion welding as well as friction welding. Use of each of the welding methods mentioned above during production of heat-exchange equipment has its process challenges and peculiarities. This article gives a comparative analysis of weld structure and distribution of electrode potentials of welded joints and parent metal of the joints simulating welding of tube to tubesheet of steel 15H5M using the following welding methods: shielded manual arc welding, tungsten-arc inert-gas welding and friction welding. Comparative analysis of macro- and microstructures of specific zones of the studied welded joints showed that the joints produced by arc welding methods do not exhibit evident inhomogeneity of the structure after application of thermal treatment which is explained by the correctness of thermal treatment. Joints obtained via friction welding are characterized by structural inhomogeneity of the welded joint zone metal microstructure. The ultra-fine-grained structure obtained as a result of friction welding makes it possible to

  10. A Neural Network Approach for GMA Butt Joint Welding

    DEFF Research Database (Denmark)

    Christensen, Kim Hardam; Sørensen, Torben

    2003-01-01

    This paper describes the application of the neural network technology for gas metal arc welding (GMAW) control. A system has been developed for modeling and online adjustment of welding parameters, appropriate to guarantee a certain degree of quality in the field of butt joint welding with full...... penetration, when the gap width is varying during the welding process. The process modeling to facilitate the mapping from joint geometry and reference weld quality to significant welding parameters has been based on a multi-layer feed-forward network. The Levenberg-Marquardt algorithm for non-linear least...... squares has been used with the back-propagation algorithm for training the network, while a Bayesian regularization technique has been successfully applied for minimizing the risk of inexpedient over-training. Finally, a predictive closed-loop control strategy based on a so-called single-neuron self...

  11. Effect of post weld impact treatment (PWIT) on mechanical properties of spot-welded joint

    Science.gov (United States)

    Ghazali, F. A.; Salleh, Z.; Hyie, K. M.; Rozlin, N. M. Nik; Hamidi, S. H. Ahmad; Padzi, M. M.

    2017-12-01

    This paper focuses on the study of improvement for spot welding on the tensile shear and hardness by applying post weld impact treatment (PWIT) on the welded joint. The main objective of the research is to characterize and improve the mechanical properties of the joint. The method of PWIT used on the welded joint was Pneumatic Impact Treatment (PIT). The concept of PIT on spot welding is that it improves the mechanical properties of the welded zone. The working sample was undergoing a resistance spot welding of joining two similar in dimension and material of a steel plate before treated. The dimension of both plate are 110 mm × 45 mm × 1.2 mm and the material used were low carbon steel (LCS). All the welded samples were tested for its mechanical properties by performing the tensile-shear and hardness test. Tensile-shear test was conducted on the spot welded, both treated and as-welded samples using crosshead speed of 2 mm/min, while hardness test was performed using 1kgf load via Vickers hardness indenter. The effects of PIT on tensile-shear properties and hardness were evaluated and found that the implementation of PIT has increased tensile shear and hardness significantly.

  12. Fatigue life estimation in welded joints under multiaxial loadings

    Directory of Open Access Journals (Sweden)

    Sabrina Vantadori

    2009-07-01

    Full Text Available Welded joints are frequently locations for cracks initiation and propagation that may cause fatigue failure of engineering structures. Biaxial or triaxial stress-strain states are present in the vicinity of welded joints, due to local geometrical constraints, welding processes and/or multiaxial external loadings. Fatigue life evaluation of welded joints under multiaxial proportional (in-phase cyclic loading can be performed by using conventional hypotheses (e.g. see the von Mises criterion or the Tresca criterion on the basis of local approaches. On the contrary, the fatigue life predictions of welded joints under non-proportional (out-ofphase cyclic loading are generally unsafe if these conventional hypotheses are used. A criterion initially proposed by the authors for smooth and notched structural components has been extended to the fatigue assessment of welded joints. In more detail, fatigue life of welded joints under multiaxial stress states can be evaluated by considering a nonlinear combination of the shear stress amplitude (acting on the critical plane and the amplitude and the mean value of the normal stress (acting on the critical plane. In the present paper, fatigue lifetimes predicted through the proposed criterion are compared with experimental fatigue life data available in the literature, related to fatigue biaxial tests.

  13. Control of GMA Butt Joint Welding Based on Neural Networks

    DEFF Research Database (Denmark)

    Christensen, Kim Hardam; Sørensen, Torben

    2004-01-01

    in the challenging field of butt joint welding with full penetration under stochastically changing boundary conditions, e.g. major gap width variations. GMAW experiments performed on mild-steel plates (3 mm of thickness), show that high quality welds with uniform back-bead geometry are achievable for gap width...

  14. Numerical evaluation of multipass welding temperature field in API 5L X80 steel welded joints

    Directory of Open Access Journals (Sweden)

    J Nóbrega

    2016-10-01

    Full Text Available Many are the metallurgical changes suffered by materials when subjected to welding thermal cycle, promoting a considerable influence on the welded structures thermo mechanical properties. In project phase, one alternative for evaluating the welding cycle variable, would be the employment of computational methods through simulation. So, this paper presents an evaluation of the temperature field in a multipass welding of API 5L X80 steel used for oil and gas transportation, using the ABAQUS ® software, based on Finite Elements Method (FEM. During the simulation complex phenomena are considerable including: Variation in physical and mechanical properties of materials as a function of temperature, welding speed and the different mechanisms of heat exchange with the environment (convection and radiation were used. These considerations allow a more robust mathematical modeling for the welding process. An analytical heat source proposed by Goldak, to model the heat input in order to characterize the multipass welding through the GTAW (Gas Tungsten Arc Welding process on root and the SMAW (Shielded Metal Arc Welding process for the filling passes were used. So, it was possible to evaluate the effect of each welding pass on the welded joint temperature field, through the temperature peaks and cooling rates values during the welding process.

  15. Apparatus for maintaining alignment of a shrinking weld joint in an electron-beam welding operation

    Science.gov (United States)

    Trent, Jett B.; Murphy, Jimmy L.

    1981-01-01

    The present invention is directed to an apparatus for automatically maintaining a shrinking weld joint in alignment with an electron beam during an electron-beam multipass-welding operation. The apparatus utilizes a biasing device for continually urging a workpiece-supporting face plate away from a carriage mounted base that rotatably supports the face plate. The extent of displacement of the face plate away from the base is indicative of the shrinkage occuring in the weld joint area. This displacement is measured and is used to move the base on the carriage a distance equal to one-half the displacement for aligning the weld joint with the electron beam during each welding pass.

  16. Residual stress simulation of circumferential welded joints

    Directory of Open Access Journals (Sweden)

    Melicher R.

    2007-11-01

    Full Text Available Residual stresses are an important consideration in the component integrity and life assessment of welded structure. The welding process is very complex time dependent physical phenomenon with material nonlinearity. The welding is a thermal process with convection between fluid flow and welding body, between welding bodyand environment. Next type of boundary conditions is radiation and thermo-mechanical contact on the outer surface of gas pipe in the near of weld. The temperature variation so obtained is utilised to find the distribution of the stress field.In this paper, a brief review of weld simulation and residual stress modelling using the finite element method (FEM by commercial software ANSYS is presented. Thermo-elastic-plastic formulations using a von Mises yield criterion with nonlinear kinematics hardening has been employed. Residual axial and hoop stresses obtained from the analysis have been shown. The commercial FEM code ANSYS was used for coupled thermalmechanical analysis.

  17. Automatic joint tracking for CNC-programmed electron beam welding

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, M.J.; Powers, D.E.

    1985-08-01

    In an effort to provide a means for actively maintaining precise alignment during an entire welding procedure, various types of contact and non-contact joint sensing and tracking methods have been investigated over the years. A stylus riding in the groove or a cam follower running along a machined reference surface that parallels the groove, coupled to a transducer for producing a signal indicative of seam path runout, is one method that has been investigated. Another is the employment of light-sensitive devices, used in both a comparative and a discerning fashion to produce a signal indicative of beam-to-joint alignment. Also, electronic detectors that monitor the magnitude of either electron or x-ray emission coming back from a workpiece and produce a signal indicative of beam-to-joint alignment deviations have been investigated. Of the various methods tried, the one which has proved to be ideal for use in joint sensing and tracking during EB welding is that of monitoring the ''secondary'' electron backflow that results when a workpiece is bombarded with a beam of ''primary'' electrons. This is because the primary electron beam producing this secondary electron backflow is the welding beam itself. Since the welding beam becomes the means for measuring joint location, the technique of sensing secondary electron backflow automatically provides a direct correlation between the actual welding beam position and the joint location measured. Thus, any need for calibrating an auxiliary joint location device to actual welding beam position is eliminated. In addition, this method is least affected by the high amount of vapor and spatter generated during welding. In this article, a system employing Secondary Electron Emission Sensing (SEES) to provide an on-line (''realtime''), truly automatic joint tracking capability will be discussed.

  18. Effect of Post-Welding Heat Treatment on Mechanical Properties of Joints of Steel P92 Formed by Submerged Arc Welding

    Science.gov (United States)

    Mohyla, P.; Foldynová, K.

    2014-07-01

    Results of mechanical tests and metallographic studies of welded joints of steel P92 obtained by submerged arc welding are presented. The effect of the post-welding heat treatment on the mechanical properties of the welds is described.

  19. Influence of Welding Current and Joint Design on the Tensile Properties of SMAW Welded Mild Steel Joints Prof. Rohit Jha1 , Dr. A.K. Jha

    OpenAIRE

    Prof. Rohit Jha; Dr. A.K. Jha

    2014-01-01

    Present study includes welding characteristics of weldment with respect to different types of weld design and welding current. Mild steel plates of 6mm were welded using different joint designs. Single V, Double V and Flat surfaces were joined by Shielded Metal Arc Welding process. Welding current was varied in all the cases. Mechanical properties such as ultimate tensile strength, yield strength and percentage elongation were evaluated. Results indicated that the single V join...

  20. Inspection of plastic weld joints with terahertz imaging

    Science.gov (United States)

    Wietzke, S.; Krumbholz, N.; Jördens, C.; Baudrit, B.; Bastian, M.; Koch, M.

    2007-06-01

    Polymers cover the whole range from commodities to high-tech applications. Plastic products have also gained in importance for construction purposes. This draws the attention to joining techniques like welding. Common evaluation of the weld quality is mostly mechanical and destructive. Existing non-destructive techniques are mostly not entirely reliable or economically inefficient. Here, we demonstrate the potential of terahertz time-domain spectroscopy imaging as a non-destructive testing tool for the inspection of plastic weld joints. High-density polyethylene sheets welded in a lap joint with varying quality serve as samples for terahertz transmission measurements. Imperfections within the weld contact area can clearly be detected by displaying the transmitted intensity in a limited frequency range. Contaminations such as metal or sand are identified since they differ significantly from the polymer in the terahertz image. Furthermore, this new and promising technique is capable of detecting the boundaries of a weld contact area. Aside from revealing a contrast between a proper weld joint and no material connection, the size of an air gap between two plastic sheets can be determined by considering the characteristic frequency-dependent transmission through the structure: The spectral positions of the maxima and minima allow for the calculation of the air layer thickness.

  1. Fatigue classification of welded joints in orthotropic steel bridge decks

    NARCIS (Netherlands)

    Kolstein, M.H.

    2007-01-01

    This dissertation presents the research into fatigue classifications of welded joints in orthotropic steel bridge decks. These classifications are needed to calculate the fatigue life of these joints and should be included in the design codes. For years bridge design was mainly based on static

  2. Degradation Processes of Al-Zn Welded Joints

    Directory of Open Access Journals (Sweden)

    Jiří Votava

    2014-01-01

    Full Text Available Welding of metal materials belongs to non-demountable joints. Current trend especially in an automotive industry is to join materials with a different melting temperature. Most of all, there are dural profiles with ferrite or austenite steel. The reason for this is the effort to lower the weight of the whole construction and at the same time preserve sufficient mechanical characteristics. However, there is a big risk of different electrical potentials of both of these metals in this type of non-demountable joints. The experimental part of this paper brings evaluation of mechanical-corrosion processes of overlapped joints produced by the CMT (cold metal transfer method. The base material for weld bead is dural sheet AlMg3 and dural sheet with a surface treatment aluzinc DX51D+AZ 150. Material AlSi5 in the form of a wire was used as an additional material for a welding bath. Method CMT was used in order to create a weld bead. Initial analysis of weld bead was done visually using a binocular microscope. Further, a metallographic analysis of weld bead and base material was processed. The aim was to identify the heat affected area around the welded joint. Microhardness of intermetallic aluminium phases was measured, after the identification of intermetallic phases a chemical analysis EDS was processed. Prepared samples underwent corrosion degradation in a salt spray environment in compliance with the norm ČSN EN ISO 9227. Visual and metallographic evaluation of the individual samples was processed after every week of exposition to the salt spray environment. The goal of this experiment was to record the initial impulse of galvanic corrosion which consists in corrosion degradation in the area of welded joint.

  3. The Investigation of Structure Heterogeneous Joint Welds in Pipelines

    Directory of Open Access Journals (Sweden)

    Lyubimova Lyudmila

    2016-01-01

    Full Text Available Welding joints of dissimilar steels don’t withstand design life. One of the important causes of premature destructions can be the acceleration of steel structural degradation due to cyclic mechanical and thermal gradients. Two zones of tube from steel 12H18N9T, exhibiting the structural instability at early stages of the decomposition of a supersaturated solid austenite solution, were subjected to investigation. Methods of x-ray spectral and structure analysis, micro hardnessmetry were applied for the research. Made the following conclusions, inside and outside tube wall surfaces of hazardous zones in welding joint have different technological and resource characteristics. The microhardness very sensitive to changes of metal structure and can be regarded as integral characteristic of strength and ductility. The welding processes are responsible for the further fibering of tube wall structure, they impact to the characteristics of hot-resistance and long-term strength due to development of ring cracks in the welding joint of pipeline. The monitoring of microhardness and structural phase conversions can be used for control by changes of mechanical properties in result of post welding and reductive heat treatment of welding joints.

  4. Optimizing tensile strength of low-alloy steel joints in upset welding

    OpenAIRE

    Hamedi, M

    2006-01-01

    Purpose: Purpose In resistance upset welding, the heat is generated by resistance of the interface of abutting surfaces to the flow of electrical current in heating and post-weld heating stages. Upset welding typically results in solid-state welds with no melting at the joint. In this paper, the effect of process parameters including heating and post-weld heating power and their corresponding duration along with interference, on the tensile strength of the welded joint are experimentally inve...

  5. A Probabilistic Damage Tolerance Concept for Welded Joints

    DEFF Research Database (Denmark)

    Lassen, T.; Sørensen, John Dalsgaard

    2002-01-01

    The first part of this paper presented the required statistics and stochastic models for reliability analysis of the fatigue fracture of welded plate joints. This present Part 2 suggests a probabilistic damage tolerance supplement to the design S–N curves for welded joints. The goal is to provide...... are presented as dimensionless matrices and suggested for use in support of decision-making at the design stage, without any advanced fracture mechanics modelling and stochastic simulation. One important advantage of this format is that the probability levels are presented regardless of actual weld class...... and target service life (TSL). This is obtained by introducing the FDF as a key parameter to the results. This parameter is defined as the ratio of predicted fatigue life over TSL. FDF is always calculated in the S–N approach which is mandatory in fatigue life prediction. Various welded details (classes...

  6. Characterization on strength and toughness of welded joint for Q550 ...

    Indian Academy of Sciences (India)

    Abstract. Q550 high strength steel was welded using gas shielded arc welding and three different welding wires without pre- or post-heat treatments. The paper investigates the influence of welding wire on the microstructure, tensile strength and impact toughness of Q550 steel weld joints. Results showed that the ...

  7. Characterization on strength and toughness of welded joint for Q550 ...

    Indian Academy of Sciences (India)

    Q550 high strength steel was welded using gas shielded arc welding and three different welding wires without pre- or post-heat treatments. The paper investigates the influence of welding wire on the microstructure, tensile strength and impact toughness of Q550 steel weld joints. Results showed that the microstructure of ...

  8. Numerical Simulation of Residual Stresses in Linear Friction Welded Joints

    Directory of Open Access Journals (Sweden)

    R. Nikiforov

    2015-09-01

    Full Text Available A thermo-mechanical model of linear friction welding has been developed. The temperature distribution during the heating process was determined using a one-dimensional model. The distribution of temperature and stress field during the forging phase was determined by solving the coupled problem in ANSYS. The model allows to predict the effect of welding parameters on the stress field, whereas modeling data are consistent with the residual stresses in welded joints of the Ti6Al4V alloy obtained during the experiment.

  9. Mechanical Characteristics of Welded Joints of Aluminum Alloy 6061 T6 Formed by Arc and Friction Stir Welding

    Science.gov (United States)

    Astarita, A.; Squillace, A.; Nele, L.

    2016-01-01

    Butt welds formed by arc welding in inert gas with nonconsumable electrode (tungsten inert gas (TIG) welding) and by friction stir welding (FSW) from aluminum alloy AA6061 T6 are studied. Comparative analysis of the structures and mechanical properties of the welded joints is performed using the results of optical and electron microscopy, tensile tests, tests for residual bending ductility, and measurements of microhardness. The changes in the microstructure in different zones and the degrees of degradation of the mechanical properties after the welding are determined. It is shown that the size of the tool for the friction stir welding affects the properties of the welds. Quantitative results showing the relation between the microscopic behavior of the alloy and the welding-induced changes in the microstructure are obtained. Friction stir welding is shown to provide higher properties of the welds.

  10. The structure and phase composition of welded joint after deformation

    Science.gov (United States)

    Smirnov, Aleksander; Popova, Natalya; Ozhiganov, Eugeniy; Nikonenko, Elena; Ababkov, Nikolay; Kalashnikov, Mark; Koneva, Nina; Kozlov, Eduard

    2017-01-01

    The paper addresses the issue of the structure and phase composition of welded joint and focuses on their investigation after plastic deformation. The contribution of internal stresses to the formation of phase composition and fine structure of welded joint is shown herein. Electrode welding is used to obtain welded joint in St3 steel. Specimens are subjected to a quasi-static tensile deformation ranging from 0 to 5% under 370 MPa loading. TEM investigations on thin foil specimens allow studying the structure and phase composition within the heat-affected zone at 1 mm distance from base material and 0.5 mm from welding material. The degree of plastic deformation is shown for both base and welding materials and includes their morphology, phase composition, defect structure and its parameters. Long-range stresses are divided into plastic and elastic. Plastic deformation has no qualitative effect on the material structure, however, it modifies its quantitative parameters. With the increase of deformation degree, the perlite component becomes more imperfect and transforms, first, to a fractured perlite and then to ferrite, thereby decreasing the volume ratio of perlite. Polarization of the dislocation structure is observed. The amplitude of internal stress fields grows. Unlike the shear stresses, long-range stresses manifest their intensive growth. The elastic component makes the major contribution to the long-range stresses resulting in the formation of microcracks.

  11. A novel weld seam detection method for space weld seam of narrow butt joint in laser welding

    Science.gov (United States)

    Shao, Wen Jun; Huang, Yu; Zhang, Yong

    2018-02-01

    Structured light measurement is widely used for weld seam detection owing to its high measurement precision and robust. However, there is nearly no geometrical deformation of the stripe projected onto weld face, whose seam width is less than 0.1 mm and without misalignment. So, it's very difficult to ensure an exact retrieval of the seam feature. This issue is raised as laser welding for butt joint of thin metal plate is widely applied. Moreover, measurement for the seam width, seam center and the normal vector of the weld face at the same time during welding process is of great importance to the welding quality but rarely reported. Consequently, a seam measurement method based on vision sensor for space weld seam of narrow butt joint is proposed in this article. Three laser stripes with different wave length are project on the weldment, in which two red laser stripes are designed and used to measure the three dimensional profile of the weld face by the principle of optical triangulation, and the third green laser stripe is used as light source to measure the edge and the centerline of the seam by the principle of passive vision sensor. The corresponding image process algorithm is proposed to extract the centerline of the red laser stripes as well as the seam feature. All these three laser stripes are captured and processed in a single image so that the three dimensional position of the space weld seam can be obtained simultaneously. Finally, the result of experiment reveals that the proposed method can meet the precision demand of space narrow butt joint.

  12. [The effects of different welding wires on the mechanical properties of laser welding joints].

    Science.gov (United States)

    Huang, Qing-feng; Zhang, Jian-zhong; Jiang, Wei-dong; Li, Quan; Yu, Jin-xing

    2006-08-01

    To evaluate the mechanical properties and microstructure of laser-welded joints with different welding wires for clinical use of welding wire. The standard tensile test and three-point bending test rods were made from Co-Cr and Ni-Cr alloy, and were laser-welded with different welding wire (commercially welding wire and casting wire). Then the tensile rods were tested for the ultimate tensile strength (UTS), and the bending rods for the ultimate bending strength (UBS). The results was analyzed by one-way ANOVA. The tensile fracture surface were examined by scanning electron microscopy (SEM). Metallurgical analysis were also performed on polished longitudinal sectioned samples. For Co-Cr alloy, the UTS of casting wire group and commercially welding wire group was respectively (606.40+/-82.53)MPa and (693.61+/-47.68)MPa; the UBS was respectively (997.95+/-88.89)MPa and (1160.76+/-91.59)MPa. ANOVA showed a significant difference of UTS and UBS between the two groups at the 0.05 level (Pwelding wire group was respectively (558.14+/-46.75)MPa and (582.32+/-35.43)MPa; the UBS was respectively (1084.75+/-46.02)MPa and (1078.29+/-36.25)MPa. There was no significant difference between the two groups (P>0.05). SEM and metallurgical examination showed the welded zone exhibiting more cracks in the casting wire group than in the commercially welding wire group. It would be advisable to work with commercially welding wire for the joints that need better strength.

  13. Microstructural Characterization of Friction Stir Welded Aluminum-Steel Joints

    Science.gov (United States)

    Patterson, Erin E.; Hovanski, Yuri; Field, David P.

    2016-06-01

    This work focuses on the microstructural characterization of aluminum to steel friction stir welded joints. Lap weld configuration coupled with scribe technology used for the weld tool have produced joints of adequate quality, despite the significant differences in hardness and melting temperatures of the alloys. Common to friction stir processes, especially those of dissimilar alloys, are microstructural gradients including grain size, crystallographic texture, and precipitation of intermetallic compounds. Because of the significant influence that intermetallic compound formation has on mechanical and ballistic behavior, the characterization of the specific intermetallic phases and the degree to which they are formed in the weld microstructure is critical to predicting weld performance. This study used electron backscatter diffraction, energy dispersive spectroscopy, scanning electron microscopy, and Vickers micro-hardness indentation to explore and characterize the microstructures of lap friction stir welds between an applique 6061-T6 aluminum armor plate alloy and a RHA homogeneous armor plate steel alloy. Macroscopic defects such as micro-cracks were observed in the cross-sectional samples, and binary intermetallic compound layers were found to exist at the aluminum-steel interfaces of the steel particles stirred into the aluminum weld matrix and across the interfaces of the weld joints. Energy dispersive spectroscopy chemical analysis identified the intermetallic layer as monoclinic Al3Fe. Dramatic decreases in grain size in the thermo-mechanically affected zones and weld zones that evidenced grain refinement through plastic deformation and recrystallization. Crystallographic grain orientation and texture were examined using electron backscatter diffraction. Striated regions in the orientations of the aluminum alloy were determined to be the result of the severe deformation induced by the complex weld tool geometry. Many of the textures observed in the weld

  14. A Probabilistic Damage Tolerance Concept for Welded Joints

    DEFF Research Database (Denmark)

    Lassen, T.; Sørensen, John Dalsgaard

    2002-01-01

    The present paper presents the necessary crack growth statistics and suggests stochastic models for a reliability analysis of the fatigue fracture of welded steel plate joints. The reliability levels are derived from extensive testing with fillet-welded joints for which the entire crack growth....... The derived statistics and distribution function for these parameters are used as variables in a Monte Carlo simulation (MCS). In addition a Markov model is developed as an alternative stochastic model. It is a Markov chain for which the discrete damage states are related to chosen crack depths...

  15. Research of the Resistance of Contact Welding Joint of R65 Type Rail

    Directory of Open Access Journals (Sweden)

    Kęstutis Dauskurdis

    2015-03-01

    Full Text Available In the article the R65 type rail joints that were welded by resistance welding are analysed. Survey methodology of the research consists of the following parts: visual inspection of welded joint, ultrasonic rail inspection, hardness test of upper part of the rail, fusion area research, the measurement hardness test of heat-softened area, the measurement microhardness test, microstructure research of the welded joint, impact strength experiments, chemical analysis of welded joint, wheel-rail interaction research using the finite element method (FEM. The results of the research are analysed and the quality of weld is evaluated. The conclusion is based on the results of this research.

  16. Superconducting properties of ultra-pure niobium welded joints

    Science.gov (United States)

    Demyanov, S. E.; Kaniukov, E. Yu.; Pobol, I. L.; Yurevich, S. V.; Baturitsky, M. A.; Shirkov, G. D.; Budagov, Yu. A.; Demin, D. L.; Azaryan, N. S.

    2015-07-01

    An optimal electron-beam welding operating regime for ultra-pure sheet niobium has been developed for use in a superconducting resonator for the International Linear Collider (ILC). The formation of weld joints is studied and their microstructure and microhardness are investigated taking the required geometry of the weld seams into account. Low-temperature electrical measurements in magnetic fields up to 2 T are used to determine the critical parameters of the superconducting transition in the weld area. From the standpoint of the superconducting properties of the resonator, the slight degradation in the characteristics of sheet niobium observed in the thermally affected area (about 10% on average) is not of fundamental importance.

  17. Size effect of welded thin-walled tubular joints

    OpenAIRE

    Mashiri, Fidelis Rutendo; Zhao, Xiao-Ling; Hirt, Manfred A.; NUSSBAUMER, Alain

    2007-01-01

    This paper clarifies the terminologies used to describe the size effect on fatigue behaviour of welded joints. It summarizes the existing research on size effect in the perspective of newly defined terminologies. It identifies knowledge gaps in designing tubular joints using the hot spot stress method, i.e. thin-walled tubular joints with wall thickness less than 4 mm and thick-walled tubular joints with wall thickness larger than 50 mm or diameter to thickness ratio less than 24. It is the t...

  18. Laser welding head tailored to tube-sheet joint requirements for heat exchangers manufacturing

    OpenAIRE

    Vandewynckéle, Ambroise; Vaamonde, Eva; Fontán, Marcos; Herwig, Patrick; Mascioletti, Alessandro

    2013-01-01

    Tube to tube-sheet joints in heat exchangers are currently welded by the orbital TIG process characterized by very high quality of the weld beads and good repeatability. However, due to high number of welds, a reduction in the welding cycle time would have an interesting impact on manufacturing costs and delays and laser welding technology is aimed to improve this factor. The main disadvantage is the positioning accuracy required by the laser welding process since beam deviations from real jo...

  19. Investigation of Welded Joints with Linear Turned Beech Elements

    Directory of Open Access Journals (Sweden)

    ŽUPČIĆ, Ivica

    2010-01-01

    Full Text Available Welding of wood is a process where chemical and physical reactions take place, heat isformed during the friction, which melts and softens the structure of wood, and a firm joint is formedby cooling of the melt.The paper discusses the present knowledge about wood welding and the results of wood weldingresearch obtained in the Faculty of Forestry, University of Zagreb. The results were obtained onsamples (solid beech wood with tapered entrance holes 9 mm in diameter, the bottom of the hole7 mm in diameter and dowel lengths of 20 mm and 30 mm, as well as samples with 8 mm holediameters and dowel lengths of 20 mm and 30 mm. The tensile strength of welded joints was analysed.The analysis results show that there is a big difference in tensile strength between the samples with 20and 30 mm long dowels and profile holes. 30 mm long dowels give better results than the 20 mmdowels.

  20. Designing aluminium friction stir welded joints against multiaxial fatigue

    Directory of Open Access Journals (Sweden)

    L. Susmel

    2016-07-01

    Full Text Available The present paper investigates the accuracy of the Modified Wöhler Curve Method (MWCM in estimating multiaxial fatigue strength of aluminium friction stir (FS welded joints. Having developed a bespoke joining technology, circumferentially FS welded tubular specimens of Al 6082-T6 were tested under proportional and non-proportional tension and torsion, the effect of non-zero mean stresses being also investigated. The validation exercise carried out using the experimental results have demonstrated that the MWCM applied in terms of nominal stresses, notch stresses, and also the Point Method is accurate in predicting the fatigue lifetime of the tested FS welded joints, with its use resulting in life estimates that fall within the uniaxial and torsional calibration scatter bands.

  1. Multiaxial fatigue of aluminium friction stir welded joints: preliminary results

    Directory of Open Access Journals (Sweden)

    D. G. Hattingh

    2015-07-01

    Full Text Available The aim of the present research is to check the accuracy of the Modified Wöhler Curve Method (MWCM in estimating the fatigue strength of friction stir (FS welded tubular joints of Al 6082-T6 subjected to in-phase and out-of-phase multiaxial fatigue loading. The welded samples being investigated were manufactured by equipping an MTS I-STIR process development system with a retracting tool that was specifically designed and optimised for this purpose. These specimens were tested under proportional and non-proportional tension and torsion, the effect of non-zero mean stresses being also investigated. The validation exercise carried out by using the generated experimental results allowed us to prove that the MWCM (applied in terms of nominal stresses is highly accurate in predicting the fatigue strength of the tested FS welded joints, its usage resulting in estimates falling with the uniaxial and torsional calibration scatter bands.

  2. Relaxation cracking in austenitic welded joints: an underestimated problem

    NARCIS (Netherlands)

    Wortel, J.C. van

    1995-01-01

    In both power generation and chemical process industries austenitic materials, including 800H, 321H and 316H, are often used at temperatures between 500 and 700 degrees Celsius. The critical pressure containment components typically contain circumferential and longitudinal welded joints of varying

  3. Comparison of Tensile Damage Evolution in Ti6A14V Joints Between Laser Beam Welding and Gas Tungsten Arc Welding

    Science.gov (United States)

    Gao, Xiao-Long; Zhang, Lin-Jie; Liu, Jing; Zhang, Jian-Xun

    2014-12-01

    The present paper studied the evolution of tensile damage in joints welded using laser beam welding (LBW) and gas tungsten arc welding (TIG) under a uniaxial tensile load. The damage evolution in the LBW joints and TIG-welded joints was studied by using digital image correlation (DIC) technology and monitoring changes in Young's modulus during tensile testing. To study the mechanism of void nucleation and growth in the LBW joints and TIG-welded joints, test specimens with various amounts of plastic deformation were analyzed using a scanning electron microscope (SEM). Compared with TIG-welded joints, LBW-welded joints have a finer microstructure and higher microhardness in the fusion zone. The SEM analysis and DIC test results indicated that the critical strain of void nucleation was greater in the LBW-welded joints than in the TIG-welded joints, while the growth rate of voids was lower in the LBW-welded joints than in the TIG-welded joints. Thus, the damage ratio in the LBW joints was lower than that in the TIG-welded joints during tensile testing. This can be due to the coarser martensitic α' and the application of TC-1 welding rods in the TIG-welded joint.

  4. Comparison of Post Weld Treatment of High Strength Steel Welded Joints in Medium Cycle Fatigue

    DEFF Research Database (Denmark)

    Pedersen, Mikkel Melters; Mouritsen, Ole Ø.; Hansen, Michael Rygaard

    2010-01-01

    the stress range can exceed the yield-strength of ordinary structural steel, especially when considering positive stress ratios (R > 0). Fatigue experiments and qualitative evaluation of the different post-weld treatments leads to the selection of TIG dressing. The process of implementing TIG dressing......This paper presents a comparison of three post-weld treatments for fatigue life improvement of welded joints. The objective is to determine the most suitable post-weld treatment for implementation in mass production of certain crane components manufactured from very high-strength steel....... The processes investigated are: burr grinding, TIG dressing and ultrasonic impact treatment. The focus of this investigation is on the so-called medium cycle area, i.e. 10 000-500 000 cycles and very high stress ranges. In this area of fatigue design, the use of very high strength steel becomes necessary, since...

  5. The analysis of spot welding joints of steel sheets with closed profile by ultrasonic method

    OpenAIRE

    Dariusz Ulbrich; Jakub Kowalczyk; Marian Jósko; Jarosław Selech

    2015-01-01

    Resistance spot welding is widely used in the fabrication of vehicle bodies and parts of their equipment. The article presents the methodology and the results of non-destructive ultrasonic testing of resistance spot welded joints of thin steel sheet with closed profile. Non-destructive test results were verified on the basis of welded joint area after destructive testing. The obtained results were used to develop an assessment technique for spot welded joints of closed profile with steel shee...

  6. Effect of Welding Processes on the Microstructure, Mechanical Properties and Residual Stresses of Plain 9Cr-1Mo Steel Weld Joints

    Science.gov (United States)

    Nagaraju, S.; Vasantharaja, P.; Brahadees, G.; Vasudevan, M.; Mahadevan, S.

    2017-12-01

    9Cr-1Mo steel designated as P9 is widely used in the construction of power plants and high-temperature applications. It is chosen for fabricating hexcan fuel subassembly wrapper components of fast breeder reactors. Arc welding processes are generally used for fabricating 9Cr-1Mo steel weld joints. A-TIG welding process is increasingly being adopted by the industries. In the present study, shielded metal arc (SMA), tungsten inert gas (TIG) and A-TIG welding processes are used for fabricating the 9Cr-1Mo steel weld joints of 10 mm thickness. Effect of the above welding processes on the microstructure evolution, mechanical properties and residual stresses of the weld joints has been studied in detail. All the three weld joints exhibited comparable strength and ductility values. 9Cr-1Mo steel weld joint fabricated by SMAW process exhibited lower impact toughness values caused by coarser grain size and inclusions. 9Cr-1Mo steel weld joint fabricated by TIG welding exhibited higher toughness due to finer grain size, while the weld joint fabricated by A-TIG welding process exhibited adequate toughness values. SMA steel weld joint exhibited compressive residual stresses in the weld metal and HAZ, while TIG and A-TIG weld joint exhibited tensile residual stresses in the weld metal and HAZ.

  7. Fatigue and Damage Tolerance of Friction Stir Welded Joints for Aerospace Applications

    NARCIS (Netherlands)

    Lemmen, H.J.K.

    2010-01-01

    Friction stir welding is a young welding process with high potential to replace riveted joints in aerospace structures like the fuselage. Friction stir welding is a robust process and capable of welding high strength aluminum alloys. Therefore it can lead to both costs and weight savings. To

  8. Virtual Welded-Joint Design Integrating Advanced Materials and Processing Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Z.; Dong, P.; Liu, S.; Babu, S.; Olson, G.; DebRoy, T.

    2005-04-15

    The primary goal of this project is to increase the fatigue life of a welded-joint by 10 times and to reduce energy use by 25% through product performance and productivity improvements using an integrated modeling approach. The fatigue strength of a welded-joint is currently the bottleneck to design high performance and lightweight welded structures using advanced materials such as high strength steels. In order to achieve high fatigue strength in a welded-joint it is necessary to manage the weld bead shape for lower stress concentration, produce preferable residual stress distribution, and obtain the desired microstructure for improved material toughness and strength. This is a systems challenge that requires the optimization of the welding process, the welding consumable, the base material, as well as the structure design. The concept of virtual welded-joint design has been proposed and established in this project. The goal of virtual welded-joint design is to develop a thorough procedure to predict the relationship of welding process, microstructure, property, residual stress, and the ultimate weld fatigue strength by a systematic modeling approach. The systematic approach combines five sub-models: weld thermal-fluid model, weld microstructure model, weld material property model, weld residual stress model, and weld fatigue model. The systematic approach is thus based on interdisciplinary applied sciences including heat transfer, computational fluid dynamics, materials science, engineering mechanics, and material fracture mechanics. The sub-models are based on existing models with further development. The results from modeling have been validated with critical experiments. The systematic modeling approach has been used to design high fatigue resistant welds considering the combined effects of weld bead geometry, residual stress, microstructure, and material property. In particular, a special welding wire has been developed in this project to introduce

  9. Mechanical Properties and Microstructure of Dissimilar Material Welded Joints

    Directory of Open Access Journals (Sweden)

    Ziewiec A.

    2014-10-01

    Full Text Available The paper presents results of the mechanical testing and the microstructure analysis of dissimilar welded joint of the R350HT steel and the high-manganese (Hadfield cast steel using Cr-Ni cast steel spacer. The simulation tests of the welded joint surface deformation were carried out. The macroscopic and microscopic investigation were made using light microscopy (LM and scanning electron microscopy (SEM. Content of the magnetic phase was measured using magnetoscope. The quantitative metallographic investigation was used for assessment of ferrite and martensite contents and X-ray diffraction phase analysis was carried out. The results showed that during cooling of the spacer after welding, the transformation of metastable austenite into martensite proceeded. In addition to work hardening, the phase transformation of austenite into martensite occurs during the process of the superficial deformation of the spacer while simulated exploitation. This leads to a substantial increase of hardness, and at the same time, causes the increase of wear resistance of the welded joints of crossovers.

  10. Mechanical characteristics of welded joints between different stainless steels grades

    Science.gov (United States)

    Topolska, S.; Łabanowski, J.

    2017-08-01

    Investigation of mechanical characteristics of welded joints is one of the most important tasks that allow determining their functional properties. Due to the very high, still rising, cost of some stainless steels it is justified, on economic grounds, welding austenitic stainless steel with steels that are corrosion-resistant like duplex ones. According to forecasts the price of corrosion resistant steels stil can increase by 26 ÷ 30%. For technical reasons welded joints require appropriate mechanical properties such as: tensile strength, bending, ductility, toughness, and resistance to aggressive media. Such joints are applied in the construction of chemical tankers, apparatus and chemical plants and power steam stations. Using the proper binder makes possible the welds directly between the elements of austenitic stainless steels and duplex ones. It causes that such joits behave satisfactorily in service in such areas like maritime constructions and steam and chemical plants. These steels have high mechanical properties such as: the yield strength, the tensile strength and the ductility as well as the resistance to general corrosion media. They are resistant to both pitting and stress corrosions. The relatively low cost of production of duplex steels, in comparison with standard austenitic steels, is inter alia, the result of a reduced amount of scarce and expensive Nickel, which is seen as a further advantage of these steels.

  11. Optimal transfer, ordering and payment policies for joint supplier-buyer inventory model with price-sensitive trapezoidal demand and net credit

    Science.gov (United States)

    Shah, Nita H.; Shah, Digeshkumar B.; Patel, Dushyantkumar G.

    2015-07-01

    This study aims at formulating an integrated supplier-buyer inventory model when market demand is variable price-sensitive trapezoidal and the supplier offers a choice between discount in unit price and permissible delay period for settling the accounts due against the purchases made. This type of trade credit is termed as 'net credit'. In this policy, if the buyer pays within offered time M1, then the buyer is entitled for a cash discount; otherwise the full account must be settled by the time M2; where M2 > M1 ⩾ 0. The goal is to determine the optimal selling price, procurement quantity, number of transfers from the supplier to the buyer and payment time to maximise the joint profit per unit time. An algorithm is worked out to obtain the optimal solution. A numerical example is given to validate the proposed model. The managerial insights based on sensitivity analysis are deduced.

  12. Ultrasonic inspection of AA6013 laser welded joints

    Directory of Open Access Journals (Sweden)

    Adriano Passini

    2011-09-01

    Full Text Available Interest in laser beam welding for aerospace applications is continuously growing, mainly for aluminum alloys. The joints quality is usually assessed by non-destructive inspection (NDI. In this work, bead on plate laser welds on 1.6 mm thick AA6013 alloy sheets, using a 2 kW Yb-fiber laser were obtained and inspected by pulse/echo ultrasonic phased-array technique. Good and poor quality welds were inspected in order to verify the limits of inspection, comparing also to X-ray radiography and metallographic inspections. The results showed that ultrasonic phased array technique was able to identify the presence of grouped porosity, through the attenuation of the amplitude of the echo signal. This attenuation is attributed to the scattering of the waves caused by micro pores, with individual size below the resolution limit of the equipment, but when grouped, can cause a perceptive effect on the reflection spectra.

  13. Characterising electron beam welded dissimilar metal joints to study residual stress relaxation from specimen extraction

    OpenAIRE

    Abburi Venkata, Kiranmayi; Truman, Christopher E; Smith, David J.; Bhaduri, Arun K

    2016-01-01

    Nuclear power plants require dissimilar metal weld joints to connect the primary steam generator made from ferritic steel to the intermediate heat exchanger made from austenitic steel. Such joints are complex because of the mismatch in the thermal and the mechanical properties of the materials used in the joint. Electron Beam (EB) welding is emerging as a promising technique to manufacture dissimilar joints providing a great many advantages over conventional welding techniques, in terms of lo...

  14. Ultrasonic Welding of Thermoplastic Composite Coupons for Mechanical Characterization of Welded Joints through Single Lap Shear Testing

    Science.gov (United States)

    Villegas, Irene F.; Palardy, Genevieve

    2016-01-01

    This paper presents a novel straightforward method for ultrasonic welding of thermoplastic-composite coupons in optimum processing conditions. The ultrasonic welding process described in this paper is based on three main pillars. Firstly, flat energy directors are used for preferential heat generation at the joining interface during the welding process. A flat energy director is a neat thermoplastic resin film that is placed between the parts to be joined prior to the welding process and heats up preferentially owing to its lower compressive stiffness relative to the composite substrates. Consequently, flat energy directors provide a simple solution that does not require molding of resin protrusions on the surfaces of the composite substrates, as opposed to ultrasonic welding of unreinforced plastics. Secondly, the process data provided by the ultrasonic welder is used to rapidly define the optimum welding parameters for any thermoplastic composite material combination. Thirdly, displacement control is used in the welding process to ensure consistent quality of the welded joints. According to this method, thermoplastic-composite flat coupons are individually welded in a single lap configuration. Mechanical testing of the welded coupons allows determining the apparent lap shear strength of the joints, which is one of the properties most commonly used to quantify the strength of thermoplastic composite welded joints. PMID:26890931

  15. Ultrasonic Welding of Thermoplastic Composite Coupons for Mechanical Characterization of Welded Joints through Single Lap Shear Testing.

    Science.gov (United States)

    Villegas, Irene F; Palardy, Genevieve

    2016-02-11

    This paper presents a novel straightforward method for ultrasonic welding of thermoplastic-composite coupons in optimum processing conditions. The ultrasonic welding process described in this paper is based on three main pillars. Firstly, flat energy directors are used for preferential heat generation at the joining interface during the welding process. A flat energy director is a neat thermoplastic resin film that is placed between the parts to be joined prior to the welding process and heats up preferentially owing to its lower compressive stiffness relative to the composite substrates. Consequently, flat energy directors provide a simple solution that does not require molding of resin protrusions on the surfaces of the composite substrates, as opposed to ultrasonic welding of unreinforced plastics. Secondly, the process data provided by the ultrasonic welder is used to rapidly define the optimum welding parameters for any thermoplastic composite material combination. Thirdly, displacement control is used in the welding process to ensure consistent quality of the welded joints. According to this method, thermoplastic-composite flat coupons are individually welded in a single lap configuration. Mechanical testing of the welded coupons allows determining the apparent lap shear strength of the joints, which is one of the properties most commonly used to quantify the strength of thermoplastic composite welded joints.

  16. Numerical modeling of welded joints by the "Friction Stir Welding" process

    Directory of Open Access Journals (Sweden)

    Diego H. Santiago

    2004-12-01

    Full Text Available The present work is aimed to simulate the Friction Stir Welding process as a three-dimensional thermally coupled viscoplastic flow. A Finite Element technique is employed, within the context of a general purpose FEM framework, to provide the temperature distributions and the patterns of plastic flow for the material involved in the welded joints. The computational tool presented here may be of great relevance for technologist seeking to set the process control variables, as they are intended to obtain suitable material properties that yield the adequate on service response of the structural components.

  17. Microstructure and Failure Analysis of Flash Butt Welded HSLA 590CL Steel Joints in Wheel Rims

    Science.gov (United States)

    Lu, Ping; Xu, Zhixin; Shu, Yang; Ma, Feng

    2017-02-01

    The aim of the present investigation was to evaluate the microstructures, mechanical properties and failure behavior of flash butt welded high strength low alloy 590CL steel joints. Acicular ferrite, Widmanstatten ferrite and granular bainite were observed in the weld. The micro-hardness values of the welded joints varied between 250 HV and 310 HV. The tensile strength of the welded joints met the strength standard of the wheel steel. The Charpy V-notch impact absorbing energy of the welded joints was higher than the base metal, and the impact fracture of the welded joints was composed of shearing and equiaxed dimples. The fracture mode of the wheel rim in the flaring and expanding process was brittle fracture and ductile fracture, respectively. A limited deviation was found in the terminal of the crack for the wheel in the flaring process. A transition from the weld to the Heat Affected Zone was observed for the wheel in the expanding process.

  18. Microstructures and mechanical properties of friction stir welded dissimilar steel-copper joints

    Energy Technology Data Exchange (ETDEWEB)

    Jafari, M.; Abbasi, M.; Poursina, D.; Gheysarian, A. [University of Kashan, Kashan (Iran, Islamic Republic of); Bagheri, B. [Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

    2017-03-15

    Welding dissimilar metals by fusion welding is challenging. It results in welding defects. Friction stir welding (FSW) as a solid-state joining method can overcome these problems. In this study, 304L stainless steel was joined to copper by FSW. The optimal values of the welding parameters traverse speed, rotational speed, and tilt angle were obtained through Response surface methodology (RSM). Under optimal welding conditions, the effects of welding pass number on the microstructures and mechanical properties of the welded joints were investigated. Results indicated that appropriate values of FSW parameters could be obtained by RSM and grain size refinement during FSW mainly affected the hardness in the weld regions. Furthermore, the heat from the FSW tool increased the grain size in the Heat-affected zones (HAZs), especially on the copper side. Therefore, the strength and ductility decreased as the welding pass number increased because of grain size enhancement in the HAZs as the welding pass number increased.

  19. Material test data of SUS304 welded joints

    Energy Technology Data Exchange (ETDEWEB)

    Asayama, Tai [Japan Nuclear Cycle Development Inst., Oarai, Ibaraki (Japan). Oarai Engineering Center; Kawakami, Tomohiro [Nuclear Energy System Incorporation, Tokyo (Japan)

    1999-10-01

    This report summarizes the material test data of SUS304 welded joints. Numbers of the data are as follows: Tensile tests 71 (Post-irradiation: 39, Others: 32), Creep tests 77 (Post-irradiation: 20, Others: 57), Fatigue tests 50 (Post-irradiation: 0), Creep-fatigue tests 14 (Post-irradiation: 0). This report consists of the printouts from 'the structural material data processing system'. (author)

  20. Structural and mechanical properties of welded joints of reduced activation martensitic steels

    Energy Technology Data Exchange (ETDEWEB)

    Filacchioni, G. E-mail: gianni.filacchioni@casaccia.enea.it; Montanari, R.; Tata, M.E.; Pilloni, L

    2002-12-01

    Gas tungsten arc welding and electron beam welding methods were used to realise welding pools on plates of reduced activation martensitic steels. Structural and mechanical features of these simulated joints have been investigated in as-welded and post-welding heat-treated conditions. The research allowed to assess how each welding technique affects the original mechanical properties of materials and to find suitable post-welding heat treatments. This paper reports results from experimental activities on BATMAN II and F82H mod. steels carried out in the frame of the European Blanket Project - Structural Materials Program.

  1. The Analysis of Welding Conditions Under the Flux of Double-Sides Joints Without Edge Preparation

    Science.gov (United States)

    Sidorov, Vladimir P.

    2017-10-01

    This paper represents the results of analysis for automatic welding conditions under the flux of double-sides butt joint without edge preparation. As the process characteristics, a specific energy of welding, joint formation rate, average weld width, fusion rate of base metal and other parameters were used. It is determined an optimal joint rate of about 1 cm2/s, that can be used to calculate welding conditions. The paper founds the use of linear dependence between specific energy of welding and cross-section area of base metal’s fusion.

  2. The influence of manual metal arc multiple repair welding of long operated waterwall on the structure and hardness of the heat affected zone of welded joints

    Directory of Open Access Journals (Sweden)

    Pikuła J.

    2017-03-01

    Full Text Available Welded installations failures of power plants, which are often result from a high degree of wear, requires suitable repairs. In the case of cracks formed in the weld bead of waterwall, weld bead is removed and new welded joint is prepared. However, it is associated with consecutive thermal cycles, which affect properties of heat affected zone of welded joint. This study presents the influence of multiple manual metal arc welding associated with repair activities of long operated waterwall of boiler steel on properties of repair welded joints. The work contains the results of macro and microscopic metallographic examination as well as the results of hardness measurements.

  3. Fatigue Properties of Welded Butt Joint and Base Metal of MB8 Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    Ying-xia YU

    2016-09-01

    Full Text Available The fatigue properties of welded butt joint and base metal of MB8 magnesium alloy were investigated. The comparative fatigue tests were carried out using EHF-EM200K2-070-1A fatigue testing machine for both welded butt joint and base metal specimens with the same size and shape. The fatigue fractures were observed and analyzed by a scanning electron microscope of 6360 LA type. The experimental results show that the fatigue performance of the welded butt joint of MB8 magnesium alloy is sharply decreased. The conditional fatigue limit (1×107 of base metal and welded butt joint is about 69.41 and 32.76 MPa, respectively. The conditional fatigue limit (1×107 of the welded butt joint is 47.2 % of that of base metal. The main reasons are that the welding can lead to stress concentration in the weld toe area, tensile welding residual stress in the welded joint, as well as grain coarsening in the welding seam. The cleavage steps or quasi-cleavage patterns present on the fatigue fracture surface, indicating the fracture type of the welded butt joint belongs to a brittle fracture.DOI: http://dx.doi.org/10.5755/j01.ms.22.3.9132

  4. Verification of Strength of the Welded Joints by using of the Aramis Video System

    Directory of Open Access Journals (Sweden)

    Pała Tadeusz

    2017-03-01

    Full Text Available In the paper are presented the results of strength analysis for the two types of the welded joints made according to conventional and laser technologies of high-strength steel S960QC. The hardness distributions, tensile properties and fracture toughness were determined for the weld material and heat affect zone material for both types of the welded joints. Tests results shown on advantage the laser welded joints in comparison to the convention ones. Tensile properties and fracture toughness in all areas of the laser joints have a higher level than in the conventional one. The heat affect zone of the conventional welded joints is a weakness area, where the tensile properties are lower in comparison to the base material. Verification of the tensile tests, which carried out by using the Aramis video system, confirmed this assumption. The highest level of strains was observed in HAZ material and the destruction process occurred also in HAZ of the conventional welded joint.

  5. Fabrication of niobium superconducting accelerator cavity by electron beam welded joints

    Science.gov (United States)

    Saha, T. K.; Mondal, J.; Mittal, K. C.; Bhushan, K. G.; Bapat, A. V.

    2012-11-01

    Fabrication of superconducting cavities has been taken up as a part of the development of accelerator driven sub critical system (ADSS) by Bhabha Atomic Research Centre. Large grain (RRR>99) pure niobium was chosen as the material for the cavity. Niobium,for its application as superconductor requires extremely high quality joints, feasible only by electron beam welding at high vacuum environment. An indigenously developed 100kV, 4kW high vacuum electron beam welding machine has been utilized to carry out the welding operations. Planning of the weld sequences was chalked out. Holding fixtures for the cavity, consists of seven numbers of joints have been fabricated beforehand. A few coupons were welded for optimization of the weld parameters and for inspection of the weld purity by indigenously developed secondary ion mass spectroscopy. The report describes the welding equipment and the stage wise joining operations of the cavity in details and also discusses the qualification testing of the welded cavity.

  6. The investigation of ultrasonic mechanical forging influence on the structure and mechanical properties of VT23 welded joints by methods of laser and electron beam welding

    Science.gov (United States)

    Smirnova, A. S.; Pochivalov, Yu. I.; Panin, V. E.; Orishich, A. M.; Malikov, A. G.; Fomin, V. M.

    2016-11-01

    The structure and mechanical properties of welded joints of VT23 titanium alloy received by methods of laser and electron beam welding with subsequent thermomechanical treatment (TMP1 and TMP2) including ultrasonic mechanical forging are investigated. X-ray structure analysis, scanning electron and transmission electron microscopy have revealed the features of phase structure, microstructure and fractography of welded joints after electron beam and laser welding with subsequent ultrasonic mechanical forging. Application of ultrasonic mechanical forging of welded joints produced by electron beam and laser welding has allowed increasing fatigue life of samples of welded joints after laser welding from 6369 to 19 569 cycles and from 54 616 cycles to 77 126 cycles for electron beam welding. Thus, the application of ultrasonic mechanical forging can significantly raise fatigue and mechanical characteristics of welded connections.

  7. MICROSTRUCTURE AND FATIGUE PROPERTIES OF DISSIMILAR SPOT WELDED JOINTS OF AISI 304 AND AISI 1008

    Directory of Open Access Journals (Sweden)

    Nachimani Charde

    2013-06-01

    Full Text Available Carbon steel and stainless steel composites are being more frequently used for applications requiring a corrosion resistant and attractive exterior surface and a high strength structural substrate. Spot welding is a potentially useful and efficient jointing process for the production of components consisting of these two materials. The spot welding characteristics of weld joints between these two materials are discussed in this paper. The experiment was conducted on dissimilar weld joints using carbon steel and 304L (2B austenitic stainless steel by varying the welding currents and electrode pressing forces. Throughout the welding process; the electrical signals from the strain sensor, current transducer and terminal voltage clippers are measured in order to understand each and every millisecond of the welding process. In doing so, the dynamic resistances, heat distributions and forging forces are computed for various currents and force levels within the good welds’ regions. The other process controlling parameters, particularly the electrode tip and weld time, remained constant throughout the experiment. The weld growth was noted for the welding current increment, but in the electrode force increment it causes an adverse reaction to weld growth. Moreover, the effect of heat imbalance was clearly noted during the welding process due to the different electrical and chemical properties. The welded specimens finally underwent tensile, hardness and metallurgical testing to characterise the weld growth.

  8. Investigation on edge joints of Inconel 625 sheets processed with laser welding

    Science.gov (United States)

    Caiazzo, F.; Alfieri, V.; Cardaropoli, F.; Sergi, V.

    2017-08-01

    Laser welding of Inconel 625 edge joint beads in square groove configuration was investigated. The use of different weld geometries in new aerospace solutions explains research on edge joints. A structured plan was carried out in order to characterize the process defining the influence of laser power and welding speed and to study possible interactions among the governing factors. As weld pool protection is crucial in order to obtain sound joints when processing superalloys, a special glove box for gas supply was designed to upgrade the welding head. Welded joints were characterized referring to bead profile, microstructure and X-rays. It was found that heat input plays an important role as it affects welding stability, porosity content and bead shape. Results suggest operating with low values of heat input to reduce porosity and guarantee stable bead conformation. Furthermore, a decrease in the grain size has been observed as a consequence of decreasing heat input.

  9. Evaluation of cold crack susceptibility on HSLA steel welded joints

    Directory of Open Access Journals (Sweden)

    Silverio-Freire Júnior, R. C.

    2003-04-01

    Full Text Available The present study addresses an evaluation of the effect of several welding parameters on cold cracking formation in welded joints of High Strength and Low Alloy steels, as well as the resulting microstructures and hardness values. The main parameters studied include the variation of the preheating temperature, drying time of the electrode, chemical composition and thickness of the base metal. The presence of cold cracking in the joints was analyzed from Tekken tests using steel plates made of SAR 80 T, 100 T and 120 T with of various thickness. The plates were welded by Shielded Metal Arc Welding either with or without pre-heating. Different preheating temperatures were studied, i.e., 375, 455 and 525 K. AWS E 12018 G and 11018 G electrodes were used under different conditions, i.e., not dried or dried up to 2, 3 and 4 h at 515 K. The results indicated the presence of cracks in the welded metals with the combination of hardness values above 230 HV and the formation of high contents of acicular ferrite (above 93 % in the welds without preheating. Higher crack susceptibility was also observed in the thick welded metal plates.

    Este trabajo evalúa la influencia de la variación de temperatura de precalentamiento, del tiempo de secado del electrodo, de la composición química y del espesor del metal base sobre la formación de fisuras en frío, inducidas por el hidrógeno en juntas soldadas de aceros de alta resistencia y baja aleación y su relación con la microestructura y dureza resultante. Para esto, se analizó la presencia de fisuras en frío en probetas para ensayos Tekken, fabricadas a partir de chapas de aceros SAR 80 T, 100 T y 120 T, con diferentes espesores y soldados por proceso de arco eléctrico con electrodo revestido, sin precalentamiento y con precalentamiento, a 375, 455 y 525 K, empleando electrodos AWS E 12018 G y 11018 G no secados y secados durante 2, 3 y 4 h. Los resultados obtenidos indicaron la presencia de fisuras

  10. The analysis of spot welding joints of steel sheets with closed profile by ultrasonic method

    Directory of Open Access Journals (Sweden)

    Dariusz Ulbrich

    2015-11-01

    Full Text Available Resistance spot welding is widely used in the fabrication of vehicle bodies and parts of their equipment. The article presents the methodology and the results of non-destructive ultrasonic testing of resistance spot welded joints of thin steel sheet with closed profile. Non-destructive test results were verified on the basis of welded joint area after destructive testing. The obtained results were used to develop an assessment technique for spot welded joints of closed profile with steel sheet, which could be used in factories employing such joints. In addition, the article makes comparison between the costs of the developed assessment technique and currently used destructive method.

  11. A Study of Microstructure and Mechanical Properties of Grade 91 Steel A-TIG Weld Joint

    Science.gov (United States)

    Arivazhagan, B.; Vasudevan, M.

    2013-12-01

    In the present study, A-TIG welding was carried out on grade 91 steel plates of size 220 × 110 × 10 mm using the in-house developed activated flux to produce butt-joints. The room-temperature impact toughness of the A-TIG as-welded joint was low due to the presence of untempered martensite matrix despite the low microinclusion density caused by activated flux and also low δ-ferrite (TIG-processed grade 91 steel weld joint was found to meet the toughness requirements after PWHT at 760 °C-3 h. Observations of fracture surfaces using SEM revealed that the as-welded joint failed by brittle fracture, whereas post-weld heat-treated weld joints failed by decohesive rupture mode.

  12. Gas metal arc welding of butt joint with varying gap width based on neural networks

    DEFF Research Database (Denmark)

    Christensen, Kim Hardam; Sørensen, Torben

    2005-01-01

    This paper describes the application of the neural network technology for gas metal arc welding (GMAW) control. A system has been developed for modeling and online adjustment of welding parameters, appropriate to guarantee a certain degree of quality in the field of butt joint welding with full...

  13. Mechanical Properties of Steel P92 Welded Joints Obtained By TIG Technology

    Science.gov (United States)

    Mohyla, P.; Havelka, L.; Schmidová, E.; Vontorová, J.

    2017-11-01

    Mechanical properties of P92 steel welded joints obtained using the TIG (141) technology have been studied upon post-welding heat treatment (PWHT). The microhardness, tensile strength, and impact toughness of metal in the weld and heat-affected zone are determined. The PWHT is shown to be obligatory.

  14. Electric pulse treatment of welded joint of aluminum alloy

    Directory of Open Access Journals (Sweden)

    A.A. Mitiaev

    2013-08-01

    Full Text Available Purpose. Explanation of the redistribution effect of residual strengthes after electric pulse treatment of ark welding seam of the aluminum alloy. Methodology. Alloy on the basis of aluminium of АК8М3 type served as the research material. As a result of mechanical treatment of the ingots after alloy crystallization the plates with 10 mm thickness were obtained. After edge preparation the elements, which are being connected were butt welded using the technology of semiautomatic argon arc welding by the electrode with a diameter of 3 mm of AK-5 alloy. Metal structure of the welded joint was examined under the light microscope at a magnification of 200 and under the scanning electronic microscope «JSM-6360 LA». The Rockwell hardness (HRF was used as a strength characteristic of alloy. Hardness measuring of the phase constituents (microhardness was carried out using the device PМТ-3, with the indenter loadings 5 and 10 g. The crystalline structure parameters of alloy (dislocation density, second kind of the crystalline grid distortion and the scale of coherent scattering regions were determined using the methods of X-ray structural analysis. Electric pulse treatment (ET was carried out on the special equipment in the conditions of the DS enterprise using two modes A and В. Findings. On the basis of researches the previously obtained microhardness redistribution effect in the area of welded connection after ET was confirmed. As a result of use of the indicated treatment it was determined not only the reduction of microhardness gradient but also the simultaneous hardening effect in the certain thermal affected areas near the welding seam. During study of chemical composition of phase constituents it was discovered, that the structural changes of alloy as a result of ET first of all are caused by the redistribution of chemical elements, which form the connections themselves. By the nature of the influence the indicated treatment can be

  15. Effect of welding speed on microstructural evolution and mechanical properties of laser welded-brazed Al/brass dissimilar joints

    Science.gov (United States)

    Zhou, L.; Luo, L. Y.; Tan, C. W.; Li, Z. Y.; Song, X. G.; Zhao, H. Y.; Huang, Y. X.; Feng, J. C.

    2018-01-01

    Laser welding-brazing process was developed for joining 5052 aluminum alloy and H62 brass in butt configuration with Zn-15%Al filler. Effect of welding speed on microstructural characteristics and mechanical properties of joints were investigated. Acceptable joints without obvious defect were obtained with the welding speed of 0.5-0.6 m/min, while lower and higher welding speed caused excessive back reinforcement and cracking, respectively. Three reaction layers were observed at welding speed of 0.3 m/min, which were Al4.2Cu3.2Zn0.7 (τ‧)/Al4Cu9/CuZn from weld seam side to brass side; while at welding speed of 0.4-0.6 m/min, two layers Al4.2Cu3.2Zn0.7 and CuZn formed. The thickness of interfacial reaction layers increased with the decrease of welding speed, but varied little at different interfacial positions from top to bottom in one joint. Tensile test results indicated that the maximum joint tensile strength of 128 MPa was obtained at 0.5 m/min, which was 55.7% of that of Al base metal. All the joints fractured along the weld seam/brass interface. Some differences were found regarding fracture locations with three and two reaction layers. The joint fractured between Al4Cu9 and τ‧ IMC layer when the interface had three layers, while the crack occurred between CuZn and τ‧ phase in the case of two layers.

  16. Testing of the shopprimer’s influence on the quality of welded joint

    Directory of Open Access Journals (Sweden)

    T. Šolić

    2017-01-01

    Full Text Available This paper presents the process of preparing the surface of construction material and applying the temporary protection that refers to the two-component epoxy workshop primer (shopprimer in order to perform testing of its influence on mechanical properties of the weld. Testing of mechanical properties of welds after welding proved that there were no negative influences of the protective coating on the quality of welded joint.

  17. High-cycle Fatigue Properties of Alloy718 Base Metal and Electron Beam Welded Joint

    Science.gov (United States)

    Ono, Yoshinori; Yuri, Tetsumi; Nagashima, Nobuo; Sumiyoshi, Hideshi; Ogata, Toshio; Nagao, Naoki

    High-cycle fatigue properties of Alloy 718 plate and its electron beam (EB) welded joint were investigated at 293 K and 77 K under uniaxial loading. At 293 K, the high-cycle fatigue strength of the EB welded joint with the post heat treatment exhibited somewhat lower values than that of the base metal. The fatigue strengths of both samples basically increased at 77 K. However, in longer life region, the EB welded joint fractured from a blow hole formed in the welded zone, resulting in almost the same fatigue strength at 107 cycles as that at 293 K.

  18. Butt Welding of 2205/X65 Bimetallic Sheet and Study on the Inhomogeneity of the Properties of the Welded Joint

    Science.gov (United States)

    Gou, Ning-Nian; Zhang, Jian-Xun; Wang, Jian-Long; Bi, Zong-Yue

    2017-04-01

    The explosively welded 2205 duplex stainless steel/X65 pipe steel bimetallic sheets were butt jointed by multilayer and multi-pass welding (gas tungsten arc welding for the flyer and gas metal arc welding for the transition and parent layers of the bimetallic sheets). The microstructure and mechanical properties of the welded joint were investigated. The results showed that in the thickness direction, microstructure and mechanical properties of the welded joint exhibited obvious inhomogeneity. The microstructures of parent filler layers consisted of acicular ferrite, widmanstatten ferrite, and a small amount of blocky ferrite. The microstructure of the transition layer and flyer layer consisted of both austenite and ferrite structures; however, the transition layer of weld had a higher volume fraction of austenite. The results of the microhardness test showed that in both weld metal (WM) and heat-affected zone (HAZ) of the parent filler layers, the average hardness decreased with the increasing (from parent filler layer 1 to parent filler layer 3) welding heat input. The results of hardness test also indicated that the hardness of the WM and the HAZ for the flyer and transition layers was equivalent. The tensile test combined with Digital Specklegram Processing Technology demonstrated that the fracturing of the welded joint started at the HAZ of the flyer, and then the fracture grew toward the base metal of the parent flyer near the parent HAZ. The stratified impact test at -5 °C showed that the WM and HAZ of the flyer exhibited lower impact toughness, and the fracture mode was ductile and brittle mixed fracture.

  19. Application of welding simulation to block joints in shipbuilding and assessment of welding-induced residual stresses and distortions

    Directory of Open Access Journals (Sweden)

    Fricke Wolfgang

    2014-06-01

    Full Text Available During ship design, welding-induced distortions are roughly estimated as a function of the size of the component as well as the welding process and residual stresses are assumed to be locally in the range of the yield stress. Existing welding simulation methods are very complex and time-consuming and therefore not applicable to large structures like ships. Simplified methods for the estimation of welding effects were and still are subject of several research projects, but mostly concerning smaller structures. The main goal of this paper is the application of a multi-layer welding simulation to the block joint of a ship structure. When welding block joints, high constraints occur due to the ship structure which are assumed to result in accordingly high residual stresses. Constraints measured during construction were realized in a test plant for small-scale welding specimens in order to investigate their and other effects on the residual stresses. Associated welding simulations were successfully performed with fine-mesh finite element models. Further analyses showed that a courser mesh was also able to reproduce the welding-induced reaction forces and hence the residual stresses after some calibration. Based on the coarse modeling it was possible to perform the welding simulation at a block joint in order to investigate the influence of the resulting residual stresses on the behavior of the real structure, showing quite interesting stress distributions. Finally it is discussed whether smaller and idealized models of definite areas of the block joint can be used to achieve the same results offering possibilities to consider residual stresses in the design process.

  20. Application of welding simulation to block joints in shipbuilding and assessment of welding-induced residual stresses and distortions

    Science.gov (United States)

    Fricke, Wolfgang; Zacke, Sonja

    2014-06-01

    During ship design, welding-induced distortions are roughly estimated as a function of the size of the component as well as the welding process and residual stresses are assumed to be locally in the range of the yield stress. Existing welding simulation methods are very complex and time-consuming and therefore not applicable to large structures like ships. Simplified methods for the estimation of welding effects were and still are subject of several research projects, but mostly concerning smaller structures. The main goal of this paper is the application of a multi-layer welding simulation to the block joint of a ship structure. When welding block joints, high constraints occur due to the ship structure which are assumed to result in accordingly high residual stresses. Constraints measured during construction were realized in a test plant for small-scale welding specimens in order to investigate their and other effects on the residual stresses. Associated welding simulations were successfully performed with fine-mesh finite element models. Further analyses showed that a courser mesh was also able to reproduce the welding-induced reaction forces and hence the residual stresses after some calibration. Based on the coarse modeling it was possible to perform the welding simulation at a block joint in order to investigate the influence of the resulting residual stresses on the behavior of the real structure, showing quite interesting stress distributions. Finally it is discussed whether smaller and idealized models of definite areas of the block joint can be used to achieve the same results offering possibilities to consider residual stresses in the design process.

  1. Fatigue properties and fracture mechanism of load carrying type fillet joints with one-sided welding

    OpenAIRE

    Takamasa Abe; Hiroyuki Akebono; Masahiko Kato; Atsushi Sugeta

    2016-01-01

    The structures of the hydraulic excavator and the crane have numerous one-sided welded joints. However, attachments with box like structures are difficult to weld at both sides. Therefore, high accurate evaluation method is needed. In this study, the fatigue properties and the fracture mechanism of the load carrying type fillet joints with one-sided welding were investigated experimentally to evaluate its fatigue damage with high accuracy based on the experimental results. As the ...

  2. Methodologies for Crack Initiation in Welded Joints Applied to Inspection Planning

    OpenAIRE

    Zou, Guang; Banisoleiman, Kian; González, Arturo

    2016-01-01

    Crack initiation and propagation threatens structural integrity of welded joints and normally inspections are assigned based on crack propagation models. However, the approach based on crack propagation models may not be applicable for some high-quality welded joints, because the initial flaws in them may be so small that it may take long time for the flaws to develop into a detectable size. This raises a concern regarding the inspection planning of high-quality welded joins, as there is no g...

  3. Structure and Corrosion Resistance of Welded Joints of Alloy 1151 in Marine Atmosphere

    Science.gov (United States)

    Bakulo, A. V.; Yakushin, B. F.; Puchkov, Yu. A.

    2017-07-01

    The corrosion behavior of joints formed by TIG and IMIG welding from clad sheets of heat-hardenable aluminum alloy 1151 of the Al - Cu - Mg system is studied. The corrosion tests are performed in an aqueous solution of NaCl in a salt-spray chamber. The welded joints are subjected to a metallographic analysis.

  4. Mechanical properties of TIG and EB weld joints of F82H

    Energy Technology Data Exchange (ETDEWEB)

    Hirose, Takanori, E-mail: hirose.takanori@jaea.go.jp; Sakasegawa, Hideo; Nakajima, Motoki; Tanigawa, Hiroyasu

    2015-10-15

    Highlights: • Narrow groove TIG minimized volume of F82H weld. • Mechanical properties of TIG and EB welds of F82H have been characterized. • Post weld heat treatment successfully moderate the toughness of weld metal without softening the base metal. - Abstract: This work investigates mechanical properties of weld joints of a reduced activation ferritic/martensitic steel, F82H and effects of post weld heat treatment on the welds. Vickers hardness, tensile and Charpy impact tests were conducted on F82H weld joints prepared using tungsten-inert-gas and electron beam after various heat treatments. Although narrow groove tungsten-inert-gas welding reduced volume of weld bead, significant embrittlement was observed in a heat affected zone transformed due to heat input. Post weld heat treatment above 993 K successfully moderated the brittle transformed region. The hardness of the brittle region strongly depends on the heat treatment temperature. Meanwhile, strength of base metal was slightly reduced by the treatment at temperature ranging from 993 to 1053 K. Moreover, softening due to double welding was observed only in the weld metal, but negligible in base metal.

  5. Effect of the rotational speed of on the surface quality of 6061 Al-alloy welded joint using friction stir welding

    Science.gov (United States)

    Feng, T. T.; Zhang, X. H.; Fan, G. J.; Xu, L. F.

    2017-06-01

    The rotational speed of the stir-welding head is an important technological parameter in friction stir welding (FSW) process. For investigating the effect of the rotational speed of the stir-welding head on the surface quality of the welded joint, in this study, the weld tests were conducted under different rotational speeds (in which the welding speed was fixed), and then the effects were analyzed using the heat-fluid analysis model established. The test results revealed that cracks or grooves could be observed on the welded joint at small rotational speeds; with the increase of rotational speed, the weld surface became bright and clean; as the rotational speed further increased, the surface of the welded joint may be over burnt. Through analysis, it can be observed that appropriate increasing the rotational speed of the stir-welding joint increased the heat input in welding; meanwhile, fewer materials participated in the formation of weld, the material’s flowability was improved, and the resistance that impeded the advance of the stir-welding needle was reduced, thereby improving the quality of the welded joint.

  6. Effect of Multipass TIG and Activated TIG Welding Process on the Thermo-Mechanical Behavior of 316LN Stainless Steel Weld Joints

    Science.gov (United States)

    Ganesh, K. C.; Balasubramanian, K. R.; Vasudevan, M.; Vasantharaja, P.; Chandrasekhar, N.

    2016-04-01

    The primary objective of this work was to develop a finite element model to predict the thermo-mechanical behavior of an activated tungsten inert gas (ATIG)-welded joint. The ATIG-welded joint was fabricated using 10 mm thickness of 316LN stainless steel plates in a single pass. To distinguish the merits of ATIG welding process, it was compared with manual multipass tungsten inert gas (MPTIG)-welded joint. The ATIG-welded joint was fabricated with square butt edge configuration using an activating flux developed in-house. The MPTIG-welded joint was fabricated in thirteen passes with V-groove edge configuration. The finite element model was developed to predict the transient temperature, residual stress, and distortion of the welded joints. Also, microhardness, impact toughness, tensile strength, ferrite measurement, and microstructure were characterized. Since most of the recent publications of ATIG-welded joint was focused on the molten weld pool dynamics, this research work gives an insight on the thermo-mechanical behavior of ATIG-welded joint over MPTIG-welded joint.

  7. Mechanical properties of type 316L stainless steel welded joint for ITER vacuum vessel (1). Experiment of unirradiated welded joint

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Shigeru; Fukaya, Kiyoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Ishiyama, Shintaro [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment; Takahashi, Hiroyuki; Koizumi, Kouichi [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

    2001-01-01

    In design activity of ITER, the vacuum vessel (VV) is ranked as one of the most important components in core reactor from the view point of first barrier to tritium release from the reactor. The VV of ITER is designed as double walled structure so that some parts of them are not qualified in the conventional design standards. So it is necessary to prepare the new design standards to be applied them. JAERI has executed the preparation activity of the new design standards and the technical data to support them. In this study, the results of metallographic observation and mechanical properties of unirradiated type 316L stainless steel welded joint were reported. (author)

  8. Research on the microstructure and properties of laser-MIG hybrid welded joint of Invar alloy

    Science.gov (United States)

    Zhan, Xiaohong; Zhang, Dan; Wei, Yanhong; Wang, Yuhua

    2017-12-01

    In order to solve the problem of large deformation, low production efficiency and high tendency of hot cracking in welding 19.05 mm thick plates of Fe36Ni Invar alloy, laser-MIG hybrid multi-layer welding technique (LMHMW) has been developed. To investigate the influence of different welding parameters on the joint properties, optical microscope observation, SEM, EDS and microhardness measurement were conducted. Experimental results illustrated that different matching of welding parameters significantly affected the depth-to-width ratio, formation of defects and HAZ width. Besides, weld zone were consisted of two regions according to the different grain shape. The region near center of weld seam (region 1) was columnar dendrite induced by laser, while the region far away from weld seam center (region 2) was cellular dendrite which was mainly caused by MIG arc. The peak value of microhardness appeared at the center of weld seam since the grains in region 1 were relatively fine, and the lowest hardness value was obtained in HAZ. In addition, results showed that the sheets can be welded at optimum process parameters, with few defects such as, surface oxidation, porosity, cracks and lack of penetration in the welding seam: laser power of backing weld P = 5500 W, welding current I = 240 A, welding speed v = 1 m/min. laser power of filling weld P = 2000 W, welding current I = 220 A, welding speed v = 0.35 m/min. laser power of cosmetic weld P = 2000 W, welding current I = 300 A, welding speed v = 0.35 m/min.

  9. Wear Resistance Analysis of A359/SiC/20p Advanced Composite Joints Welded by Friction Stir Welding

    Directory of Open Access Journals (Sweden)

    O. Cuevas Mata

    Full Text Available Abstract Advancement in automotive part development demands new cost-effective materials with higher mechanical properties and improved wear resistance as compared to existing materials. For instance, Aluminum Matrix Composites (AMC shows improved mechanical properties as wear and abrasion resistance, high strength, chemical and dimensional stability. Automotive industry has focused in AMC for a variety of applications in automotive parts in order to improve the fuel economy, minimize vehicle emissions, improve design options, and increase the performance. Wear resistance is one of the most important factors in useful life of the automotive components, overall in those components submitted to mechanical systems like automotive brakes and suspensions. Friction Stir Welding (FSW rises as the most capable process to joining AMC, principally for the capacity to weld without compromising their ceramic reinforcement. The aim of this study is focused on the analysis of wear characteristics of the friction-stir welded joint of aluminum matrix reinforced with 20 percent in weight silicon carbide composite (A359/SiC/20p. The experimental procedure consisted in cut samples into small plates and perform three welds on these with a FSW machine using a tool with 20 mm shoulder diameter and 8 mm pin diameter. The wear features of the three welded joints and parent metal were analyzed at constant load applying 5 N and a rotational speed of 100 rpm employing a Pin-on - Disk wear testing apparatus, using a sapphire steel ball with 6 mm diameter. The experimental results indicate that the three welded joints had low friction coefficient compared with the parent metal. The results determine that the FSW process parameters affect the wear resistance of the welded joints owing to different microstructural modifications during welding that causes a low wear resistance on the welded zone.

  10. Microstructural changes in welded joints of 316 SS by dual-ion irradiation

    Science.gov (United States)

    Kohyama, A.; Kohno, Y.; Baba, K.; Katoh, Y.; Hishinuma, A.

    1992-09-01

    As a part of the activity to establish joining methods to fabricate in-vessel components and to evaluate their performance under fusion environment, microstructural evolution was studied by means of the dual-ion irradiation method. The base material used in this study was solution annealed 316 stainless steel. Welded joints were made by the tungsten inert gas (TIG) welding method and electron beam (EB) welding method. For the prospective improvement of swelling in welded joints, modified TIG or EB welding procedures utilizing titanium or nickel foil insertions were investigated. TEM disk specimens from various positions of welded joints were irradiated to 25 dpa at 673, 773 and 873 K. He/dpa ratio in Ni/He dual-ion irradiation was 15 appm He/dpa. The present results indicate some concern about the microstructures which result in the fusion zone and heat affected zones.

  11. Effect of Welding Consumables on Fatigue Performance of Shielded Metal Arc Welded High Strength, Q&T Steel Joints

    Science.gov (United States)

    Magudeeswaran, G.; Balasubramanian, V.; Madhusudhan Reddy, G.

    2009-02-01

    Quenched and Tempered (Q&T) steels are widely used in the construction of military vehicles due to their high strength-to-weight ratio and high hardness. These steels are prone to hydrogen-induced cracking in the heat affected zone (HAZ) after welding. The use of austenitic stainless steel consumables to weld the above steel was the only remedy because of higher solubility for hydrogen in austenitic phase. Recent studies proved that high nickel steel and low hydrogen ferritic steel consumables can be used to weld Q&T steels, which can give very low hydrogen levels in the weld deposits. In this investigation an attempt has been made to study the effect of welding consumables on high cycle fatigue properties of high strength, Q&T steel joints. Three different consumables namely (i) austenitic stainless steel, (ii) low hydrogen ferritic steel, and (iii) high nickel steel have been used to fabricate the joints by shielded metal arc (SMAW) welding process. The joints fabricated using low hydrogen ferritic steel electrodes showed superior fatigue properties than other joints.

  12. Modeling Stress-Strain State in Butt-Welded Joints after TIG Welding

    Directory of Open Access Journals (Sweden)

    V. Atroshenko

    2015-09-01

    Full Text Available In this paper mathematical model was developed for definition of thermal-welding cycle influence on welding deformations distribution in flat samples of austenitic steels after TIG welding and developed recommendations to reduce the welding deformation on o the machinery for welding with a copper backing.

  13. Effect of Strength Matching on Mechanical Properties of WELDOX 960 Steel Welded Joint

    Science.gov (United States)

    Wang, Zhiling

    2017-10-01

    In this paper, WELDOX 960 high strength steel sheet was used as the research object, and the welding method was adopted with Ar-CO2 mixed gas welding method. The change of microstructure and properties under different strength matching was studied by changing the strength matching method of welded joint. The main research contents are as follows: The comprehensive mechanical properties of the weld are tested, including the tensile, impact and microhardness tests. The changes of the comprehensive mechanical properties of the welds under different strength matching are obtained, and the selection of the best strength matching under different application conditions is put forward.

  14. Effect of Laser Heat Treatment on Microstructures of 1Cr5Mo Steel Welded Joint

    Directory of Open Access Journals (Sweden)

    GUO Wei

    2017-01-01

    Full Text Available The surface of 1Cr5Mo heat-resistant steel welded joint was treated with CO2 laser,the microstructure and grain size grades of welded joints before and after laser heat treatment (LHT were analyzed with 4XC type optical microscope (OM,and the distribution of residual stress and retained austenite content in the surface of the welded joints were measured with X-ray diffraction (XRD stress tester.The results show that the grains of 1Cr5Mo steel welded joints are refined by LHT,and the microstructure uniformity improves significantly,the grain levels of welded zone,fusion zone,overheated zone and normalized zone increase from level 9,level 9.8,level 8 and level 10.7 to level 10,level 10.2,level 8.5 and level 11 respectively,the mechanical weak areas reduce from overheated zone,welded zone and fusion zone to the overheated zone.The tensile residual stress in the welded joint surface is eliminated by LHT and a layer of compressive residual stress with thickness of about 0.28mm is formed.The residual austenite content in the welded joint surface increases after LHT,of which the distribution is more uniform and conducive to the improvement of mechanical properties.

  15. Qualification of electron-beam welded joints between copper and stainless steel for cryogenic application

    Science.gov (United States)

    Lusch, C.; Borsch, M.; Heidt, C.; Magginetti, N.; Sas, J.; Weiss, K.-P.; Grohmann, S.

    2015-12-01

    Joints between copper and stainless steel are commonly applied in cryogenic systems. A relatively new and increasingly important method to combine these materials is electron-beam (EB) welding. Typically, welds in cryogenic applications need to withstand a temperature range from 300K down to 4K, and pressures of several MPa. However, few data are available for classifying EB welds between OFHC copper and 316L stainless steel. A broad test program was conducted in order to qualify this kind of weld. The experiments started with the measurement of the hardness in the weld area. To verify the leak-tightness of the joints, integral helium leak tests at operating pressures of 16 MPa were carried out at room- and at liquid nitrogen temperature. The tests were followed by destructive tensile tests at room temperature, at liquid nitrogen and at liquid helium temperatures, yielding information on the yield strength and the ultimate tensile strength of the welds at these temperatures. Moreover, nondestructive tensile tests up to the yield strength, i.e. the range in which the weld can be stressed during operation, were performed. Also, the behavior of the weld upon temperature fluctuations between room- and liquid nitrogen temperature was tested. The results of the qualification indicate that EB welded joints between OFHC copper and 316L stainless steel are reliable and present an interesting alternative to other technologies such as vacuum brazing or friction welding.

  16. The Microstructure and Pitting Resistance of Weld Joints of 2205 Duplex Stainless Steel

    Science.gov (United States)

    Wu, Mingfang; Liu, Fei; Pu, Juan; Anderson, Neil E.; Li, Leijun; Liu, Dashuang

    2017-11-01

    2205 duplex stainless steel (DSS) was welded by submerged arc welding. The effects of both heat input and groove type on the ferrite/austenite ratio and elemental diffusion of weld joints were investigated. The relationships among welding joint preparation, ferrite/austenite ratio, elemental diffusion, and pitting corrosion resistance of weld joints were analyzed. When the Ni content of the weld wire deposit was at minimum 2-4% higher than that of 2205 DSS base metal, the desired ratio of ferrite/austenite and elemental partitioning between the austenite and ferrite phases were obtained. While the pitting sensitivity of weld metal was higher than that of base metal, the self-healing capability of the passive film of weld metal was better than that of the base metal when a single V-type groove was used. Furthermore, the heat input should be carefully controlled since pitting corrosion occurred readily in the coarse-grained heat-affected zone near the fusion line of welded joints.

  17. Effect of post weld heat treatment on the mechanical and corrosion behaviour of welded Al-Fe-Si alloy joints

    Directory of Open Access Journals (Sweden)

    Isiaka Oluwole OLADELE

    2017-06-01

    Full Text Available Al-Fe-Si alloy was joined by shielded metal arc welding (SMAW process and the effects of post weld heat treatment (PWHT on the mechanical (tensile and hardness properties, corrosion behaviour and microstructure of the welded joints were investigated. The welded samples were divided into as-weld (AW, PWHT, base metal (BM and heat treated base metal (HT BM samples. Artificial aging was carried out on part of the welded sample at 177 °C with holding time of 8 hours to obtain the PWHT samples. The various samples were subjected to tensile, hardness and corrosion tests while microstructures of the fractured surfaces were viewed under optical microscope. From the results, it was observed that corrosion susceptibility of the alloy in 3.5 wt% NaCl solution was highly reduced after PWHT. The hardness was reduced after PWHT while the yield strength and joint efficiency was improved compared to the AW sample. The improvement in corrosion resistance, yield strength and joint efficiency are 78, 8.4 and 8.7 %, respectively.

  18. Microstructure and properties of weld joint during 10 kW laser welding with surface-active element sulfur

    Science.gov (United States)

    Li, Shichun; Deng, Zhaohui; Deng, Hui; Xu, Wei

    2017-12-01

    The present work has been focused on the effects of surface-active element sulfur on welding properties during 10 kW high power laser welding of 304 stainless steel thick plate. Molten pool behavior, morphology feature of sulfide inclusions, metallographic structures, XRD patterns, microhardness, potentiodynamic polarization curves and pitted surface have been investigated and discussed. The results indicated that the added sulfur powder improved the weld depth by increasing molten metal fluidity, elongating molten pool and promoting heat transmission. The observed sulfide inclusions had small particle size of 0.65 μm in average and were distributed sparsely in weld joint. The WWS (weld joint with sulfur powder) had higher δ-ferrite content and finer grain size than the WWOS (weld joint without sulfur powder) and BM (base metal) due to the effects of sulfide inclusions on crystallizing process. The preferred orientations of γ-austenite along the (200) and (220) directions were promoted both in WWS and WWOS. Fine grain size and high δ-ferrite content led to high microhardness. The WWS had the highest microhardness among all the specimens. The WWOS and BM had a similar corrosion resistance. By comprehensive comparison, the WWS had a relative lower corrosion resistance than others, since sulfide inclusions in WWS not only had some benefits but also had some bad effects on corrosion property.

  19. On some other preferred method for optimizing the welded joint

    Directory of Open Access Journals (Sweden)

    Pejović Branko B.

    2016-01-01

    Full Text Available The paper shows an example of performed optimization of sizes in terms of welding costs in a characteristic loaded welded joint. Hence, in the first stage, the variables and constant parameters are defined, and mathematical shape of the optimization function is determined. The following stage of the procedure defines and places the most important constraint functions that limit the design of structures, that the technologist and the designer should take into account. Subsequently, a mathematical optimization model of the problem is derived, that is efficiently solved by a proposed method of geometric programming. Further, a mathematically based thorough optimization algorithm is developed of the proposed method, with a main set of equations defining the problem that are valid under certain conditions. Thus, the primary task of optimization is reduced to the dual task through a corresponding function, which is easier to solve than the primary task of the optimized objective function. The main reason for this is a derived set of linear equations. Apparently, a correlation is used between the optimal primary vector that minimizes the objective function and the dual vector that maximizes the dual function. The method is illustrated on a computational practical example with a different number of constraint functions. It is shown that for the case of a lower level of complexity, a solution is reached through an appropriate maximization of the dual function by mathematical analysis and differential calculus.

  20. Experimental assessment of the influence of welding process parameters on Lamb wave transmission across ultrasonically welded thermoplastic composite joints

    Science.gov (United States)

    Ochôa, Pedro; Fernandez Villegas, Irene; Groves, Roger M.; Benedictus, Rinze

    2018-01-01

    One of the advantages of thermoplastic composites relative to their thermoset counterparts is the possibility of assembling components through welding. Ultrasonic welding in particular is very promising for industrialization. However, uncertainty in the fatigue and fracture behaviour of composites is still an obstacle to the full utilisation of these materials. Health monitoring is then of vital importance, and Lamb wave techniques have been widely recognised as some of the most promising approaches for that end. This paper presents the first experimental study about the influence of welding travel on the transmission of Lamb waves across ultrasonically welded thermoplastic composite joints in single-lap configuration. The main aim of this research is to start to understand how guided waves interact with the internal structure of ultrasonic welds, so that benign, manufacturing-related structural features can be distinguished from damaging ones in signal interpretation. The power transmission coefficient and the correlation coefficient proved to be suitable for analysing the wave propagation phenomena, allowing quantitative identification of small variations of weld-line thickness and intermolecular diffusion at the weld interface. The conclusions are used to develop a tentative damage detection criterion which can later on assist the design of a Lamb wave based structural health monitoring system for thermoplastic composite structures. The Lamb wave test results are backed up by phased-array inspections, which also provide some extra insight on the internal structure of ultrasonic welds.

  1. Upper Bound Limit Load Solutions for Welded Joints with Cracks

    CERN Document Server

    Alexandrov, Sergey

    2012-01-01

    The present short monograph concerns analytic and semi-analytic techniques for finding an approximate value of the limit load. The limit load is an essential input parameter of flaw assessment procedures. In most cases, finding the limit load involves some numerical calculations of different levels of complexity, including numerical minimization of functions of one or several arguments, the slip-line technique and the finite element method. This book shows in particular how to use singular behavior of the real velocity field in the vicinity of bi-material interfaces in kinematically admissible velocity fields to increase the accuracy of upper bound solutions. An approach to recalculate the limit load for a class of structures with defects with the use of its value for the corresponding structure with no defect is discussed. The upper bound technique is applied to evaluate the limit load of overmatched and undermatched welded joints with cracks subject to various loading conditions of practical importance in c...

  2. Assessment of Stress Corrosion Cracking Resistance of Activated Tungsten Inert Gas-Welded Duplex Stainless Steel Joints

    Science.gov (United States)

    Alwin, B.; Lakshminarayanan, A. K.; Vasudevan, M.; Vasantharaja, P.

    2017-11-01

    The stress corrosion cracking behavior of duplex stainless steel (DSS) weld joint largely depends on the ferrite-austenite phase microstructure balance. This phase balance is decided by the welding process used, heat input, welding conditions and the weld metal chemistry. In this investigation, the influence of activated tungsten inert gas (ATIG) and tungsten inert gas (TIG) welding processes on the stress corrosion cracking (SCC) resistance of DSS joints was evaluated and compared. Boiling magnesium chloride (45 wt.%) environment maintained at 155 °C was used. The microstructure and ferrite content of different weld zones are correlated with the outcome of sustained load, SCC test. Irrespective of the welding processes used, SCC resistance of weld joints was inferior to that of the base metal. However, ATIG weld joint exhibited superior resistance to SCC than the TIG weld joint. The crack initiation and final failure were in the weld metal for the ATIG weld joint; they were in the heat-affected zone for the TIG weld joint.

  3. Assessment of Stress Corrosion Cracking Resistance of Activated Tungsten Inert Gas-Welded Duplex Stainless Steel Joints

    Science.gov (United States)

    Alwin, B.; Lakshminarayanan, A. K.; Vasudevan, M.; Vasantharaja, P.

    2017-12-01

    The stress corrosion cracking behavior of duplex stainless steel (DSS) weld joint largely depends on the ferrite-austenite phase microstructure balance. This phase balance is decided by the welding process used, heat input, welding conditions and the weld metal chemistry. In this investigation, the influence of activated tungsten inert gas (ATIG) and tungsten inert gas (TIG) welding processes on the stress corrosion cracking (SCC) resistance of DSS joints was evaluated and compared. Boiling magnesium chloride (45 wt.%) environment maintained at 155 °C was used. The microstructure and ferrite content of different weld zones are correlated with the outcome of sustained load, SCC test. Irrespective of the welding processes used, SCC resistance of weld joints was inferior to that of the base metal. However, ATIG weld joint exhibited superior resistance to SCC than the TIG weld joint. The crack initiation and final failure were in the weld metal for the ATIG weld joint; they were in the heat-affected zone for the TIG weld joint.

  4. Ultrasonic Impact Treatment to Improve Stress Corrosion Cracking Resistance of Welded Joints of Aluminum Alloy

    Science.gov (United States)

    Yu, J.; Gou, G.; Zhang, L.; Zhang, W.; Chen, H.; Yang, Y. P.

    2016-07-01

    Stress corrosion cracking is one of the major issues for welded joints of 6005A-T6 aluminum alloy in high-speed trains. High residual stress in the welded joints under corrosion results in stress corrosion cracking. Ultrasonic impact treatment was used to control the residual stress of the welded joints of 6005A-T6 aluminum alloy. Experimental tests show that ultrasonic impact treatment can induce compressive longitudinal and transverse residual stress in the welded joint, harden the surface, and increase the tensile strength of welded joints. Salt-fog corrosion tests were conducted for both an as-welded sample and an ultrasonic impact-treated sample. The surface of the treated sample had far fewer corrosion pits than that of the untreated sample. The treated sample has higher strength and lower tensile residual stress than the untreated sample during corrosion. Therefore, ultrasonic impact treatment is an effective technique to improve the stress corrosion cracking resistance of the welded joints of 6005A-T6 aluminum alloy.

  5. Different types of cracking of P91 steel weld joints after long-term creep tests

    Energy Technology Data Exchange (ETDEWEB)

    Jandova, D.; Kasl, J.; Chvostova, E. (SKODA VYZKUM s.r.o., Plzen (Czech Republic))

    2010-05-15

    This paper deals with creep testing and microstructural investigation of trial weld joints prepared of wrought and cast 9Cr-1Mo-V steels using GTAW & SMAW method. Creep testing was carried out at temperature range from 525 degC to 625 degC, the longest time to rupture of 45 811 hrs was achieved. The creep strengths of weld joints for 100 000 hrs were calculated. Different types of cracking were observed in dependency on conditions of creep test and the type of weld joint. Type 1 and Type 2 fractures occurred at high applied stress at relatively low temperatures in the tube weld joint and also in two speciments of the cast plate weld joint after creep test at the lowest temperature and the highest temperature. All other fractures were of the Type 4. Causes of different fracture location in tested weld joints were elucidated on the base of substructure evolution in individual zones - the weld metal, the heat affected zone and the base material. Two processes occur simultaneously, which result in the creep damage: (i) softening of solid solution as a result of Laves phase precipitation and (ii) formation and coalescence of cavities in the soft fine grained parts of heat affected zone. (orig.)

  6. Microstructure and Mechanical Properties of Hybrid Welded Joints with Laser and CO2-Shielded Arc

    Science.gov (United States)

    Wahba, M.; Mizutani, M.; Katayama, S.

    2016-07-01

    With the objective of reducing the operating costs, argon-rich shielding gas was replaced by 100% CO2 gas in hybrid laser-arc welding of shipbuilding steel. The welding parameters were optimized to obtain buried-arc transfer in order to mitigate spatter formation. Sound butt joints could be successfully produced for plates of 14 and 17 mm thickness in one welding pass. Subsequently, the welded joints were subjected to different tests to evaluate the influence of CO2 shielding gas on the mechanical properties of the welded joints. All tensile-tested specimens failed in the base material, indicating the higher strength of the welded joints. The impact toughness of the welded joints, measured at -20 °C, reached approximately 76% of that of the base material, which was well above the limit set by the relevant standard. The microstructure of the fusion zone consisted of grain boundary ferrite and acicular ferrite uniformly over the plate thickness except for the joint root where the microstructure was chiefly ferrite with an aligned second phase. This resulted in higher hardness in the root region compared with the top and middle parts of the fusion zone.

  7. Experimental study of hot cracking at circular welding joints of 42CrMo steel

    Science.gov (United States)

    Zhang, Yan; Chen, Genyu; Chen, Binghua; Wang, Jinhai; Zhou, Cong

    2017-12-01

    The hot cracking at circular welding joints of quenched and tempered 42CrMo steel were studied. The flow of the molten pool and the solidification process of weld were observed with a high-speed video camera. The information on the variations in the weld temperature was collected using an infrared (IR) thermal imaging system. The metallurgical factors of hot cracking were analyzed via metallographic microscope and scanning electron microscope (SEM). The result shows that leading laser laser-metal active gas (MAG) hybrid welding process has a smaller solid-liquid boundary movement rate (VSL) and a smaller solid-liquid boundary temperature gradient (GSL) compared with leading arc laser-MAG hybrid welding process and laser welding process. Additionally, the metal in the molten pool has superior permeability while flowing toward the dendritic roots and can compensate for the inner-dendritic pressure balance. Therefore, leading laser laser-MAG hybrid welding process has the lowest hot cracking susceptibility.

  8. Influence of temperature on strength and failure mechanisms of resistance welded thermoplastic composites joints

    NARCIS (Netherlands)

    Koutras, N.; Fernandez Villegas, I.; Benedictus, R.

    2015-01-01

    In this work, the effect of temperature exposure on the strength of resistance welded joints is analysed. Glass fibre polyphenylene sulphide (GF/PPS) laminates were joined using the resistance welding technique and a stainless steel metal mesh as the heating element. Single lap shear tests at

  9. Experiments and simulation for 6061-T6 aluminum alloy resistance spot welded lap joints

    Science.gov (United States)

    Florea, Radu Stefanel

    This comprehensive study is the first to quantify the fatigue performance, failure loads, and microstructure of resistance spot welding (RSW) in 6061-T6 aluminum (Al) alloy according to welding parameters and process sensitivity. The extensive experimental, theoretical and simulated analyses will provide a framework to optimize the welding of lightweight structures for more fuel-efficient automotive and military applications. The research was executed in four primary components. The first section involved using electron back scatter diffraction (EBSD) scanning, tensile testing, laser beam profilometry (LBP) measurements, and optical microscopy(OM) images to experimentally investigate failure loads and deformation of the Al-alloy resistance spot welded joints. Three welding conditions, as well as nugget and microstructure characteristics, were quantified according to predefined process parameters. Quasi-static tensile tests were used to characterize the failure loads in specimens based upon these same process parameters. Profilometer results showed that increasing the applied welding current deepened the weld imprints. The EBSD scans revealed the strong dependency between the grain sizes and orientation function on the process parameters. For the second section, the fatigue behavior of the RSW'ed joints was experimentally investigated. The process optimization included consideration of the forces, currents, and times for both the main weld and post-heating. Load control cyclic tests were conducted on single weld lap-shear joint coupons to characterize the fatigue behavior in spot welded specimens. Results demonstrate that welding parameters do indeed significantly affect the microstructure and fatigue performance for these welds. The third section comprised residual strains of resistance spot welded joints measured in three different directions, denoted as in-plane longitudinal, in-plane transversal, and normal, and captured on the fusion zone, heat affected zone

  10. Non-destructive three-dimensional evaluation of pores at different welded joints and their effects on joints strength.

    Science.gov (United States)

    Nomoto, Rie; Takayama, Yasuko; Tsuchida, Fujio; Nakajima, Hiroyuki

    2010-12-01

    The purpose of this study was to measure the porosity in different laser welded cast alloys non-destructively using X-ray micro-focus computerized tomography (micro-CT) and to evaluate the effect of porosity on the tensile strength of the welded joints. The welding procedure was conducted in rectangular cast metals, CoCr, Ti and platinum added gold alloy (AuPt). The metal plates were butted CoCr to CoCr (CoCr/CoCr) or Ti to Ti (Ti/Ti) for welding of similar metals and Ti to AuPt (Ti/AuPt) for welding of dissimilar metals. Specimens were welded under several laser-welding conditions; with groove (normal), without groove (no groove), spatter, crack, or no overlapped welding (no overlap) (n=5). Porosity in the welded area was evaluated using a micro-CT. Tensile strength of the welded specimens was measured at a crosshead speed of 1mm/min. Multiple comparisons of the group means were performed using ANOVA and Fisher's multiple comparisons test (α=.05). The relationship between the porosity and the tensile strength was investigated with a regression analysis. Three-dimensional images of Ti/AuPt could not be obtained due to metal artifacts and the tensile specimens of Ti/AuPt were debonded prior to the tensile test. All other welded specimens had porosity in the welded area and the porosities ranged from 0.01% to 0.17%. The fractures of most of the CoCr/CoCr and Ti/Ti specimens occurred in the parent metals. Joint strength had no relationship with the porosity in the welded area (R(2)=0.148 for CoCr/CoCr, R(2)=0.088 for Ti/Ti, respectively). The small amount of porosity caused by the laser-welding procedures did not affect the joint strength. The joint strength of Ti/AuPt was too weak to be used clinically. Copyright © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  11. A Study on the Optimal Welding Condition for Root-Pass in Horizontal Butt-Joint TIG Welding

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Sung Hun; Kim, Jae-Woong [Yeungnam Univ., Gyeongsan (Korea, Republic of)

    2017-04-15

    In this study, to investigate the shape of the back bead as a weld quality parameter and to select the optimal condition of the root-pass TIG welding of a horizontal butt-joint, an experimental design and the response surface method (RSM) have been employed. Three parameters are used as input variables, which include the base current, peak current, and welding speed. The back bead width is selected as an output variable representing the weld quality, the target value of the width is 5.4 mm. Conducting the experiments according to the Box-Behnken experimental design, a 2nd regression model for the back bead width was made, and the validation of the model was confirmed by using the F-test. The desirability function was designed through the nominal-the-best formula for the appropriate back bead width. Finally, the following optimal condition for welding was selected using the RSM: base current of 0.9204, peak current of 0.8676, and welding speed of 0.3776 in coded values. For verification, a test welding process under the optimal condition was executed and the result showed the back bead width of 5.38 mm that matched the target value well.

  12. Structural, chemical and deformation changes in friction welded joint of dissimilar steels

    Directory of Open Access Journals (Sweden)

    N. Ratković

    2014-10-01

    Full Text Available Fundamental principles of friction welding of dissimilar steels (high speed and tempering steel from the aspect of metallurgical and chemical processes occurring in the joint zone are presented in this paper. Considering that phenomena accompanying the friction welding are interdependent, it was necessary to experimentally determine the process variable parameters, to establish the optimal welding regime. The experiments were set and realized so that all the variables were analyzed as a function of the friction time. The metallographic investigations included analysis of the joint zone microstructure through structural phases and hardness changes, due to influence of the heat treatment - annealing. The experimental work included analysis of the geometry changes, the joint zone structure and the basic mechanical characteristics of the joint realized by the friction welding.

  13. Effects of Metal Types on Residual Stress in Electron-Beam Welding Joints with Sheet Metals

    National Research Council Canada - National Science Library

    Nagai, Takuya; Kasai, Ryu; Ueno, Kunika; Mochizuki, Masahito; Suga, Tetsuo

    2015-01-01

    The effect of metal types on the residual stresses has been researched through X-ray stress measurement for the electron-beam welding joints made of sheet metals with a thickness of approximately 10 mm...

  14. Insights into intermetallic phases on pulse welded dissimilar metal joints

    OpenAIRE

    Beyer, E.; Brenner, B; Göbel, G.; Herrmannsdörfer, T.; Kaspar, J.

    2010-01-01

    The Magnetic Pulse Welding (MPW) process has been developed to an industrially used joining method which is considered to be a fast, noncontact, clean and "cold" solid state welding process. Unlike fusion welding, the absence of direct heat during the welding cycle makes it possible to join dissimilar metals, for instance aluminium to copper or copper to steel, without noticeable detrimental metallurgical defects. This is very desirable, as today s industry lacks technologies to join often no...

  15. Microstructural Characterization of Friction Stir Welded Aluminum-Steel Joints

    Science.gov (United States)

    2013-08-01

    plasticized by the rotation around the back of the tool in preparation for adhesion to the faying surface of the other alloy. In the case of a lap weld...strengths from lap - shear tests than the welds performed using the tool with the scribe. The cross-sectional morphology of the weld was different as...alloy serving as the matrix. Lap - shear samples from the welds performed with the scribe not only produced higher failure stresses but were also more

  16. Microstructure and Fatigue Properties of Laser Welded DP590 Dual-Phase Steel Joints

    Science.gov (United States)

    Xie, Chaojie; Yang, Shanglei; Liu, Haobo; Zhang, Qi; Cao, Yaming; Wang, Yuan

    2017-08-01

    In this paper, cold-rolled DP590 dual-phase steel sheets with 1.5 mm thickness were butt-welded by a fiber laser, and the evolution and effect on microhardness, tensile property and fatigue property of the welded joint microstructure were studied. The results showed that the base metal is composed of ferrite and martensite, with the martensite dispersed in the ferrite matrix in an island manner. The microstructure of the weld zone was lath-shaped martensite that can be refined further by increasing the welding speed, while the heat-affected zone was composed of ferrite and tempered martensite. The microhardness increased with increasing welding speed, and the hardness reached its highest value—393.8 HV—when the welding speed was 5 m/min. Static tensile fracture of the welded joints always occurred in the base metal, and the elongation at break was more than 16%. The conditional fatigue limits of the base metal and the weld joints were 354.2 and 233.6 MPa, respectively, under tension-tension fatigue tests with a stress rate of 0.1. After observation of the fatigue fracture morphology, it was evident that the fatigue crack of the base metal had sprouted into the surface pits and that its expansion would be accelerated under the action of a secondary crack. The fatigue source of the welded joint was generated in the weld zone and expanded along the martensite, forming a large number of fatigue striations. Transient breaking, which occurred in the heat-affected zone of the joint as a result of the formation of a large number of dimples, reflected the obvious characteristics of ductile fracture.

  17. Use of coatings for protection of welded joints of steels, their structure and properties

    Science.gov (United States)

    Bezborodov, V. P.; Saraev, Yu N.

    2017-05-01

    The paper studies the structure and demonstrates the efficiency of application of eutectic nickel coatings for protection of welded joints of the 10G2S-type steels from corrosive action. It increases simultaneously with the increase of eutectic content and chemical compounds along the grain boundaries of the γ-solid solution based on nickel. The refinement of the coatings’ structure and the reduction of their heterogeneity allow enhancing the protective properties and resistance of welded joints to corrosion.

  18. Design of a welded joint for robotic, on-orbit assembly of space trusses

    Science.gov (United States)

    Rule, William K.

    1992-12-01

    In the future, some spacecraft will be so large that they must be assembled on-orbit. These spacecraft will be used for such tasks as manned missions to Mars or used as orbiting platforms for monitoring the Earth or observing the universe. Some large spacecraft will probably consist of planar truss structures to which will be attached special purpose, self-contained modules. The modules will most likely be taken to orbit fully outfitted and ready for use in heavy-lift launch vehicles. The truss members will also similarly be taken to orbit, but most unassembled. The truss structures will need to be assembled robotically because of the high costs and risks of extra-vehicular activities. Some missions will involve very large loads. To date, very few structures of any kind have been constructed in space. Two relatively simple trusses were assembled in the Space Shuttle bay in late 1985. Here the development of a design of a welded joint for on-orbit, robotic truss assembly is described. Mechanical joints for this application have been considered previously. Welded joints have the advantage of allowing the truss members to carry fluids for active cooling or other purposes. In addition, welded joints can be made more efficient structurally than mechanical joints. Also, welded joints require little maintenance (will not shake loose), and have no slop which would cause the structure to shudder under load reversal. The disadvantages of welded joints are that a more sophisticated assembly robot is required, weld flaws may be difficult to detect on-orbit, the welding process is hazardous, and welding introduces contamination to the environment. In addition, welded joints provide less structural damping than do mechanical joints. Welding on-orbit was first investigated aboard a Soyuz-6 mission in 1969 and then during a Skylab electron beam welding experiment in 1973. A hand held electron beam welding apparatus is currently being prepared for use on the MIR space station

  19. On Post-Weld Heat Treatment of a Single Crystal Nickel-Based Superalloy Joint by Linear Friction Welding

    Directory of Open Access Journals (Sweden)

    T. J. Ma

    2015-09-01

    Full Text Available Three types of post-weld heat treatment (PWHT, i.e. solution treatment + primary aging + secondary aging (I, secondary aging (II, and primary aging + secondary aging (III, were applied to a single crystal nickel-based superalloy joint made with linear friction welding (LFW. The results show that the grains in the thermomechanically affected zone (TMAZ coarsen seriously and the primary γ' phase in the TMAZ precipitates unevenly after PWHT I. The primary γ' phase in the TMAZ and weld zone (WZ precipitates insufficiently and fine granular secondary γ' phase is observed in the matrix after PWHT II. After PWHT III, the primary γ' phase precipitates more sufficiently and evenly compared to PWHTs I and II. Moreover, the grains in the TMAZ have not coarsened seriously and fine granular secondary γ' phase is not found after PWHT III. PWHT III seems more suitable to the LFWed single crystal nickel-based superalloy joints when performing PWHT.

  20. JOINTING PROCESS OF THE SAE 1020 WITH MAG WELD'S REGION HAVE BEEN INVESTIGATED AND FACTOR OF MISMATCH DETERMINED

    Directory of Open Access Journals (Sweden)

    Cevdet MERİÇ

    1997-03-01

    Full Text Available In this study, the jointing process of the SAE 1020 low carbon steel, generally used in the industry, has been done by the MAG weld method. The aim of this study is to examine the mismatch between base and weld metal. After the jointing process, mechanical and metalographical properties of the weld region, HAZ, and the weld metal of the samples considered here were searched, and CTOD (Crack Tip Opening Displacement was identified.

  1. JOINTING PROCESS OF THE SAE 1020 WITH MAG WELD'S REGION HAVE BEEN INVESTIGATED AND FACTOR OF MISMATCH DETERMINED

    OpenAIRE

    Cevdet MERİÇ; Mesut TOKDEMİR

    1997-01-01

    In this study, the jointing process of the SAE 1020 low carbon steel, generally used in the industry, has been done by the MAG weld method. The aim of this study is to examine the mismatch between base and weld metal. After the jointing process, mechanical and metalographical properties of the weld region, HAZ, and the weld metal of the samples considered here were searched, and CTOD (Crack Tip Opening Displacement) was identified.

  2. A Study of the Structure of Steel - Titanium Joints Formed by Diffusion Welding with the Use of Ultrafine Nickel Powder

    Science.gov (United States)

    Uvarov, A. A.; Semenov, A. N.; Krestnikov, N. S.; Lyushinskii, A. V.; Nikitina, E. V.

    2017-11-01

    The structure and phase composition of welded joints of austenitic steel 08Kh17N10T and titanium alloy PT-3V formed by diffusion welding with an intermediate layer of ultrafine nickel powder have been studied. The microstructure of joints welded in various regimes was studied using metallographic and energy-dispersive x-ray microanalysis techniques. Good prospects of the application of ultrafine dispersed media for diffusion welding of steels and titanium alloys are shown.

  3. Influence of Material Model on Prediction Accuracy of Welding Residual Stress in an Austenitic Stainless Steel Multi-pass Butt-Welded Joint

    Science.gov (United States)

    Deng, Dean; Zhang, Chaohua; Pu, Xiaowei; Liang, Wei

    2017-04-01

    Both experimental method and numerical simulation technology were employed to investigate welding residual stress distribution in a SUS304 steel multi-pass butt-welded joint in the current study. The main objective is to clarify the influence of strain hardening model and the yield strength of weld metal on prediction accuracy of welding residual stress. In the experiment, a SUS304 steel butt-welded joint with 17 passes was fabricated, and the welding residual stresses on both the upper and bottom surfaces of the middle cross section were measured. Meanwhile, based on ABAQUS Code, an advanced computational approach considering different plastic models as well as annealing effect was developed to simulate welding residual stress. In the simulations, the perfect plastic model, the isotropic strain hardening model, the kinematic strain hardening model and the mixed isotropic-kinematic strain hardening model were employed to calculate the welding residual stress distributions in the multi-pass butt-welded joint. In all plastic models with the consideration of strain hardening, the annealing effect was also taken into account. In addition, the influence of the yield strength of weld metal on the simulation result of residual stress was also investigated numerically. The conclusions drawn by this work will be helpful in predicting welding residual stresses of austenitic stainless steel welded structures used in nuclear power plants.

  4. Structural Phase Evolution in Ultrasonic-Assisted Friction Stir Welded 2195 Aluminum Alloy Joints

    Science.gov (United States)

    Eliseev, A. A.; Fortuna, S. V.; Kalashnikova, T. A.; Chumaevskii, A. V.; Kolubaev, E. A.

    2017-10-01

    The authors examined the structural and phase state of fixed joints produced by method of friction stir welding (FSW) and ultrasonic-assisted friction stir welding (UAFSW) from extruded profile of aluminum alloy AA2195. In order to identify the role of ultrasonic application in the course of welding, such characteristics, as volume fraction and average size of secondary particles are compared in the base material and stir zones of FSW and UAFSW joints. By applying the methods of SEM and TEM analysis, researchers established the complex character of phase transitions as a result of ultrasonic application.

  5. Role of heat equation in lap joint for welding process

    Science.gov (United States)

    Kumar, P.; Rohit, Sooraj

    2017-07-01

    Welding is predominantly used in industrial purposes and growth in their industry, which gives exact welding and more efficient. The major advantage of using this welding technique at initial stage it takes very low heat to weld the portion and gives a good result of low distortion in modules. In this context, two dissimilar metals copper and nickel are chosen for analysis in tungsten inert gas welding (TIG) in which length is 300 mm and breadth is 100 mm thickness 15 mm welded at room temperature a welded portion zone is formed simulation analysis has done on CATIA® and ANSYS®and MATLAB® code is generated for calculating temperatures at each node to calculate temperature at each node a new technique is used tri-diagonal matrix algorithm is used (TDMA) Steady state one dimension heat is calculated results compared between simulation analysis and analytical analysis temperature at each node is calculated both the temperatures are equal with error.

  6. Measurement and Analysis of the Diffusible Hydrogen in Underwater Wet Welding Joint

    Directory of Open Access Journals (Sweden)

    Kong Xiangfeng

    2016-01-01

    Full Text Available The diffusible hydrogen in steel weldments is one of the main reasons that led to hydrogen assisted cracking. In this paper, the results of literatures survey and preliminary tests of the diffusible hydrogen in underwater wet welding joint were presented. A fluid-discharge method of for measuring the diffusible hydrogen in weldment was introduced in detail. Two kinds of underwater welding electrode diffusible hydrogen are 26.5 mL/100g and 35.5 mL/100g by fluid-discharge method, which are high levels. The diffusible hydrogen of underwater welding is higher than atmospheric welding, and the result is closely related to welding material. The best way to control the diffusible hydrogen is adjusting welding material and improving fluidity of slag.

  7. Characterization of Mechanical Properties and Residual Stress in API 5L X80 Steel Welded Joints

    Science.gov (United States)

    de Sousa Lins, Amilton; de Souza, Luís Felipe Guimarães; Fonseca, Maria Cindra

    2018-01-01

    The use of high-strength and low-alloy steels, high design factors and increasingly stringent safety requirements have increased the operating pressure levels and, consequently, the need for further studies to avoid and prevent premature pipe failure. To evaluate the possibility of improving productivity in manual arc welding of this type of steel, this work characterizes the mechanical properties and residual stresses in API 5L X80 steel welded joints using the SMAW and FCAW processes. The residual stresses were analyzed using x-ray diffraction with the sin2 ψ method at the top and root of the welded joints in the longitudinal and transverse directions of the weld bead. The mechanical properties of the welded joints by both processes were characterized in terms of tensile strength, impact toughness and Vickers microhardness in the welded and shot peening conditions. A predominantly compressive residual stress was found, and shot peening increased the tensile strength and impact toughness in both welded joints.

  8. Dual beam Nd:YAG laser welding: influence of lubricants to lap joint welding of steel sheets

    Science.gov (United States)

    Geiger, M.; Merklein, M.; Otto, A.; Blankl, A.

    2007-05-01

    Laser welding is applied in large-volume production since the late eighties and has revolutionized the possibilities of designing and engineering products. Nevertheless, problems appear during application because the operational conditions in industrial environments fluctuate and can influence the welding process negatively. Contaminations, like lubricants and organic solids, are an example of changing conditions in laser beam welding. If a lap joint is welded, these materials have to be removed from the sheets, otherwise pores and surface failures may appear due to keyhole instabilities induced by uncontrolled outgassing. One possibility for solving this problem is the use of two separate laser beams. For producing these two beams several systems are available for all different kind of lasers. A bifocal optic is such a solution for an Nd:YAG laser. By using this system, the laser beam is divided after collimation with a prism. Afterwards the two beams are focussed with a lens to the surface of the sheet and two single spots are produced. If the distance between the two spots is low, one common, elliptical keyhole is created. With this system two different welding strategies are possible. The spots can be oriented parallel or normal to the feed direction. For stabilizing the laser welding of contaminated steel sheets the parallel arrangement is better, because the amount of contamination is nearly the same as in single spot welding but the total volume of the keyhole is greater and so pressure variations due to uncontrolled evaporation of contaminations are lower. In order to prove this theory and to determine the exact effects some investigations were made at the Chair of Manufacturing Technology of the University of Erlangen-Nuremberg. A 4 kW Nd:YAG laser with a beam parameter product of 25 mm*mrad and a focal distance of 200 mm was used to weld two 1 mm DC04 steel sheets together with a lap joint. Between the sheets a deep drawing lubricant, Castrol FST 6, was

  9. Analysis and Comparison of Aluminum Alloy Welded Joints Between Metal Inert Gas Welding and Tungsten Inert Gas Welding

    Science.gov (United States)

    Zhao, Lei; Guan, Yingchun; Wang, Qiang; Cong, Baoqiang; Qi, Bojin

    2015-09-01

    Surface contamination usually occurs during welding processing and it affects the welds quality largely. However, the formation of such contaminants has seldom been studied. Effort was made to study the contaminants caused by metal inert gas (MIG) welding and tungsten inert gas (TIG) welding processes of aluminum alloy, respectively. SEM, FTIR and XPS analysis was carried out to investigate the microstructure as well as surface chemistry. These contaminants were found to be mainly consisting of Al2O3, MgO, carbide and chromium complexes. The difference of contaminants between MIG and TIG welds was further examined. In addition, method to minimize these contaminants was proposed.

  10. Microstructure of friction stir welded joints of 2017A aluminium alloy sheets.

    Science.gov (United States)

    Mroczka, K; Dutkiewicz, J; Pietras, A

    2010-03-01

    The present study examines a friction stir welded 2017A aluminium alloy. Transmission electron microscope investigations of the weld nugget revealed the average grain size of 5 microm, moderate density of dislocations as well as the presence of nanometric precipitates located mostly in grains interiors. Scanning electron microscope observations of fractures showed the presence of ductile fracture in the region of the weld nugget with brittle precipitates in the lower part. The microhardness analysis performed on the cross-section of the joints showed fairly small changes; however, after the artificial ageing process an increase in hardness was observed. The change of the joint hardness subject to the ageing process indicates partial supersaturation in the material during friction stir welding and higher precipitation hardening of the joint.

  11. Improved TIG weld joint strength in aluminum alloy 2219-T87 by filler metal substitution

    Science.gov (United States)

    Poorman, R. M.; Lovoy, C. V.

    1972-01-01

    The results of an investigation on weld joint characteristics of aluminum alloy 2219-T87 are given. Five different alloys were utilized as filler material. The mechanical properties of the joints were determined at ambient and cryogenic temperatures for weldments in the as-welded condition and also, for weldments after elevated temperature exposures. Other evaluations included hardness surveys, stress corrosion susceptibility, and to a limited extent, the internal metallurgical weld structures. The overall results indicate that M-943 filler weldments are superior in strength to weldments containing either the standard 2319 filler or fillers 2014, 2020, and a dual wire feed consisting of three parts 2319 and one part 5652. In addition, no deficiencies were evident in M-934 filler weldments with regard to ductility, joint strength after elevated temperature exposure, weld hardness, metallographic structures, or stress corrosion susceptibility.

  12. Experimental analysis of dissimilar metal weld joint: Ferritic to austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Rathod, Dinesh W., E-mail: dineshvrathod@gmail.com [Department of Mechanical Engineering, Indian Institute of Technology Delhi, New Delhi 110016 (India); Pandey, Sunil [Department of Mechanical Engineering, Indian Institute of Technology Delhi, New Delhi 110016 (India); Singh, P.K. [Bhabha Atomic Research Centre, Mumbai 400085 (India); Prasad, Rajesh [Department of Applied Mechanics, Indian Institute of Technology Delhi, New Delhi 110016 (India)

    2015-07-15

    The dissimilar metal weld (DMW) joint between SA508Gr.3Cl.1 ferritic steel and SS304LN using Inconel 82/182 consumables was required in the nuclear power plants. The joint integrity assessment of these welds requires mechanical and metallurgical properties evaluation in weldment regions. The joint was subjected to 100% radiography test and bend test and transverse tensile test. Welding and testing were carried out as per the requirements of ASME Sec-IX and acceptance criteria as per ASME Sec-III. The transverse tensile test results indicated the failure from the weld metal although it satisfies the minimum strength requirement of the ASME requirements; therefore, the DMW joint was analyzed in detail. Straight bead deposition technique, fine slag inclusion, less reliable radiograph technique, plastic instability stress, yield strength ratio and metallurgical deteriorations have been contributed to failure of the DMW joint from the weld region. In the present work, the factors contributing to the fracture from weld metal have been discussed and analyzed.

  13. Effects of Porosity, Heat Input and Post-Weld Heat Treatment on the Microstructure and Mechanical Properties of TIG Welded Joints of AA6082-T6

    Directory of Open Access Journals (Sweden)

    Bo Wang

    2017-11-01

    Full Text Available Various heat input conditions and post-weld heat treatments were adopted to investigate the microstructure evolution and mechanical properties of tungsten inert gas (TIG welded joints of AA6082-T6 with porosity defects. The results show that the fracture location is uncertain when an as-welded joint has porosities in the weld zone (WZ, and overaging in the heat-affected zone (HAZ at the same time. When the fracture of the as-welded joint occurs in the HAZ, the total heat input has a linear relation with the tensile strength of the joint. An excess heat input induces the overgrowth of Mg2Si precipitates in HAZ and the coarsening of α-Al grains in WZ, resulting in a decrease in the microhardness of the corresponding areas. After artificial aging treatment, the tensile strength of the welded joint is increased by approximately 9–13% as compared to that of as-welded joint, and fracture also occurs in HAZ. In contrast, for solution treated and artificial aging treated joint, fracture occurs suddenly at the rising phase of the tensile curve due to porosity defects throughout the weld metal. Furthermore, the eutectic Si particles of WZ coarsen and spheroidize after solution treatment and artificial aging treatment, due to the diffusion of Si to the surface of the original Si phases when soaking at high temperature.

  14. Numerical and microstructural evaluation of 9%Cr welded joints

    Energy Technology Data Exchange (ETDEWEB)

    Sawada, K. [National Institute for Materials Science (Japan); Bauer, M.; Kauffmann, F.; Klenk, A. [Stuttgart Univ. (Germany). MPA

    2008-07-01

    Microstructural changes after creep at 600 C were investigated on E911 welded joints, focusing on the influence of multiaxiality of stress on microstructure of the fine-grained heat-affected zone (FGHAZ). In FGHAZ, more creep voids were observed in the interior portion of the specimen, compared with the outer surface. This is due to the higher multiaxiality of stress in the interior portion. There was no significant growth of VX particles during creep because of their higher thermal stability in base metal and FGHAZ. For M{sub 23}C{sub 6}, the growth during creep in FGHAZ was faster than in the base metal. There was no large difference in the growth rate of M{sub 23}C{sub 6} between the interior portion and near the outer surface. The number of Z-phase particles after creep in the base metal was higher than that in the FGHAZ. For FGHAZ, the number of Z-phase particles was higher in the interior portion of the specimen in contrast with near the outer surface. Increase in subgrain size and decrease in dislocation density were observed after creep in the base metal and the FGHAZ. For FGHAZ, the subgrain size and dislocation density after creep in the interior portion were almost the same as near the outer surface. (orig.)

  15. FE analysis of cruciform welded joints considering different mechanical properties for base material, heat affected zone and weld metal

    Directory of Open Access Journals (Sweden)

    Pasqualino Corigliano

    2014-10-01

    Full Text Available The aim of this scientific work was to investigate the behaviour of cruciform welded joints under static loading using a full-field technique: Digital Image Correlation. The material curves, relative to different zones (base material, heat affected zone, weld, were obtained by hardness measurements, which were done by means of a fully automated hardness scanner with high resolution. This innovative technique, based on the UCI method, allowed to identify the different zones and to assess their different mechanical properties, which were considered in the finite element model. Finally the finite element model was validated experimentally, comparing the results with the measurements obtained using the Digital Image Correlation technique.

  16. Improved design bases of welded joints in seawater

    DEFF Research Database (Denmark)

    Ólafsson, Ólafur Magnús

    were tested in a corrosion environment with cathodic protection. The specimens were subjected to high fatigue loading at the samestress ratio as the tests performed in-air. A direct comparison to the specimens testedunder in-air conditions was performed in order to evaluate the effects of the corrosion...... different environments, i.e. under in-air conditions and in a corrosion environment. Welded structures of all sizes and shapes exhibit fatigue failure primarily in the welded region, rather than in the base material, due to imperfections and flaws relating to the welding procedure. The welded region has...

  17. Effect of Temperature on Microstructure and Fracture Mechanisms in Friction Stir Welded Al6061 Joints

    Science.gov (United States)

    Dorbane, A.; Ayoub, G.; Mansoor, B.; Hamade, R. F.; Imad, A.

    2017-05-01

    Aluminum and its alloys are widely used in different industries due to such attractive properties as adequate strength, ductility, and low density. It is desirable to characterize welds of aluminum alloys obtained using "friction stir welding" at high temperatures. Al-to-Al (both 6061-T6) butt joints are produced by friction stir welding at tool rotation speed of 1600 rpm and four levels of tool advancing speeds: 250, 500, 750, and 1000 mm/min. Microstructural properties of the different welds are investigated. Observed are noticeable differences in microstructure characteristics between the various weld zones. Mechanical properties of these welded joints are characterized under tensile tests at temperatures of 25, 100, 200, and 300 °C, at a constant strain rate of 10-3/s. The optimum microstructural and mechanical properties were obtained for the samples FS welded with 1600 rpm tool rotation speed at 1000 mm/min tool advancing speed. The studied welds exhibited yield strength, ultimate tensile strength, and strain to failure with values inferior of those of the base material. Observations of postmortem samples revealed that in the temperature range of 25-200 °C the locus of failure originates at the region between the thermo-mechanically affected zone and the heat-affected zones. However, at higher temperatures (300 °C), the failure occurs in the stir zone. A change in the crack initiation mechanism with temperature is suggested to explain this observation.

  18. Long-term creep testing and microstructure evaluation of P91 steel weld joints

    Energy Technology Data Exchange (ETDEWEB)

    Jandova, D.; Kasl, J.; Kanta, V. [SKODA VYZKUM s.r.o., Plzen (Czech Republic)

    2007-06-15

    Trial weld joints were made from wrought and cast modified 9Cr-lMo-V steel using GTAW and SMAW methods. Creep testing was carried out at temperature range from 525 deg C to 625 deg C and stresses from 50 to 240 MPa. Time to rupture of welds made from tube segments and cast plates reached almost 30 000 hours and 20 000 hours respectively. Creep strength was evaluated according the Larson-Miller parametric equation and microstructure was investigated using both light and electron microscopy. Creep rupture strength of both weld joints tested at temperatures below 600 deg C falls into the {+-}20% scatter band of the creep rupture strength of the parent material. At 600 deg C and 625 deg C the creep strength dropped by 27% and 30% for the plate weld and the tube weld respectively. All ruptures occurred in fine grain and intercritically reheated heat affected zones either in the parent material or in the weld metal. Observation of thin foils prepared from selected regions of the weld joints revealed differences in precipitation processes and the structure recovery causing decrease of dislocation density in some regions. Fine ferritic grains with low density of fine carbonitride precipitate occurred in critical localities. Soft grains were deformed and cavities at grain boundaries initiated the crack propagation. (orig.)

  19. Microstructure and Mechanical Properties of TIG Weld Joint of ZM5 Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    QIN Ren-yao

    2016-06-01

    Full Text Available The ZM5 magnesium alloy plates were welded by TIG welding method. The microstructural characteristics and mechanical properties of ZM5 magnesium alloy joint were studied by optical microscopy, microhardness and tensile testers. The results show that the TIG weld joint of ZM5 magnesium alloy is composed of heat affected zone, partially melted zone and weld metal. The heat affected zone is consisted of primary α-Mg phase and eutectic phase that is composed of eutectic α-Mg and eutectic β-Mg17Al12 phase and mainly precipitated at grain boundaries. In the partially melted zone, the eutectic phase is not only increasingly precipitated at grain boundaries, but also dispersed in grains, and the growth of the β-Mg17Al12 phase is obviously observed. The microstructure in the weld is the typical dendritic morphology. The dendrites are considered as primary α-Mg phase, and the interdendritic regions are α+β eutectic phase. The difference in the microstructure of the heat affected zone, partially melted zone and weld results in their various microhardness values, and leads to the smaller tensile strength and ductility in the ZM5 alloy weld joint than parent metal.

  20. Microstructures and Mechanical Properties of 12Cr1MoVG Tube Welded Joints With/Without Post-weld Heat Treatment

    Science.gov (United States)

    Wang, Jingjing; Sun, Jian; Yu, Xinhai; Chen, Guohong; Fu, Qiuhua; Gao, Chao; Tang, Wenming

    2017-10-01

    Small-caliber, thick-wall 12Cr1MoVG seamless steel tube welded joints were fabricated in this study by gas tungsten arc welding and shielded metal arc welding techniques, then the microstructures, mechanical properties, and residual stress distributions of the joints with or without post-weld heat treatment (PWHT) were compared. The welded joints are mainly composed of bcc ferrite (F), Fe3C, and M7C3 carbides. PWHT did not cause an apparent microstructure evolution in the joints, but promoted granular pearlite decomposition and growth of F grains and carbides, therefore decreasing the yield, tensile strength, and hardness while increasing the impact toughness and elongation of the welded joints. PWHT also released the circumferential residual stress and altered the stress state in the joint from tensile to compressive. Although the mechanical properties and bending performance of the small-caliber, thick-wall 12Cr1MoVG seamless welded joints without PWHT are acceptable, our results show that the joints with PWHT are more reliable.

  1. Influence of the Overlapping Factor and Welding Speed on T-Joint Welding of Ti6Al4V and Inconel 600 Using Low-Power Fiber Laser

    Directory of Open Access Journals (Sweden)

    Shamini Janasekaran

    2016-06-01

    Full Text Available Double-sided laser beam welding of skin-stringer joints is an established method for many applications. However, in certain cases with limited accessibility, single-sided laser beam joining is considered. In the present study, single-sided welding of titanium alloy Ti6Al4V and nickel-based alloy Inconel 600 in a T-joint configuration was carried out using continuous-wave (CW, low-power Ytterbium (Yb-fiber laser. The influence of the overlapping factor and welding speed of the laser beam on weld morphology and properties was investigated using scanning electron microscopy (SEM and X-ray diffraction (XRD, respectively. XRD analysis revealed the presence of intermetallic layers containing NiTi and NiTi2 at the skin-stringer joint. The strength of the joints was evaluated using pull testing, while the hardness of the joints was analyzed using Vickers hardness measurement at the base metal (BM, fusion zone (FZ and heat-affected zone (HAZ. The results showed that the highest force needed to break the samples apart was approximately 150 N at a laser welding power of 250 W, welding speed of 40 mm/s and overlapping factor of 50%. During low-power single-sided laser welding, the properties of the T-joints were affected by the overlapping factor and laser welding speed.

  2. Structure and properties of fixed joints formed by ultrasonic-assisted friction-stir welding

    Energy Technology Data Exchange (ETDEWEB)

    Fortuna, S. V., E-mail: s-fortuna@ispms.ru; Ivanov, K. V., E-mail: ikv@ispms.ru; Eliseev, A. A., E-mail: alan@ispms.ru [Institute of Strength Physics and Materials ScienceTomsk, 634055 (Russian Federation); Tarasov, S. Yu., E-mail: tsy@ispms.ru; Ivanov, A. N., E-mail: ivan@ispms.ru; Rubtsov, V. E., E-mail: rvy@ispms.ru; Kolubaev, E. A., E-mail: eak@ispms.ru [Institute of Strength Physics and Materials ScienceTomsk, 634055 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    This paper deals with structure and properties of aluminum alloy 7475 and its joints obtained by friction stir welding including under ultrasonic action. Microhardness measurements show that ultrasonic action increases strength properties of the joints. Optical and transmission electron microscopy reveals that this effect is related to the precipitation of tertiary coherent S-and T-phase particles.

  3. An investigation on the strain distribution of resistance welded thermoplastic composite joints

    NARCIS (Netherlands)

    Shi, H.; Fernandez-Villegas, I.; Bersee, H.E.N.

    2012-01-01

    In order to better understand the usefulness of single lap shear testing for the characterization of resistance welded thermoplastic composite joints, finite element method (FEM) and digital image correlation measurements (DIC) were combined to investigate the strain distributions of the joints

  4. Numerical and Experimental Determination of Strain (Stress) Concentration Factors of Welded Joints between Square Hollow Sections

    NARCIS (Netherlands)

    Puthli, R.S.; Wardenier, J.; De Koning, C.H.M.; Van Wingerde, A.M.; Van Dooren, F.J.

    1988-01-01

    This article presents methods of approach for finite element modelling of joints made of rectangular hollow steel sections where the brace members are welded to the face of the chord, to obtain strain (stress) concentration factors, SNCF (SCF). X, T and K type joints are considered. Simple modelling

  5. Finite element modelling and updating of friction stir welding (FSW joint for vibration analysis

    Directory of Open Access Journals (Sweden)

    Zahari Siti Norazila

    2017-01-01

    Full Text Available Friction stir welding of aluminium alloys widely used in automotive and aerospace application due to its advanced and lightweight properties. The behaviour of FSW joints plays a significant role in the dynamic characteristic of the structure due to its complexities and uncertainties therefore the representation of an accurate finite element model of these joints become a research issue. In this paper, various finite elements (FE modelling technique for prediction of dynamic properties of sheet metal jointed by friction stir welding will be presented. Firstly, nine set of flat plate with different series of aluminium alloy; AA7075 and AA6061 joined by FSW are used. Nine set of specimen was fabricated using various types of welding parameters. In order to find the most optimum set of FSW plate, the finite element model using equivalence technique was developed and the model validated using experimental modal analysis (EMA on nine set of specimen and finite element analysis (FEA. Three types of modelling were engaged in this study; rigid body element Type 2 (RBE2, bar element (CBAR and spot weld element connector (CWELD. CBAR element was chosen to represent weld model for FSW joints due to its accurate prediction of mode shapes and contains an updating parameter for weld modelling compare to other weld modelling. Model updating was performed to improve correlation between EMA and FEA and before proceeds to updating, sensitivity analysis was done to select the most sensitive updating parameter. After perform model updating, total error of the natural frequencies for CBAR model is improved significantly. Therefore, CBAR element was selected as the most reliable element in FE to represent FSW weld joint.

  6. Mehanical Properties of Electron Beam Welded Joints in Thick Gage CA6NM Stainless Steel

    Science.gov (United States)

    Sarafan, Sheida; Wanjara, Priti; Gholipour, Javad; Champliaud, Henri; Mathieu, Louis

    2017-10-01

    Design of hydroelectric turbine components requires high integrity welds (without detectable volumetric defects) in heavy gage sections of stainless steel materials, such as ASTM A743 grade CA6NM—a low carbon 13% Cr-4% Ni martensitic stainless steel that is manufactured in cast form. In this work, 90-mm-thick plates of CA6NM were joined using a single-pass autogenous electron beam (EB) welding process and the mechanical properties were evaluated in the as-welded condition to characterize the performance of the joints. The static tensile properties that were evaluated in two directions—transverse and longitudinal to the EB weld seam—demonstrated conformance of the joints with the requirements of the ASME Section IX standard. The Charpy impact energies of the EB welds—measured at -18 °C on samples with V-notch roots located in the fusion and heat-affected zones—met the minimum requirements of 27 J specified in ASME Section VIII standard. In addition, bend tests that were conducted on the entire weld cross section displayed no discontinuities on the tension side of the bent joints. Hence, the developed EB welding process was demonstrated to render high-performance joints and promises key advantages for industrialization, such as cost savings through reductions in consumable material, production time and labor intensity.

  7. Morphology, microstructure, and mechanical properties of laser-welded joints in GH909 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chunming; Cai, Yuanzheng; Hu, Chongjing; Zhang, Xiong; Yan, Fei; Hu, Xiyuan [Huazhong University of Science and Technology, Wuhan (China)

    2017-05-15

    The experimental laser welding of GH909 alloy was conducted in this study. The morphology, microstructure, and mechanical properties of laser-welded joints were analyzed by scanning electron microscopy, energy diffraction spectroscopy, and other techniques. Results revealed that the microstructure of the welded joints mainly consisted of tiny cellular structures, dendritic structures, and equiaxed crystals. Pores appeared in the interdendritic regions because of the insufficient local feeding of molten metal during solidification. Nb segregation in the heat-affected zone caused liquation cracking, whereas C segregation further induced the formation of carbide precipitates along the grain boundaries during the welding thermal cycle. The instability of the keyhole significantly promoted the escape of the metal vapor/plasma from the hole; as a result, porosity defects formed in the weld. The average tensile strength of the test joints was 756 MPa, which is 93.1 % of that of the base metal. The average microhardness of the weld zone (250 HV) was higher than that of the GH909 alloy substrate (208 HV), peaking at 267 HV. Microcracks appeared along the grain boundaries, proving that the grain boundaries were the weakest areas in the joint.

  8. Mehanical Properties of Electron Beam Welded Joints in Thick Gage CA6NM Stainless Steel

    Science.gov (United States)

    Sarafan, Sheida; Wanjara, Priti; Gholipour, Javad; Champliaud, Henri; Mathieu, Louis

    2017-09-01

    Design of hydroelectric turbine components requires high integrity welds (without detectable volumetric defects) in heavy gage sections of stainless steel materials, such as ASTM A743 grade CA6NM—a low carbon 13% Cr-4% Ni martensitic stainless steel that is manufactured in cast form. In this work, 90-mm-thick plates of CA6NM were joined using a single-pass autogenous electron beam (EB) welding process and the mechanical properties were evaluated in the as-welded condition to characterize the performance of the joints. The static tensile properties that were evaluated in two directions—transverse and longitudinal to the EB weld seam—demonstrated conformance of the joints with the requirements of the ASME Section IX standard. The Charpy impact energies of the EB welds—measured at -18 °C on samples with V-notch roots located in the fusion and heat-affected zones—met the minimum requirements of 27 J specified in ASME Section VIII standard. In addition, bend tests that were conducted on the entire weld cross section displayed no discontinuities on the tension side of the bent joints. Hence, the developed EB welding process was demonstrated to render high-performance joints and promises key advantages for industrialization, such as cost savings through reductions in consumable material, production time and labor intensity.

  9. Microstructure and mechanical characteristics of a laser welded joint in SA508 nuclear pressure vessel steel

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Wei, E-mail: wei.guo-2@manchester.ac.uk [Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Sackville Street, Manchester, M13 9 PL (United Kingdom); Dong, Shiyun [Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Sackville Street, Manchester, M13 9 PL (United Kingdom); Institute of Laser Engineering, Beijing University of Technology, Beijing 100124 (China); Guo, Wei; Francis, John A.; Li, Lin [Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Sackville Street, Manchester, M13 9 PL (United Kingdom)

    2015-02-11

    SA508 steels are typically used in civil nuclear reactors for critical components such as the reactor pressure vessel. Nuclear components are commonly joined using arc welding processes, but with design lives for prospective new build projects exceeding 60 years, new welding technologies are being sought. In this exploratory study, for the first time, autogenous laser welding was carried out on 6 mm thick SA508 Cl.3 steel sheets using a 16 kW fiber laser system operating at a power of 4 kW. The microstructure and mechanical properties (including microhardness, tensile strength, elongation, and Charpy impact toughness) were characterized and the microstructures were compared with those produced through arc welding. A three-dimensional transient model based on a moving volumetric heat source model was also developed to simulate the laser welding thermal cycles in order to estimate the cooling rates included by the process. Preliminary results suggest that the laser welding process can produce welds that are free of macroscopic defects, while the strength and toughness of the laser welded joint in this study matched the values that were obtained for the parent material in the as-welded condition.

  10. Corrosion Behavior of MIG Brazed and MIG Welded Joints of Automotive DP600-GI Steel Sheet

    Science.gov (United States)

    Basak, Sushovan; Das, Hrishikesh; Pal, Tapan Kumar; Shome, Mahadev

    2016-12-01

    Galvanized dual-phase steel sheets are extensively used by the auto industry for their corrosion resistance property. Welding by the metal inert gas (MIG) process causes degradation of the steel in the vicinity of the joint due to excessive zinc evaporation. In order to minimize Zn loss, the MIG brazing process has been tried out in lap joint configuration over a heat input range of 136-204 J mm-1. The amount of zinc loss, intermetallic formation and corrosion properties in the joint area has been evaluated for both MIG brazing and MIG welding. Corrosion rate of 21 mm year-1 has been reduced to 2 mm year-1 by adopting MIGB in place MIGW. Impedance study has shown that the corrosion mechanism in base metal, MIG brazed and MIG welded joints is dominated by charge transfer, diffusion and mixed mode control processes, respectively.

  11. Fatigue Tests on Welded Joints Improved by Grinding

    DEFF Research Database (Denmark)

    Agerskov, Henning; Bjørnbak-Hansen, Jørgen; Olesen, John Forbes

    The present project is a part of an investigation on the fatigue life of the welded structure of large two-stroke diesel engines. Of special interest has been a study of the improvement in fatigue life, due to grinding of the weld toes. The test series carried through showed a significant increas...

  12. Modelling of damage development and ductile failure in welded joints

    DEFF Research Database (Denmark)

    Nielsen, Kim Lau

    conducted ([P1], [P2], [P7]-[P9]). The focus in the thesis is on FS-welded 2xxx and 6xxx series of aluminum alloys, which are attractive, for example, to the aerospace industry, since the 2024 aluminum in particular, is typically classified as un-weldable by conventional fusion welding techniques. Secondly...

  13. Inhibition of the formation of intermetallic compounds in aluminum-steel welded joints by friction stir welding

    Directory of Open Access Journals (Sweden)

    Torres López, Edwar A.

    2015-12-01

    Full Text Available Formation of deleterious phases during welding of aluminum and steel is a challenge of the welding processes, for decades. Friction Stir Welding (FSW has been used in an attempt to reduce formation of intermetallic compounds trough reducing the heat input. In this research, dissimilar joint of 6063-T5 aluminum alloy and AISI-SAE 1020 steel were welded using this technique. The temperature of welded joints was measured during the process. The interface of the welded joints was characterized using optical microscopy, scanning and transmission electron microscopy. Additionally, composition measurements were carried out by X-EDS and DRX. The experimental results revealed that the maximum temperature on the joint studied is less than 360 °C. The microstructural characterization in the aluminum-steel interface showed the absence of intermetallic compounds, which is a condition attributed to the use of welding with low thermal input parameters.La unión de juntas aluminio-acero, sin la formación de fases deletéreas del tipo FexAly, ha sido, por décadas, un desafío para los procesos de soldadura. La soldadura por fricción-agitación ha sido empleada para intentar reducir el aporte térmico y evitar la formación de compuestos intermetálicos. Usando esta técnica fueron soldadas juntas disimilares de aluminio 6063-T5 y acero AISI-SAE 1020. La soldadura fue acompañada de medidas de temperatura durante su ejecución. La interfase de las juntas soldadas fue caracterizada utilizando microscopía óptica, electrónica de barrido y electrónica de transmisión. Adicionalmente fueron realizadas medidas puntuales X-EDS y DRX. Los resultados experimentales revelan que la temperatura máxima en la junta es inferior a 360 °C. La caracterización microestructural en la interfase aluminio-acero demostró la ausencia de compuestos intermetálicos, condición atribuida al uso de parámetros de soldadura con bajo aporte térmico.

  14. Modelling of ultrasonic impact treatment (UIT of welded joints and its effect on fatigue strength

    Directory of Open Access Journals (Sweden)

    K.L. Yuan

    2015-10-01

    Full Text Available Ultrasonic impact treatment (UIT is a remarkable post-weld technique applying mechanical impacts in combination with ultrasound into the welded joints. In the present work, a 3D simulation method including welding simulation, numerical modelling of UIT-process and an evaluation of fatigue crack growth has been developed. In the FE model, the actual treatment conditions and local mechanical characteristics due to acoustic softening are set as input parameters. The plastic deformation and compressive stress layer are found to be more pronounced when acoustic softening takes place. The predicted internal residual stress distributions of welded joint before and after UIT are compared with experimental results, showing a fairly good agreement with each other. Finally, simulated results of fatigue crack growth in various residual stress fields are well compared with test results, so that the proposed model may provide an effective tool to simulate UIT-process in engineering structures.

  15. Predictive Modeling of Mechanical Properties of Welded Joints Based on Dynamic Fuzzy RBF Neural Network

    Directory of Open Access Journals (Sweden)

    ZHANG Yongzhi

    2016-10-01

    Full Text Available A dynamic fuzzy RBF neural network model was built to predict the mechanical properties of welded joints, and the purpose of the model was to overcome the shortcomings of static neural networks including structural identification, dynamic sample training and learning algorithm. The structure and parameters of the model are no longer head of default, dynamic adaptive adjustment in the training, suitable for dynamic sample data for learning, learning algorithm introduces hierarchical learning and fuzzy rule pruning strategy, to accelerate the training speed of model and make the model more compact. Simulation of the model was carried out by using three kinds of thickness and different process TC4 titanium alloy TIG welding test data. The results show that the model has higher prediction accuracy, which is suitable for predicting the mechanical properties of welded joints, and has opened up a new way for the on-line control of the welding process.

  16. Tensile properties and fracturing behavior of weld joints in the CLAM at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Yucheng [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Xiao, Chengwen, E-mail: emoryxiao@163.com [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Wang, Xu; Yue, Jiajia; Zhu, Qiang [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2015-06-15

    Highlights: • We use the stress triaxiality theory to explain the plastic deformation and facture behavior of the joints during the short term tensile tests at high temperature. • The tensile strength of CLAM welded joint at high temperature is lower compared with that at room temperature. • We explained the formation of crack and the reason of fracture. - Abstract: The tensile properties and fracturing behavior of weld joints in the Chinese low activation martensitic steel (CLAM) at high temperatures were studied. The result revealed that the cracks of weld joints in the base metal would appear in the heat-affected zone, after post-weld heat treatment for the high-temperature tensile test. The microstructure in the fractured frontier had different deformation and directions, and the fractured surface had different angles, a result associating with the normal faulting and shear fracturing. The tri-axial theory of stress can well explain the deformation and fracturing behavior of weld joints in the high-temperature tensile.

  17. Effect of welding processes on mechanical and microstructural characteristics of high strength low alloy naval grade steel joints

    Directory of Open Access Journals (Sweden)

    S. Ragu Nathan

    2015-09-01

    Full Text Available Naval grade high strength low alloy (HSLA steels can be easily welded by all types of fusion welding processes. However, fusion welding of these steels leads to the problems such as cold cracking, residual stress, distortion and fatigue damage. These problems can be eliminated by solid state welding process such as friction stir welding (FSW. In this investigation, a comparative evaluation of mechanical (tensile, impact, hardness properties and microstructural features of shielded metal arc (SMA, gas metal arc (GMA and friction stir welded (FSW naval grade HSLA steel joints was carried out. It was found that the use of FSW process eliminated the problems related to fusion welding processes and also resulted in the superior mechanical properties compared to GMA and SMA welded joints.

  18. Research of Technological Properties of Steel X6CRNITI18-10 Welded Joints Exploited in Nitric Acid Medium

    Directory of Open Access Journals (Sweden)

    Gediminas Mikalauskas

    2016-04-01

    Full Text Available The repair of chemical industry equipments often requires to replace long time operated pipes or welded inserts with the simi-lar chemical composition. During the study the joints from corro-sion resistant steel X6CrNiTi18-10 were welded by manual metal arc welding with covered electrodes (MMA process 111 and tungsten inert gas welding (TIG process 141 at different welding parameters. The visual, radiographic, penetrant control and ferrite content analysis were carried out. The transverse tensile and bending samples were produced from welded samples; also the macroscopic and microscopic analyse were carried out.

  19. A non-conventional technique for evaluating welded joints based on the electrical conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Santos, T.G.; Sorger, G., E-mail: telmo.santos@fct.unl.pt, E-mail: lgs18243@campus.fct.unl.pt [Universidade Nova de Lisboa, UNIDEMI, Departamento de Engenharia Mecanica e Industrial, Faculdade de Ciencias e Tecnologia, Caparica (Portugal); Vilaca, P., E-mail: pedro.vilaca@aalto.fi [Aalto Univ., Dept. of Engineering Design and Production, School of Engineering, Aalto (Finland); Miranda, R., E-mail: rmiranda@fct.unl.pt [Universidade Nova de Lisboa, UNIDEMI, Departamento de Engenharia Mecanica e Industrial, Faculdade de Ciencias e Tecnologia, Caparica (Portugal)

    2015-01-15

    Recent studies showed that electrical conductivity is a valuable technique to identify the different zones of solid-state welded joints with a good correlation with the microstructure and hardness. This is a relevant result since this technique is fast and, in some cases, non destructive, The concept was applied to other welding processes such as the ones involving fusion to a wide range of materials, For this, a comprehensive study was performed using friction stir welding, tungsten inert gas (TlG) and gas metal arc (MAG) welding processes in either bead on plate or butt joints in: carbon steel, magnesium and titanium, Eddy current nondestructive testing (NDT) was used to measure the electrical conductivity at different depths in transverse sections of the processed materials. The profiles were compared to the hardness profiles in the same sections. As a result, a correlation was observed in most materials welded by solid state and by fusion processes. The variation of the electrical conductivity closely follows that measured in the hardness. Another interesting conclusion is that, even for fusion welding of carbon steels, the technique has potential to complement the hardness measurements and microstructural observations, allowing the identification of the distinct zones of welds in materials commonly used in industry. (author)

  20. The reliability of the repair weld joints of aged high temperature components in fossil power boilers

    Energy Technology Data Exchange (ETDEWEB)

    Okamura, Hiroyuki [Science Univ. of Tokyo (Japan); Ohtani, Ryuichi [Kyoto Univ. (Japan); Fujii, Kazuya [Japan Power Engineering and Inspection Corp., Tokyo (Japan); Yokoyama, Tomomitsu; Nishimura, Nobuhiko [Mitsubishi Heavy Industries Ltd., Tokyo (Japan); Suzuki, Komei [Japan Steel Works Ltd., Tokyo (Japan)

    1998-11-01

    It is of fundamental engineering importance to be able to give reliable assessments of the effective service life of the critical components used within fossil power plants, particularly for those operating for prolonged periods. It is common practice for such assessments to have been estimated using destructive tests, typically the stress rupture test, this having been recognized as one of the most reliable evaluation methods available. Its only drawback is that it often does not permit the component to be in use following the sampling of the test specimen without repairing. The current piece of work focuses on the reliability of the repair welds of components for specimens taken from fossil power plants, having been in service for prolonged periods. Several such repairs to welds have been made to an old power boiler, in particular to a superheater header which is fabricated from 2.25Cr-1Mo steel. Under close examination the repairs to the girth weldment showed susceptibilities of weld cracking, similar to that observed in as-manufactured material. Within the repaired region of the welded joint the microstructure, tensile properties and toughness seemed to be unaffected. The hardness attained its minimum value within the heat affected zone, HAZ of the repair weld, overlapping that of original girth weld HAZ. Furthermore, the stress rupture strength achieved its minimum value at the same position taking on the same value as the strength associated with the aged girth welded joint. (orig.)

  1. Welding.

    Science.gov (United States)

    South Carolina State Dept. of Education, Columbia. Office of Vocational Education.

    This curriculum guide is designed for use by South Carolina vocational education teachers as a continuing set of lesson plans for a two-year course on welding. Covered in the individual sections of the guide are the following topics: an orientation to welding, oxyacetylene welding, advanced oxyacetylene welding, shielded metal arc welding, TIG…

  2. Effect of joint design and welding type on the flexural strength and weld penetration of Ti-6Al-4V alloy bars.

    Science.gov (United States)

    Simamoto Júnior, Paulo Cézar; Resende Novais, Veridiana; Rodrigues Machado, Asbel; Soares, Carlos José; Araújo Raposo, Luís Henrique

    2015-05-01

    Framework longevity is a key factor for the success of complete-arch prostheses and commonly depends on the welding methods. However, no consensus has been reached on the joint design and welding type for improving framework resistance. The purpose of this study was to assess the effect of different joint designs and welding methods with tungsten inert gas (TIG) or laser to join titanium alloy bars (Ti-6Al-4V). Seventy titanium alloy bar specimens were prepared (3.18 mm in diameter × 40.0 mm in length) and divided into 7 groups (n=10): the C-control group consisting of intact specimens without joints and the remaining 6 groups consisting of specimens sectioned perpendicular to the long-axis and rejoined using an I-, X30-, or X45-shaped joint design with TIG welding (TI, TX30, and TX45) or laser welding (LI, LX30, and LX45). The specimens were tested with 3-point bending. The fracture surfaces were first evaluated with stereomicroscopy to measure the weld penetration area and then analyzed with scanning electron microscopy (SEM). The data were statistically analyzed with 2-way ANOVA and the Tukey post hoc test, 1-way ANOVA and the Dunnett test, and the Pearson correlation test (α=.05). Specimens from the X30 and X45 groups showed higher flexural strength (Pwelded area (Pwelding type. TIG welded groups showed significantly higher flexural strength than the laser groups (PTIG welding also resulted in higher welded areas than laser welding for the I-shaped specimens. No significant differences were found for the weld penetration area in the X45 group, either for laser or TIG welding. SEM analysis showed more pores at the fracture surfaces of the laser specimens. Fracture surfaces indicative of regions of increased ductility were detected for the TIG specimens. TIG welding resulted in higher flexural strength for the joined titanium specimens than laser welding. For both welding methods, X30- and X45-shaped joint designs resulted in higher flexural strength and

  3. Simulation and experimental study on distortion of butt and T-joints using WELD PLANNER

    Energy Technology Data Exchange (ETDEWEB)

    Sulaiman, Mohd Shahar; Manurung, Yupiter HP; Rahim, Mohammad Ridzwan Abdul Mohd; Redza, Ridhwan; Lidam, Robert Ngendang Ak.; Abas, Sunhaji Kiyai; Tham, Ghalib [Universiti Teknologi MARA, Kuala Lumpur (Malaysia); Haruman, Esa [Bakrie University, Jakarta (Indonesia); Chau, Chan Yin [ESI Group, Kuala Lumpur (Malaysia)

    2011-10-15

    This paper investigates the capability of linear thermal elastic numerical analysis to predict the welding distortion that occurs due to GMAW process. Distortion is considered as the major stumbling block that can adversely affect the dimensional accuracy and thus lead to expensive corrective work. Hence, forecast of distortion is crucially needed and ought to be determined in advance in order to minimize the negative effects, improve the quality of welded parts and finally to reduce the production costs. In this study, the welding deformation was simulated by using relatively new FEM software WELD PLANNER developed by ESI Group. This novel Welding Simulation Solution was employed to predict welding distortion induced in butt and T-joints with thickness of 4 mm. Low carbon steel material was used for the simulation and experimental study. A series of experiments using fully automated welding process were conducted for verification purpose to measure the distortion. By comparing between the simulation and experimental results, it was found out that this program code offered fast solution analysis time in estimating weld induced distortion within acceptable accuracy.

  4. Microstructure and mechanical properties of GTAW welded joints of AA6105 aluminum alloy

    Directory of Open Access Journals (Sweden)

    Minerva Dorta-Almenara

    2016-09-01

    Full Text Available Gas Tungsten Arc Welding (GTAW is one of the most used methods to weld aluminum. This work investigates the influence of welding parameters on the microstructure and mechanical properties of GTAW welded AA6105 aluminum alloy joints. AA6105 alloy plates with different percent values of cold work were joined by GTAW, using various combinations of welding current and speed. The fusion zone, in which the effects of cold work have disappeared, and the heat affected zone of the welded samples were examined under optical and scanning electron microscopes, additionally, mechanical tests and measures of Vickers microhardness were performed. Results showed dendritic morphology with solute micro- and macrosegregation in the fusion zone, which is favored by the constitutional supercooling when heat input increases. When heat input increased and welding speed increased or remained constant, greater segregation was obtained, whereas welding speed decrease produced a coarser microstructure. In the heat affected zone recrystallization, dissolution, and coarsening of precipitates occurred, which led to variations in hardness and strength.

  5. Numerical analysis of weld pool for galvanized steel with lap joint in GTAW

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Hunchul; Park, Kyungbae; Kim, Yougjun; Cho, Jungho [Chungbuk National University, Cheongju (Korea, Republic of); Kim, Dong-Yoon; Kang, Moon-Jin [Korea Institute of Industrial Technology, Incheon (Korea, Republic of)

    2017-06-15

    Galvanized steel is widely used and its demand is growing in automotive industry due to high quality requirement for corrosion resistance. Although there are a lot of demands on using galvanized steel as automotive parts especially for outer body, it has a grave flaw in its welding process. The difficulty is low weldability due to various defects such as porosities and blow holes in weldment, which occurred during welding. A solution to prevent these defects is using hybrid welding process, with two more welding processes. One of the hybrid solutions is using Gas tungsten arc welding (GTAW) as leading position in order to remove the zinc (Zn) coating on the surface before the followed practical fusion welding process. In this research, a numerical analysis model which can predict the eliminated Zn coated layers and the area of Fusion zone (FZ). Developed numerical analysis model was validated through comparing experiment to simulation. Basically, arc heat flux, arc pressure, electromagnetic force and Marangoni flow were employed as the boundary conditions and body force terms. Governing equations such as the continuity, momentum, Volume of fluid (VOF) and energy equations were adopted as usual. In addition to previous model, concentrated arc heat flux and contact thermal conductance models are newly suggested and showed successful result. They are adopted to realize edge concentrated arc and interfacial thermal conductance in lap joint fillet arc welding. Developed numerical analysis model successfully simulated the weld pool and temperature profile therefore the predicted Zn removed area considerably coincided with experimental result.

  6. The effect of postprocessing on tensile property and microstructure evolution of friction stir welding aluminum alloy joint

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Z.L., E-mail: zhilihuhit@163.com [Hubei Key Laboratory of Advanced Technology of Automobile Parts, Wuhan University of Technology, Wuhan 430070 (China); State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology (China); Wang, X.S. [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Pang, Q. [School of Mechanical and Electrical Engineering, Wuhan Donghu University, Wuhan 430070 (China); Huang, F.; Qin, X.P.; Hua, L. [Hubei Key Laboratory of Advanced Technology of Automobile Parts, Wuhan University of Technology, Wuhan 430070 (China)

    2015-01-15

    Friction stir welding is an efficient manufacturing method for joining aluminum alloy and can dramatically reduce grain size conferring excellent plastic deformation properties. Consequently, friction stir welding is used to manufacture tailor welded blanks to optimize weight or performance in the final component. In the study, the microstructural evolution and mechanical properties of friction stir welding joint during plastic forming and subsequent heat treatment were investigated. The microstructural characteristics of the friction stir welding joints were studied by Electron Backscattered Diffraction and Transmission Electron Microscopy. The mechanical properties were evaluated by tensile and microhardness tests. It is found that the tensile and yield strengths of friction stir welding joints are significantly improved after severe plastic deformation due to the grain refinement. Following heat treatment, the strength of the friction stir welding joints significantly decrease due to the obvious abnormal grain growth. Careful attention must be given to the processing route of any friction stir welding joint intended for plastic forming, especially the annealing between forming passes. Severe plastic deforming of the friction stir welding joint leads to a high level of stored energy/dislocation density, which causes the abnormal grain growth during subsequent heat treatment, and consequently reduce the mechanical properties of the friction stir welding joint. - Highlights: • Great changes are observed in the microstructure of FSW joint after postprocessing. • Postprocessing shows great effect on the microstructure stability of FSW joint. • The weld shows more significant decrease in strength than the BM due to the AGG. • Attention must be given to the processing route of FSW joint for plastic forming.

  7. Effect of welding processes and consumables on fatigue crack growth behaviour of armour grade quenched and tempered steel joints

    Directory of Open Access Journals (Sweden)

    G. Magudeeswaran

    2014-03-01

    Full Text Available Quenched and Tempered (Q&T steels are widely used in the construction of military vehicles due to its high strength to weight ratio and high hardness. These steels are prone to hydrogen induced cracking (HIC in the heat affected zone (HAZ after welding. The use of austenitic stainless steel (ASS consumables to weld the above steel was the only available remedy because of higher solubility for hydrogen in austenitic phase. The use of stainless steel consumables for a non-stainless steel base metal is not economical. Hence, alternate consumables for welding Q&T steels and their vulnerability to HIC need to be explored. Recent studies proved that low hydrogen ferritic steel (LHF consumables can be used to weld Q&T steels, which can give very low hydrogen levels in the weld deposits. The use of ASS and LHF consumables will lead to distinct microstructures in their respective welds. This microstructural heterogeneity will have a drastic influence in the fatigue crack growth resistance of armour grade Q&T steel welds. Hence, in this investigation an attempt has been made to study the influence of welding consumables and welding processes on fatigue crack growth behaviour of armour grade Q&T Steel joints. Shielded metal arc welding (SMAW and Flux cored arc welding (FCAW were used for fabrication of joints using ASS and LHF consumables. The joints fabricated by SMAW process using LHF consumable exhibited superior fatigue crack growth resistance than all other joints.

  8. A Water-Drop Method of Hardening of the Welded Joints of Drill Pipes

    Science.gov (United States)

    Maisuradze, M. V.; Yudin, Yu. V.; Eismondt, Yu. G.

    2015-09-01

    A combined computational and experimental technique is developed for implementing a scientifically based approach to the selection of a technology of heat hardening of welded joints of drill pipes made of steel 25KhGM with the use of water-drop quenching. The basic service characteristics of the water-drop cooling device are presented. An analytic model that relates the parameters of the water-drop quenching device (standard size and number of jets in device, pressure of fed water, distance from the jet nozzle to the cooled surface) to the properties of the welded joint is proposed. With the new technique the construction of a quenching device may be developed and the technology of heat treatment of the welded joints of drill pipes optimized in order to increase the level of mechanical properties.

  9. Fracture Behaviour of Nickel-Titanium Laser Welded Joints

    Science.gov (United States)

    Maletta, C.; Falvo, A.; Furgiuele, F.; Barbieri, G.; Brandizzi, M.

    2009-08-01

    In this study, the effects of Nd:YAG laser welding on the fracture behavior of Ni-rich nickel-titanium sheets are analyzed by experimental investigations. The welding was carried out in open air conditions by using a special shielding/clamping system to avoid the chemical contamination of the molten zone and the formation of hot cracks. Mechanical tests of standard dog bone-shaped and single edge crack specimens were carried out to measure the stress-strain response and the fracture resistance of both the base and the welded materials. Furthermore, scanning electron microscopy observations of the fracture surfaces were carried out in order to better understand the failure mechanisms. Finally, systematic comparative studies between base and laser-welded materials were carried out.

  10. Vision and spectroscopic sensing for joint tracing in narrow gap laser butt welding

    Science.gov (United States)

    Nilsen, Morgan; Sikström, Fredrik; Christiansson, Anna-Karin; Ancona, Antonio

    2017-11-01

    The automated laser beam butt welding process is sensitive to positioning the laser beam with respect to the joint because a small offset may result in detrimental lack of sidewall fusion. This problem is even more pronounced in case of narrow gap butt welding, where most of the commercial automatic joint tracing systems fail to detect the exact position and size of the gap. In this work, a dual vision and spectroscopic sensing approach is proposed to trace narrow gap butt joints during laser welding. The system consists of a camera with suitable illumination and matched optical filters and a fast miniature spectrometer. An image processing algorithm of the camera recordings has been developed in order to estimate the laser spot position relative to the joint position. The spectral emissions from the laser induced plasma plume have been acquired by the spectrometer, and based on the measurements of the intensities of selected lines of the spectrum, the electron temperature signal has been calculated and correlated to variations of process conditions. The individual performances of these two systems have been experimentally investigated and evaluated offline by data from several welding experiments, where artificial abrupt as well as gradual deviations of the laser beam out of the joint were produced. Results indicate that a combination of the information provided by the vision and spectroscopic systems is beneficial for development of a hybrid sensing system for joint tracing.

  11. Electric pulse treatment of welded joint of aluminum alloy

    OpenAIRE

    A.A. Mitiaev; I. P. Volchok; Yu. L. Nadezhdin; V.A. Sokirko; I. A. Vakulenko

    2013-01-01

    Purpose. Explanation of the redistribution effect of residual strengthes after electric pulse treatment of arc welding seam of the aluminum alloy. Methodology. Alloy on the basis of aluminium of АК8М3 type served as the research material. As a result of mechanical treatment of the ingots after alloy crystallization the plates with 10 mm thickness were obtained. After edge preparation the elements, which are being connected were butt welded using the technology of semiautomatic argon arc weldi...

  12. Ultrasonic methods of testing austenite weld joints and identifying defects

    Energy Technology Data Exchange (ETDEWEB)

    Grebennikov, V.V.; Glek, Yu.S.; Grigor' ev, M.V.; Gurvich, A.K.; Markelova, E.A.; Matynova, N.A.; Zakharov, Yu.V.

    1985-01-01

    Testing welds with an austenitic structure and determining the nature of the defect by ultrasonic methods are the most complex and urgent problems in non-destructive testing of nuclear power station equipment and in many other engineering fields. A dual-frequency method and device for ultrasonic testing of austenitic welds are described. A method is presented for identifying the defects, based on ultrasonic-wave diffraction on the defect tips.

  13. Comparative study on transverse shrinkage, mechanical and metallurgical properties of AA2219 aluminium weld joints prepared by gas tungsten arc and gas metal arc welding processes

    Directory of Open Access Journals (Sweden)

    S. Arunkumar

    2015-09-01

    Full Text Available Aluminium alloy AA2219 is a high strength alloy belonging to 2000 series. It has been widely used for aerospace applications, especially for construction of cryogenic fuel tank. However, arc welding of AA2219 material is very critical. The major problems that arise in arc welding of AA2219 are the adverse development of residual stresses and the re-distribution as well as dissolution of copper rich phase in the weld joint. These effects increase with increase in heat input. Thus, special attention was taken to especially thick section welding of AA2219-T87 aluminium alloy. Hence, the present work describes the 25 mm-thick AA2219-T87 aluminium alloy plate butt welded by GTAW and GMAW processes using multi-pass welding procedure in double V groove design. The transverse shrinkage, conventional mechanical and metallurgical properties of both the locations on weld joints were studied. It is observed that the fair copper rich cellular (CRC network is on Side-A of both the weldments. Further, it is noticed that, the severity of weld thermal cycle near to the fusion line of HAZ is reduced due to low heat input in GTAW process which results in non dissolution of copper rich phase. Based on the mechanical and metallurgical properties it is inferred that GTAW process is used to improve the aforementioned characteristics of weld joints in comparison to GMAW process.

  14. Sensitivity Analysis for Residual Stress on DVI (Direct Vessel Injection) Nozzle Welded Joint

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Byeong Wook; Chung, Sung Ho; Lee, Jung Hun; Kim, Oak Sug [DOOSAN Heavy Industries and Construction Co. LTD, Reactor Design Team, 555 Guygok-dong Changwon (Korea, Republic of)

    2008-07-01

    Generally, any welding process produces high compressive or tensile residual stresses in the heat affected zone depending on the method, shape and procedures of the weldment. In particular, the tensile residual stresses have a considerable effect on the material strength, fatigue strength and corrosion cracking. For this reason, it is important that some knowledge of the internal stress state be deduced either from measurements or from modeling predictions. In this study, the residual stresses after a multi-pass welding process for DVI nozzle welding joint were evaluated by a numerical simulation method. The welding joint considered three weld joint angles of 40 deg., 6 deg. and 2 deg. Computations were made using a 2-D finite element model based on the simulation of cooling from the heat treatment temperature to room temperature with two cooling conditions at the inside surface. In these results, it is shown that the residual stress increased at the inner surface, when water cooling was applied to the inner surface, and axial compressive residual stress increased at the inner surface when the joint angle was decreased. (authors)

  15. Microstructure and Mechanical Properties of Friction Welding Joints with Dissimilar Titanium Alloys

    Directory of Open Access Journals (Sweden)

    Yingping Ji

    2016-05-01

    Full Text Available Titanium alloys, which are important in aerospace application, offer different properties via changing alloys. As design complexity and service demands increase, dissimilar welding of the titanium alloys becomes a particular interest. Linear friction welding (LFW is a relatively novel bond technique and has been successfully applied for joining titanium alloys. In this paper, dissimilar joints with Ti-6Al-4V and Ti-5Al-2Sn-2Zr-4Mo-4Cr alloys were produced by LFW process. Microstructure was studied via optical microscopy and scanning electron microscopy (SEM, while the chemical composition across the welded samples was identified by energy dispersive X-ray spectroscopy. Mechanical tests were performed on welded samples to study the joint mechanical properties and fracture characteristics. SEM was carried out on the fracture surface to reveal their fracture modes. A significant microstructural change with fine re-crystallization grains in the weld zone (WZ and small recrystallized grains in the thermo-mechanically affected zone on the Ti-6Al-4V side was discovered in the dissimilar joint. A characteristic asymmetrical microhardness profile with a maximum in the WZ was observed. Tensile properties of the dissimilar joint were comparable to the base metals, but the impact toughness exhibited a lower value.

  16. Structural health monitoring of multi-spot welded joints using a lead zirconate titanate based active sensing approach

    Science.gov (United States)

    Yao, Ping; Kong, Qingzhao; Xu, Kai; Jiang, Tianyong; Huo, Lin-sheng; Song, Gangbing

    2016-01-01

    Failures of spot welded joints directly reduce the load capacity of adjacent structures. Due to their complexity and invisibility, real-time health monitoring of spot welded joints is still a challenge. In this paper, a lead zirconate titanate (PZT) based active sensing approach was proposed to monitor the structural health of multi-spot welded joints in real time. In the active sensing approach, one PZT transducer was used as an actuator to generate a guided stress wave, while another one, as a sensor, detected the wave response. Failure of a spot welded joint reduces the stress wave paths and attenuates the wave propagation energy from the actuator to the sensor. A total of four specimens made of dual phase steel with spot welds, including two specimens with 20 mm intervals of spot welded joints and two with 25 mm intervals, were designed and fabricated for this research. Under tensile tests, the spot welded joints successively failed, resulting in the PZT sensor reporting decreased received energy. The energy attenuations due to the failures of joints were clearly observed by the PZT sensor signal in both the time domain and frequency domain. In addition, a wavelet packet-based spot-weld failure indicator was developed to quantitatively evaluate the failure condition corresponding to the number of failed joints.

  17. Microstructural and Mechanical Characterization of Electron Beam Welded Joints of High Strength S960QL and Weldox 1300 Steel Grades

    Directory of Open Access Journals (Sweden)

    Błacha S.

    2017-06-01

    Full Text Available The paper shows the results of metallographic examination and mechanical properties of electron beam welded joints of quenched and tempered S960QL and Weldox 1300 steel grades. The aim of this study was to examine the feasibility of producing good quality electron beam welded joints without filler material.

  18. Validation and implementation of sandwich structure bottom plate to rib weld joint in the base section of ITER Cryostat

    Energy Technology Data Exchange (ETDEWEB)

    Prajapati, Rajnikant, E-mail: rajnikant@iter-india.org [ITER-India, Institute For Plasma Research, A-29, GIDC Electronics Estate, Sector-25, Gandhinagar 382016 (India); Bhardwaj, Anil K.; Gupta, Girish; Joshi, Vaibhav; Patel, Mitul; Bhavsar, Jagrut; More, Vipul; Jindal, Mukesh; Bhattacharya, Avik; Jogi, Gaurav; Palaliya, Amit; Jha, Saroj; Pandey, Manish [ITER-India, Institute For Plasma Research, A-29, GIDC Electronics Estate, Sector-25, Gandhinagar 382016 (India); Jadhav, Pandurang; Desai, Hemal [Larsen & Toubro Limited, Heavy Engineering, Hazira Manufacturing Complex, Gujarat (India)

    2016-11-01

    Highlights: • ITER Cryostat base section sandwich structure bottom plate to rib weld joint is qualified through mock-up. • Established welding sequence was successfully implemented on all six sectors of cryostat base section. • Each layer liquid penetrant examination has been carried out for these weld joints and found satisfactory. - Abstract: Cryostat is a large stainless steel vacuum vessel providing vacuum environment to ITER machine components. The cryostat is ∼30 m in diameter and ∼30 m in height having variable thickness from 25 mm to 180 mm. Sandwich structure of cryostat base section withstands vacuum loading and limits the deformation under service conditions. Sandwich structure consists of top and bottom plates internally strengthened with radial and circular ribs. In current work, sandwich structure bottom plate to rib weld joint has been designed with full penetration joint as per ITER Vacuum Handbook requirement considering nondestructive examinations and welding feasibility. Since this joint was outside the scope of ASME Section VIII Div. 2, it was decided to validate through mock-up of bottom plate to rib joint. Welding sequence was established to control the distortion. Tensile test, macro-structural examination and layer by layer LPE were carried out for validation of this weld joint. However possibility of ultrasonic examination method was also investigated. The test results from the welded joint mock-up were found to confirm all code and specification requirements. The same was implemented in first sector (0–60°) of base section sandwich structure.

  19. Investigation of welding crack in micro laser welded NiTiNb shape memory alloy and Ti6Al4V alloy dissimilar metals joints

    Science.gov (United States)

    Yuhua, Chen; Yuqing, Mao; Weiwei, Lu; Peng, He

    2017-06-01

    Dissimilar metals of NiTiNb shape memory alloy and Ti6Al4V alloy with a same thickness of 0.2 mm were joined by micro laser welding. The effect of laser power on crack sensitivity of the weld was investigated. The results show that full penetrated welds are obtained when the laser power of 7.2 W is used, many cracks are observed in the weld. With increasing the laser power to 12 W, the number of all cracks and cracking width first increase and then decrease. By XRD analysis, three different kinds of Ti2Ni, NbNi3 and AlNbTi2 intermetallic compounds are found in the weld. According to the formation enthalpy and binary phase diagram, brittle Ti2Ni phase with more contents is existed in the weld due to final solidification, and which is the main reason of crack formation along with large stress concentration. Moreover, the welding cracks like the weld center longitudinal solidification cracks, weld metal toe transversal liquid cracks, heat-affected-zone hot cracks and crater cracks are classified in the laser welded joints. A brittle cleavage fracture with cleavage planes and river patterns in the joints is presented from the fracture surface.

  20. A comparative study of the microstructure and properties of 800 MPa microalloyed C-Mn steel welded joints by laser and gas metal arc welding

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Qian [The State Key Laboratory of Rolling and Automation of Northeastern University, Shenyang 110819 (China); Di, Hong-Shuang, E-mail: hongshuangdi_ral@126.com [The State Key Laboratory of Rolling and Automation of Northeastern University, Shenyang 110819 (China); Li, Jun-Chen [The State Key Laboratory of Rolling and Automation of Northeastern University, Shenyang 110819 (China); Wu, Bao-Qiang [National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China); Misra, R.D.K. [Laboratory for Excellence in Advanced Steel Research, Department of Metallurgical, Material and Biomedical Engineering, University of Texas at El Paso, TX 79968 (United States)

    2016-07-04

    The differences in microstructure and mechanical properties of laser beam welded (LBW) and gas metal arc welded (GMAW) joints of 800 MPa grade Nb-Ti-Mo microalloyed C-Mn steel of 5 mm thickness were studied. The study suggested that the microstructure in welded seam (WS) of GMAW was acicular ferrite and fine grained ferrite, whereas lath martensite (LM) was obtained in WS of LBW, where inclusions were finer and did not act as nucleation sites for acicular ferrite. The microstructure of coarse-grained HAZ (CGHAZ) obtained using the two welding methods was LM and granular bainite (GB), respectively. The original austenite grain size in CGHAZ of LBW was 1/3 of GMAW. The microstructure of fine-grained HAZ and mixed-grained HAZ using the two welding methods was ferrite and M-A constituents, while that of LBW was significantly fine. The hardness of LBW welded joints was higher than the base metal (BM), which was the initiation site for tensile fracture. The tensile fracture location of GMAW welded joints was in WS. The impact toughness of LBW welded joints was excellent and the impact absorption energy was similar to BM.

  1. Correlation between microstructure and hardness of a low activation ferritic steel (JLF-1) weld joint

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, N.; Muroga, T.; Nishimura, A.; Motojima, O. [National Inst. for Fusion Science (NIFS), Toki (Japan)

    1998-10-01

    Fe-Cr-W ferritic steels are candidate low activation materials for fusion reactor structural components. Under a surveillance test program of the Japanese low activation Fe-9Cr-2WVTa steel (JLF-1), JLF-1-HEAT2 was made by Japanese universities. The present paper reports the results of microstructural observation and hardness testing of JLF-1-HEAT2 and its weld joint. The relation of microstructure with local hardness and tensile properties at various positions on the weld joint was investigated, and the correlation qualitatively interpreted in terms of the martensitic lath width. (orig.) 4 refs.

  2. Modeling and analysis of novel laser weld joint designs using optical ray tracing.

    Energy Technology Data Exchange (ETDEWEB)

    Milewski, J. O. (John O.)

    2002-01-01

    Reflection of laser energy presents challenges in material processing that can lead to process inefficiency or process instability. Understanding the fundamentals of non-imaging optics and the reflective propagation of laser energy can allow process and weld joint designs to take advantage of these reflections to enhance process efficiency or mitigate detrimental effects. Optical ray tracing may be used within a 3D computer model to evaluate novel joint and fixture designs for laser welding that take advantage of the reflective propagation of laser energy. This modeling work extends that of previous studies by the author and provides comparison with experimental studies performed on highly reflective metals. Practical examples are discussed.

  3. Experimental characterization of fatigue strength in butt welded joint considering the geometry and the effect of cooling rate of the weld

    Science.gov (United States)

    Arzola, Nelson; Hernández, Edgar

    2017-05-01

    In this work the experimental characterization of fatigue strength in butt welded joints considering the geometry and the post-weld cooling cycle was performed. ASTM A-36 structural steel was used as the base metal for the shielded metal arc welding process, with welding electrode E6013. Two experimental factors were established: weld bead geometry and the post-weld cooling rate. Two levels for each factor, the welding reinforcement (1 and 3 mm), and the rate of cooling, slow (quiet air) and fast (immersion in water) are evaluated respectively. For the uniaxial fatigue tests, 8 samples were selected for each treatment for a total of 32 specimens. The mechanical and fractomechanical properties of fusion zone, heat affected zone and base metal in relation to the analysis of failure mechanisms were analysed. The fatigue crack growth rates were estimated based on the counting of microstrations. Furthermore, experimental tests, such as uniaxial tension, microindentation hardness, Charpy impact and metallographic analysis, were made to know the influence of the experimental factors in the fatigue strength. On this research, about the 78.13% of the samples obtained a resistance higher than the recommended one by class FAT 100. The results showed that the geometry of the joint is the factor of greatest influence on fatigue strength for butt welded joints; the greater the weld reinforcement the lower the fatigue strength of the joint. Although it is also important to consider other geometric factors of less impact as it is the weld toe radius and the welding chord width.

  4. Metallurgical and Corrosion Characterization of POST Weld Heat Treated Duplex Stainless Steel (uns S31803) Joints by Friction Welding Process

    Science.gov (United States)

    Asif M., Mohammed; Shrikrishna, Kulkarni Anup; Sathiya, P.

    2016-02-01

    The present study focuses on the metallurgical and corrosion characterization of post weld heat treated duplex stainless steel joints. After friction welding, it was confirmed that there is an increase in ferrite content at weld interface due to dynamic recrystallization. This caused the weldments prone to pitting corrosion attack. Hence the post weld heat treatments were performed at three temperatures 1080∘C, 1150∘C and 1200∘C with 15min of aging time. This was followed by water and oil quenching. The volume fraction of ferrite to austenite ratio was balanced and highest pit nucleation resistance were achieved after PWHT at 1080∘C followed by water quench and at 1150∘C followed by oil quench. This had happened exactly at parameter set containing heating pressure (HP):40 heating time (HT):4 upsetting pressure (UP):80 upsetting time (UP):2 (experiment no. 5). Dual phase presence and absence of precipitates were conformed through TEM which follow Kurdjumov-Sachs relationship. PREN of ferrite was decreasing with increase in temperature and that of austenite increased. The equilibrium temperature for water quenching was around 1100∘C and that for oil quenching was around 1140∘C. The pit depths were found to be in the range of 100nm and width of 1.5-2μm.

  5. Influence of friction stir welding parameters on properties of 2024 T3 aluminium alloy joints

    Directory of Open Access Journals (Sweden)

    Eramah Abdsalam M.

    2014-01-01

    Full Text Available The aim of this work is to analyse the process of friction stir welding (FSW of 3mm thick aluminium plates made of high strength aluminium alloy - 2024 T3, as well as to assess the mechanical properties of the produced joints. FSW is a modern procedure which enables joining of similar and dissimilar materials in the solid state, by the combined action of heat and mechanical work. This paper presents an analysis of the experimental results obtained by testing the butt welded joints. Tensile strength of the produced joints is assessed, as well as the distribution of hardness, micro-and macrostructure through the joints (in the base material, nugget, heat affected zone and thermo-mechanically affected zone. Different combinations of the tool rotation speed and the welding speed are used, and the dependence of the properties of the joints on these parameters of welding technology is determined. [Projekat Ministarstva nauke Republike Srbije, br. TR 34018 i br. TR 35006

  6. Finite element normal mode analysis of resistance welding jointed of dissimilar plate hat structure

    Science.gov (United States)

    Nazri, N. A.; Sani, M. S. M.

    2017-10-01

    Structural joints offer connection between structural element (beam, plate, solid etc.) in order to build a whole assembled structure. The complex behaviour of connecting elements plays a valuable role in characteristics of dynamic such as natural frequencies and mode shapes. In automotive structures, the trustworthiness arrangement of the structure extremely depends on joints. In this paper, top hat structure is modelled and designed with spot welding joint using dissimilar materials which is mild steel 1010 and stainless steel 304, using finite element software. Different types of connector elements such as rigid body element (RBE2), welding joint element (CWELD), and bar element (CBAR) are applied to represent real connection between two dissimilar plates. Normal mode analysis is simulated with different types of joining element in order to determine modal properties. Natural frequencies using RBE2, CBAR and CWELD are compared to equivalent rigid body method. Connection that gives the lowest percentage error among these three will be selected as the most reliable joining for resistance spot weld. From the analysis, it is shown that CWELD is better compared to others in term of weld joining among dissimilar plate materials. It is expected that joint modelling of finite element plays significant role in structural dynamics.

  7. Structure and Microhardness of Cu-Ta Joints Produced by Explosive Welding

    Science.gov (United States)

    Maliutina, Iu. N.; Mali, V. I.; Bataev, I. A.; Bataev, A. A.; Esikov, M. A.; Smirnov, A. I.; Skorokhod, K. A.

    2013-01-01

    The structure and microhardness of Cu-Ta joints produced by explosive welding were studied. It was found that, during explosive welding, an intermediate layer 20⋯40 μm thick with a finely dispersed heterophase structure, formed between the welded copper and tantalum plates. The structure of the layer was studied by scanning and transmission electron microscopy. Microvolumes with tantalum particles distributed in a copper matrix and microvolumes of copper particles in a tantalum matrix were detected. The tantalum particles in copper have a size of 5⋯500 nm, with a predominance of 5⋯50 nm particles. A mechanism for the formation of the finely dispersed heterophase structure in explosive welding is proposed. The microhardness of interlayers with the heterophase structure reaches 280 HV, which far exceeds the microhardness of copper (~130 HV) and tantalum (~160 HV). Many twins of deformation origin were found in the structure of the copper plate. The effect of heating temperature in the range from 100 to 900°C on the microhardness of copper, tantalum, and the Cu-Ta welded joint was studied. Upon heating to 900°C, the microhardness of the intermediate layer decreases from 280 to 150 HV. The reduction in the strength properties of the weld material is mainly due to structural transformations in copper. PMID:24453818

  8. Fatigue properties and fracture mechanism of load carrying type fillet joints with one-sided welding

    Directory of Open Access Journals (Sweden)

    Takamasa Abe

    2016-01-01

    Full Text Available The structures of the hydraulic excavator and the crane have numerous one-sided welded joints. However, attachments with box like structures are difficult to weld at both sides. Therefore, high accurate evaluation method is needed. In this study, the fatigue properties and the fracture mechanism of the load carrying type fillet joints with one-sided welding were investigated experimentally to evaluate its fatigue damage with high accuracy based on the experimental results. As the results, fatigue cracks in the test piece initiated from the tip of the unwelded portion and propagated into the welding materials. Multiple welding defects were observed in the unwelded portion, but did not appear to be crack origins. Although these welding defects affected the direction of crack propagation they exerted minimal influence. The three-dimensional observations revealed that fatigue cracks initiate at an early stage of the fatigue development. We infer that the fatigue lifetime is chiefly governed by the crack propagation lifetime. Cracks were initiated at multiple sites in the test piece. As the number of cycles increased, these cracks propagated and combined. So considering the combination of cracks from multiple crack origins is important for a precise evaluation of fatigue damage.

  9. Fatigue properties and fracture mechanism of load carrying type fillet joints with one-sided welding

    Directory of Open Access Journals (Sweden)

    Takamasa Abe

    2016-02-01

    Full Text Available The structures of the hydraulic excavator and the crane have numerous one-sided welded joints. However, attachments with box like structures are difficult to weld at both sides. Therefore, high accurate evaluation method is needed. In this study, the fatigue properties and the fracture mechanism of the load carrying type fillet joints with one-sided welding were investigated experimentally to evaluate its fatigue damage with high accuracy based on the experimental results. As the results, fatigue cracks in the test piece initiated from the tip of the unwelded portion and propagated into the welding materials. Multiple welding defects were observed in the unwelded portion, but did not appear to be crack origins. Although these welding defects affected the direction of crack propagation they exerted minimal influence. The three-dimensional observations revealed that fatigue cracks initiate at an early stage of the fatigue development. We infer that the fatigue lifetime is chiefly governed by the crack propagation lifetime. Cracks were initiated at multiple sites in the test piece. As the number of cycles increased, these cracks propagated and combined. So considering the combination of cracks from multiple crack origins is important for a precise evaluation of fatigue damage.

  10. Investigation on Mechanical Properties of 9%Cr/CrMoV Dissimilar Steels Welded Joint

    Science.gov (United States)

    Liu, Xia; Lu, Fenggui; Yang, Renjie; Wang, Peng; Xu, Xiaojin; Huo, Xin

    2015-04-01

    Advanced 9%Cr steel with good heat resistance and CrMoV with good toughness were chosen as candidate materials to fabricate combined rotor for steam turbine operating at over 620 °C. But the great difference in base metals properties presents a challenge in achieving sound defect-free joint with optimal properties in dissimilar welded rotor. In this paper, appropriate selection of filler metal, welding parameters, and post-weld heat treatment was combined to successfully weld 1100-mm-diameter 9%Cr/CrMoV dissimilar experimental rotor through ultra-narrow gap submerge arc welding. Some properties such as hardness, low-cycle fatigue (LCF), and high-cycle fatigue (HCF) combined with microstructural characterization qualify the integrity of the weld. Microstructural analysis indicated the presence of high-temperature tempered martensite as the phase responsible for the improved properties obtained in the weld. The Coffin-Manson parameters were obtained by fitting the data in LCF test, while the conditional fatigue strength was derived from the HCF test based on S-N curve. Analysis of hardness profile showed that the lowest value occurred at heat-affected zone adjacent to base metal which represents the appropriate location of fracture for the samples after LCF and HCF tests.

  11. Fatigue Life Improvement for Cruciform Welded Joint by Mechanical Surface Treatment using Hammer Peening and UNSM

    Science.gov (United States)

    Han, Seung-Ho; Han, Jeong-Woo; Nam, Yong-Yun; Cho, In-Ho

    For the improvement of fatigue strength of welded structures, mechanical post treatments have been applied in various industrial fields and have in most cases been founded to give substantial increases in their fatigue lives. These methods, generally, consist of the modification of weld toe geometry and the introduction of compressive residual stresses. In mechanical surface treatments, e.g. PHP (pneumatic hammer peening) and UNSM (ultrasonic nano-crystal surface modification), the weld profile is modified due to remove or reduce minute crack-like flaws, and compressive residual stresses are also induced. In this study, a pneumatic hammer peening procedure and a UNSM device were introduced, and a quantitative measure of fatigue strength improvement was performed. The fatigue strength at 2 × 106 cycles of hammer-peened and UNSM treated on a non-load carrying cruciform welded joint shows 220 and 260MPa, respectively, which are more than two times higher than that of as-welded specimen. Especially, the surface layer in the vicinity weld toe treated by the UNSM provides nano-crystal structure created by an ultrasonic cold forging and introduces very high welding residual stress in compression.

  12. Double Fillet Welding of Carbon Steel T-Joint by Double Channel Shielding Gas Metal Arc Welding Method Using Metal Cored Wire

    Directory of Open Access Journals (Sweden)

    Mert T.

    2017-06-01

    Full Text Available Low carbon steel material and T-joints are frequently used in ship building and steel constructions. Advantages such as high deposition rates, high quality and smooth weld metals and easy automation make cored wires preferable in these industries. In this study, low carbon steel materials with web and flange thicknesses of 6 mm, 8 mm and 10 mm were welded with conventional GMAW and double channel shielding gas metal arc welding (DMAG method to form double fillet T-joints using metal cored wire. The difference between these two methods were characterized by measurements of mean welding parameters, Vickers hardness profiles, weld bead and HAZ geometry of the joints and thermal camera temperature measurements. When weld bead and HAZ geometries are focused, it was seen filler metal molten area increased and base metal molten area decreased in DMAG of low carbon steel. When compared with traditional GMAW, finer and acicular structures in weld metal and more homogenous and smaller grains in HAZ are obtained with double channel shielding gas metal arc welding.

  13. A study on an efficient prediction of welding deformation for T-joint laser welding of sandwich panel PART I : Proposal of a heat source model

    Directory of Open Access Journals (Sweden)

    Jae Woong Kim

    2013-09-01

    Full Text Available The use of I-Core sandwich panel has increased in cruise ship deck structure since it can provide similar bending strength with conventional stiffened plate while keeping lighter weight and lower web height. However, due to its thin plate thickness, i.e. about 4~6 mm at most, it is assembled by high power CO2 laser welding to minimize the welding deformation. This research proposes a volumetric heat source model for T-joint of the I-Core sandwich panel and a method to use shell element model for a thermal elasto-plastic analysis to predict welding deformation. This paper, Part I, focuses on the heat source model. A circular cone type heat source model is newly suggested in heat transfer analysis to realize similar melting zone with that observed in experiment. An additional suggestion is made to consider negative defocus, which is commonly applied in T-joint laser welding since it can provide deeper penetration than zero defocus. The proposed heat source is also verified through 3D thermal elasto-plastic analysis to compare welding deformation with experimental results. A parametric study for different welding speeds, defocus values, and welding powers is performed to investigate the effect on the melting zone and welding deformation. In Part II, focuses on the proposed method to employ shell element model to predict welding deformation in thermal elasto-plastic analysis instead of solid element model.

  14. Microstructures and Mechanical Properties of Weld Metal and Heat-Affected Zone of Electron Beam-Welded Joints of HG785D Steel

    Science.gov (United States)

    Zhang, Qiang; Han, Jianmin; Tan, Caiwang; Yang, Zhiyong; Wang, Junqiang

    2016-12-01

    Vacuum electron beam welding (EBW) process was employed to butt weld 10-mm-thick HG785D high-strength steels. The penetration into the steel was adjusted by beam current. Microstructures at weld metal and heat-affected zone (HAZ) regions were comparatively observed. Mechanical properties of the EBWed joints including Vickers hardness, tensile and Charpy impact tests were evaluated. The results indicated that microstructures at the weld metal consisted of coarse lath martensite and a small amount of acicular martensite, while that in the HAZ was tempered sorbite and martensite. The grain size in the weld metal was found to be larger than that in the HAZ, and its proportion in weld metal was higher. The hardness in the weld metal was higher than the HAZ and base metal. The tensile strength and impact toughness in the HAZ was higher than that in the weld metal. All the behaviors were related to microstructure evolution caused by higher cooling rates and state of base metal. The fracture surfaces of tensile and impact tests on the optimized joint were characterized by uniform and ductile dimples. The results differed significantly from that obtained using arc welding process.

  15. Optimization of weld characteristics of friction welded AA 6061-AA 6351 joints using grey-principal component analysis (G-PCA)

    Energy Technology Data Exchange (ETDEWEB)

    Adalarasan, R.; Santhanakumar, M. [Saveetha Engineering College, Chennai (India); Sundaram, A. Shanmuga [Sree Sastha Institute of Engineering and Technology, Chennai (India)

    2014-01-15

    Friction welding is a solid state joining process in which the quality of welded joint is influenced by the input parameter setting. The objective of the present study is to conduct experimental investigation of the bond strength and hardness of the friction welded joints involving AA 6061 and AA 6351 alloys by conducting experiments designed by Taguchi's L{sub 9} orthogonal matrix array. A systematic approach becomes essential to find the optimal setting of friction welding parameters. Hence a new approach named grey-principal component analysis (G-PCA) is presented in which the principal component analysis (PCA) is used to generate weights for the grey relational coefficients obtained in the grey relational analysis (GRA). The results of the confirmation experiment conducted with the optimal setting predicted by the G-PCA have shown improvements in the performance characteristics. Hence G-PCA can be used for experimental welding optimization.

  16. Re-analysis of fatigue data for welded joints using the notch stress approach

    DEFF Research Database (Denmark)

    Pedersen, Mikkel Melters; Mouritsen, Ole Ø.; Hansen, Michael Rygaard

    2010-01-01

    Experimental fatigue data for welded joints have been collected and subjected to re-analysis using the notch stress approach according to IIW recommendations. This leads to an overview regarding the reliability of the approach, based on a large number of results (767 specimens). Evidently......, there are some limitations in the approach regarding mild notch joints, such as butt joints, which can be assessed non-conservatively. In order to alleviate this problem, an increased minimum notch factor of Kw>2.0 is suggested instead of the current recommendation of Kw>1.6. The data for most fillet......-welded joints agree quite well with the FAT 225 curve; however a reduction to FAT 200 is suggested in order to achieve approximately the same safety as observed in the nominal stress approach....

  17. High-power Laser Welding of Thick Steel-aluminum Dissimilar Joints

    Science.gov (United States)

    Lahdo, Rabi; Springer, André; Pfeifer, Ronny; Kaierle, Stefan; Overmeyer, Ludger

    According to the Intergovernmental Panel on Climate Change (IPCC), a worldwide reduction of CO2-emissions is indispensable to avoid global warming. Besides the automotive sector, lightweight construction is also of high interest for the maritime industry in order to minimize CO2-emissions. Using aluminum, the weight of ships can be reduced, ensuring lower fuel consumption. Therefore, hybrid joints of steel and aluminum are of great interest to the maritime industry. In order to provide an efficient lap joining process, high-power laser welding of thick steel plates (S355, t = 5 mm) and aluminum plates (EN AW-6082, t = 8 mm) is investigated. As the weld seam quality greatly depends on the amount of intermetallic phases within the joint, optimized process parameters and control are crucial. Using high-power laser welding, a tensile strength of 10 kN was achieved. Based on metallographic analysis, hardness tests, and tensile tests the potential of this joining method is presented.

  18. Comparative Analysis of Welded and Adhesive Joints Strength Made of Acid-Resistant Stainless Steel Sheets

    Directory of Open Access Journals (Sweden)

    Izabela Miturska

    2017-12-01

    Full Text Available The article presents the selected results of strength tests on the effectiveness of bonding high-alloy steel 1.4310. Sheet steel is one of the materials that are difficult to activate energy. Effective joining of it is difficult, requires selection of the appropriate bonding technology. The paper focuses on the comparative tests the shear strength of one-single lap welded and bonded joints. The welding process was performed 3 groups of samples TIG welding and argon, where the variable value of the welding process was current: 60A, 70A, 80A. The adhesion process was performed in 6 groups of samples which differed in the method of surface preparation and the type of the adhesive. Adhesive joints were made by using adhesive of epoxy resin and a hardener: Epidian 61/TFF at a mass ratio of 100:22 and Epidian 61/IDA at a mass ratio of 100:40. As a way of surface preparation applied 3 different, but simplified and environmentally friendly methods of surface preparation: degreasing with using cleaner Loctite 7061, abrasive machining with P320 and degreasing and grinding with abrasive T800 and degreasing were used. Make joints and curing the adhesive joints were carried out at ambient temperature. Analyzed the joints were tested destructive - which set out the shear strength, in accordance with DIN EN 1465 on the testing machine Zwick / Roell Z150. Based on the results of research it was found that better results were obtained for the maximum welded joints, but this result was similar to the maximum value of the strength of the adhesive bond.

  19. Evaluation of the diffusivity and susceptibility to hydrogen embrittlement of API 5L X80 steel welded joints

    Directory of Open Access Journals (Sweden)

    B Araújo

    2016-09-01

    Full Text Available This paper presents a study of susceptibility to hydrogen embrittlement of API 5L X80 steel welded joints by SMAW and GTAW processes. By varying the consumables used and the use of the same interpass temperature three different welded joints were obtained. Tests of hydrogen embrittlement susceptibility were performed according to ASTM G129-2006 with an aqueous solution (Solution A - TM0177/2005 NACE sodium thiosulfate (Na2S2O3 replacing the bubbling of H2S. From the elongation values was observed that the joint obtained in all welding conditions showed susceptibility to hydrogen embrittlement, which was determined by the elongation ratio. The joints that showed higher levels of hardness showed higher susceptibility to hydrogen embrittlement. The joints obtained with higher welding speeds for the same amount of heat input presented a reduction in the rate of hydrogen embrittlement. All joints tested in solution showed fracture surfaces with quasi cleavage zones.

  20. Microstructure and Properties of TIG/FSW Welded Joints of a New Al-Zn-Mg-Sc-Zr Alloy

    Science.gov (United States)

    Lei, Xuefeng; Deng, Ying; Peng, Yongyi; Yin, Zhimin; Xu, Guofu

    2013-09-01

    A new Al-Zn-Mg-Sc-Zr alloy with low Sc content was welded by tungsten inert gas (TIG) and friction stir welding (FSW) techniques. The microstructure and properties of those two welded joints were investigated by property tests and microstructural observations. The results show that the new Al-Zn-Mg-Sc-Zr alloy has desirable welding property. The ultimate tensile strength and welding coefficient of the TIG joint reach 405 MPa and 76.7%, respectively, and in FSW joint those property values reach 490 MPa and 92.6%, respectively. The studied base metal has a deformed fibrous subgrains structure, many nano-scaled Al3(Sc,Zr) particles, and very fine aging precipitates. In the TIG joint, the fusion zone consists of coarsened dendritic grains and the heat-affected zone (HAZ) has fibrous micro-scaled subgrains. The FSW welded joint is characterized by a weld nugget zone, thermo-mechanically affected zone (TMAZ), and HAZ. Due to plastic deformation around the rotating pin and anti-recrystallized effectiveness of Al3(Sc,Zr) particles, the weld nugget zone has a very fine subgrain structure. The TMAZ experiences some dissolution of aging precipitates. Coarsening of aging precipitates was observed in the HAZ. The better mechanical properties of the FSW joint are derived from a fine subgrain structure and homogeneous chemical compositions.

  1. Application of electrochemical methods for the investigation of intergranular corrosion welded joint austenitic stainless steel 19Cr-9Ni

    Directory of Open Access Journals (Sweden)

    Jegdić Bore V.

    2011-01-01

    Full Text Available Sensitization degree of the austenitic stainless steel welded joints was investigated by electrochemical methods of the double loop electrochemical potentiokinetic reactivation (DL EPR in H2SO4 + KSCN solution, and by the measurement of corrosion potential of the steel in the drop of the solution of HNO3 + FeCl3 + HCl. The welded joints were tested by X-ray radiographic method in order to check the presence of the weld defects. Grain size of the base metal and the welded joints were determined by optical microscopy. Good agreement between the results obtained by different electrochemical methods was obtained. Heat-affected zone (HAZ of the austenitic stainless steel welded joints has shown significant degree of sensitization. The double loop electrochemical potentiokinetic method gave quantitative evidence about susceptibility of the stainless steel to intergranular corrosion.

  2. ANSYS Simulation of Residual Strains in Butt-welded Joints

    Directory of Open Access Journals (Sweden)

    A. Atroshenko

    2014-07-01

    Full Text Available The effect of thermal-strain cycle on residual strains in thin-walled circular seams of cylindrical shells using TIG butt welds was studied. Estimates were calculated using numerical modelling. The structure was made of corrosion-resistant austenitic steels.

  3. Upsetting Butt Edge Increases Weld-Joint Strength

    Science.gov (United States)

    Vesco, D.

    1964-01-01

    Mechanical upsetting /a mode of cold forging/ of butt edges to be welded is accomplished by the use of hydraulic rams and pressure rollers. The mechanical upsetting increases the thickness of the material in the heat-affected zone and compensates for the lower specific strength per unit thickness common to this area.

  4. Experimental Investigation and Stochastic Modelling of the Fatigue Behaviour of Welded Steel Joints

    DEFF Research Database (Denmark)

    Lassen, Tom

    The present report describes the fatigue behaviour of surface cracks in welded steel joints. Emphasis is laid on fracture mechanics modelling and the stochastic nature of the fatigue process. Various sources which may contribute to the observed scatter in time to crack initiation and time spent...

  5. Ductile damage development in friction stir welded aluminum (AA2024) joints

    DEFF Research Database (Denmark)

    Nielsen, Kim Lau

    2008-01-01

    Ductile damage development in a friction stir welded aluminum joint subjected to tension is analyzed numerically by FE-analysis, based on a total Lagrangian formulation. An elastic-viscoplastic constitutive relation that accounts for nucleation and growth of microvoids is applied. Main focus in t...

  6. Digital image correlation in analysis of striffness in local zones of welded joints

    Czech Academy of Sciences Publication Activity Database

    Milosevic, M.; Milosevic, N.J.; Sedmak, S.; Tatic, U.; Mitrovic, N.; Hloch, Sergej; Jovicic, R.

    2016-01-01

    Roč. 23, č. 1 (2016), s. 19-24 ISSN 1330-3651 Institutional support: RVO:68145535 Keywords : Aramis software * digital image correlation * strain analysis * stiffness * welded joints Subject RIV: JQ - Machines ; Tools Impact factor: 0.723, year: 2016 http://hrcak.srce.hr/file/225545

  7. The effect of micro-swinging on joint formation in linear friction welding

    Directory of Open Access Journals (Sweden)

    Wenya Li

    2014-07-01

    Full Text Available A 3D Eulerian numerical model was developed to investigate the effect of micro-swing on joint formation during workpiece oscillation in linear friction welding (LFW. The temperature field and axial shortening history for different amplitudes of micro-swing have been studied. Results show that the amplitude of micro-swing influences flash morphology and axial shortening. The micro-swing contributes to the extrusion of viscoplastic metal and the formation of flash during the LFW process. Flash volume and axial shortening increase as the amplitude of micro-swing becomes larger. When the amplitude of micro-swing is more than a critical value, a sudden change of axial shortening (different from the period of the oscillation cycle would occur at certain welding time, which change would also have a periodic nature. Although different amplitudes of micro-swing affect joint morphology, the inner temperature field and the highest temperature of joints remain constant. The high temperature region inside the joints remains about the same, when the amplitude of micro-swing is constant. This indicates that the heat generated through plastic deformation could maintain the welding process, and so that the welding process would enter the equilibrium phase.

  8. Effect of Stress Relief Annealing on Microstructure & Mechanical Properties of Welded Joints Between Low Alloy Carbon Steel and Stainless Steel

    Science.gov (United States)

    Nivas, R.; Das, G.; Das, S. K.; Mahato, B.; Kumar, S.; Sivaprasad, K.; Singh, P. K.; Ghosh, M.

    2017-01-01

    Two types of welded joints were prepared using low alloy carbon steel and austenitic stainless steel as base materials. In one variety, buttering material and weld metal were Inconel 82. In another type, buttering material and weld metal were Inconel 182. In case of Inconel 82, method of welding was GTAW. For Inconel 182, welding was done by SMAW technique. For one set of each joints after buttering, stress relief annealing was done at 923 K (650 °C) for 90 minutes before further joining with weld metal. Microstructural investigation and sub-size in situ tensile testing in scanning electron microscope were carried out for buttered-welded and buttered-stress relieved-welded specimens. Adjacent to fusion boundary, heat-affected zone of low alloy steel consisted of ferrite-pearlite phase combination. Immediately after fusion boundary in low alloy steel side, there was increase in matrix grain size. Same trend was observed in the region of austenitic stainless steel that was close to fusion boundary between weld metal-stainless steel. Close to interface between low alloy steel-buttering material, the region contained martensite, Type-I boundary and Type-II boundary. Peak hardness was obtained close to fusion boundary between low alloy steel and buttering material. In this respect, a minimum hardness was observed within buttering material. The peak hardness was shifted toward buttering material after stress relief annealing. During tensile testing no deformation occurred within low alloy steel and failure was completely through buttering material. Crack initiated near fusion boundary between low alloy steel-buttering material for welded specimens and the same shifted away from fusion boundary for stress relieved annealed specimens. This observation was at par with the characteristics of microhardness profile. In as welded condition, joints fabricated with Inconel 82 exhibited superior bond strength than the weld produced with Inconel 182. Stress relief annealing

  9. Tensile strength and corrosion resistance of brazed and laser-welded cobalt-chromium alloy joints.

    Science.gov (United States)

    Zupancic, Rok; Legat, Andraz; Funduk, Nenad

    2006-10-01

    The longevity of prosthodontic restorations is often limited due to the mechanical or corrosive failure occurring at the sites where segments of a metal framework are joined together. The purpose of this study was to determine which joining method offers the best properties to cobalt-chromium alloy frameworks. Brazed and 2 types of laser-welded joints were compared for their mechanical and corrosion characteristics. Sixty-eight cylindrical cobalt-chromium dental alloy specimens, 35 mm long and 2 mm in diameter, were cast. Sixteen specimens were selected for electrochemical measurements in an artificial saliva solution and divided into 4 groups (n=4). In the intact group, the specimens were left as cast. The specimens of the remaining 3 groups were sectioned at the center, perpendicular to the long-axis, and were subsequently rejoined by brazing (brazing group) or laser welding using an X- or I-shaped joint design (X laser and I laser groups, respectively). Another 16 specimens were selected for electrochemical measurements in a more acidic artificial saliva solution. These specimens were also divided into 4 groups (n=4) as described above. Electrochemical impedance spectroscopy and potentiodynamic polarization were used to assess corrosion potentials, breakdown potentials, corrosion current densities, total impedances at lowest frequency, and polarization charge-transfer resistances. The remaining 36 specimens were used for tensile testing. They were divided into 3 groups in which specimen pairs (n=6) were joined by brazing or laser welding to form 70-mm-long cylindrical rods. The tensile strength (MPa) was measured using a universal testing machine. Differences between groups were analyzed using 1-way analysis of variance (alpha=.05). The fracture surfaces and corrosion defects were examined with a scanning electron microscope. The average tensile strength of brazed joints was 792 MPa and was significantly greater (Pcobalt-chromium alloy joints, but strength is

  10. A comparative evaluation of low-cycle fatigue behavior of type 316LN base metal, 316 weld metal, and 316LN/316 weld joint

    Science.gov (United States)

    Valsan, M.; Sundararaman, D.; Rao, K. Bhanu Sankara; Mannan, S. L.

    1995-05-01

    A comparative evaluation of the low-cycle fatigue (LCF) behavior of type 316LN base metal, 316 weld metal, and 316LN/316 weld joints was carried out at 773 and 873 K. Total strain-controlled LCF tests were conducted at a constant strain rate of 3 × 10-3 s-1 with strain amplitudes in the range ±0.20 to ±1.0 pct. Weld pads with single V and double V configuration were prepared by the shielded metal-arc welding (SMAW) process using 316 electrodes for weld-metal and weld-joint specimens. Optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) of the untested and tested samples were carried out to elucidate the deformation and the fracture behavior. The cyclic stress response of the base metal shows a very rapid hardening to a maximum stress followed by a saturated stress response. Weld metal undergoes a relatively short initial hardening followed by a gradual softening regime. Weld joints exhibit an initial hardening and a subsequent softening regime at all strain amplitudes, except at low strain amplitudes where a saturation regime is noticed. The initial hardening observed in base metal has been attributed to interaction between dislocations and solute atoms/complexes and cyclic saturation to saturation in the number density of slip bands. From TEM, the cyclic softening in weld metal was ascribed to the annihilation of dislocations during LCF. Type 316LN base metal exhibits better fatigue resistance than weld metal at 773 K, whereas the reverse holds true at 873 K. The weld joint shows the lowest life at both temperatures. The better fatigue resistance of weld metal is related to the brittle transformed delta ferrite structure and the high density of dislocations at the interface, which inhibits the growth rate of cracks by deflecting the crack path. The lower fatigue endurance of the weld joint was ascribed to the shortening of the crack initiation phase caused by surface intergranular crack initiation and to the poor

  11. Microstructure and mechanical properties of laser welded DP600 steel joints

    Energy Technology Data Exchange (ETDEWEB)

    Farabi, N. [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Chen, D.L., E-mail: dchen@ryerson.ca [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Li, J.; Zhou, Y. [Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1 (Canada); Dong, S.J. [School of Mechanical Engineering, Hubei University of Technology, Wuhan, Hubei (China)

    2010-02-15

    To reduce fuel consumption and greenhouse gas emissions, dual phase (DP) steels have been considered for automotive applications due to their higher tensile strength, better initial work hardening along with larger elongation compared to conventional grade of steels. In such applications welding and joining have to be involved, which would lead to a localized alteration of materials and create potential safety and reliability issues under cyclic loading. The aim of this investigation was to evaluate microstructural change after laser welding and its effect on the tensile and fatigue properties in DP600 steel. The welding resulted in a significant increase of hardness in the fusion zone, but also the formation of a soft zone in the outer heat-affected zone (HAZ). While the ductility decreased after welding, the yield strength increased and the ultimate tensile strength remained almost unchanged. Fatigue life at higher stress amplitudes was almost the same between the base metal and welded joints despite slightly lower fatigue limit after welding. Tensile fracture and fatigue failure at higher stress amplitudes occurred at the outer HAZ. Fatigue crack initiation was observed to occur from the specimen surface and crack propagation was characterized by the characteristic mechanism of striation formation. Dimples and deformation bands were observed in the fast propagation area.

  12. Thermo-mechanic and Microstructural Analysis of an Underwater Welding Joint

    Directory of Open Access Journals (Sweden)

    Pedro Hernández Gutiérrez

    Full Text Available Abstract The aim of this research is to present a comparative analysis between theoretical and experimental thermal fields as well as a microstructural behaviour and residual stresses applying multiple weld beads in the joint of two API 5L X52 pipe sections. The thermal field, microstructural and residual stresses were numerically modelled through the finite element method (FEM and compared to experimentally. The simulation conditions used in the FEM analysis were similar considerations to the underwater welding conditions. The finite element analysis was carried out, first by a non-linear transient thermal analysis for obtaining the global temperature history generated during the underwater welding process. Subsequently, a microstructural behaviour was determined using the temperatures distribution obtained in the pipe material by calculating the structural transformations of the material during the welding process, and finally a stress analysis was developed using the temperatures obtained from the thermal analysis. It was found that this simulation method can be used efficiently to determinate with accuracy the optimum welding parameters of this kind of weld applications.

  13. Strategies for reduced distortion during laser beam welding of shaft-hub joints

    Energy Technology Data Exchange (ETDEWEB)

    Buschenhenke, F.; Seefeld, T.; Vollertsen, F. [Bremer Institut fuer angewandte Strahltechnik, Bremen (Germany)

    2012-01-15

    The joining of shaft-hub connections is gaining in importance in the area of power train applications. The quality demands in abrasion and power transmission are playing a major role. Dimensional as well as repeat accuracies are essential quality criteria, which have to be focused on. The understanding of the whole process chain in view of different distortion potentials introduced in each processing step provides the ability to control the distortion of the welded components. The laser beam sources of the new generation permit a high power welding process and high beam quality at the same time. These laser beams are capable of producing deep and narrow weld seams. This work deals with compensation strategies of deformations during laser beam welding in axial welded shaft-hub joints made of steel. Furthermore, simultaneous welding with two laser beams and the influence of the process chain were investigated to characterise the influence of these strategies tactile differential measurements were done. The results were discussed regarding numerical calculations in the FEM application SYSWELD. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Recommendations for fatigue design of welded joints and components

    CERN Document Server

    Hobbacher, A F

    2016-01-01

    This book provides a basis for the design and analysis of welded components that are subjected to fluctuating forces, to avoid failure by fatigue. It is also a valuable resource for those on boards or commissions who are establishing fatigue design codes. For maximum benefit, readers should already have a working knowledge of the basics of fatigue and fracture mechanics. The purpose of designing a structure taking into consideration the limit state for fatigue damage is to ensure that the performance is satisfactory during the design life and that the survival probability is acceptable. The latter is achieved by the use of appropriate partial safety factors. This document has been prepared as the result of an initiative by Commissions XIII and XV of the International Institute of Welding (IIW).

  15. Heat input effect of friction stir welding on aluminum alloy AA 6061-T6 welded joint

    Czech Academy of Sciences Publication Activity Database

    Sedmak, A.; Kumar, R.; Chattopadhyaya, S.; Hloch, Sergej; Tadić, S.; Djurdjević, A. A.; Čeković, I. R.; Dončeva, E.

    2016-01-01

    Roč. 20, č. 2 (2016), s. 637-641 ISSN 0354-9836 Institutional support: RVO:68145535 Keywords : friction stir welding * defect * heat input * maximum temperature Subject RIV: JQ - Machines ; Tools Impact factor: 1.093, year: 2016 http://www.doiserbia.nb.rs/img/doi/0354-9836/2016/0354-98361500147D.pdf

  16. Corrosion behavior of dissimilar weld joint of 316L and alloy 182 filler metal with different post-weld heat treatments in saline environments

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Joao H.N.; Santos, Neice F.; Esteves, Luiza; Campos, Wagner R.C.; Rabello, Emerson G., E-mail: joao.garcia@cdtn.br, E-mail: nfs@cdtn.br, E-mail: luiza.esteves@cdtn.br, E-mail: wrcc@cdtn.br, E-mail: egr@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (SEIES/CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Serviço de Integridade Estrutural

    2017-11-01

    Austenitic stainless steel and nickel alloys are widely used in nuclear reactors components and other plants of energy generation, chemical and petrochemical industries, due to their high corrosion resistance. These metals require post weld heat treatment (PWHT) to relieve stresses from the welding processes, although it can lead to a degradation of the weld microstructure. The aim of this work was to evaluate the influence of different PWHT on corrosion behavior of a dissimilar weld joint of two AISI 316L austenitic stainless steel plates with nickel alloy as filler material in saline environments. The material was submitted to heat treatments for three hours at 600, 700 and 800 °C. The weld joint was examined by optical microscopy to determine the effects of PWHT in the microstructure. The corrosion behavior of the samples before and after heat treatment was evaluated using cyclic potentiodynamic polarization (CPP) in sodium chloride solutions (19% v/v) and pH 4.0 at room temperature. Metallographic analyses showed that delta ferrite dissolute with PWHT temperature increase. CPP curves demonstrated an increase of pitting corrosion resistance as the PWHT temperature increases, although the pit size has been increased. The heat treated weld joint at 600 °C showed corrosion resistance close to the as welded material. (author)

  17. Effect of Tool Geometry and Welding Speed on Mechanical Properties and Microstructure of Friction Stir Welded Joints of Aluminium Alloys AA6082-T6

    Directory of Open Access Journals (Sweden)

    Patil Hiralal Subhash

    2014-12-01

    Full Text Available Friction stir welding is a solid state innovative joining technique, widely being used for joining aluminium alloys in aerospace, marine automotive and many other applications of commercial importance. The welding parameters and tool pin profile play a major role in deciding the weld quality. In this paper, an attempt has been made to understand the influences of welding speed and pin profile of the tool on friction stir welded joints of AA6082-T6 alloy. Three different tool pin profiles (tapered cylindrical four flutes, triangular and hexagonal have been used to fabricate the joints at different welding speeds in the range of 30 to 74 mm/min. Microhardness (HV and tensile tests performed at room temperature were used to evaluate the mechanical properties of the joints. In order to analyse the microstructural evolution of the material, the weld’s cross-sections were observed optically and SEM observations were made of the fracture surfaces. From this investigation it is found that the hexagonal tool pin profile produces mechanically sound and metallurgically defect free welds compared to other tool pin profiles.

  18. A mathematical model for a pseudo-plastic welding joint

    OpenAIRE

    Iosifescu, Oana; Juntharee, Pongpol; Licht, Christian; Michaille, Gérard

    2009-01-01

    An elementary situation in welding involves the perfect assembly of two adherents and a strong adhesive occupying a thin layer. The bulk energy density of the hyperelastic adherents grows superlinearly while that of the pseudo-plastic adhesive grows linearly with a stiffness of the order of the inverse of its thickness epsilon. We propose a simplified but accurate model by studying the asymptotic behavior, when epsilon goes to zero, through variational convergence methods: at the limit, the i...

  19. Effect of Manganese on the Mechanical Properties of Welded As-Cast Aluminium Joint

    Directory of Open Access Journals (Sweden)

    Isiaka Oluwole OLADELE

    2013-11-01

    Full Text Available The effects of manganese on the mechanical properties of welded and un-weld as-cast 6063 aluminium alloy has been studied. Alloys of varying percentage of manganese from 0.019 to 0.24 were sand cast. A wooden pattern of dimensions 200×100×100mm was used, the aluminium (500g was charged into an induction furnace and heated to 750°C for 15 minutes, this was followed by the addition of weighed powdered manganese, stirred and heated at the same temperature for another 5 minutes and thereafter poured into the already prepared sand mould at a temperature of 690°C. The as-cast aluminium samples, were sectioned into two equal parts of 45mm each using power hack saw; a weld groove was created between the sides of the samples using an electric hand grinding machine, the groove served as the path along which the filler metal was deposited on the aluminium, a single v butt joint was produced from each sample and Metal Inert Gas Welding process was carried out to produce the required joint design. The different cast samples were machined to the different test pieces after which they were assessed to determine their mechanical properties (impact, hardness (welded joint and heat affected zone and tensile tests. The microstructures of the welded samples were also studied. From the results, it was observed that Sample F, which has 0.172% Mn, has the best hardness and impact strength while sample C with 0.160% Mn has the highest ultimate tensile strength.

  20. Influence of structure on static cracking resistance and fracture of welded joints of pipe steels of strength class K60

    Science.gov (United States)

    Tereshchenko, N. A.; Tabatchikova, T. I.; Yakovleva, I. L.; Makovetskii, A. N.; Shander, S. V.

    2017-07-01

    The static cracking resistance of a number of welded joints made from pipe steels of K60 strength class has been determined. It has been established that the deformation parameter CTOD varies significantly at identical parameters of weldability of steels. The character of fracture has been investigated and the zone of local brittleness of welded joints has been studied. It has been shown that the ability of a metal to resist cracking is determined by the austenite grain size and by the bainite morphology in the region of overheating in the heat-affected zone of a welded joint.

  1. Local strain energy density for the fatigue assessment of hot dip galvanized welded joints: some recent outcomes

    Directory of Open Access Journals (Sweden)

    M. Peron

    2017-10-01

    Full Text Available Since in literature only data about the effect of the hot-dip galvanizing coating on fatigue behavior of unnotched specimens are available, whereas very few for notched components and none for welded joints, the aim of this paper is to partially fill this lack of knowledge comparing fatigue strength of uncoated and hot-dip galvanized fillet welded cruciform joints made of structural steel S355 welded joints, subjected to a load cycle R = 0. 34. The results are shown in terms of stress range ?s and of the averaged strain energy density range DW in a control volume of radius R0 = 0.28 mm

  2. Numerical investigation on stress corrosion cracking behavior of dissimilar weld joints in pressurized water reactor plants

    Directory of Open Access Journals (Sweden)

    Lingyan Zhao

    2014-07-01

    Full Text Available There have been incidents recently where stress corrosion cracking (SCC observed in the dissimilar metal weld (DMW joints connecting the reactor pressure vessel (RPV nozzle with the hot leg pipe. Due to the complex microstructure and mechanical heterogeneity in the weld region, dissimilar metal weld joints are more susceptible to SCC than the bulk steels in the simulated high temperature water environment of pressurized water reactor (PWR. Tensile residual stress (RS, in addition to operating loads, has a great contribution to SCC crack growth. Limited experimental conditions, varied influence factors and diverging experimental data make it difficult to accurately predict the SCC behavior of DMW joints with complex geometry, material configuration, operating loads and crack shape. Based on the film slip/dissolution oxidation model and elastic-plastic finite element method (EPFEM, an approach is developed to quantitatively predict the SCC growth rate of a RPV outlet nozzle DMW joint. Moreover, this approach is expected to be a pre-analytical tool for SCC experiment of DMW joints in PWR primary water environment.

  3. Experimental and numerical evaluation of the fatigue behaviour in a welded joint

    Science.gov (United States)

    Almaguer, P.; Estrada, R.

    2014-07-01

    Welded joints are an important part in structures. For this reason, it is always necessary to know the behaviour of them under cyclic loads. In this paper a S - N curve of a butt welded joint of the AISI 1015 steel and Cuban manufacturing E6013 electrode is showed. Fatigue tests were made in an universal testing machine MTS810. The stress ratio used in the test was 0,1. Flaws in the fatigue specimens were characterized by means of optical and scanning electron microscopy. SolidWorks 2013 software was used to modeling the specimens geometry, while to simulate the fatigue behaviour Simulation was used. The joint fatigue limit is 178 MPa, and a cut point at 2 039 093 cycles. Some points of the simulations are inside of the 95% confidence band.

  4. Study on Microstructure and Mechanical Properties of 304 Stainless Steel Joints by Tig-Mig Hybrid Welding

    Science.gov (United States)

    Ogundimu, Emmanuel O.; Akinlabi, Esther T.; Erinosho, Mutiu F.

    Stainless steel is a family of Fe-based alloys having excellent resistance to corrosion and as such has been used imperatively for kitchen utensils, transportation, building constructions and much more. This paper presents the work conducted on the material characterizations of a tungsten inert gas (TIG)-metal inert gas (MIG) hybrid welded joint of type 304 austenitic stainless steel. The welding processes were conducted in three phases. The phases of welding employed are MIG welding using a current of 170A, TIG welding using a current of 190A, and a hybrid TIG-MIG welding with currents of 190/170A, respectively. The MIG, TIG, and hybrid TIG-MIG weldments were characterized with incomplete penetration, full penetration and excess penetration of weld. Intergranular austenite was created toward transition and heat affected zones. The thickness of the delta ferrite (δ-Fe) formed in the microstructures of the TIG weld is more than the thickness emerged in the microstructures of MIG and hybrid TIG-MIG welds. A TIG-MIG hybrid weld of specimen welded at the currents of 190/170A has the highest ultimate tensile strength value and percentage elongation of 397.72MPa and 35.7%. The TIG-MIG hybrid welding can be recommended for high-tech industrial applications such as nuclear, aircraft, food processing, and automobile industry.

  5. Geometry and Material Constraint Effects on Creep Crack Growth Behavior in Welded Joints

    Science.gov (United States)

    Li, Y.; Wang, G. Z.; Xuan, F. Z.; Tu, S. T.

    2017-02-01

    In this work, the geometry and material constraint effects on creep crack growth (CCG) and behavior in welded joints were investigated. The CCG paths and rates of two kinds of specimen geometry (C(T) and M(T)) with initial cracks located at soft HAZ (heat-affected zone with lower creep strength) and different material mismatches were simulated. The effect of constraint on creep crack initiation (CCI) time was discussed. The results show that there exists interaction between geometry and material constraints in terms of their effects on CCG rate and CCI time of welded joints. Under the condition of low geometry constraint, the effect of material constraint on CCG rate and CCI time becomes more obvious. Higher material constraint can promote CCG due to the formation of higher stress triaxiality around crack tip. Higher geometry constraint can increase CCG rate and reduce CCI time of welded joints. Both geometry and material constraints should be considered in creep life assessment and design for high-temperature welded components.

  6. Joining of Materials with Diferent Properties Through Submerged Arc Welding Process and Destructive and Non-Destructive Testing of the Joints

    Directory of Open Access Journals (Sweden)

    Yakup Kaya

    2013-01-01

    Full Text Available In this study, X60, X65 and X70 steels used in petroleum and natural gas pipeline were joined with Submerged Arc Welding by using different type of welding fluxes (LN761 and P223 and wires (S1 and S2Mo. Initially, visual and radiographic inspection techniques were subjected to welded joints for determining surface and subsurface defects. After that, spectral analyses were carried out in order to determine the compositions of wire-flux-base metal on the joints. Impact toughness test were performed for determining toughness properties the joints. Furthermore, hardness and microstructure studies were also carried out on the samples. As a result of the visual and radiographic inspection on the welded samples, there were no weld defects on joints were observed. It was clearly understood that carbon ratio in the compositions of weld metal higher than base metal but lower than filler metal in terms of spectral analyses results. According to impact toughness test results, the joints obtained by using S2Mo welding wire and P223 welding flux had better impact toughness value than the joints obtained by S1 welding wire and LN 761 welding flux. With respect to hardness test, the highest hardness values were measured on weld metal. When the microstructure images were examined, it is clearly understood that similar images for all the joints were shown adjacent zones to weld metals heat affected zones and welding boundary, due to heat input constant.

  7. Fatigue behaviour of welded joints from magnesium alloy (AZ31) according to the local strain concept

    Energy Technology Data Exchange (ETDEWEB)

    Karakas, Oe.; Guelsoez, A. [Engineering Faculty, Department of Mechanical Engineering, University Pamukkale, Denizli (Turkey); Kaufmann, H.; Sonsino, C.M. [Fraunhofer - Institute for Structural Durability and System Reliability, LBF, Darmstadt (Germany)

    2010-02-15

    In the present study, the results of fatigue tests with the magnesium alloy AZ31 (ISO-MgAl3Zn1) in the material states base metal, heat affected zone and weld metal obtained under strain control at room temperature within a range from 2.10{sup 2} to 5 .10 {sup 6} cycles are presented. The fatigue behaviour was characterized by the Coffin-Manson-Basquin equations and the stress - strain behaviour by the Ramberg-Osgood equation. The data can be used to assess welded magnesium joints according to the local strain concept. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  8. Investigation of Residual Stresses and Distortion in Welded Pipe-Flange Joint of Different Classes

    Directory of Open Access Journals (Sweden)

    Muhammad Abid

    2012-10-01

    Full Text Available ABSTRACT: Pipe and flange joints are commonly used in petrochemical, nuclear and process industries. Commonly, welding is used to make these joints which produces residual stresses and distortions. These stresses have detrimental effects on the structural integrity and service performance of the welded pipe joints. The objective of this study is to investigate the residual stresses and distortions during Gas Metal Arc Welding of pipe of schedule 40, nominal diameter 200 mm with different ANSI flanges of class numbers 150, 300, 600, 900, 1500, and 2500. Welding parameters including: voltage, current and heat as inputs were selected based on the literature available. The behaviour of the flanges of different classes is also discussed. In addition, the finite element methodology presented, in this paper, can be helpful for developing welding procedures for a range of pipe flange welded joint sizes in order to control the residual stresses and deformations. This will lead to optimised performance during bolt up and operating conditions.ABSTRAK: Paip dan sambungan flan biasanya digunakan dalam industri petrokimia, nuklear dan proses. Kimpalan menghasilkan tegasan sisa dan herotan, yang memberikan kesan yang merbahaya ke atas integriti struktur dan prestasi servis sambungan kimpalan paip. Objektif kajian ini adalah untuk mengkaji tegasan sisa dan herotan ketika kimpalan arka logam gas paip berjadual 40, diameter nominal 200mm dengan flan ANSI yang berbeza kelas # 150, 300, 600, 900, 1500, dan 2500. Parameter kimpalan termasuklah; voltan, arus dan haba input yang dipilih berdasarkan literatur sediada. Kelakuan flan yang berbeza kelas telah dibincangkan. Kaedah elemen finit yang dibentangkan adalah berguna dalam membangunkan prosedur kimpalan bagi julat saiz kimpalan flan paip unutk mengawal tegasan sisa dan canggaan i.e. bagi mengoptimakan prestasi ketika bolt up dan sedang beroperasi.                                 

  9. Effect of Friction Stir Welding Parameters on the Mechanical and Microstructure Properties of the Al-Cu Butt Joint

    Directory of Open Access Journals (Sweden)

    Sare Celik

    2016-05-01

    Full Text Available Friction Stir Welding (FSW is a solid-state welding process used for welding similar and dissimilar materials. FSW is especially suitable to join sheet Al alloys, and this technique allows different material couples to be welded continuously. In this study, 1050 Al alloys and commercially pure Cu were produced at three different tool rotation speeds (630, 1330, 2440 rpm and three different tool traverse speeds (20, 30, 50 mm/min with four different tool position (0, 1, 1.5, 2 mm by friction stir welding. The influence of the welding parameters on the microstructure and mechanical properties of the joints was investigated. Tensile and bending tests and microhardness measurements were used to determine the mechanical properties. The microstructures of the weld zone were investigated by optical microscope and scanning electron microscope (SEM and were analyzed in an energy dispersed spectrometer (EDS. Intermetallic phases were detected based on the X-ray diffraction (XRD analysis results that evaluated the formation of phases in the weld zone. When the welding performance of the friction stir welded butt joints was evaluated, the maximum value obtained was 89.55% with a 1330 rpm tool rotational speed, 20 mm/min traverse speed and a 1 mm tool position configuration. The higher tensile strength is attributed to the dispersion strengthening of the fine Cu particles distributed over the Al material in the stir zone region.

  10. Investigation of residual stresses in welded joints of heat-resistant magnesium alloy ML10 after electrodynamic treatment

    Directory of Open Access Journals (Sweden)

    L.M. Lobanov

    2016-06-01

    Full Text Available In repair of aircraft structures of magnesium alloy ML10, the argon arc non-consumable electrode welding is used. In this case, the residual welding stresses occur in repair welds, being one of the causes for reducing the service characteristics of the restored products. Residual stresses arise as a result of welding. Post-weld heat treatment is used to reduce the residual stresses. The heat treatment, which occurs after welding, increases the cost of repair. This leads to the search for alternative methods to control the stressed state of welded joints, one of which is electrodynamic treatment, which reduces the level of residual stresses in repair welds, and as a consequence, the cost of the welding repair in restoring aircraft structures. It was found from the results of experiments carried out, that the electrodynamic treatment allows reduces the initial level of stresses in welded joints, reaching 120 MPa, to 30 MPa, and at definite geometric characteristics of the specimens forming the field of compressive stresses, the values of which are equal to –50 MPa. It is shown that the optimum distance between the zones of treatment, being 5 mm, provides the guaranteed covering the zones of electrodynamic effect and, as a consequence, the maximum efficiency of the electric dynamic treatment.

  11. Reasons for crack nucleation in welded joints of main gas-pipelines after a long-term operation

    Science.gov (United States)

    Maruschak, P. O.; Bishchak, R. T.; Shlapak, L. S.; Panin, S. V.

    2017-02-01

    A crack of operational origin in the welded joint of the main gas pipeline is analyzed. The reasons for its nucleation and impact on technological microdefects that were formed earlier during the welding are found. Micromechanisms and stages of nucleation and propagation of the crack are investigated.

  12. Tight butt joint weld detection based on optical flow and particle filtering of magneto-optical imaging

    Science.gov (United States)

    Gao, Xiangdong; Mo, Ling; You, Deyong; Li, Zhuman

    2017-11-01

    It is a challenge to detect the weld position during tight butt joint laser welding in that the tight butt joint is non-grooved and invisible. This paper proposes a novel method for tight butt joint weld detection based on magneto optical imaging. Two pieces of weldment were magnetized by an electromagnet so that they could show magnetic N and S polarity respectively. When a polarized light was projected on a magneto-optical film, it would deflect due to magneto-optical effect. In accordance with magneto field distribution, an image formed on the visual sensor. A transition zone of magnetic field distribution which corresponded to the butt joint could be shown in a magneto optical image of weldment. Variation features of magnetic field distribution were obtained by using image sequence optical flow method, and a particle filter was integrated to make an accurate prediction on weld position. Weld position was obtained by calculating the maximum value of optical flow intensity in the vertical direction, and a particle filter was used to realize the accurate prediction on weld position. Experimental results showed that the proposed method was effective in detection of weld and realizing weld seam tracking.

  13. Heat input effect of friction stir welding on aluminium alloy AA 6061-T6 welded joint

    Directory of Open Access Journals (Sweden)

    Sedmak Aleksandar

    2016-01-01

    Full Text Available This paper deals with the heat input and maximum temperature developed during friction stir welding with different parameters. Aluminium alloy (AA 6061-T6 has been used for experimental and numerical analysis. Experimental analysis is based on temperature measurements by using infrared camera, whereas numerical analysis was based on empirical expressions and finite element method. Different types of defects have been observed in respect to different levels of heat input.

  14. Strength of Welded Joints in Tubular Members for Aircraft

    Science.gov (United States)

    1930-02-06

    cleuwd of milI scaIe or surface oxides, or foreign matter, such as oil, grease, pa@, etc., oxide to be removed by a wire brush , file, or emery paper, as... brush , a file, or emery paper, or by grinding if llece.ssaxy. Welder to seleot tip and determine gas presmes. Welder to weld one filIet forward and...r??- —. --.- .— .—— .— — — ,.:— — — FIGum Z6.- Teet -k forhtth jOhtS610tO660. ThO s&?59- _ndc9 hve kn PIot&d S3~tdY fm the

  15. Reproducibility of pop-ins in laboratory testing of welded joints

    Directory of Open Access Journals (Sweden)

    C. Berejnoi

    2000-10-01

    Full Text Available The pop-in phenomenon, quite common in fracture mechanics tests of welded joints, corresponds to a brittle crack initiation grown from a local brittle zone (LBZ that is arrested in reaching the higher toughness material that surrounds this LBZ. A methodology to obtain a high percentage of pop-in occurrence in laboratory testing is necessary to study the pop-in significance. Such a method is introduced in this work and includes the consumable combination and welding procedures for the SMAW welding process to generate artificial LBZ. In order to find out the influence of the loading state upon the pop-in phenomenon, laboratory CTOD tests were performed using two specimen configurations: some single edge-notched specimens were loaded on a three-point bending (SE(B fixture while others were tested in tensile load (SE(T. A higher frequency of pop-in occurrence was observed in the SE(B geometry.

  16. Creep properties and microstructure evaluation of weld joint of the pipe made of P92 steel

    Energy Technology Data Exchange (ETDEWEB)

    Kasl, Josef; Jandova, Dagmar; Chvostova, Eva [SKODA VYZKUM s.r.o., Plzen (Czech Republic); Folkova, Eva [SKODA POWER a.s., Plzen (Czech Republic)

    2010-07-01

    One-side weld joint of W type was prepared from P92 type steel using GTAW and SMAW method. Creep test to the rupture of smooth cross-weld samples has been carried out at temperatures ranging from 575 to 650 C and at stresses from 70 to 240 MPa. Fractographic analysis, hardness measurement and detailed study of submicrostructure have been performed using light, scanning and transmission electron microscopy. Changes of microstructure were correlated with the creep strength. Increase in size of secondary phases and cavities formation were evident after creep tests at temperatures above 575 C. Voids were concentrated in the fine prior austenite grain heat affected zones, where fracture occurred. In addition, a sporadic occurrence of individual cavities was found out in the base material and the weld metal after tests at 625 and 650 C. During creep exposures at temperatures above 600 C Laves phase precipitated. (orig.)

  17. WOOD WELDING

    OpenAIRE

    Marcos Theodoro Muller; Rafael Rodolfo de Melo; Diego Martins Stangerlin

    2010-01-01

    The term "wood welding" designates what can be defined as "welding of wood surfaces". This new process, that it provides the joint of wood pieces without the use of adhesives or any other additional material, provokes growing interest in the academic environment, although it is still in laboratorial state. Linear friction welding induced bymechanical vibration yields welded joints of flat wood surfaces. The phenomenon of the welding occurs in less time than 10 seconds, with the temperature in...

  18. Microstructure and mechanical properties of laser welded dissimilar DP600/DP980 dual-phase steel joints

    Energy Technology Data Exchange (ETDEWEB)

    Farabi, N. [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Chen, D.L., E-mail: dchen@ryerson.ca [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Zhou, Y. [Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1 (Canada)

    2011-01-21

    Research highlights: > Laser welding results in a significant hardness rise in the fusion zone, but the formation of a soft zone in the heat-affected zone. > A characteristic unsymmetrical hardness profile is observed across the dissimilar joint. > Yield point phenomenon with only stage III strain hardening occurs after welding. > Fatigue life at higher stress amplitudes is equivalent to that of DP600 steel despite slightly lower fatigue limit. - Abstract: The use of dual phase (DP) steels in the automobile industry unavoidably involves welding and dynamic loading. The aim of this investigation was to evaluate the microstructural change and mechanical properties of laser welded dissimilar DP600/DP980 steel joints. The dissimilar joints showed a significant microstructural change from nearly full martensite in the fusion zone (FZ) to the unchanged ferrite-martensite dual-phase microstructure in the base metal. The welding resulted in a significant hardness increase in the FZ but the formation of a soft zone in the heat-affected zone (HAZ). The dissimilar welded joints were observed to exhibit a distinctive unsymmetrical hardness profile, yield-point-like phenomenon, and single-stage work hardening characteristic, with yield strength and work hardening rate lying in-between those of DP600 and DP980 base metals, and ultimate tensile strength equivalent to that of DP600 base metal. Although the welded joints showed a lower fatigue limit than the base metals, the fatigue life of the welded joints at higher stress amplitudes was almost the same as that of the DP600 base metal. The welded joints failed in the soft zone at the DP600 side under tensile loading and fatigue loading at the higher stress amplitudes. Fatigue crack initiation occurred from the specimen surface and crack propagation was characterized by typical fatigue striation together with secondary cracks.

  19. The Role of Mechanical Connection during Friction Stir Keyholeless Spot Welding Joints of Dissimilar Materials

    Directory of Open Access Journals (Sweden)

    Xiao Liu

    2017-06-01

    Full Text Available Contrast experiments of lap joints among dissimilar AZ31B Mg alloy, Mg99.50, zinc-coated DP600 sheet, and non-zinc-coated DP600 sheet were made by friction stir keyholeless spot welding (FSKSW and vacuum diffusion welding (VDW, respectively. Scanning electron microscopy (SEM and energy disperse spectroscopy (EDS were used to investigate the microstructures and components of the joints welded. The experimental results show that the FSKSW bonding method is a kind of compound mode that contains a mechanical connection and element diffusion fusion connection, in which mechanical connection has the main decisive function on joints of Mg/steel. Elements diffusion exists in the interfacial region of the joints and the elements diffusion extent is basically the same to that of VDW. The elements’ diffusion in Mg/steel using FSKSW is defined in the reaction between small amounts elements of the base metal and zinc-coated metals. The intermetallic compounds and composite oxide perform some reinforcement on the mechanical connection strength.

  20. Influence of microstructure and elemental partitioning on pitting corrosion resistance of duplex stainless steel welding joints

    Science.gov (United States)

    Zhang, Zhiqiang; Jing, Hongyang; Xu, Lianyong; Han, Yongdian; Zhao, Lei; Zhang, Jianli

    2017-02-01

    The influences of microstructure and elemental partitioning on pitting corrosion resistance of duplex stainless steel joints welded by gas tungsten arc welding (GTAW) and flux-cored arc welding (FCAW) with different shielding gas compositions were studied by optical microscopy, electron backscatter diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, electron probe microanalysis, and potentiostatic and potentiodynamic polarization methods The adding 2% N2 in shielding gas facilitated primary austenite formation in GTAW weld metal (WM) and suppressed Cr2N precipitation in GTAW weld root. In the HAZ, the banded microstructure disappeared while the coarse ferrite grains maintained same orientation as the banded ferrite in the BM. In the WM, the ferrite had one single orientation throughout a grain, whereas several families of austenite appeared. The austenite both in BM and WM enriched in Ni and nitro`gen, while Cr and Mo were concentrated in the ferrite and thus no element showed clear dendritic distribution in the WM (ER2209 and E2209T1). In addition, the secondary austenite had higher Ni content but lower Cr and Mo content than the primary austenite. The N2-supplemented shielding gas promoted nitrogen solid-solution in the primary and secondary austenite. Furthermore, the secondary austenite had relatively lower pitting resistance equivalent number (PREN) than the ferrite and primary austenite, thereby resulting in its preferential corrosion. The Cr2N precipitation led to relatively poor resistance to pitting corrosion in three HAZs and pure Ar shielding GTAW weld root. The N2-supplemented shielding gas improved pitting corrosion resistance of GTAW joint by increasing PREN of secondary austenite and suppressing Cr2N precipitation. In addition, the FCAW WM had much poorer resistance to pitting corrosion than the GTAW WM due to many O-Ti-Si-Mn inclusions. In the BM, since the austenite with lower PREN compared

  1. Welded repair joints of boiler steels following operation in creep conditions exceeding the design time of operation

    Energy Technology Data Exchange (ETDEWEB)

    Dobrzanski, J.; Paszkowska, H.; Zielinski, A. [Institute for Ferrous Metallurgy, Gliwice (Poland)

    2010-07-01

    The assessment of suitability for further operation for materials and welded repair joints of thick-walled main steam pipeline components, made of steel 14MoV63, as well as steam superheater outlet headers made of steel X20CrMoV121 following operation in creep conditions in time periods considerably longer than the specified calculated time of operation. Strength properties, impact strength and transition temperature into brittle condition, as well as structure condition have been evaluated. On the basis of shortened creep tests, the residual life and disposable residual life of materials and welded joints have been determined. Material properties following operation and those of fabricated circumferential welded repair joints have been compared. The condition of examined components and suitability of the fabricated welded repair joints for further operation have been assessed. (orig.)

  2. The effects of alloying elements on microstructures and mechanical properties of tungsten inert gas welded AZ80 magnesium alloys joint

    Science.gov (United States)

    Li, Hui; Zhang, Jiansheng; Ding, Rongrong

    2017-11-01

    The effects of alloying elements on the macrostructures, microstructures and tensile strength of AZ80 Mg alloy weldments were studied in the present study. The results indicate that with the decrease of Al element content of filler wire, the welding defects of seam are gradually eliminated and the β-Mg17Al12 phases at α-Mg boundaries are refined and become discontinuous, which are beneficial to the improvement of tensile strength. With AZ31 Mg alloy filler wire, the maximum tensile strength of AZ80 weldment is 220 MPa and fracture occurs at the welding seam of joint. It is experimentally proved that robust AZ80 Mg alloy joints can be obtained by tungsten inert gas (TIG) welding process with AZ31 Mg alloy filler wire. However, further study is required to improve the microstructures and reduce welding defects of joint in order to further improve the joining strength of AZ80 Mg alloy joint.

  3. Prediction of Tensile Strength of Friction Stir Weld Joints with Adaptive Neuro-Fuzzy Inference System (ANFIS) and Neural Network

    Science.gov (United States)

    Dewan, Mohammad W.; Huggett, Daniel J.; Liao, T. Warren; Wahab, Muhammad A.; Okeil, Ayman M.

    2015-01-01

    Friction-stir-welding (FSW) is a solid-state joining process where joint properties are dependent on welding process parameters. In the current study three critical process parameters including spindle speed (??), plunge force (????), and welding speed (??) are considered key factors in the determination of ultimate tensile strength (UTS) of welded aluminum alloy joints. A total of 73 weld schedules were welded and tensile properties were subsequently obtained experimentally. It is observed that all three process parameters have direct influence on UTS of the welded joints. Utilizing experimental data, an optimized adaptive neuro-fuzzy inference system (ANFIS) model has been developed to predict UTS of FSW joints. A total of 1200 models were developed by varying the number of membership functions (MFs), type of MFs, and combination of four input variables (??,??,????,??????) utilizing a MATLAB platform. Note EFI denotes an empirical force index derived from the three process parameters. For comparison, optimized artificial neural network (ANN) models were also developed to predict UTS from FSW process parameters. By comparing ANFIS and ANN predicted results, it was found that optimized ANFIS models provide better results than ANN. This newly developed best ANFIS model could be utilized for prediction of UTS of FSW joints.

  4. Exemplification of Tomographic Method to Evaluate the Quality of Welded Joints Made from EN 5754-H22 Alloy

    Directory of Open Access Journals (Sweden)

    Błachnio Józef

    2016-12-01

    Full Text Available The quality of welded joints depends on many factors. The relevant standards stipulate technical conditions of welds quality assessment, which provides the basis for stating whether the given joint is compatible with the requirements or whether it is defective. In practice, making welded joints that are totally devoid of defects is extremely difficult. To conduct the control of inner structure of the given joint a non-destructive method with the application of industrial CT scanner might be applied. This modern diagnosing method combines the x-ray examination with advanced computer technology. The basic advantage of computer-assisted tomography consists in examining objects in three dimensions and the possibility to carry out three-dimensional reconstructions. The aim of this article is to discuss the use of this method to evaluate the quality of welded joints made of aluminium alloys. Capabilities of computer-assisted tomography were depicted by the case of weld probes constructed with TIG (ang. Tungsten Inert Gas welding by different process variables. One has made the analysis of the quality of probes showing the smallest and the biggest internal and external welding defects.

  5. 78 FR 47486 - Joint Failure on Continuous Welded Rail Track

    Science.gov (United States)

    2013-08-05

    ..., telephone (202) 493-6399; or Ms. Elisabeth Galotto, Trial Attorney, Office of Chief Counsel, FRA, 1200 New... rail gap, defective joint bolts, disturbed ballast, surface deviations, gap between tie plates and rail...

  6. Effects of the Heterogeneity in the Electron Beam Welded Joint on Mechanical Properties of Ti6Al4V Alloy

    Science.gov (United States)

    Liu, Jing; Gao, Xiao-Long; Zhang, Lin-Jie; Zhang, Jian-Xun

    2015-01-01

    The aim of this investigation was to evaluate the effect of microstructure heterogeneity on the tensile and low cycle fatigue properties of electron beam welded (EBW) Ti6Al4V sheets. To achieve this goal, the tensile and low cycle fatigue property in the EBW joints and base metal (BM) specimens is compared. During the tensile testing, digital image correlation technology was used to measure the plastic strain field evolution within the specimens. The experimental results showed that the tensile ductility and low cycle fatigue strength of EBW joints are lower than that of BM specimens, mainly because of the effect of microstructure heterogeneity of the welded joint. Moreover, the EBW joints exhibit the cyclic hardening behavior during low fatigue process, while BM specimens exhibit the cyclic softening behavior. Compared with the BM specimens with uniform microstructure, the heterogeneity of microstructure in the EBW joint is found to decrease the mechanical properties of welded joint.

  7. On the visualization of joint formation during linear friction welding

    Directory of Open Access Journals (Sweden)

    A.T. Bikmeyev

    2015-09-01

    Full Text Available A 3D computer model of the preliminary and the transition phases of LFW using ANSYS was developed. Based on the adhesion phenomena theory, we introduce a simple method to evaluate the areas of joint formation. Results of this evaluation are in good agreement with experiments. Custom software for the 3D-simulation of the process of joint formation and material movement into the flash was built, which used the results of the FEM model.

  8. Corrosion behavior of friction stir welded AZ31B Mg alloy - Al6063 alloy joint

    Directory of Open Access Journals (Sweden)

    B. Ratna Sunil

    2016-12-01

    Full Text Available In the present work, AZ31B Mg alloy and Al6063 alloy-rolled sheets were successfully joined by friction stir welding. Microstructural studies revealed a sound joint with good mechanical mixing of both the alloys at the nugget zone. Corrosion performance of the joint was assessed by immersing in 3.5% NaCl solution for different intervals of time and the corrosion rate was calculated. The joint has undergone severe corrosion attack compared with both the base materials (AZ31B and Al6063 alloys. The predominant corrosion mechanism behind the high corrosion rate of the joint was found to be high galvanic corrosion. From the results, it can be suggested that the severe corrosion of dissimilar Mg–Al joints must be considered as a valid input while designing structures intended to work in corroding environment.

  9. High Temperature Plasticity of Bimetallic Magnesium and Aluminum Friction Stir Welded Joints

    Science.gov (United States)

    Regev, Michael; El Mehtedi, Mohamad; Cabibbo, Marcello; Quercetti, Giovanni; Ciccarelli, Daniele; Spigarelli, Stefano

    2014-02-01

    The high temperature deformation of a bimetallic AZ31/AA6061 Friction Stir Welded joint was investigated in the present study by constant load creep experiments carried out at 473 K (200 °C). The microstructural analysis revealed the strongly inhomogeneous nature of the weld, which was characterized by an extremely fine grain size in the magnesium-rich zones and by the extensive presence of intermetallic phases. In the high stress regime, the creep strain was concentrated in the refined and particle-rich microstructure of the weld zone, while the AA6061 base metal remained undeformed. In the low stress regime, deformation became more homogeneously distributed between the AZ31 base metal and the weld zone. The creep behavior of the weld was found to obey the constitutive equation describing the minimum creep rate dependence on applied stress for the base AZ31, slightly modified to take into account the finer microstructure and the role of secondary phase particles, i.e., the retardation of grain growth and the obstruction of grain boundary sliding.

  10. Experimental Research on Fatigue Failure for 2219-T6 Aluminum Alloy Friction Stir-Welded Joints

    Science.gov (United States)

    Sun, Guo-Qin; Niu, Jiang-Pei; Chen, Ya-Jing; Sun, Feng-Yang; Shang, De-Guang; Chen, Shu-Jun

    2017-08-01

    The fatigue experiment was executed for the 2219-T6 aluminum alloy friction stir-welded joints at the rotation speed of 800 r/min and the welding velocity of 150 mm/min. Most fatigue failures occurred in the weld nugget zone (WNZ), the thermo-mechanical affected zone and the nearby areas. The experimental results demonstrated that the sudden hardness gradient increases sites corresponding to the fatigue failure locations. The high-angle grain boundaries with the highest concentration were scattered within the WNZ. The microcracks initiated at the intersection of the soft grains. More than one crack initiation site was observed within the WNZ and the thermo-mechanical affected zone, when the fracture occurred in these areas. The rough surface of the welding area should be one of the main reasons for the fatigue failure occurrence. The fatigue crack growth rate in the WNZ at the first stage was fastest in comparison with the fatigue crack growth rate in the other areas of the joint.

  11. Stress corrosion cracking behaviour of gas tungsten arc welded super austenitic stainless steel joints

    Directory of Open Access Journals (Sweden)

    M. Vinoth Kumar

    2015-09-01

    Full Text Available Super 304H austenitic stainless steel with 3% of copper posses excellent creep strength and corrosion resistance, which is mainly used in heat exchanger tubing of the boiler. Heat exchangers are used in nuclear power plants and marine vehicles which are intended to operate in chloride rich offshore environment. Chloride stress corrosion cracking is the most likely life limiting failure with austenitic stainless steel tubing. Welding may worsen the stress corrosion cracking susceptibility of the material. Stress corrosion cracking susceptibility of Super 304H parent metal and gas tungsten arc (GTA welded joints were studied by constant load tests in 45% boiling MgCl2 solution. Stress corrosion cracking resistance of Super 304H stainless steel was deteriorated by GTA welding due to the formation of susceptible microstructure in the HAZ of the weld joint and the residual stresses. The mechanism of cracking was found to be anodic path cracking, with transgranular nature of crack propagation. Linear relationships were derived to predict the time to failure by extrapolating the rate of steady state elongation.

  12. The Measurement of Hardness and Elastic Modulus of non-Metallic Inclusions in Steely Welding Joints

    Directory of Open Access Journals (Sweden)

    Ignatova Anna

    2015-08-01

    Full Text Available Trunk pipelines work under a cyclic dynamical mechanical load because when oil or gas is pumped, the pressure constantly changes - pulsates. Therefore, the fatigue phenomenon is a common reason of accidents. The fatigue phenomenon more often happens in the zone of non-metallic inclusions concentration. To know how the characteristics of nonmetallic inclusions influence the probability of an accident the most modern research methods should be used. It is determined with the help of the modern research methods that the accident rate of welded joints of pipelines is mostly influenced by their morphological type, composition and size of nonmetallic inclusions, this effect is more important than the common level of pollution by non-metallic inclusions. The article presents the results of the investigations of welded joints, obtained after the use of different common welding materials. We used the methods, described in the state standards: scanning electronic microscopy, spectral microprobe analysis and nano-indentation. We found out that non-metallic inclusions act like stress concentrators because they shrink, forming a blank space between metal and nonmetallic inclusions; it strengthens the differential properties on this boundary. Nonmetallic inclusion is not fixed, it can move. The data that we have received mean that during welded joints’ contamination (with non-metallic inclusions monitoring process, more attention should be paid to the content of definite inclusions, but not to total contamination.

  13. Welding simulation and fatigue assessment of tubular K-joints in high-strength steel

    Energy Technology Data Exchange (ETDEWEB)

    Zamiri Akhlaghi, F.

    2014-07-01

    Application of newly developed high strength steel hollow sections is increasing in construction industry – especially for bridge structures – due to their satisfactory material properties and fabrication advantages. These sections allow for longer spans, more slender structures. Savings in weight and volume of material compared to traditional steel grades increase sustainability of construction and compensate for part of higher unit cost of material. Nevertheless, use of high strength steels cannot be promoted unless potential fatigue issues are properly addressed. Two fabrication methods are currently available for the planar Warren trusses made of circular hollow sections (CHS): welding the tubes together, or using cast steel nodes and connecting truss members to them by girth welds. Previous research on tubular bridge trusses indicates that the problematic fatigue cracking sites for the first fabrication method are located at weld toes in the gap region of the truss joints. For the second method, cracking occurs at the root of CHS–cast butt welds. Fatigue performance of these two methods were investigated by constant amplitude fatigue testing of two full scale trusses made of steel grade S690QH and with a geometry similar to previous S355J2H investigation. Fatigue lives of K-joints were in agreement with current recommended code values. For CHS–cast welded connections, no visible cracking was observed up to 2£10{sup 6} cycles. Due to the effect of residual stresses, fatigue cracking was observed in compressive joints as well as tensile joints. Indeed, tensile welding residual stresses keep the crack open during all or part of the compressive load cycle. Their distribution and impact on fatigue life of tubular joints has not been fully investigated before for a complex detail such as Tubular K-joint made of high strength steel. Experimental and numerical methods were utilized for assessment of welding residual stresses. Neutron diffraction experiments

  14. Characteristics of AZ31 Mg alloy joint using automatic TIG welding

    Science.gov (United States)

    Liu, Hong-tao; Zhou, Ji-xue; Zhao, Dong-qing; Liu, Yun-teng; Wu, Jian-hua; Yang, Yuan-sheng; Ma, Bai-chang; Zhuang, Hai-hua

    2017-01-01

    The automatic tungsten-inert gas welding (ATIGW) of AZ31 Mg alloys was performed using a six-axis robot. The evolution of the microstructure and texture of the AZ31 auto-welded joints was studied by optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and electron backscatter diffraction. The ATIGW process resulted in coarse recrystallized grains in the heat affected zone (HAZ) and epitaxial growth of columnar grains in the fusion zone (FZ). Substantial changes of texture between the base material (BM) and the FZ were detected. The {0002} basal plane in the BM was largely parallel to the sheet rolling plane, whereas the c-axis of the crystal lattice in the FZ inclined approximately 25° with respect to the welding direction. The maximum pole density increased from 9.45 in the BM to 12.9 in the FZ. The microhardness distribution, tensile properties, and fracture features of the AZ31 auto-welded joints were also investigated.

  15. The porosity formation mechanism in the laser-MIG hybrid welded joint of Invar alloy

    Science.gov (United States)

    Zhan, Xiaohong; Gao, Qiyu; Gu, Cheng; Sun, Weihua; Chen, Jicheng; Wei, Yanhong

    2017-10-01

    The porosity formation mechanism in the laser-metal inter gas (MIG) multi-layer hybrid welded (HW) joint of 19.05 mm thick Invar alloy is investigated. The microstructure characteristics and energy dispersive spectroscopy (EDS) are analyzed. The phase identification was conducted by the X-ray diffractometer (XRD). Experimental results show that the generation of porosity is caused by the relatively low laser power in the root pass and low current in the cover pass. It is also indicated that the microstructures of the welded joints are mainly observed to be columnar crystal and equiaxial crystal, which are closely related to the porosity formation. The EDS results show that oxygen content is significantly high in the inner wall of the porosity. The XRD results indicate that the BM and the WB of laser-MIG HW all are composed of Fe0.64Ni0.36 and γ-(Fe,Ni). When the weld pool is cooled quickly, [NiO] [FeO] and [MnO] are formed that react on C to generate CO/CO2 gases. The porosity of laser-MIG HW for Invar alloy is oxygen pore. The root source of metallurgy porosity formation is that the dissolved gases are hard to escape sufficiently and thus exist in the weld pool. Furthermore, 99.99% pure Argon is recommended as protective gas in the laser-MIG HW of Invar alloy.

  16. Inhibition of the formation of intermetallic compounds in aluminum-steel welded joints by friction stir welding; Inhibicion de la formacion de compuestos intermetalicos en juntas aluminio-acero soldadas por friccion-agitacion

    Energy Technology Data Exchange (ETDEWEB)

    Torres Lopez, E. A.; Ramirez, A. J.

    2015-07-01

    Formation of deleterious phases during welding of aluminum and steel is a challenge of the welding processes, for decades. Friction Stir Welding (FSW) has been used in an attempt to reduce formation of intermetallic compounds trough reducing the heat input. In this research, dissimilar joint of 6063-T5 aluminum alloy and AISI-SAE 1020 steel were welded using this technique. The temperature of welded joints was measured during the process. The interface of the welded joints was characterized using optical microscopy, scanning and transmission electron microscopy. Additionally, composition measurements were carried out by X-EDS and DRX. The experimental results revealed that the maximum temperature on the joint studied is less than 360 degree centigrade. The microstructural characterization in the aluminum-steel interface showed the absence of intermetallic compounds, which is a condition attributed to the use of welding with low thermal input parameters. (Author)

  17. Numerical analysis of the adherends with similar thickness on weld-bonded single lap aluminium joint

    Directory of Open Access Journals (Sweden)

    Li Jianli

    2017-01-01

    Full Text Available The effect of the adherend with similar thickness varied from 1 mm to 3 mm on the stress distribution in weld-bonded single lap aluminium joint was investigated using elasto-plastic finite element method (FEM. The results from the numerical simulation show that all the values of the peak stresses along the mid-bondline at the points near the both ends of the lap zone as well as the ones in the region of the nugget are increased when the adherend thickness increased. It is suggested that the adherend thickness of 2 mm to 2.5 mm be appropriate to optimize the stress distribution in the weld-bonded single lap aluminium joint.

  18. Fatigue Crack Growth Characteristics of Cold Stretched STS 304 Welded Joint

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Won; Na, Seong Hyeon; Yoon, Dong Hyun; Kim, Jae Hoon [Chungnam Nat’l Univ., Daejeon (Korea, Republic of); Kim, Young Kyun; Kim, Ki Dong [Korea Gas Coporation R& D Division, Daejeon (Korea, Republic of)

    2017-09-15

    STS 304 steel is used as pressure vessel material, and although it exhibits excellent mechanical characteristics at a low temperature, it is heavier than other materials. To address this issue, a method using cold-stretching techniques for STS 304 can be applied. In this study, a cold-stretching part and welded joint specimen were directly obtained from a cold-stretching pressure vessel manufactured according to ASME code. Fatigue crack propagation tests were carried out at room temperature and -170℃ using the compliance method for stress ratios of 0.1 and 0.5. The results indicate that crack growth rate of the welded joint is higher than that of the cold-stretching part within the same stress intensity factor range. The outcome of this work is expected to serve as a basis for the development of a cold-stretched STS 304 pressure vessel.

  19. Numerical study of electron beam welded butt joints with the GTN model

    Science.gov (United States)

    Tu, Haoyun; Schmauder, Siegfried; Weber, Ulrich

    2012-08-01

    The fracture behavior of S355NL electron beam welded steel joints is investigated experimentally and numerically. The simulation of crack propagation in an electron beam welded steel joint was performed with the Gurson-Tvergaard-Needleman (GTN) damage model. A parameter study of the GTN model was adopted which reveals the influence of parameters on the material behavior of notched round and compact tension specimens. Based on the combined method of metallographic investigations and numerical calibration, the GTN parameters were fixed. The same parameters were used to predict the ductile fracture of compact tension specimens with the initial crack located at different locations. Good match can be found between the numerical and experimental results in the form of force versus Crack Opening Displacement as well as fracture resistance curves.

  20. Effect of adding powder on joint properties of laser penetration welding for dual phase steel and aluminum alloy

    Science.gov (United States)

    Zhou, D. W.; Liu, J. S.; Lu, Y. Z.; Xu, S. H.

    2017-09-01

    The experiments of laser penetration welding for dual phase steel and aluminum alloy were carried out, and the effect of adding Mn or Si powder on mechanical properties and microstructure of the weld was investigated. Some defects, such as spatter, inclusion, cracks and softening in heat affected zone (HAZ), can be avoided in welding joints, and the increased penetration depth is obtained by adding Mn or Si powder. The average tensile-shear strength of Si-added joint is 3.84% higher than that of Mn-added joint, and the strength of both joints exceeds that of no-added joint. In the case of adding Mn powder, small amount of liquid Al is mixed into steel molten pool, and the Al content increases in both sides of the weld, which leads to the increased weld width in aluminum molten pool. Thus, transverse area increases in jointing steel to aluminum, which is significant for the improved tensile-shear strength of joints. As far as adding Si powder is concerned, it is not the case, the enhancement of the joint properties benefits from improvement of metallurgical reaction.

  1. Effect of Peculiarities of Heat Transfer, Diffusion and Phase Transformation on Joint Formation During Welding of Dissimilar Materials by High Power Fiber Laser

    Science.gov (United States)

    Turichin, Gleb; Klimova, Olga; Valdaytseva, Ekaterina

    The article describes mathematical models of diffusion and thermal processes for welding of dissimilar materials and kinetic model of diffusion-controlled deposition and growth of intermetallic inclusions in the weld. Developed models were combined and implemented in the model of weld joint formation for dissimilar materials. To verify a model the microstructure analysis of weld joints and elemental analysis in the diffusion zone by SEM has been made for welding of systems Fe-Cu, Al-Ti, Fe-Al. The good agreement between calculated and experimental data has been obtained. Examples of developed technologies of welding of dissimilar materials using high-power fiber lasers were discussed also.

  2. Identifying Combination of Friction Stir Welding Parameters to Maximize Strength of Lap Joints of AA2014-T6 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Rajendrana C.

    2017-01-01

    Full Text Available AA2014 aluminum alloy (Al-Cu alloy has been widely utilized in fabrication of lightweight structures like aircraft structures, demanding high strength to weight ratio and good corrosion resistance. The fusion welding of these alloys will lead to solidification problems such as hot cracking. Friction stir welding is a new solid state welding process, in which the material being welded does not melt and recast. Lot of research works have been carried out by many researchers to optimize process parameters and establish empirical relationships to predict tensile strength of friction stir welded butt joints of aluminum alloys. However, very few investigations have been carried out on friction stir welded lap joints of aluminum alloys. Hence, in this investigation, an attempt has been made to optimize friction stir lap welding (FSLW parameters to attain maximum tensile strength using statistical tools such as design of experiment (DoE, analysis of variance (ANOVA, response graph and contour plots. By this method, it is found that maximum tensile shear fracture load of 12.76 kN can be achieved if a joint is made using tool rotational speed of 900 rpm, welding speed of 110 mm/min, tool shoulder diameter of 12 mm and tool tilt angle of 1.5°.

  3. Dual-beam laser welding of AZ31B magnesium alloy in zero-gap lap joint configuration

    Science.gov (United States)

    Harooni, Masoud; Carlson, Blair; Kovacevic, Radovan

    2014-03-01

    Porosity within laser welds of magnesium alloys is one of the main roadblocks to achieving high quality joints. One of the causes of pore formation is the presence of pre-existing coatings on the surface of magnesium alloy such as oxide or chromate layers. In this study, single-beam and dual-beam laser heat sources are investigated in relation to mitigation of pores resulting from the presence of the as-received oxide layer on the surface of AZ31B-H24 magnesium alloy during the laser welding process. A fiber laser with a power of up to 4 kW is used to weld samples in a zero-gap lap joint configuration. The effect of dual-beam laser welding with different beam energy ratios is studied on the quality of the weld bead. The purpose of this paper is to identify the beam ratio that best mitigates pore formation in the weld bead. The laser molten pool and the keyhole condition, as well as laser-induced plasma plume are monitored in real-time by use of a high speed charge-coupled device (CCD) camera assisted with a green laser as an illumination source. Tensile and microhardness tests were used to measure the mechanical properties of the laser welded samples. Results showed that a dual-beam laser configuration can effectively mitigate pore formation in the weld bead by a preheating-welding mechanism.

  4. Thermo-mechanic and Microstructural Analysis of an Underwater Welding Joint

    OpenAIRE

    Pedro Hernández Gutiérrez; Francisco Cepeda Rodríguez; Jose Jorge Ruiz Mondragón; Jorge Leobardo Acevedo Dávila; Martha Patricia Guerrero Mata; Carlos Alberto Guevara Chavez

    2016-01-01

    Abstract The aim of this research is to present a comparative analysis between theoretical and experimental thermal fields as well as a microstructural behaviour and residual stresses applying multiple weld beads in the joint of two API 5L X52 pipe sections. The thermal field, microstructural and residual stresses were numerically modelled through the finite element method (FEM) and compared to experimentally. The simulation conditions used in the FEM analysis were similar considerations to t...

  5. Influence of the Strength Mismatch of a Narrow Gap Welded Joint of SA508 on the Plastic η Factor

    Science.gov (United States)

    Koo, J. M.; Huh, Y.; Seok, C. S.

    2012-11-01

    In this article, the influence of the strength mismatch of a narrow gap welded joint of SA508 on the η factor was evaluated. The η factor is the principal parameter that determines the plastic portion of the J-integral. The specimens for tensile and hardness tests were collected from piping with narrow gap welding and the stress-strain curve and hardness were obtained from those. From these results, the Ramberg-Osgood (R-O) constant was obtained. Also, the finite element analysis was performed with variations in the strength mismatch and the weld width. The η factor equation considering the strength mismatch and the weld width of a narrow gap welded joint was suggested.

  6. Influence of temperature and exploitation period on fatigue crack growth parameters in different regions of welded joints

    Directory of Open Access Journals (Sweden)

    Ivica Camagic

    2016-03-01

    Full Text Available The influence of exploitation period and temperature on the fatigue crack growth parameters indifferent regions of a welded joint is analysed for new and exploited low-alloyed Cr-Mo steel A-387 Gr. B. The parent metal is a part of a reactor mantle which was exploited for over 40 years, and recently replaced with new material. Fatigue crack growth parameters, threshold value Kth, coefficient C and exponent m, have been determined, both at room and exploitation temperature. Based on testing results, fatigue crack growth resistance in different regions of welded joint is analysed in order to justify the selected welding procedure specification.

  7. Influence of microstructure and elemental partitioning on pitting corrosion resistance of duplex stainless steel welding joints

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhiqiang; Jing, Hongyang [School of Materials Science and Engineering, Tianjin University, Tianjin 300350 (China); Tianjin Key Laboratory of Advanced Joining Technology, Tianjin 300350 (China); Xu, Lianyong, E-mail: xulianyong@tju.edu.cn [School of Materials Science and Engineering, Tianjin University, Tianjin 300350 (China); Tianjin Key Laboratory of Advanced Joining Technology, Tianjin 300350 (China); Han, Yongdian; Zhao, Lei [School of Materials Science and Engineering, Tianjin University, Tianjin 300350 (China); Tianjin Key Laboratory of Advanced Joining Technology, Tianjin 300350 (China); Zhang, Jianli [Welding laboratory, Offshore Oil Engineering (Qing Dao) Company, Qing Dao 266520 (China)

    2017-02-01

    Highlights: • N{sub 2}-supplemented shielding gas promoted nitrogen solid-solution in the austenite. • Secondary austenite had higher Ni but lower Cr and Mo than primary austenite. • Pitting corrosion preferentially occurred at secondary austenite and Cr{sub 2}N. • Adding N{sub 2} in shielding gas improved pitting corrosion resistance of GTAW joint. • E2209T{sub 1} weld metal had very poor pitting corrosion resistance due to inclusions. - Abstract: The influences of microstructure and elemental partitioning on pitting corrosion resistance of duplex stainless steel joints welded by gas tungsten arc welding (GTAW) and flux-cored arc welding (FCAW) with different shielding gas compositions were studied by optical microscopy, electron backscatter diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, electron probe microanalysis, and potentiostatic and potentiodynamic polarization methods The adding 2% N{sub 2} in shielding gas facilitated primary austenite formation in GTAW weld metal (WM) and suppressed Cr{sub 2}N precipitation in GTAW weld root. In the HAZ, the banded microstructure disappeared while the coarse ferrite grains maintained same orientation as the banded ferrite in the BM. In the WM, the ferrite had one single orientation throughout a grain, whereas several families of austenite appeared. The austenite both in BM and WM enriched in Ni and nitrogen, while Cr and Mo were concentrated in the ferrite and thus no element showed clear dendritic distribution in the WM (ER2209 and E2209T{sub 1}). In addition, the secondary austenite had higher Ni content but lower Cr and Mo content than the primary austenite. The N{sub 2}-supplemented shielding gas promoted nitrogen solid-solution in the primary and secondary austenite. Furthermore, the secondary austenite had relatively lower pitting resistance equivalent number (PREN) than the ferrite and primary austenite, thereby resulting in its preferential

  8. Microstructure, Hardness, and Residual Stress Distributions in T-Joint Weld of HSLA S500MC Steel

    Science.gov (United States)

    Frih, Intissar; Montay, Guillaume; Adragna, Pierre-Antoine

    2017-03-01

    This paper investigates the characterization of the microstructure, hardness, and residual stress distributions of MIG-welded high-strength low-alloy S500MC steel. The T-joint weld for 10-mm-thick plates was joined using a two passes MIG welding technology. The contour method was performed to measure longitudinal welding residual stress. The obtained results highlighted a good correlation between the metallurgical phase constituents and hardness distribution within the weld zones. In fact, the presence of bainite and smaller ferrite grain size in the weld-fusion zone might be the reason for the highest hardness measured in this region. A similar trend of the residual stress and hardness distributions was also obtained.

  9. Effect of buffer-layered buttering on microstructure and mechanical properties of dissimilar metal weld joints for nuclear plant application

    Energy Technology Data Exchange (ETDEWEB)

    Rathod, Dinesh W., E-mail: dineshvrathod@gmail.com [Department of Mechanical Enggineering, Indian Institute of Technology Delhi, Hauz-khas, New Delhi 110016 (India); Singh, P.K. [Bhabha Atomic Research Centre, Mumbai 400085 (India); Pandey, Sunil; Aravindan, S. [Department of Mechanical Enggineering, Indian Institute of Technology Delhi, Hauz-khas, New Delhi 110016 (India)

    2016-06-01

    In this study, we present the metallurgical and mechanical investigation of four dissimilar welds between SA508Gr.3Cl.1 and SS304LN. The welding processes for buttering deposition and fill-pass welding were varied with ERNiCr-3/ENiCrFe-3 consumables. The Ni-Fe alloy buffer layer was introduced as intermediate layer in buttering and then the joints (with and without buffer layer in buttering) were fabricated. The effect of Ni-Fe buffer layered buttering and welding processes on the resulting weld joints properties has been addressed. Metallurgical and mechanical properties, fracture toughness were measured and various examinations were carried out for integrity assessment on all the weld joints. Addition of a Ni-Fe buttering layer leads to the development of more favourable properties than observed in welded joints made using the current practice without a buffer layer. Control of carbon migration and its subsequent effect on metallurgical, mechanical properties due to buffer layer has been justified in the study. Conventional procedure of DMW fabrication has been proven to be the least favourable against the new technique suggested. Modification in current integrity assessment procedure would be possible by considering the properties at interfacial regions, introduction of yield strength ratio mismatch and the plastic instability strength in the integrity assessment.

  10. Simulation Study on Multipassed Welding Distortion of Combined Joint Types using Thermo-Elastic-Plastic FEM

    Directory of Open Access Journals (Sweden)

    RN Lidam

    2012-12-01

    Full Text Available This paper investigates the angular distortion induced by the gas metal arc welding (GMAW process on the combined butt and T-joint with a thickness of 9 mm. The material used in this study was low manganese carbon steel S355J2G3. A 2-D and 3-D thermo-elastic-plastic finite element (FE analysis has been developed to simulate the induced distortion of multipassed welding. In this research, SYSWELD 2010 with its computation management tool, known as multipassed welding advisor (MPA, was applied to analyze the distortion behavior of combined joint types. To model the heat source of GMAW, Goldak's double ellipsoid representation, which is available within this finite element analysis (FEA code was selected. Prior to the results discussion, this paper also shows the step-bystep procedures to simulate combined jointing which begins with metallurgical and customized heat source modeling, and is followed by creating geometrical mesh using Visual-Mesh 6.5 for analyzing and processing the results. Apart from 2-D and 3-D comparison analysis, the final objective of this research is also aimed to be a baseline study to provide preliminary information in preparing the tools and equipment for experimental investigation.

  11. Fatigue limits of titanium-bar joints made with the laser and the electric resistance welding techniques: microstructural characterization and hardness properties.

    Science.gov (United States)

    Degidi, Marco; Nardi, Diego; Morri, Alessandro; Sighinolfi, Gianluca; Tebbel, Florian; Marchetti, Claudio

    2017-09-01

    Fatigue behavior of the titanium bars is of utmost importance for the safe and reliable operation of dental implants and prosthetic constructions based on these implants. To date, however, only few data are available on the fatigue strength of dental prostheses made with electric resistance welding and laser welding techniques. This in-vitro study highlighted that although the joints made with the laser welding approach are credited of a superior tensile strength, joints made with electric resistance welding exhibited double the minimum fatigue strength with respect to the joints made with laser welding (120 vs 60 N).

  12. Updating failure probability of a welded joint in offshore wind turbine substructures

    DEFF Research Database (Denmark)

    Mai, Quang A.; Sørensen, John Dalsgaard; Rigo, Philippe

    2016-01-01

    . Updating the reliability of a welded joint can theoretically be done using Bayesian updating. However, for tubular joints in offshore wind turbine substructures when considering a two dimensional crack growth and a failure criterion combining brittle fracture and material strength, the updating is quite...... complex due to the wind turbine loading obtained during operation. This paper solves that updating problem by using the Failure Assessment Diagram as a limit state function. It is discussed how application of the updating procedure can be used for inspection planning for offshore wind turbine...... substructures, and thus also for reducing the required safety factors at the design stage....

  13. Microstructure and Hardness Profiles of Bifocal Laser-Welded DP-HSLA Steel Overlap Joints

    Science.gov (United States)

    Grajcar, A.; Matter, P.; Stano, S.; Wilk, Z.; Różański, M.

    2017-04-01

    The article presents results related to the bifocal laser welding of overlap joints made of HSLA and DP high-strength steels. The joints were made using a disk laser and a head enabling the 50-50% distribution of laser power. The effects of the laser welding rates and the distance between laser spots on morphological features and hardness profiles were analyzed. It was established that the positioning of beams at angles of 0° or 90° determined the hardness of the individual zones of the joints, without causing significant differences in microstructures of the steels. Microstructural features were inspected using scanning electron microscopy. Both steels revealed primarily martensitic-bainitic microstructures in the fusion zone and in the heat-affected zone. Mixed multiphase microstructures were revealed in the inter-critical heat-affected zone of the joint. The research involved the determination of parameters making it possible to reduce the hardness of joints and prevent the formation of the soft zone in the dual-phase steel.

  14. Analysis on the Fracture of Al-Cu Dissimilar Materials Friction Stir Welding Lap Joint

    Science.gov (United States)

    Sun, Hongyu; Zhou, Qi; Zhu, Jun; Peng, Yong

    2017-12-01

    Friction stir welding (FWS) is regarded as a more plausible alternative to other welding methods for Al-Cu dissimilar joining. However, the structure of an FSW joint is different from others. In this study, lap joints of 6061 aluminum alloy and commercially pure copper were produced by FSW, and the effects of rotation rate on macromorphology, microstructure and mechanical properties were investigated. In addition, a fracture J integral model was used to analyze the effect of microstructure on the mechanical properties. The results revealed that the macrodefect-free joints were obtained at a feed rate of 150 mm/min and 1100 rpm and that the failure load of the joint reached as high as 4.57 kN and only reached 2.91 kN for the 900 rpm, where tunnel defects were identified. Particle-rich zones composed of Cu particles dispersed in an Al matrix, and "Flow tracks" were observed by the EDS. The J integral results showed that the microdefects on the advancing side cause serious stress concentration compared with the microdefects located on the Al-Cu interface, resulting in the fracture of the joints.

  15. Analysis on the Fracture of Al-Cu Dissimilar Materials Friction Stir Welding Lap Joint

    Science.gov (United States)

    Sun, Hongyu; Zhou, Qi; Zhu, Jun; Peng, Yong

    2017-11-01

    Friction stir welding (FWS) is regarded as a more plausible alternative to other welding methods for Al-Cu dissimilar joining. However, the structure of an FSW joint is different from others. In this study, lap joints of 6061 aluminum alloy and commercially pure copper were produced by FSW, and the effects of rotation rate on macromorphology, microstructure and mechanical properties were investigated. In addition, a fracture J integral model was used to analyze the effect of microstructure on the mechanical properties. The results revealed that the macrodefect-free joints were obtained at a feed rate of 150 mm/min and 1100 rpm and that the failure load of the joint reached as high as 4.57 kN and only reached 2.91 kN for the 900 rpm, where tunnel defects were identified. Particle-rich zones composed of Cu particles dispersed in an Al matrix, and "Flow tracks" were observed by the EDS. The J integral results showed that the microdefects on the advancing side cause serious stress concentration compared with the microdefects located on the Al-Cu interface, resulting in the fracture of the joints.

  16. Physical Nature of the Processes in Structure Forming, Phase and Chemical Composition of pipe Permanent Joints when MMA Welding

    Science.gov (United States)

    Il'yaschenko, D. P.; Chinakhov, D. A.; Danilov, V. I.; Sadykov, I. D.

    2016-04-01

    The paper outlines peculiarities of structure formation, phase and chemical composition in regard to heat content in molten electrode metal beads when pipe steel (steel 09G2S) welding using power sources with various energy characteristics. Mathematical calculations indicate an inverter power source provides minor heat content into the bead of electrode metal when welding. Experimental research has pointed at 4-9 % increase in impact strength of joints produced using an inverter power source in comparison with samples produced applying a diode rectifier. The following factors can possibly give rise to the increasing impact strength: difference in microstructures of weld joints, up to 50% shortening ferritic plates in metal of weld joint, change in dimensions of ferritic grains in the heat-affected zone by as much as 17.5 %, and decrease in the extent of heat-affected zone by 50%.

  17. The Effect of Tool Profiles on Mechanical Properties of Friction Stir Welded Al5052 T-Joints.

    Science.gov (United States)

    Kim, Byeong-Jin; Bang, Hee-Seon; Bang, Han-Sur

    2018-03-01

    Al5052 T butt joints with two skins (5 mm) and one stringer (3 mm) has been successfully welded by friction stir welding (FSW). Notably, this paper has been investigated the effect of tool shape on welded formation mechanism and mechanical properties. The used shapes of tool pin are two types which are cylinder (type 1) and frustum (type 2). Dimension on two types of tool pin shape is respectively pin length of 4.7 mm and pin diameter of frustum type of top (5 mm) and bottom (3 mm). The results of experiment show that inner defects in FSWed T-joints increase significantly in accordance with traverse speed. The maximum tensile strength of welded joint fabricated using type 1 is equivalent to 85% that of the base metal, which is approximately 10% higher than that of type 2. Because welded joint of type 1 has more smoothly plastic flow in comparison with type 2. Consequently, the results show that type 1 is better appropriate for friction stir welded Al5052 T butt joints than type 2.

  18. Prediction of Welded Joint Strength in Plasma Arc Welding: A Comparative Study Using Back-Propagation and Radial Basis Neural Networks

    Science.gov (United States)

    Srinivas, Kadivendi; Vundavilli, Pandu R.; Manzoor Hussain, M.; Saiteja, M.

    2016-09-01

    Welding input parameters such as current, gas flow rate and torch angle play a significant role in determination of qualitative mechanical properties of weld joint. Traditionally, it is necessary to determine the weld input parameters for every new welded product to obtain a quality weld joint which is time consuming. In the present work, the effect of plasma arc welding parameters on mild steel was studied using a neural network approach. To obtain a response equation that governs the input-output relationships, conventional regression analysis was also performed. The experimental data was constructed based on Taguchi design and the training data required for neural networks were randomly generated, by varying the input variables within their respective ranges. The responses were calculated for each combination of input variables by using the response equations obtained through the conventional regression analysis. The performances in Levenberg-Marquardt back propagation neural network and radial basis neural network (RBNN) were compared on various randomly generated test cases, which are different from the training cases. From the results, it is interesting to note that for the above said test cases RBNN analysis gave improved training results compared to that of feed forward back propagation neural network analysis. Also, RBNN analysis proved a pattern of increasing performance as the data points moved away from the initial input values.

  19. Trapezoid fracture caused by assault

    Directory of Open Access Journals (Sweden)

    Malshikare V

    2007-01-01

    Full Text Available In this report we describe an open fracture of trapezoid and break in anterior cortex of capitate due to assault in a young adult male. Direct impact force of a sharp object to the first web space caused the above fractures. Open reduction and internal fixation of the trapezoid was carried out using Kirschner wires. Cut extensor tendons, extensor retaniculum, capsule, adductor pollicis muscle, first dorsal interosseous muscle, soft tissue and overlying skin were sutured primarily. Three months after the operation the patient has made a complete recovery. There is no similar case reported in the literature.

  20. Microstructural characterisation of friction stir welding joints of mild steel to Ni-based alloy 625

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, J. [Brazilian Nanotechnology National Laboratory (LNNano), P.O. Box 6192, Campinas, SP (Brazil); University of Campinas (UNICAMP), Campinas, SP (Brazil); Ramirez, A.J., E-mail: ramirezlondono.1@osu.edu [Brazilian Nanotechnology National Laboratory (LNNano), P.O. Box 6192, Campinas, SP (Brazil); University of Campinas (UNICAMP), Campinas, SP (Brazil); Department of Materials Science and Engineering, The Ohio State University — OSU, Columbus, OH 43221 (United States)

    2015-12-15

    In this study, 6-mm-thick mild steel and Ni-based alloy 625 plates were friction stir welded using a tool rotational speed of 300 rpm and a travel speed of 100 mm·min{sup −1}. A microstructural characterisation of the dissimilar butt joint was performed using optical microscopy, scanning and transmission electron microscopy, and energy dispersive X-ray spectroscopy (XEDS). Six different weld zones were found. In the steel, the heat-affected zone (HAZ) was divided into three zones and was composed of ferrite, pearlite colonies with different morphologies, degenerated regions of pearlite and allotriomorphic and Widmanstätten ferrite. The stir zone (SZ) of the steel showed a coarse microstructure consisting of allotriomorphic and Widmanstätten ferrite, degenerate pearlite and MA constituents. In the Ni-based alloy 625, the thermo-mechanically affected zone (TMAZ) showed deformed grains and redistribution of precipitates. In the SZ, the high deformation and temperature produced a recrystallised microstructure, as well as fracture and redistribution of MC precipitates. The M{sub 23}C{sub 6} precipitates, present in the base material, were also redistributed in the stir zone of the Ni-based alloy. TMAZ in the steel and HAZ in the Ni-based alloy could not be identified. The main restorative mechanisms were discontinuous dynamic recrystallisation in the steel, and discontinuous and continuous dynamic recrystallisation in the Ni-based alloy. The interface region between the steel and the Ni-based alloy showed a fcc microstructure with NbC carbides and an average length of 2.0 μm. - Highlights: • Comprehensive microstructural characterisation of dissimilar joints of mild steel to Ni-based alloy • Friction stir welding of joints of mild steel to Ni-based alloy 625 produces sound welds. • The interface region showed deformed and recrystallised fcc grains with NbC carbides and a length of 2.0 μm.

  1. Fatigue Crack Growth Behavior of a New Type of 10% Cr Martensitic Steel Welded Joints with Ni-Based Weld Metal

    Science.gov (United States)

    Zhang, Qunbing; Zhang, Jianxun

    2017-08-01

    In the present work, the fatigue crack growth (FCG) behavior of a new type of 10% Cr martensitic steel welded joints with Ni-based weld metal was comparatively studied for different regions including base metal (BM), heat-affected zone (HAZ) and weld metal (WM). FCG results indicated that the tempered lath martensite BM has a higher fatigue crack growth resistance than the tempered granular martensite HAZ that without a typical lath structure. In comparison, the austenitic WM has the highest fatigue crack growth threshold. Meanwhile, due to the microstructural and chemical compositional differences between BM and WM, a clear interface existed in the welded joints. At the region of the interface, the microstructures were physically connected and an element transition layer was formed. Although the starter notch was positioned at the region of interface, the fatigue crack gradually deviated from the interface and ultimately propagated along the inter-critically heat-affected zone. The difference in microstructure is considered as the primary factor that resulted in the different fatigue crack growth behaviors of the welded joints. In addition, the continuous microstructure connection and composition transition at the interface contributed to the good fatigue resistance at this region.

  2. Creep Deformation and Rupture Behavior of Single- and Dual-Pass 316LN Stainless-Steel-Activated TIG Weld Joints

    Science.gov (United States)

    Vijayanand, V. D.; Vasudevan, M.; Ganesan, V.; Parameswaran, P.; Laha, K.; Bhaduri, A. K.

    2016-06-01

    Creep deformation and rupture behavior of single-pass and dual-pass 316LN stainless steel (SS) weld joints fabricated by an autogenous activated tungsten inert gas welding process have been assessed by performing metallography, hardness, and conventional and impression creep tests. The fusion zone of the single-pass joint consisted of columnar zones adjacent to base metals with a central equiaxed zone, which have been modified extensively by the thermal cycle of the second pass in the dual-pass joint. The equiaxed zone in the single-pass joint, as well as in the second pass of the dual-pass joint, displayed the lowest hardness in the joints. In the dual-pass joint, the equiaxed zone of the first pass had hardness comparable to the columnar zone. The hardness variations in the joints influenced the creep deformation. The equiaxed and columnar zone in the first pass of the dual-pass joint was more creep resistant than that of the second pass. Both joints possessed lower creep rupture life than the base metal. However, the creep rupture life of the dual-pass joint was about twofolds more than that of the single-pass joint. Creep failure in the single-pass joint occurred in the central equiaxed fusion zone, whereas creep cavitation that originated in the second pass was blocked at the weld pass interface. The additional interface and strength variation between two passes in the dual-pass joint provides more restraint to creep deformation and crack propagation in the fusion zone, resulting in an increase in the creep rupture life of the dual-pass joint over the single-pass joint. Furthermore, the differences in content, morphology, and distribution of delta ferrite in the fusion zone of the joints favors more creep cavitation resistance in the dual-pass joint over the single-pass joint with the enhancement of creep rupture life.

  3. Experimental and numerical investigations of hybrid laser arc welding of aluminum alloys in the thick T-joint configuration

    Science.gov (United States)

    Mazar Atabaki, M.; Nikodinovski, M.; Chenier, P.; Ma, J.; Liu, W.; Kovacevic, R.

    2014-07-01

    In the present investigation, a numerical finite element model was developed to simulate the hybrid laser arc welding of different aluminum alloys, namely 5××× to 6××× series. The numerical simulation has been considered two double-ellipsoidal heat sources for the gas metal arc welding and laser welding. The offset distance of the metal arc welding and laser showed a significant effect on the molten pool geometry, the heat distribution and penetration depth during the welding process. It was confirmed that when the offset distance is within the critical distance the laser and arc share the molten pool and specific amount of penetration and dilution can be achieved. The models and experiments show that the off-distance between the two heat sources and shoulder width have considerable influence on the penetration depth and appearance of the weld beads. The experiments also indicate that the laser power, arc voltage and type of the filler metal can effectively determine the final properties of the bonds, specifically the bead appearance and microhardness of the joints. The experiments verified the numerical simulation as the thermocouples assist to comprehend the amount of heat distribution on the T-joint coupons. The role of the welding parameters on the mechanism of the hybrid laser welding of the aluminum alloys was also discussed.

  4. Influence of Friction Stir Welding on Mechanical Properties of Butt Joints of AZ61 Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    Seung-Ju Sun

    2017-01-01

    Full Text Available In this study, the effect of heat input on the mechanical properties and fracture behaviors of AZ61 magnesium alloy joints has been studied. Magnesium alloy AZ61 plates with thickness of 5 mm were welded at different ratios of tool rotational speed to welding speed (ω/ν. The average ultimate tensile strength of all weld conditions satisfying a ω/ν ratio of 3 reached 100% of the strength of the base material. Fractures occurred at the interface between the thermomechanical affected zone at advancing side and the stir zone in all welded specimens. From the scanning electron microscope and electron backscatter diffraction analysis, it was determined that the interface between the thermomechanical affected zone and the stir zone, which is the region where the grain orientation changes, was the weakest part; the advancing side region was relatively weaker than the retreating side region because the grain orientation change occurred more dramatically in the advancing side region.

  5. The influence of radiation on the properties of welds and joints

    Science.gov (United States)

    Tavassoli, A. A.

    1988-07-01

    The effect of radiation on mechanical properties of candidate structural materials for the first wall and breeder blanket of fusion reactors is reviewed. The emphasis is placed on austenitic stainless steel type 316L and its weld metals; design parameters considered are similar to those currently specified for the Next European Torus, namely, irradiation doses ≤15 dpa, temperatures ≤ 400°C, number of pulse cycles ≈10 5 and hold times ≤15 mn. The effect of irradiation on other materials, including austenitic stainless steel Type 304L, weld metal Type 308L and ferritic/martensitic steels (9-12% Cr-Mo), as well as other service conditions such as temperatures as high as 550°C are also briefly discussed. The data collected and presented in this review are those usually measured before and after irradiation, through tensile, impact toughness, fracture toughness, fatigue, creep-fatigue and fatigue crack propagation testing. In each case the influence of irradiation parameters on the observed changes are discussed and relative conclusions are drawn. The most important observation made is the lack of medium dose irradiation data on the weld metal and in particular on the electron beam welded joints.

  6. The Effects of Laser Welding Direction on Joint Quality for Non-Uniform Part-to-Part Gaps

    Directory of Open Access Journals (Sweden)

    Rocku Oh

    2016-08-01

    Full Text Available Controlling part-to-part gaps is a crucial task in the laser welding of galvanized steel sheets for ensuring the quality of the assembly joint. However, part-to-part gaps are frequently non-uniform. Hence, elevations and depressions from the perspective of the heading direction of the laser beam always exist throughout the gap, creating ascending, descending, and flat travelling paths for laser welding. In this study, assuming non-uniform part-to-part gaps, the effects of welding direction on the quality of the joint of galvanized steel sheets—SGARC440 (lower part and SGAFC590DP (upper part—were examined using 2-kW fiber and 6.6-kW disk laser welding systems. The experimental analysis of coupon tests confirmed that there is no statistically significant correlation between the direction of welding and weld pool quality if the gap exceeds the tolerable range. However, when the gap is controlled within the tolerable range, the welding direction can be considered as an important process control variable to enhance the quality of the joint.

  7. Mechanical properties of API X80 steel pipe joints welded by Flux Core Arc Weld Process; Propriedades mecanicas de juntas de tubos de aco API X80 soldadas com arame tubulares

    Energy Technology Data Exchange (ETDEWEB)

    Ordonez, Robert E. Cooper; Silva, Jose Hilton F.; Trevisan, Roseana E. [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica. Dept. de Engenharia de Fabricacao

    2003-07-01

    Flux Core Arc Welding processes (FCAW) are beginning to be applied in pipeline welds, however, very limited experimental data regarding mechanical properties of pipeline weld joints with these processes are available in the literature. In this paper, the effects of preheat temperature and type of FCAW on mechanical properties (microhardness and tensile strength) of API X80 weld joint steel are presented. FCAW processes with gas protection and self-shielded were used. Multipasses welding were applied in 30'' diameter and 0,625'' thickness tubes. Influence factors were: FCAW type and preheat temperature. Acceptance criteria of welded joints were evaluated by API 1104 standard for tensile strength test and ASTM E384-99 for microhardness test. The results obtained showed that FCAW type and preheat temperature have no influence on mechanical properties of API X80 joint steel. (author)

  8. Effects of thermal aging on microstructure and hardness of China low activation martensitic steel welded joint

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wei; Zhang, Junyu [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); University of Science and Technology of China, Hefei, Anhui (China); Xu, Gang, E-mail: gang.xu@fds.org.cn [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China)

    2016-08-15

    Highlights: • The hardness of HAZ and WM decreases obviously after aging. • The precipitation of the Laves-phase in BM is similar to that in HAZ. • M{sub 23}C{sub 6} particles are conducive to the nucleation of Laves-phase. • Ta may have a role to retard the early precipitation of the Laves-phase. - Abstract: The aim of this paper is to investigate the microstructure evolution and the change in hardness distribution of China low activation martensitic steel welded joints after thermal aging at 550 °C for 6000 h. The joint was processed by electron beam welding. Compared to the base metal (BM) and heat affected zone (HAZ), Laves-phase was not formed in weld metal (WM) in the as-aged condition due to the higher tantalum content and less precipitation in WM before aging. The dislocation density decreased in HAZ and WM after aging for 6000 h. The property results showed that hardness of WM and HAZ was decreased significantly after aging for 6000 h due to the weakening of solution strengthening and dislocations strengthening. However, the change in the hardness of the base metal by aging remained at a minor level.

  9. Characteristics of friction welded AZ31B magnesium–commercial pure titanium dissimilar joints

    Directory of Open Access Journals (Sweden)

    A.K. Lakshminarayanan

    2015-12-01

    Full Text Available It is essential to understand the weld interface characteristics and mechanical properties of dissimilar joints to improve its quality. This study is aimed at exploring the properties of friction welded magnesium–titanium dissimilar joint using tensile testing coupled with digital image correlation, optical and scanning electron microscopy, x-ray diffraction and microhardness measurements. Microstructurally different regions such as contact zone, dynamic recrystallized zone, thermo-mechanically affected zone, and partially deformed zone in the magnesium side were observed. No discernible regions were observed in the titanium side, as it had not undergone any significant plastic deformation. Phase analysis indicated that the aluminium from the magnesium side diffused toward the weld interface and formed a thin continuous intermetallic layer by reacting with the titanium. Microhardness mapping showed a steep hardness gradient from the titanium to magnesium side. Critical analysis is done on the tensile characteristics of the specimen and the response of the local regions to the deformation process is mapped.

  10. Effects of aging treatment and heat input on the microstructures and mechanical properties of TIG-welded 6061-T6 alloy joints

    Science.gov (United States)

    Peng, Dong; Shen, Jun; Tang, Qin; Wu, Cui-ping; Zhou, Yan-bing

    2013-03-01

    Aging treatment and various heat input conditions were adopted to investigate the microstructural evolution and mechanical properties of TIG welded 6061-T6 alloy joints by microstructural observations, microhardness tests, and tensile tests. With an increase in heat input, the width of the heat-affected zone (HAZ) increases and grains in the fusion zone (FZ) coarsen. Moreover, the hardness of the HAZ decreases, whereas that of the FZ decreases initially and then increases with an increase in heat input. Low heat input results in the low ultimate tensile strength of the welded joints due to the presence of partial penetrations and pores in the welded joints. After a simple artificial aging treatment at 175°C for 8 h, the microstructure of the welded joints changes slightly. The mechanical properties of the welded joints enhance significantly after the aging process as few precipitates distribute in the welded seam.

  11. IIW recommendations for the HFMI treatment for improving the fatigue strength of welded joints

    CERN Document Server

    Marquis, Gary B

    2016-01-01

    This book of recommendations presents an overview of High Frequency Mechanical Impact (HFMI) techniques existing today in the market and their proper procedures, quality assurance measures and documentation. Due to differences in HFMI tools and the wide variety of potential applications, certain details of proper treatments and quantitative quality control measures are presented generally. An example of procedure specification as a quality assurance measure is given in the Appendix. Moreover, the book presents procedures for the fatigue life assessment of HFMI-improved welded joints based on nominal stress, structural hot spot stress and effective notch stress. It also considers the extra benefit that has been experimentally observed for HFMI-treated high-strength steels. The recommendations offer proposals on the effect of loading conditions like high mean stress fatigue cycles, variable amplitude loading and large amplitude/low cycle fatigue cycles. Special considerations for low stress concentration welded...

  12. Properties and Microstructure of Laser Welded VM12-SHC Steel Pipes Joints

    Directory of Open Access Journals (Sweden)

    Skrzypczyk A.

    2016-06-01

    Full Text Available Paper presents results of microstructure and tests of welded joints of new generation VM12-SHC martensitic steel using high power CO2 laser (LBW method with bifocal welding head. VM12-SHC is dedicated to energetic installation material, designed to replace currently used. High content of chromium and others alloying elements improve its resistance and strength characteristic. Use of VM12-SHC steel for production of the superheaters, heating chambers and walls in steam boilers resulted in various weldability researches. In article are presented results of destructive and non-destructive tests. For destructive: static bending and Vickers hardness tests, and for non-destructive: VT, RT, UT, micro and macroscopic tests were performed.

  13. Comparative analysis of in-plane and out-of-plane mechanical behaviour of spot-welded and mechaincally fastened joints in thermoplastic composites

    NARCIS (Netherlands)

    Zhao, T.; Palardy, G.; Rans, C.D.; Benedictus, R.; Drechsler, K.

    2016-01-01

    Ultrasonic welding is a promising assembly technique for thermoplastic composites and it is well-suited for spot welding. In this paper, the in-plane and out-of-plane mechanical behaviour of ultrasonically spot-welded and mechanically fastened joints are investigated by double-lap shear and

  14. Experimental and theoretical investigations on temperature distribution at the joint interface for copper joints using ultrasonic welding

    Directory of Open Access Journals (Sweden)

    Elangovan Sooriya

    2014-01-01

    Full Text Available Ultrasonic welding is a solid-state joining process that produces joints by the application of high frequency vibratory energy in the work pieces held together under pressure without melting. Copper and its alloys are extensively used in electrical and electronic industry because of its excellent electrical and thermal properties. This paper mainly focused on temperature distribution and the influence of process parameters at the joint interface while joining copper sheets using ultrasonic welding process. Experiments are carried out using Cu sheets (0.2 mm and 0.3 mm thickness and the interface temperature is measured using Data Acquisition (DAQ System (thermocouple and thermal imager. Numerical and finite element based model for temperature distribution at the interface are developed and solved the same using Finite Difference Method (FDM and Finite Element Analysis (FEA. The results obtained from FDM and FEA model shows similar trend with experimental results and are found to be in good agreement.

  15. Strength of 30KhGSA and 12Kh18N10T steel joints, made by diffusion welding

    Energy Technology Data Exchange (ETDEWEB)

    Kazakov, N.F.; Trifonov, V.A. (Moskovskij Aviatsionnyj Tekhnologicheskij Inst. (USSR)); Nikolaenko, V.V.; Varyanitsa, V.Yu.; Ermakova, N.V. (Vsesoyuznyj Nauchno-Issledovatel' skij Inst. po Zashchite Metallov ot Korrozii, Moscow (USSR))

    1984-01-01

    The optimum regime of diffusion welding (T=1470 K, P=10 MPa, tau=20 min) of the steels 30KhGSA and 12Kh18N10T has been suggested. It is established, that during welding of the given metals a transition zone (10...15 ..mu..m) is formed, the microhardness of which is higher than that of materials welded. Formation of the transition zone is explained by the 30KhGSA steel decarbonization and chromium, titanium and nickel penetration to the zone. Destruction of 30KhGSA and 12Kh18N10T steel welded joints, produced by means of diffusion welding in the above-mentioned regime, takes place in the basic metal-steel 12Kh18N10T.

  16. Research of state of metal welded joint by deformation and corrosion surface projection parameters

    Directory of Open Access Journals (Sweden)

    Demchenko Maria Vyacheslavovna

    2017-10-01

    Full Text Available At industrial enterprises in building structures and equipment one can see corrosion damage, as well as damage accumulated during operation period. The areas of stress concentration are welded joints as their structure is heterogeneous. From the point of view of the scale hierarchy, the welded joint represents the welded and base metal zones at the meso-macrolevel, the weld zone, the thermal zone, the base metal at the micro-mesolevel, the grain constituents at the nano-microlevel. Borders are the stress concentrators at different scale levels, thus they becomes the most dangerous places of metal structure. Modeling by the molecular dynamics method at the atomic level has shown nanocracks initiation in triple junctions of grain boundaries and on the ledges of the grain boundaries. Due to active development of nanotechnology, it became possible to evaluate the state of the weld metal at the nanoscale, where irreversible changes take place from the very beginning. Existing methods of nondestructive testing can detect damage only at the meso- and macrolevel. Modern equipment makes it possible to use other methods of control and approaches. For example, according to GOST R55046-2012 and R57223-2016, the analysis of the parameters of the surface projection deformation performed by confocal laser scanning microscopy should be taken into account when the evaluation of state of metal pipelines is carried out. However, there is a problem to monitore it due to various factors affecting the surface during operation. The paper proposes an additional method to estimate the state of weld metal at any stage of deformation that uses 3D analysis of the parameters of the «artificial» corrosion relief of surface. During the operation period changes in the stress-strain state and structure of the metal take place, as the result the character and depth of etching of the grains of the structural components and their boundaries change too. Evaluation of the

  17. Identification of optimum friction stir spot welding process parameters controlling the properties of low carbon automotive steel joints

    Directory of Open Access Journals (Sweden)

    A.K. Lakshminarayanan

    2015-07-01

    Full Text Available Friction stir spot welding is a novel solid state process that has recently received considerable attention from various industries including automotive sectors due to many advantages over the resistance spot welding. However to apply this technique, the process parameters must be optimized to obtain improved mechanical properties compared to resistance spot welding. To achieve this, in this investigation, design of experiments was used to conduct the experiments for exploring the interdependence of the process parameters. A second order quadratic model for predicting the lap shear tensile strength of friction stir spot welded low carbon automotive steel joints was developed from the experimental obtained data. It is found that dwell time plays a major role in deciding the joint properties, which is followed by rotational speed and plunge depth. Further optimum process parameters were identified for maximum lap shear tensile strength using numerical and graphical optimization techniques.

  18. Aluminum 6060-T6 friction stir welded butt joints: fatigue resistance with different tools and feed rates

    Energy Technology Data Exchange (ETDEWEB)

    Baragetti, S.; D' Urso, G. [University of Bergamo, Viale Marconi (Italy)

    2014-03-15

    The fatigue behavior of AA6060-T6 friction stir welded butt joints was investigated. The joints were produced by using both a standard and a threaded tri-flute cylindrical-tool with flat shoulder. The friction stir welding process was carried out using different feed rates. Preliminary tensile tests, micrograph analyses and hardness profile measurements across the welds were carried out. Welded and unwelded fatigue samples were tested under axial loading (R = 0.1) with upper limits of 10{sup 4} and 10{sup 5} cycles, using threaded and unthreaded (standard) tools at different feed rates. The best tensile and fatigue performance was obtained using the standard tool at low feed rate.

  19. Surface Plastic Deformation and Nanocrystallization Mechanism of Welded Joint of 16MnR Steel Treated by Ultrasonic Impact

    Directory of Open Access Journals (Sweden)

    Yingxia YU

    2015-11-01

    Full Text Available The welded joint surfaces of 16MnR steel were treated using an ultrasonic impact machine. The effects of ultrasonic impact treating (UIT on the plastic deformation and nanocrystallization mechanism of the welded joints of 16MnR steel were studied. The micro-structural features of the surface layer produced by UIT were observed by scanning electron microscopy (SEM and high resolution transmission electron microscopy (HRTEM, and micro-hardness measurements were performed. Experimental results showed that the thickness of the plastic deformation layer was approximately 80 μm. It was found that grains in the surfaces of the welded joints of 16MnR were greatly refined by UIT. Obvious grain refinement was observed, with resultant gain sizes less than 100nm. The micro-hardness of the treated surface layer of the welded joint was enhanced significantly compared to that of the un-treated sample. The micro-hardness on the treated surface of the welded joint was 62.3% higher than that of the un-treated surface.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9563

  20. An Analysis of the Microstructure, Macrostructure and Microhardness of Nicr-Ir Joints Produced by Laser Welding with and without Preheat

    Directory of Open Access Journals (Sweden)

    Różowicz S.

    2016-06-01

    Full Text Available This paper discusses some of the basic problems involved in laser welding of dissimilar materials with significant differences in melting points. It focuses on the micro and macrostructure of laser welded NiCr-Ir microjoints used in central spark plug electrodes. The joints were produced by welding with and without preheat using an Nd,YAG laser. The structure and composition of the welded joints were analyzed by means of a light microscope (LM and a scanning electron microscope (SEM equipped with an energy dispersive X-ray (EDX spectrometer. The microhardness of the weld area was also studied.

  1. Factors that determine depth perception of trapezoids, windsurfers, runways.

    Science.gov (United States)

    Tseng, Chia-Huei; Gobell, Joetta L; Sperling, George

    2015-01-01

    We report here a windsurfer illusion, a naturally occurring trapezoidal illusion in which the small end of the sail viewed at a distance appears to be pointed away from the observer even when it is closer. This naturally occurring illusion is so compelling that observers are unaware of their gross perceptual misinterpretation of the scene. Four laboratory experiment of this kind of trapezoidal illusion investigated the joint effects of retinal orientation, head position, relative motion, and the relative direction of gravity on automatic depth perception. Observers viewed two adjacent white trapezoids outlined on a black background rotating back and forth ± 20° on a vertical axis much like the sails of two adjacent windsurfers. Observers reported which side of the trapezoids (long or short) appeared to be closer to them (i.e., in front). The longer edge of the trapezoid was reported in front 76 ± 2% of trials ("windsurfer effect") whether it was on the left or on the right. When the display was rotated 90°to produce a runway configuration, there was a striking asymmetry: the long edge was perceived to be in front 97% when it was on the bottom but only 43% when it was on top ("runway effect"). The runway effect persisted when the head was tilted 90° or when displays on the ceiling were viewed from the floor. Ninety-five percent of the variance of the variance in the strikingly different 3D perceptions produced by the same 2D trapezoid image was quantitatively explained by a model that assumes there are just three additive bias factors that account for perceiving an edge as closer: Implicit linear perspective, lower position on the retina (based on an automatic assumption of viewing from above), and being lower in world coordinates.

  2. Factors that Determine Depth Perception of Trapezoids, Windsurfers, Runways

    Directory of Open Access Journals (Sweden)

    Chia-Huei eTseng

    2015-04-01

    Full Text Available We report here a windsurfer1 illusion, a naturally occurring trapezoidal illusion in which the small endof the sail viewed at a distance appears to be pointed away from the observer even when it is closer.This naturally occurring illusion is so compelling that observers are unaware of their gross perceptualmisinterpretation of the scene. Four laboratory experiment of this kind of trapezoidal illusion investigatedthe joint effects of retinal orientation, head position, relative motion, and the relative direction ofgravity on automatic depth perception. Observers viewed two adjacent white trapezoids outlined on ablack background rotating back and forth +/- 20 deg on a vertical axis much like the sails of two adjacentwindsurfers. Observers reported which side of the trapezoids (long or short appeared to becloser to them (i.e., in front. The longer edge of the trapezoid was reported in front 76+/-2% of trials(windsurfer effect whether it was on the left or on the right. When the display was rotated 90 deg toproduce a runway configuration, there was a striking asymmetry: the long edge was perceived to bein front 97% when it was on the bottom but only 43% when it was on top (runway effect. The runwayeffect persisted when the head was tilted 90 deg or when displays on the ceiling were viewedfrom the floor. 95% of the variance of the variance in the strikingly different 3D perceptions producedby the same 2D trapezoid image was quantitatively explained by a model that assumes there are justthree additive bias factors that account for perceiving an edge as closer: Implicit linear perspective,lower position on the retina (based on an automatic assumption of viewing from above, and beinglower in world coordinates.

  3. Fatigue strength: effect of welding type and joint design executed in Ti-6Al-4V structures.

    Science.gov (United States)

    Pantoja, Juliana M C Nuñez; Farina, Ana P; Vaz, Luis G; Consani, Rafael L X; Nóbilo, Mauro A de Arruda; Mesquita, Marcelo F

    2012-06-01

    This study evaluated the fatigue strength of Ti-6Al-4V-machined structures submitted to laser (L)-welding and TIG (TIG)-welding procedures, varying the joint designs. Seventy dumbbell rods were machined in Ti-6Al-4V alloy with central diameters of 3.5 mm. The specimens were sectioned and welded using TIG or L and three joint designs {'I' design, varying welding distances [0.0 mm (I00) or 0.6 mm (I06)], or 'X' [X] design}. The combinations of variables created six groups, which, when added to the intact group, made a total of seven groups (n = 10). L was executed as follows: 360 V/8 ms (X) and 390 V/9 ms (I00 and I06), with focus and frequency regulated to zero. TIG was executed using 2:2 (X) and 3:2 (I00 and I06) as welding parameters. Joints were finished, polished and submitted to radiographic examination to be analysed visually for the presence of porosity. The specimens were then subjected to mechanical cyclic tests, and the number of cycles completed until failure was recorded. The fracture surface was examined using a scanning electron microscope. The Kruskal-Wallis and Dunn test (α = 0.05) indicated that the number of cycles resisted for fracture was higher to X for both welding procedures. To L, I06 was as resistant as X. The Mann-Whitney U-test (α = 0.05) indicated that L joints were more resistant than TIG to I00 and I06. Spearman's correlation coefficient (α = 0.05) indicated a negative correlation between the number of cycles and presence of porosity. Thus, to weld Ti-6Al-4V structures, the best condition is X, independent of the welding method employed. © 2011 The Gerodontology Society and John Wiley & Sons A/S.

  4. Corrosion Performance of Friction Stir Linear Lap Welded AM60B Joints

    Science.gov (United States)

    Kish, J. R.; Birbilis, N.; McNally, E. M.; Glover, C. F.; Zhang, X.; McDermid, J. R.; Williams, G.

    2017-11-01

    A corrosion investigation of friction stir linear lap welded AM60B joints used to fabricate an Mg alloy-intensive automotive front end sub-assembly was performed. The stir zone exhibited a slightly refined grain size and significant break-up and re-distribution of the divorced Mg17Al12 (β-phase) relative to the base material. Exposures in NaCl (aq) environments revealed that the stir zone was more susceptible to localized corrosion than the base material. Scanning vibrating electrode technique measurements revealed differential galvanic activity across the joint. Anodic activity was confined to the stir zone surface and involved initiation and lateral propagation of localized filaments. Cathodic activity was initially confined to the base material surface, but was rapidly modified to include the cathodically-activated corrosion products in the filament wake. Site-specific surface analyses revealed that the corrosion observed across the welded joint was likely linked to variations in Al distribution across the surface film/metal interface.

  5. Analysis of Deformation and Failure Behaviors of TIG Welded Dissimilar Metal Joints Using Miniature Tensile Specimens

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Ji-Hwan; Jahanzeb, Nabeel; Kim, Min-Seong; Hwang, Ji-Hyun; Choi, Shi-Hoon [Sunchon National University, Suncheon (Korea, Republic of)

    2017-02-15

    The deformation and failure behaviors of dissimilar metal joints between SS400 steel and STS316L steel were investigated. The dissimilar metal joints were fabricated using the tungsten inert gas (TIG) welding process with STS309 steel as a filler metal. The microstructures of the dissimilar metal joints were investigated using an optical microscope and EBSD technique. The mechanical properties of the base metal (BM), heat affected zone (HAZ) and weld metal (WM) were measured using a micro-hardness and micro-tension tester combined with the digital image correlation (DIC) technique. The HAZ of the STS316L steel exhibited the highest micro-hardness value, and yield/tensile strengths, while the BM of the SS440 steel exhibited the lowest micro-hardness value and yield /tensile strengths. The grain size refinement in the HAZ of SS400 steel induced an enhancement of micro-hardness value and yield/tensile strengths compared to the BM of the SS400 steel. The WM, which consists of primary δ-ferrite and a matrix of austenite phase, exhibited relatively a high micro-hardness value, yield /tensile strengths and elongation compared to the BM and HAZ of the SS400 steel.

  6. Effect of post-weld heat treatment on the mechanical properties of CLAM/316L dissimilar joint

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Junyu [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); University of Science and Technology of China, Hefei, Anhui 230027 (China); Huang, Bo [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Wu, Qingsheng, E-mail: qingsheng.wu@fds.org.cn [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Li, Chunjing; Huang, Qunying [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China)

    2015-11-15

    Highlights: • Dissimilar joints between CLAM and 316L steels welded by TIG were investigated. • After PWHTs, the hardening in HAZ on the CLAM steel side decreased remarkably. • Tempering at 740 °C for 2 h was considered as the preferable treatment rule. - Abstract: Dissimilar welding between China low activation martensitic (CLAM) steel and 316L austenitic stainless steel was investigated to achieve the reliable connection between test blanket modules (TBMs) and piping system in the international thermonuclear experimental reactor (ITER). The dissimilar joints were welded by tungsten inert gas (TIG) welding process with a filler material type-309. In order to stabilize the microstructure and improve the strength and toughness, post-weld heat treatments (PWHTs) of tempering at 740 °C, 780 °C and 820 °C, respectively, for 2 h were performed. The microstructure observation showed that tempering at 740 °C for 2 h was the preferable PWHT rule in this work. After the treatment, the hardening in heat affected zone (HAZ) on the CLAM steel side decreased remarkably. The tensile strength of the joint was roughly the same as that of the base metal. The impact toughness of HAZ on the CLAM steel side was 77% of that of the base metal. The absorbed energy of HAZ of 316L steel decreased by 93 J, and that of weld metal (WM) was 110 J after the treatment.

  7. TRANSIENT FINITE ELEMENT SIMULATION AND MICROSTRUCTURE EVOLUTION OF AA2219 WELD JOINT USING GAS TUNGSTEN ARC WELDING PROCESS

    Directory of Open Access Journals (Sweden)

    Sivaraman Arunkumar

    2016-09-01

    Full Text Available In this study we focus on finite element simulation of gas tungsten arc welding (GTAW of AA2219 aluminum alloy and the behavioral of the microstructure before and after weld. The simulations were performed using commercial COMSOL Multiphysics software. The thermal history of the weld region was studied by initially developed mathematical model. A sweep type meshing was used and transient analysis was performed for one welding cycle. The highest temperature noted was 3568 °C during welding. The welding operation was performed on 200×100×25 mm plates. Through metallurgical characterization, it was observed that a fair copper rich cellular (CRC network existed in the weld region. A small amount of intermetallic compounds like Al2Cu is observed through the XRD pattern.

  8. Estimation of the resistance to the initiation of fatigue cracks in the welded joints of steel constructions

    Science.gov (United States)

    Odesskii, P. D.; Shuvalov, A. N.; Emel'yanov, O. V.

    2017-04-01

    The problem of choosing an effective approach to determining the fatigue strength of welded butt joints at the stage of crack nucleation is solved. The results of the calculations performed according to the existing building code from the specified strength characteristics and the calculations that take into account local elastoplastic deformation in stress concentration zones are compared. Full-scale specimens of the welded joints of pair angles are tested in the low-cycle fatigue region at a constant load. The kinetics of the state of stress in the zones of terminating flange welded joints is studied by a tensometric method. It is shown that the stage of fatigue crack nucleation is best described using the deformation criterion of fracture: a comparison of the results of calculating the number of cycles to the nucleation of a fatigue crack with experimental data demonstrates good agreement.

  9. Improved Formula for the Stress Intensity Factor of Semi-Elliptical Surface Cracks in Welded Joints under Bending Stress

    Directory of Open Access Journals (Sweden)

    Yang Peng

    2017-02-01

    Full Text Available Welded joints are prone to fatigue cracking with the existence of welding defects and bending stress. Fracture mechanics is a useful approach in which the fatigue life of the welded joint can be predicted. The key challenge of such predictions using fracture mechanics is how to accurately calculate the stress intensity factor (SIF. An empirical formula for calculating the SIF of welded joints under bending stress was developed by Baik, Yamada and Ishikawa based on the hybrid method. However, when calculating the SIF of a semi-elliptical crack, this study found that the accuracy of the Baik-Yamada formula was poor when comparing the benchmark results, experimental data and numerical results. The reasons for the reduced accuracy of the Baik-Yamada formula were identified and discussed in this paper. Furthermore, a new correction factor was developed and added to the Baik-Yamada formula by using theoretical analysis and numerical regression. Finally, the predictions using the modified Baik-Yamada formula were compared with the benchmark results, experimental data and numerical results. It was found that the accuracy of the modified Baik-Yamada formula was greatly improved. Therefore, it is proposed that this modified formula is used to conveniently and accurately calculate the SIF of semi-elliptical cracks in welded joints under bending stress.

  10. Improved Formula for the Stress Intensity Factor of Semi-Elliptical Surface Cracks in Welded Joints under Bending Stress.

    Science.gov (United States)

    Peng, Yang; Wu, Chao; Zheng, Yifu; Dong, Jun

    2017-02-13

    Welded joints are prone to fatigue cracking with the existence of welding defects and bending stress. Fracture mechanics is a useful approach in which the fatigue life of the welded joint can be predicted. The key challenge of such predictions using fracture mechanics is how to accurately calculate the stress intensity factor (SIF). An empirical formula for calculating the SIF of welded joints under bending stress was developed by Baik, Yamada and Ishikawa based on the hybrid method. However, when calculating the SIF of a semi-elliptical crack, this study found that the accuracy of the Baik-Yamada formula was poor when comparing the benchmark results, experimental data and numerical results. The reasons for the reduced accuracy of the Baik-Yamada formula were identified and discussed in this paper. Furthermore, a new correction factor was developed and added to the Baik-Yamada formula by using theoretical analysis and numerical regression. Finally, the predictions using the modified Baik-Yamada formula were compared with the benchmark results, experimental data and numerical results. It was found that the accuracy of the modified Baik-Yamada formula was greatly improved. Therefore, it is proposed that this modified formula is used to conveniently and accurately calculate the SIF of semi-elliptical cracks in welded joints under bending stress.

  11. Tensile properties of a titanium modified austenitic stainless steel and the weld joints after neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shiba, K.; Ioka, I.; Jitsukawa, S.; Hamada, A.; Hishinuma, A. [and others

    1996-10-01

    Tensile specimens of a titanium modified austenitic stainless steel and its weldments fabricated with Tungsten Inert Gas (TIG) and Electron Beam (EB) welding techniques were irradiated to a peak dose of 19 dpa and a peak helium level of 250 appm in the temperature range between 200 and 400{degrees}C in spectrally tailored capsules in the Oak Ridge Research Reactor (ORR) and the High Flux Isotope Reactor (HFIR). The He/dpa ratio of about 13 appm/dpa is similar to the typical helium/dpa ratio of a fusion reactor environment. The tensile tests were carried out at the irradiation temperature in vacuum. The irradiation caused an increase in yield stress to levels between 670 and 800 MPa depending on the irradiation temperature. Total elongation was reduced to less than 10%, however the specimens failed in a ductile manner. The results were compared with those of the specimens irradiated using irradiation capsules producing larger amount of He. Although the He/dpa ratio affected the microstructural change, the impact on the post irradiation tensile behavior was rather small for not only base metal specimens but also for the weld joint and the weld metal specimens.

  12. Hardness analysis of welded joints of austenitic and duplex stainless steels

    Science.gov (United States)

    Topolska, S.

    2016-08-01

    Stainless steels are widely used in the modern world. The continuous increase in the use of stainless steels is caused by getting greater requirements relating the corrosion resistance of all types of devices. The main property of these steels is the ability to overlap a passive layer of an oxide on their surface. This layer causes that they become resistant to oxidation. One of types of corrosion-resistant steels is ferritic-austenitic steel of the duplex type, which has good strength properties. It is easily formable and weldable as well as resistant to erosion and abrasive wear. It has a low susceptibility to stress-corrosion cracking, to stress corrosion, to intercrystalline one, to pitting one and to crevice one. For these reasons they are used, among others, in the construction of devices and facilities designed for chemicals transportation and for petroleum and natural gas extraction. The paper presents the results which shows that the particular specimens of the ][joint representing both heat affected zones (from the side of the 2205 steel and the 316L one) and the weld are characterized by higher hardness values than in the case of the same specimens for the 2Y joint. Probably this is caused by machining of edges of the sections of metal sheets before the welding process, which came to better mixing of native materials and the filler metal. After submerged arc welding the 2205 steel still retains the diphase, austenitic-ferritic structure and the 316L steel retains the austenitic structure with sparse bands of ferrite σ.

  13. Evaluation of creep damage in a welded joint of modified 9Cr-1Mo steel

    Science.gov (United States)

    Li, Yongkui; Monma, Yoshio; Hongo, Hiromichi; Tabuchi, Masaaki

    2010-10-01

    This paper aims to evaluate the creep damage of modified 9Cr-1Mo steel under 600 °C operating conditions, using constitutive equations based on the continuum damage mechanics. The accumulation of voids over a long period is believed to contribute to the formation of Type IV cracking, which in turn leads eventually to the failure of weldment under conditions of higher temperatures and lower stresses. Specimens of base metal, a simulated fine-grained heat affected zone, and a thin (thick) welded joint were kept under stress from 80 to 160 MPa at 600 °C. During the creep tests of thick plate welded joint specimens, the application of stress was suspended several times, and the creep damage as indicated by the void distribution was examined quantitatively using a laser microscope. The combined effect of the equivalent creep strain and the stress triaxial factor was considered and introduced into the constitutive equations with the aid of a finite element method. The logarithms of m and 1/λ in the continuum damage mechanics equations were determined to have a linear correlation with the ratio of the applied stress to the yield stress for homogeneous materials. In this way, the damage distribution and evolution in the fine-grained heat affected zone were evaluated successfully.

  14. Microstructure and mechanical properties of China low activation martensitic steel joint by TIG multi-pass welding with a new filler wire

    Science.gov (United States)

    Huang, Bo; Zhang, Junyu; Wu, Qingsheng

    2017-07-01

    Tungsten Inner Gas (TIG) welding is employed for joining of China low activation martensitic (CLAM) steel. A new filler wire was proposed, and the investigation on welding with various heat input and welding passes were conducted to lower the tendency towards the residual of δ ferrite in the joint. With the optimized welding parameters, a butt joint by multi-pass welding with the new filler wire was prepared to investigate the microstructure and mechanical properties. The microstructure of the joint was observed by optical microscope (OM) and scanning electron microscope (SEM). The hardness, Charpy impact and tensile tests of the joint were implemented at room temperature (25 °C). The results revealed that almost full martensite free from ferrite in the joints were obtained by multipass welding with the heat input of 2.26 kJ/mm. A certain degree of softening occurred at the heat affected zone of the joint according to the results of tensile and hardness tests. The as welded joints showed brittle fracture in the impact tests. However, the joints showed toughness fracture after tempering and relatively better comprehensive performance were achieved when the joints were tempered at 740 °C for 2 h.

  15. Welding.

    Science.gov (United States)

    Cowan, Earl; And Others

    The curriculum guide for welding instruction contains 16 units presented in six sections. Each unit is divided into the following areas, each of which is color coded: terminal objectives, specific objectives, suggested activities, and instructional materials; information sheet; transparency masters; assignment sheet; test; and test answers. The…

  16. Columnar jointing in vapor-phase-altered, non-welded Cerro Galán Ignimbrite, Paycuqui, Argentina

    Science.gov (United States)

    Wright, Heather M.; Lesti, Chiara; Cas, Ray A.F.; Porreca, Massimiliano; Viramonte, Jose G.; Folkes, Christopher B.; Giordano, Guido

    2011-01-01

    Columnar jointing is thought to occur primarily in lavas and welded pyroclastic flow deposits. However, the non-welded Cerro Galán Ignimbrite at Paycuqui, Argentina, contains well-developed columnar joints that are instead due to high-temperature vapor-phase alteration of the deposit, where devitrification and vapor-phase crystallization have increased the density and cohesion of the upper half of the section. Thermal remanent magnetization analyses of entrained lithic clasts indicate high emplacement temperatures, above 630°C, but the lack of welding textures indicates temperatures below the glass transition temperature. In order to remain below the glass transition at 630°C, the minimum cooling rate prior to deposition was 3.0 × 10−3–8.5 × 10−2°C/min (depending on the experimental data used for comparison). Alternatively, if the deposit was emplaced above the glass transition temperature, conductive cooling alone was insufficient to prevent welding. Crack patterns (average, 4.5 sides to each polygon) and column diameters (average, 75 cm) are consistent with relatively rapid cooling, where advective heat loss due to vapor fluxing increases cooling over simple conductive heat transfer. The presence of regularly spaced, complex radiating joint patterns is consistent with fumarolic gas rise, where volatiles originated in the valley-confined drainage system below. Joint spacing is a proxy for cooling rates and is controlled by depositional thickness/valley width. We suggest that the formation of joints in high-temperature, non-welded deposits is aided by the presence of underlying external water, where vapor transfer causes crystallization in pore spaces, densifies the deposit, and helps prevent welding.

  17. Influence of Filler Wire Feed Rate in Laser-Arc Hybrid Welding of T-butt Joint in Shipbuilding Steel with Different Optical Setups

    Science.gov (United States)

    Unt, Anna; Poutiainen, Ilkka; Salminen, Antti

    In this paper, a study of laser-arc hybrid welding featuring three different process fibres was conducted to build knowledge about process behaviour and discuss potential benefits for improving the weld properties. The welding parameters affect the weld geometry considerably, as an example the increase in welding speed usually decreases the penetration and a larger beam diameter usually widens the weld. The laser hybrid welding system equipped with process fibres with 200, 300 and 600 μm core diameter were used to produce fillet welds. Shipbuilding steel AH36 plates with 8 mm thickness were welded with Hybrid-Laser-Arc-Welding (HLAW) in inversed T configuration, the effects of the filler wire feed rate and the beam positioning distance from the joint plane were investigated. Based on the metallographic cross-sections, the effect of process parameters on the joint geometry was studied. Joints with optimized properties (full penetration, soundness, smooth transition from bead to base material) were produced with 200 μm and 600 μm process fibres, while fiber with 300 μm core diameter produced welds with unacceptable levels of porosity.

  18. The Optimization of Process Parameters and Microstructural Characterization of Fiber Laser Welded Dissimilar HSLA and MART Steel Joints

    Directory of Open Access Journals (Sweden)

    Celalettin Yuce

    2016-10-01

    Full Text Available Nowadays, environmental impact, safety and fuel efficiency are fundamental issues for the automotive industry. These objectives are met by using a combination of different types of steels in the auto bodies. Therefore, it is important to have an understanding of how dissimilar materials behave when they are welded. This paper presents the process parameters’ optimization procedure of fiber laser welded dissimilar high strength low alloy (HSLA and martensitic steel (MART steel using a Taguchi approach. The influence of laser power, welding speed and focal position on the mechanical and microstructural properties of the joints was determined. The optimum parameters for the maximum tensile load-minimum heat input were predicted, and the individual significance of parameters on the response was evaluated by ANOVA results. The optimum levels of the process parameters were defined. Furthermore, microstructural examination and microhardness measurements of the selected welds were conducted. The samples of the dissimilar joints showed a remarkable microstructural change from nearly fully martensitic in the weld bead to the unchanged microstructure in the base metals. The heat affected zone (HAZ region of joints was divided into five subzones. The fusion zone resulted in an important hardness increase, but the formation of a soft zone in the HAZ region.

  19. Corrosion Behavior of Metal Active Gas Welded Joints of a High-Strength Steel for Automotive Application

    Science.gov (United States)

    Garcia, Mainã Portella; Mantovani, Gerson Luiz; Vasant Kumar, R.; Antunes, Renato Altobelli

    2017-10-01

    In this work, the corrosion behavior of metal active gas-welded joints of a high-strength steel with tensile yield strength of 900 MPa was investigated. The welded joints were obtained using two different heat inputs. The corrosion behavior has been studied in a 3.5 wt.% NaCl aqueous solution using electrochemical impedance spectroscopy and potentiodynamic polarization tests. Optical microscopy images, scanning electron microscopy and transmission electron microscopy with energy-dispersive x-ray revealed different microstructural features in the heat-affected zone (HAZ) and the weld metal (WM). Before and after the corrosion process, the sample was evaluated by confocal laser scanning microscopy to measure the depth difference between HAZ and WM. The results showed that the heat input did not play an important role on corrosion behavior of HSLA steel. The anodic and cathodic areas of the welded joints could be associated with depth differences. The HAZ was found to be the anodic area, while the WM was cathodic with respect to the HAZ. The corrosion behavior was related to the amount and orientation nature of carbides in the HAZ. The microstructure of the HAZ consisted of martensite and bainite, whereas acicular ferrite was observed in the weld metal.

  20. Corrosion Behavior of Metal Active Gas Welded Joints of a High-Strength Steel for Automotive Application

    Science.gov (United States)

    Garcia, Mainã Portella; Mantovani, Gerson Luiz; Vasant Kumar, R.; Antunes, Renato Altobelli

    2017-09-01

    In this work, the corrosion behavior of metal active gas-welded joints of a high-strength steel with tensile yield strength of 900 MPa was investigated. The welded joints were obtained using two different heat inputs. The corrosion behavior has been studied in a 3.5 wt.% NaCl aqueous solution using electrochemical impedance spectroscopy and potentiodynamic polarization tests. Optical microscopy images, scanning electron microscopy and transmission electron microscopy with energy-dispersive x-ray revealed different microstructural features in the heat-affected zone (HAZ) and the weld metal (WM). Before and after the corrosion process, the sample was evaluated by confocal laser scanning microscopy to measure the depth difference between HAZ and WM. The results showed that the heat input did not play an important role on corrosion behavior of HSLA steel. The anodic and cathodic areas of the welded joints could be associated with depth differences. The HAZ was found to be the anodic area, while the WM was cathodic with respect to the HAZ. The corrosion behavior was related to the amount and orientation nature of carbides in the HAZ. The microstructure of the HAZ consisted of martensite and bainite, whereas acicular ferrite was observed in the weld metal.

  1. A Study on the compensation margin on butt welding joint of Large Steel plates during Shipbuilding construction.

    Science.gov (United States)

    Kim, J.; Jeong, H.; Ji, M.; Jeong, K.; Yun, C.; Lee, J.; Chung, H.

    2015-09-01

    This paper examines the characteristics of butt welding joint shrinkage for shipbuilding and marine structures main plate. The shrinkage strain of butt welding joint which is caused by the process of heat input and cooling, results in the difference between dimensions of the actual parent metal and the dimensions of design. This, in turn, leads to poor quality in the production of ship blocks and reworking through period of correction brings about impediment on improvement of productivity. Through experiments on butt welding joint's shrinkage strain on large structures main plate, the deformation of welding residual stress in the form of I, Y, V was obtained. In addition, the results of experiments indicate that there is limited range of shrinkage in the range of 1 ∼ 2 mm in 11t ∼ 21.5t thickness and the effect of heat transfer of weld appears to be limited within 1000 mm based on one side of seam line so there was limited impact of weight of parent metal on the shrinkage. Finally, it has been learned that Shrinkage margin needs to be applied differently based on groove phenomenon in the design phase in order to minimize shrinkage.

  2. Development of methodology for measurements of residual stresses in welded joint based on displacement of points in a coordinated table

    Directory of Open Access Journals (Sweden)

    Aníbal Veras Siqueira Filho

    2013-04-01

    Full Text Available Residual stresses in a welded joint of ASTM A131 grade AH32 steel was measured either by the X-ray diffraction or by displacements of referenced points measured on a coordinate measuring machine before and after heat treatment. For all tests, the welding was performed with Shielded Metal Arc Welding, vertical-up position, by a certified welder. After welding, some specimens were subjected to marking, made through small holes evenly spaced and mapped on a coordinate measuring machine. After labeling, the samples were subjected to heat treatment at temperatures nearby recrystallization. After heat treatment, the samples were subjected to new measurements by coordinate measuring machine to evaluate the displacements of the points produced by the recrystallization. In parallel, residual stress measurements were made by XRD for validation of this new methodology. The results obtained either by X-ray or by coordinate measuring machine showed a good correlation between the two measurement methodologies employed.

  3. The evolution of microstructures, corrosion resistance and mechanical properties of AZ80 joints using ultrasonic vibration assisted welding process

    Science.gov (United States)

    Li, Hui; Zhang, Jiansheng

    2017-12-01

    The evolution of microstructures, corrosion resistance and mechanical properties of AZ80 joints using an ultrasonic vibration assisted welding process is investigated. The results show that, with ultrasonic vibration treatment, a reliable AZ80 joint without defects is obtained. The coarsening α-Mg grains are refined to about 83.5  ±  3.3 µm and the continuous β-Mg17Al12 phases are broken to granular morphology, owing to the acoustic streaming effect and the cavitation effect evoked by ultrasonic vibration. Both immersion and electrochemical test results indicate that the corrosion resistance of the AZ80 joint welded with ultrasonic vibration is improved, attributed to microstructure evolution. With ultrasonic power of 900 W, the maximum tensile strength of an AZ80 specimen is 261  ±  7.5 MPa and fracture occurs near the heat affected zone of the joint.

  4. High temperature strength analysis of welded joint of RAF's by small punch test

    Energy Technology Data Exchange (ETDEWEB)

    Kato, T. [Muroran Institute of Technology, Dept. of Materials Science and Engineeering, Hokkaido (Japan); Komazaki, S.; Kohno, Y. [Muroran Institute of Technology, Muroran (Japan); Tanigawa, H. [Japan Atomic Energy Agency, Naga-gun, Ibaraki-ken (Japan); Kohyama, A. [Kyoto Univ., Institute of Advanced Energy (Japan)

    2007-07-01

    Full text of publication follows: Nucleation and growth of microvoids and/or small cracks in fine-grained heat affected zone (HAZ) after long-term service operation, which is recognized as Type IV creep damage, has recently been a worldwide issue for high Cr ferritic steels. In our group, a small punch (SP) creep test has been successfully applied to evaluate this damage of low alloy ferritic steel. However, the HAZ of fusion reactor material welded by electron-beam (EB) welding is so narrow that it is not easy to evaluate its mechanical properties by conventional tests including the SP creep test with a plate-type specimen (10 x 10 x 0.5 mm{sup 3}). In this study, the SP creep test using a further miniaturized specimen was developed and applied to the welded joint of reduced activation ferritic steels (RAFs), F82H-IEA (Fe-8Cr-2W-0.2V-0.02Ta), for measuring creep properties of the HAZ. For the SP creep test, TEM disk-type samples (diam. 3.0 x 0.30 mm) were removed from the base metal (BM), weld metal (WM) and HAZ, respectively. The specimen surfaces were polished up to a 0.05 {mu}m alumina powder finish and the specimen's thickness was finally adjusted to 0.25 mm. The SP creep tests were performed at temperatures of 823{approx}973 K and under loads ranging from 20 to 200 N. A constant load was applied to the center of the specimen through the Si{sub 3}N{sub 4} bail (diam. 1.0 mm) using the electric servo motor. The central deflection of the specimen was monitored by measuring the displacement of the compression rod. The tests were carried out in an argon gas atmosphere and the gas was continuously passed through during the test to prevent severe oxidation of the specimen. The differences in SP creep properties such as rupture time and minimum creep rate between the BM, WM and HAZ were discussed in terms of microstructural changes during welding thermal cycles. In addition, the result obtained from the BM was correlated with those of uniaxial creep test

  5. Qualification of phased array ultrasonic examination on T-joint weld of austenitic stainless steel for ITER vacuum vessel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, G.H. [ITER Korea, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Park, C.K., E-mail: love879@hanmail.net [ITER Korea, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Jin, S.W.; Kim, H.S.; Hong, K.H.; Lee, Y.J.; Ahn, H.J.; Chung, W. [ITER Korea, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Jung, Y.H.; Roh, B.R. [Hyundai Heavy Industries Co. Ltd., Ulsan 682-792 (Korea, Republic of); Sa, J.W.; Choi, C.H. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France)

    2016-11-01

    Highlights: • PAUT techniques has been developed by Hyundai Heavy Industries Co., LTD (HHI) and Korea Domestic Agency (KODA) to verify and settle down instrument calibration, test procedures, image processing, and so on. As the first step of development for PAUT technique, Several dozens of qualification blocks with artificial defects, which are parallel side drilled hole, embedded lack of fusion, embedded repair weld notch, and so on, have been designed and fabricated to simulate all potential defects during welding process. Real UT qualification group-1 for T-joint weld was successfully conducted in front of ANB inspector. • In this paper, remarkable progresses of UT qualification are presented for ITER vacuum vessel. - Abstract: Full penetration welding and 100% volumetric examination are required for all welds of pressure retaining parts of the ITER Vacuum Vessel (VV) according to RCC-MR Code and French Order of Nuclear Pressure Equipment (ESPN). The NDE requirement is one of important technical issues because radiographic examination (RT) is not applicable to many welding joints. Therefore the ultrasonic examination (UT) has been selected as an alternative method. Generally the UT on the austenitic welds is regarded as a great challenge due to the high attenuation and dispersion of the ultrasonic signal. In this paper, Phased array ultrasonic examination (PAUT) has been introduced on double sided T-shape austenitic welds of the ITER VV as a major NDE method as well as RT. Several dozens of qualification blocks with artificial defects, which are parallel side drilled hole, embedded lack of fusion, embedded repair weld notch, embedded parallel vertical notch, and so on, have been designed and fabricated to simulate all potential defects during welding process. PAUT techniques on the thick austenitic welds have been developed taking into account the acceptance criteria. Test procedure including calibration of equipment is derived and qualified through

  6. Microstructures and mechanical properties of Gas Tungsten Arc Welded joints of new Al–Mg–Sc and Al–Mg–Er alloy plates

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Le [Key Laboratory of Super-Microstructure and Ultrafast Process in Advanced Materials of Hunan Province, School of Physics and Electronics, Central South University, Changsha, Hunan 410083 (China); School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China); Peng, Yongyi, E-mail: pengyongyi@126.com [Key Laboratory of Super-Microstructure and Ultrafast Process in Advanced Materials of Hunan Province, School of Physics and Electronics, Central South University, Changsha, Hunan 410083 (China); Huang, Jiwu; Deng, Ying; Yin, Zhimin [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China)

    2015-01-03

    The effect of microalloy element Sc and Er on Gas Tungsten Arc Welded (GTAW) joints of Al–Mg alloy was studied by comparative method. The microstructures and mechanical properties of Al–Mg–Sc and Al–Mg–Er alloy welded joint were examined by microhardness measurement, tensile test, optical microscopy and transmission electron microscope. The strength of Al–Mg–Sc welded joint is higher than that of Al–Mg–Er welded joint. The differences of the two welded joints can be attributed to the different thermal stability and the effect of Al{sub 3}(Sc{sub 1−x},Zr{sub x}) particles and Al{sub 3}(Er{sub 1−x},Zr{sub x}) particles. Al{sub 3}(Sc{sub 1−x},Zr{sub x}) particles, which have higher thermal stability, are still coherent with Al matrix in the HAZ, can strongly pin dislocations and subgrain boundaries of the HAZ. There are strain strengthening and precipitation strengthening in the HAZ of Al–Mg–Sc welded joints. Notable coarsening of Al{sub 3}(Er{sub 1−x},Zr{sub x}) particles and recrystallization in the HAZ of Al–Mg–Er welded joint lead to the reduction and disappearance of strain strengthening and precipitation strengthening.

  7. Improvement of localised corrosion resistance of AISI 2205 Duplex Stainless Steel joints made by gas metal arc welding under electromagnetic interaction of low intensity

    Energy Technology Data Exchange (ETDEWEB)

    García-Rentería, M.A., E-mail: crazyfim@gmail.com [Instituto de Investigación en Metalurgia y Materiales, Universidad Michoacana de San Nicolás de Hidalgo, A.P. 888, CP 58000, Morelia, Michoacán (Mexico); López-Morelos, V.H., E-mail: vhlopez@umich.mx [Instituto de Investigación en Metalurgia y Materiales, Universidad Michoacana de San Nicolás de Hidalgo, A.P. 888, CP 58000, Morelia, Michoacán (Mexico); García-Hernández, R., E-mail: rgarcia@umich.mx [Instituto de Investigación en Metalurgia y Materiales, Universidad Michoacana de San Nicolás de Hidalgo, A.P. 888, CP 58000, Morelia, Michoacán (Mexico); Dzib-Pérez, L., E-mail: luirdzib@uacam.mx [Centre for Corrosion Research, Autonomous University of Campeche, Av. Agustín Melgar s/n, Col. Buenavista, CP 24039, Campeche, Cam (Mexico); García-Ochoa, E.M., E-mail: emgarcia@uacam.mx [Centre for Corrosion Research, Autonomous University of Campeche, Av. Agustín Melgar s/n, Col. Buenavista, CP 24039, Campeche, Cam (Mexico); González-Sánchez, J., E-mail: jagonzal@uacam.mx [Centre for Corrosion Research, Autonomous University of Campeche, Av. Agustín Melgar s/n, Col. Buenavista, CP 24039, Campeche, Cam (Mexico)

    2014-12-01

    Highlights: • Electromagnetic interaction in welding improved localised corrosion resistance. • Electromagnetic interaction in welding enhanced γ/δ phase balance of DuplexSS. • Welding under Electromagnetic interaction repress formation and growth of detrimental phases. • Welds made with gas protection (2% O{sub 2} + 98% Ar) have better microstructural evolution during welding. - Abstract: The resistance to localised corrosion of AISI 2205 duplex stainless steel plates joined by Gas Metal Arc Welding (GMAW) under the effect of electromagnetic interaction of low intensity (EMILI) was evaluated with sensitive electrochemical methods. Welds were made using two shielding gas mixtures: 98% Ar + 2% O{sub 2} (M1) and 97% Ar + 3% N{sub 2} (M2). Plates were welded under EMILI using the M1 gas with constant welding parameters. The modified microstructural evolution in the high temperature heat affected zone and at the fusion zone induced by application of EMILI during welding is associated with the increase of resistance to localised corrosion of the welded joints. Joints made by GMAW using the shielding gas M2 without the application of magnetic field presented high resistance to general corrosion but high susceptibility to undergo localised attack.

  8. Fatigue Behaviour of CFRP Strengthened Out-of-Plane Gusset Welded Joints with Double Cracks

    Directory of Open Access Journals (Sweden)

    Qian-Qian Yu

    2015-09-01

    Full Text Available This paper investigates the fatigue behaviour of out-of-plane gusset welded joints strengthened with carbon fibre reinforced polymer (CFRP laminates. Two notches were introduced at the weld toes adjacent to longitudinal plate ends to simulate the initial damage. Variables including the stress range, single- or double-sided strengthening and modulus of CFRP materials were considered. It was found that both cracks propagated under fatigue loading. All the specimens fractured along one predefined notch when the fatigue crack reached a certain length while the other crack also grew to some extent. Test results showed that the addition of composite materials significantly prolonged the fatigue life of specimens by as much as 1.28 to 8.17 times. Double-sided bond and ultra-high modulus CFRP materials led to a better strengthening efficiency. Thereafter, a series of numerical analyses were performed to study the stress intensity factor (SIF and crack opening displacement (COD. Local debonding around the crack tip at the adhesive-steel interface was taken into consideration. Finally, the fatigue life of all the specimens was evaluated based on the linear elastic fracture mechanism (LEFM theory and the predicted results agreed well with the experimental data.

  9. Fiber laser welding of austenitic steel and commercially pure copper butt joint

    Science.gov (United States)

    Kuryntsev, S. V.; Morushkin, A. E.; Gilmutdinov, A. Kh.

    2017-03-01

    The fiber laser welding of austenitic stainless steel and commercially pure copper in butt joint configuration without filler or intermediate material is presented. In order to melt stainless steel directly and melt copper via heat conduction a defocused laser beam was used with an offset to stainless steel. During mechanical tests the weld seam was more durable than heat affected zone of copper so samples without defects could be obtained. Three process variants of offset of the laser beam were applied. The following tests were conducted: tensile test of weldment, intermediate layer microhardness, optical metallography, study of the chemical composition of the intermediate layer, fractography. Measurements of electrical resistivity coefficients of stainless steel, copper and copper-stainless steel weldment were made, which can be interpreted or recalculated as the thermal conductivity coefficient. It shows that electrical resistivity coefficient of cooper-stainless steel weldment higher than that of stainless steel. The width of intermediate layer between stainless steel and commercially pure copper was 41-53 μm, microhardness was 128-170 HV0.01.

  10. Artificial neural network modeling studies to predict the friction welding process parameters of Incoloy 800H joints

    Directory of Open Access Journals (Sweden)

    K. Anand

    2015-09-01

    Full Text Available The present study focuses on friction welding process parameter optimization using a hybrid technique of ANN and different optimization algorithms. This optimization techniques are not only for the effective process modelling, but also to illustrate the correlation between the input and output responses of the friction welding of Incoloy 800H. In addition the focus is also to obtain optimal strength and hardness of joints with minimum burn off length. ANN based approaches could model this welding process of INCOLOY 800H in both forward and reverse directions efficiently, which are required for the automation of the same. Five different training algorithms were used to train ANN for both forward and reverse mapping and ANN tuned force approach was used for optimization. The paper makes a robust comparison of the performances of the five algorithms employing standard statistical indices. The results showed that GANN with 4-9-3 for forward and 4-7-3 for reverse mapping arrangement could outperform the other four approaches in most of the cases but not in all. Experiments on tensile strength (TS, microhardness (H and burn off length (BOL of the joints were performed with optimised parameter. It is concluded that this ANN model with genetic algorithm may provide good ability to predict the friction welding process parameters to weld Incoloy 800H.

  11. Experimental and simulation study on the microstructure of TA15 titanium alloy laser beam welded joints

    Science.gov (United States)

    Zhan, Xiaohong; Peng, Qingyu; Wei, Yanhong; Ou, Wenmin

    2017-09-01

    Laser beam welding technique offers obvious advantages over other fusion welding processes in terms of joining titanium alloy. The microstructure of welded seam and heat affected zone resulted from diverse welding speeds and laser powers were investigated after simulating welding heat treatment. The analysis of the thermal transport properties successfully explained the morphology. Optimal process parameters were obtained. The simulation results were consistent with the corresponding experimental observations.

  12. Development of Mathematic Model of Cold Welding at Drawing-up the Flange Joint of Pneumohydraulic Systems

    Science.gov (United States)

    Boyko, Y. S.

    2002-01-01

    Provision of high airtightness of joints of pipe- lines of pneumohydraulic systems (PHS) operating under high pressure, is an important task for designing and operation of launch vehicles. In the process of assembly and tests of PHS of launch vehicles, it was found that detachable flange joints do not lose their airtightness after removal of fastening elements, even in conditions of standard loads. The task of this work is in studying a phenomenon connected with initiation of the observed effect of adhesion and also stresses in the zone of contact at drawing- up the flange detachable joints with a plastic gasket. Investigations have shown that density of the joint is kept due to cold welding, as the created conditions are helpful for that process. As a result of the investigations performed, we have developed a mathematic model which is based on application of the theory of metal bonds; that theory explains the essence of the effect observed. Basic factors which provide optimum mode of cold welding, are effort which can cause microplastic deformation and form maximum contact, and also quality of processing the material of the surfaces joined. Strength of all- metal joint depends on factual area of contact. So, surface processing quality defines a configuration of microbulges which come into contact not simultaneously, and their stressed state is different, and it influences the character of dependence of the contact area on loading. Results of calculations by the mathematic model are expressed by dependencies of factual area of contact and a single diameter of the contact spot on the load applied which compresses the materials with various physical properties, and on the surface processing quality. The mathematic model allows to explain the common character of the cold welding process in detachable flange joints with the plastic gasket, to determine the nature and the character of acting forces, to define kinetics and the mechanism of formation of cold welding of

  13. Transient out-of-plane distortion of multi-pass fillet welded tube to pipe T-joints

    Directory of Open Access Journals (Sweden)

    R. Vetriselvan

    2017-04-01

    Full Text Available The out-of-plane distortion induced in a multi-pass circumferential fillet welding of tube to pipe under different weld sequences and directions was studied using Finite Element Method (FEM based Sysweld software and verified experimentally. The FEM analyses consisted of thermal and mechanical analyses. Thermal analysis was validated with experimental transient temperature measurements. In the mechanical analysis, three different weld sequences and directions were considered to understand the mechanism of out-of-plane distortion in the tube to pipe T-joints. It was learnt that the welding direction plays a major role in minimizing the out-of-plane distortion. Further, during circumferential fillet welding of the tube to pipe component, the out-of-plane distortion generated in the x direction was primarily influenced by heat input due to the start and stop points, whereas the distortion in the z direction was influenced by time lag and welding direction. The FEM predicted distortion was compared with experimental measurements and the mechanism of out-of-plane distortion was confirmed.

  14. Analysis of Formation and Interfacial WC Dissolution Behavior of WC-Co/Invar Laser-TIG Welded Joints

    Science.gov (United States)

    Xu, P. Q.; Ren, J. W.; Zhang, P. L.; Gong, H. Y.; Yang, S. L.

    2013-02-01

    During the valve fabrication, hard metal is welded to stainless steel or invar alloy for sealing purposes because of its good heat resistance operating at 500 °C. However, WC (tungsten carbide) dissolution in weld pool softens the hard metal and decreases mechanical properties near the hard metal/weld interface. In order to analyze the WC dissolution in welded joint, joining of hard metal and invar alloy was carried out using laser-tungsten inert gas hybrid welding method. Microstructures of the weld region, chemical composition were investigated using optical microscope, scanning electron microscopy, and EDAX, respectively. Mechanical properties such as microhardness and four-point bend strength test were performed. Larger and smaller WC dissolution and WC dissolution through transition layer based on thermo-dynamics were discussed. The results thus indicate that WC dissolution led to cellular microstructure, columnar crystal, and transition layer under the effect of laser beam and tungsten arc. WC dissolution was affected by metal ions Fe+, Ni+, Co+ exchange in W-M-C system, and WC grain growth was driven by forces caused by laser beam and tungsten arc in larger WC, smaller WC, and liquid Fe, Ni systems.

  15. Stress Corrosion Cracking Behavior of Peened Friction Stir Welded 2195 Aluminum Alloy Joints

    Science.gov (United States)

    Hatamleh, Omar; Singh, Preet M.; Garmestani, Hamid

    2009-06-01

    The surface treatment techniques of laser and shot peening were used to investigate their effect on stress corrosion cracking (SCC) in friction stir welded (FSW) 2195 aluminum alloy joints. The investigation consisted of two parts: the first part explored the peening effects on slow strain rate testing (SSRT) in a 3.5% NaCl solution, while the second part investigated the effects of peening on corrosion while submerged in a 3.5% NaCl solution with no external loads applied. For the SSRT, the laser-peened samples demonstrated superior properties to the other samples, but no signs of corrosion pitting or SCC were evident on any of the samples. For the second part of the study, the FSW plates were inspected periodically for signs of corrosion. After 60 days there were signs of corrosion pitting, but no stress corrosion cracking was noticed in any of the peened and unpeened samples.

  16. Change of nonlinear acoustics in ASME grade 122 steel welded joint during creep

    Science.gov (United States)

    Ohtani, Toshihiro; Honma, Takumi; Ishii, Yutaka; Tabuchi, Masaaki; Hongo, Hiromichi; Hirao, Masahiko

    2016-02-01

    In this paper, we described the changes of two nonlinear acoustic characterizations; resonant frequency shift and three-wave interaction, with electromagnetic acoustic resonance (EMAR) throughout the creep life in the welded joints of ASME Grade 122, one of high Cr ferritic heat resisting steels. EMAR was a combination of the resonant acoustic technique with a non-contact electromagnetic acoustic transducer (EMAT). These nonlinear acoustic parameters decreased from the start to 50% of creep life. After slightly increased, they rapidly increased from 80% of creep life to rupture. We interpreted these phenomena in terms of dislocation recovery, recrystallization, and restructuring related to the initiation and growth of creep void, with support from the SEM and TEM observation.

  17. Hardness and microstructural studies of electron beam welded joints of Zircaloy-4 and stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, M.; Akhter, J.I. E-mail: jiakhter@yahoo.comakhterji@hotmail.com; Shaikh, M.A.; Akhtar, M.; Iqbal, M.; Chaudhry, M.A

    2002-03-01

    Electron beam welded joints between Zircaloy-4 and stainless steel 304L are investigated due to their importance in the nuclear industry. The molten and heat affected zones (HAZs) are found to be free of defects. Diffusion of Fe, Cr and Ni is observed in Zircaloy-4 near the molten zone and of Zr and Sn in the stainless steel. A rod-shaped intermetallic compound Zr(Cr,Fe){sub 2} and eutectic phases ZrCr{sub 2}-liquid (Zr,Fe) and Zr{sub 2}Fe-Zr{sub 2}Ni are present in the molten zone. The hardness of the molten zone, containing Zr(Cr,Fe){sub 2,} is much higher than the rest of the molten zone and the HAZs.

  18. Vendor-buyer ordering policy when demand is trapezoidal

    Directory of Open Access Journals (Sweden)

    Digeshkumar B. Shah

    2012-10-01

    Full Text Available A joint vendor-buyer strategy is analyzed which is beneficial to both the players in the supply chain. The demand is assumed to be trapezoidal. It is established numerically that the joint venture decreases the total cost of the supply chain when compared with the independent decision of the buyer. To entice the buyer to order more units, a permissible credit period is offered by the vendor to the buyer. A negotiation factor is incorporated to share the cost savings.

  19. Monitoring of Varying Joint Gap Width During Laser Beam Welding by a Dual Vision and Spectroscopic Sensing System

    Science.gov (United States)

    Nilsen, Morgan; Sikström, Fredrik; Christiansson, Anna-Karin; Ancona, Antonio

    A vision and spectroscopic system for estimation of the joint gap width in autogenous laser beam butt welding is presented. Variations in joint gap width can introduce imperfections in the butt joint seam, which in turn influence fatigue life and structural integrity. The aim of the monitoring approach explored here is to acquire sufficiently robust process data to be used to guide post inspection activities and/or to enable feedback control for a decreased process variability. The dual-sensing approach includes a calibrated CMOS camera and a miniature spectrometer integrated with a laser beam tool. The camera system includes LED illumination and matching optical filters and captures images of the area in front of the melt pool in order to estimate the joint gap width from the information in the image. The intensity of different spectral lines acquired by the spectrometer has been investigated and the correlation between the intensity of representative lines and the joint gap width has been studied. Welding experiments have been conducted using a 6 kW fiber laser. Results from both systems are promising, the camera system is able to give good estimations of the joint gap width, and good correlations between the signal from the spectrometer and the joint gap width have been found. However, developments of the camera setup and vision algorithm can further improve the joint gap estimations and more experimental work is needed in order to evaluate the robustness of the systems.

  20. Effects of Vibration Amplitude on Microstructure Evolution and Mechanical Strength of Ultrasonic Spot Welded Cu/Al Joints

    Directory of Open Access Journals (Sweden)

    Jian Liu

    2017-11-01

    Full Text Available The effects of vibration amplitude on the interface reaction and mechanical strength of the Cu/Al joints were systematically investigated in ultrasonic spot welding (USW experiments. The appropriate vibration amplitude (22.5 μm was beneficial for obtaining a sound joint. The formation of the continuous intermetallic compounds (IMC layer accelerated with a higher vibration amplitude. The lap shear tensile strength of the Cu/Al joints decreased when the thickness of the intermetallic layer was greater than 1 μm at various amplitudes. With the increase in welding time, a crack occurred in the copper side owing to the occurrence of the eutectic reaction, α-A l + θ → L , at the periphery of the nugget. The remarkable decline of ultrasonic power curves occurred at various amplitude levels upon the formation of a crack in the copper side.

  1. Investigations on Laser Beam Welding of Different Dissimilar Joints of Steel and Aluminum Alloys for Automotive Lightweight Construction

    Science.gov (United States)

    Seffer, Oliver; Pfeifer, Ronny; Springer, André; Kaierle, Stefan

    Due to the enormous potential of weight saving, and the consequential reduction of pollutant emissions, the use of hybrid components made of steel and aluminum alloys is increasing steadily, especially concerning automotive lightweight construction. However, thermal joining of steel and aluminum is still being researched, due to a limited solubility of the binary system of iron and aluminum causing the formation of hard and brittle intermetallic phases, which decrease the strength and the formability of the dissimilar seam. The presented results show the investigation of laser beam welding for joining different dissimilar hybrid components of the steel materials HX220LAD+Z100, 22MnB5+AS150 and 1.4301, as well as the aluminum alloy AA6016-T4 as a lap joint. Among other things, the influences of the energy per unit length, the material grade, the sheet thickness t, the weld type (lap weld, fillet weld) and the arrangement of the base materials in a lap joint (aluminum-sided irradiation, steel-sided irradiation) on the achievable strengths are analyzed. The characterization of the dissimilar joints includes tensile shear tests and metallographic analyses, depending on the energy per unit length.

  2. Fatigue design of welded joints using the finite element method and the 2007 ASME Div. 2 Master curve

    Directory of Open Access Journals (Sweden)

    G. Nicoletto

    2009-07-01

    Full Text Available Fatigue design of welded structures is primarily based on a nominal stress; hot spot stress methods or local approaches each having several limitations when coupled with finite element modeling. An alternative recent structural stress definition is discussed and implemented in a post-processor. It provides an effective means for the direct coupling of finite element results to the fatigue assessment of welded joints in complex structures. The applications presented in this work confirm the main features of the method: mesh-insensitivity, accurate crack location and life to failure predictions.

  3. Microstructures and mechanical properties of Ti3Al/Ni-based superalloy joints arc welded with Ti–Nb and Ti–Ni–Nb filler alloys

    Directory of Open Access Journals (Sweden)

    Bingqing Chen

    2014-08-01

    Full Text Available Dissimilar joining of Ti3Al-based alloy to Ni-based superalloy has been carried out using gas tungsten arc (GTA welding technology with Ti–Nb and Ti–Ni–Nb filler alloys. The joint welded with the Ti–Nb filler alloy contained much less interfacial brittle phases than the one using the Ti–Ni–Nb filler alloy. The average room-temperature tensile strength of the joint welded with Ti–Nb was 202 MPa and the strength value of the one welded with Ti–Ni–Nb was 128 MPa. For both fillers, the weak links of the dissimilar joints were the weld/In718 interfaces. The presence of TiNi, TiNi3 and Ni3Nb intermetallic compounds in the joint welded with Ti–Ni–Nb induced microcracks at the weld/In718 interface and deteriorated the mechanical properties of the joint. And the adoption of the Ti–Nb filler alloy decreased the formation tendency of interfacial brittle phases to some extent and thus enhanced the tensile strength of the joint.

  4. Effect of Thermal Cycle on the Formation of Intermetallic Compounds in Laser Welding of Aluminum-Steel Overlap Joints

    Science.gov (United States)

    Fan, J.; Thomy, C.; Vollertsen, F.

    The intermetallic compound (IMC) (or intermetallic phase layer) has a significant influence on the mechanical properties ofjoints between dissimilar metals obtained by thermal processes such as laser welding. Its formation is basically affected by thermal cycles in the joining or contact zone, where the IMC is formed. Within this study, the influence of the thermal cycle on the formation of the IMC during laser welding of an aluminum-steel (Al99.5-DC01) overlap joint was investigated. The temperature was measured directly by a thermocouple, and the weld seam was analyzed by scanning electron microscope (SEM). The influence of peak temperature, cooling time and the integral of the thermal cycle on the thickness of the IMC was identified and discussed. It was identified that cooling time has the biggest influence on the thickness of the IMC.

  5. Fatigue properties of 6061-T6 aluminum alloy butt joints processed by vacuum brazing and tungsten inert gas welding

    Directory of Open Access Journals (Sweden)

    Huei Lin

    2016-04-01

    Full Text Available Tungsten inert gas welding and vacuum brazing butt joints of Al–Mg–Si alloy 6061 in the artificially aged condition T6 were studied. Constant amplitude and variable amplitude fatigue loading tests were performed. The experimental S-N curves were compared with the fatigue design curves recommended by the International Institute of Welding, British Standard, and Eurocode 9. Two mean stress correction methods, Goodman and Gerber, were evaluated. In terms of the size effect on the fatigue life, this article proposed an innovational thickness correction method based on the ratio of the ultimate tensile strengths of specimens with different thickness. For vacuum brazing components, the tensile strength–based thickness correction method was better than the thickness correction methods recommended by the International Institute of Welding and Eurocode 9.

  6. Micro-structure of Joints made of Dissimilar Metals using Explosion Welding

    Directory of Open Access Journals (Sweden)

    Juan Ramón Castillo-Matos

    2017-04-01

    Full Text Available The objective of this investigation is to establish the behaviour of the micro-structure of dissimilar joints made of titanium with AISI 1020, 1066 and 1008 steels through explosion welding. A detonation velocity of 2 800 m/s, a charge radius of 0,345 kg and a collision velocity of 1196, 16 m/s with an explosive volume of 600 cm3 and a density of 1,15 g/cm3 were considered. The microstructures obtained were composed of equiaxed ferrite grains, very fine grains of troostitic type and coarse grains with ferrite grid. Fine and aligned grains of ferrite type are observed in the casted area of both base materials. The metal hardness experienced an increase in samples from 120 HV AISI 1008 steel up to 250 HV for AISI 1066 steel. The AISI 1020 steel joint with titanium has an line shaped interface unlike the AISI 1008 steels with 4063 forms waves with uniform width, which provides a higher mechanical resistance associated with the ductility of the AISI 1008 steel.

  7. Effects of Pulsed Nd:YAG Laser Welding Parameters on Penetration and Microstructure Characterization of a DP1000 Steel Butt Joint

    National Research Council Canada - National Science Library

    Xin Xue; António B Pereira; Jose Amorim; Juan Liao

    2017-01-01

    Of particular importance and interest are the effects of pulsed Nd:YAG laser beam welding parameters on penetration and microstructure characterization of DP1000 butt joint, which is widely used in the automotive industry nowadays...

  8. Influence of joint line remnant on crack paths under static and fatigue loadings in friction stir welded Al-Mg-Sc alloy

    Directory of Open Access Journals (Sweden)

    Y. Besel

    2016-01-01

    Full Text Available The influence of the joint line remnant (JLR on tensile and fatigue fracture behaviour has been investigated in a friction stir welded Al-Mg-Sc alloy. JLR is one of the microstructural features formed in friction stir welds depending on welding conditions and alloy systems. It is attributed to initial oxide layer on butting surfaces to be welded. In this study, two different tool travel speeds were used. JLR was formed in both welds but its spatial distribution was different depending on the tool travel speeds. Under the tensile test, the weld with the higher heat input fractured partially along JLR, since strong microstructural inhomogeneity existed in the vicinity of JLR in this weld and JLR had weak bonding. Resultantly, the mechanical properties of this weld were deteriorated compared with the other weld. Fatigue crack initiation was not affected by the existence of JLR in all welds. But the crack propagated preferentially along JLR in the weld of the higher heat input, when it initiated on the retreating side. Consequently, such crack propagation behaviour along JLR could bring about shorter fatigue lives in larger components in which crack growth phase is dominant.

  9. Evaluation of Mechanical Properties of Alloy 82/182 Weld Joint Between SA508 Gr.3 Nozzle and F316L Safe-End

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Weon [Chosun University, Gwangju (Korea, Republic of); Lee, Kyung Soo; Park, Chi Yong [Korea Electric Power Research Institute, Daejeon (Korea, Republic of)

    2010-03-15

    This paper presents the distributions of the tensile and fracture properties of an alloy 82/182 dissimilar weld joint between an SA508 Gr.3 nozzle and F316L SS safe-end at ambient temperature. Tensile and J-R tests were conducted using specimens extracted from base metals, heat-affected zones (HAZs), buttering regions, and various regions of the weld metal. The results show that the root region of the weld has higher strength than the upper region. The yield and tensile strengths vary considerably within the root region of the weld. The buttering region had the lowest strengths. The strengths gradually increased as the F316L stainless steel weld boundary was approached. The variation of the strengths within the upper region of the weld is insignificant. The fracture toughness of the alloy 82/182 weld metal is less than those of both the base metals and both HAZs. Within the alloy 82/182 weld, the center of weld has a slightly lower fracture toughness than the weld boundary and buttering region, and the root region has greater toughness than the upper region of the weld.

  10. Distribution of mechanical properties in Alloy 82/182 dissimilar weld joint between SA508 Gr.3 nozzle and F316L safe-end

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Weon [Chosun Univ., Gwangju (Korea, Republic of)

    2009-07-01

    This paper presents the distribution of tensile properties and fracture toughness in Alloy 82/182 dissimilar weld joint between SA508 Gr.3 nozzle and F316L SS safe-end at ambient temperature. Tensile and J-R tests were conducted using the specimens extracted form both base metals, Heat Affected Zones (HAZs), buttering, and various regions of weld metal. It showed that root region of weld exhibits higher strengths than upper region. The yield and tensile strengths considerably varied within root region of weld, the lowest strengths appeared at buttering region and gradually increased with approaching boundary with F316L stainless steel, whereas the variation of strengths within the weld was insignificant at upper region of weld. It was also indicated that fracture toughness of Alloy 82/182 weld metal was lower than that of both base metals and both HAZs. Within the Alloy 82/182 weld, the center of weld showed slightly lower fracture toughness than weld boundary and buttering, and the root region showed higher toughness than upper region of weld.

  11. Detailed Microstructural Characterization and Restoration Mechanisms of Duplex and Superduplex Stainless Steel Friction-Stir-Welded Joints

    Science.gov (United States)

    Santos, T. F. A.; Torres, E. A.; Lippold, J. C.; Ramirez, A. J.

    2016-12-01

    Duplex stainless steels are successfully used in a wide variety of applications in areas such as the food industry, petrochemical installations, and sea water desalination plants, where high corrosion resistance and high mechanical strength are required. However, during fusion welding operations, there can be changes to the favorable microstructure of these materials that compromise their performance. Friction stir welding with a non-consumable pin enables welded joints to be obtained in the solid state, which avoids typical problems associated with solidification of the molten pool, such as segregation of alloying elements and the formation of solidification and liquefaction cracks. In the case of superduplex stainless steels, use of the technique can avoid unbalanced proportions of ferrite and austenite, formation of deleterious second phases, or growth of ferritic grains in the heat-affected zone. Consolidated joints with full penetration were obtained for 6-mm-thick plates of UNS S32101 and S32205 duplex stainless steels, and S32750 and S32760 superduplex steels. The welding heat cycles employed avoided the conditions required for formation of deleterious phases, except in the case of the welded joint of the S32760 steel, where SEM images indicated the formation of secondary phases, as corroborated by decreased mechanical performance. Analysis using EBSD and transmission electron microscopy revealed continuous dynamic recrystallization by the formation of cellular arrays of dislocations in the ferrite and discontinuous dynamic recrystallization in the austenite. Microtexture evaluation indicated the presence of fibers typical of shear in the thermomechanically affected zone. These fibers were not obviously present in the stir zone, probably due to the intensity of microstructural reformulation to which this region was subjected.

  12. Microstructural characterization of welded zone for Fe{sub 3}Al/Q235 fusion-bonded joint

    Energy Technology Data Exchange (ETDEWEB)

    Ma Haijun [Key Lab of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061, Shandong Province, Jing Shi Road 73, Shandong (China)], E-mail: hjma123@mail.sdu.edu.cn; Li Yajiang [Key Lab of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061, Shandong Province, Jing Shi Road 73, Shandong (China); Material Science Department, Bauman Moscow State Technical University, Moscow 105005 (Russian Federation); Puchkov, U.A. [Material Science Department, Bauman Moscow State Technical University, Moscow 105005 (Russian Federation); Wang Juan [Key Lab of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061, Shandong Province, Jing Shi Road 73, Shandong (China)

    2008-12-20

    The microstructural characterization of Fe{sub 3}Al/Q235 welded zone were analysed to investigate the welding behavior of Fe{sub 3}Al intermetallic. The results indicated that a crack-free Fe{sub 3}Al/Q235 joint was obtained when Cr25-Ni13 alloy was adopted as the filler metal. The microstructure of the welded zone presented different morphology due to the severe fluctuation of Al, Ni, Mn and Cr elements near the fusion zone. The fish-bone like structures in Q235 side fusion zone were composed of {alpha}-Fe(Cr, Al, Ni) solid solutions. Fe{sub 3}Al/Q235 joint fractured in the Fe{sub 3}Al HAZ, and shear strength of 533.33 MPa was achieved. The fracture mode of Fe{sub 3}Al side fracture surface was mainly transgranular cleavage, occured along [1 1 1] orientation on {l_brace}1 1 0{r_brace} planes. And the Q235 side fracture surface was in intergranular and quasi-cleavage mode. The phase relations of {gamma} and {alpha} in Fe{sub 3}Al side fusion zone, constituent of lower bainite in the weld and the Fe{sub 3}Al ordered transformation in HAZ were also determined.

  13. Real time monitoring of spot-welded joints under service load using lead zirconate titanate (PZT) transducers

    Science.gov (United States)

    Yao, Ping; Zheng, Botong; Dawood, Mina; Huo, Linsheng; Song, Gangbing

    2017-03-01

    This paper proposes a nondestructive method to evaluate the health status of resistance spot-welded (RSW) joint under service load using lead zirconate titanate (PZT) active sensing system, in which the PZT transducers were used as both actuator and sensor. The physical principle of the approach was validated through a numerical analysis showing that an opening between the faying faces at the welded joint occurred under tension load. The opening decreased the contact area hence reduced the amplitude of the stress wave received by the PZT sensor. Therefore, by comparing the energy index of the signals before and after the loading, the health condition of the joint can be evaluated. Five ST14 steel single lap joint specimens were tested under tension load while being monitored by the PZT sensing system and digital image correlation (DIC) system in real time. The data obtained from the DIC system validated the numerical results. By comparing the energy index of the signal obtained from the PZT sensing system before and after unloading, it was concluded that the RSW joint was intact after being loaded to the service load. The proposed method is promising in evaluating the health condition of RSW joint nondestructively.

  14. Tensile properties of shielded metal arc welded dissimilar joints of nuclear grade ferritic steel and austenitic stainless steel

    Science.gov (United States)

    Karthick, K.; Malarvizhi, S.; Balasubramanian, V.; Krishnan, S. A.; Sasikala, G.; Albert, Shaju K.

    2016-12-01

    In nuclear power plants, modified 9Cr-1Mo ferritic steel (Grade 91 or P91) is used for constructing steam generators (SG's) whereas austenitic stainless steel (AISI 316LN) is a major structural member for intermediate heat exchanger (IHX). Therefore, a dissimilar joint between these materials is unavoidable. In this investigation, dissimilar joints were fabricated by Shielded Metal Arc Welding (SMAW) process with Inconel 82/182 filler metals. Transverse tensile properties and Charpy V-notch impact toughness for different regions of dissimilar joints of modified 9Cr-1Mo ferritic steel and AISI 316LN austenitic stainless steel were evaluated as per the standards. Microhardness distribution across the dissimilar joint was recorded. Microstructural features of different regions were characterized by optical and scanning electron microscopy. The transverse tensile properties of the joint is found to be inferior to base metals. Impact toughness values of different regions of dissimilar metal weld joint (DMWJ) is slightly higher than the prescribed value. Formation of a soft zone at the outer edge of the HAZ will reduce the tensile properties of DMWJ. The complex microstructure developed at the interfaces of DMWJ will reduce the impact toughness values.

  15. Effect of Rotation Rate on Microstructure and Properties of Friction Stir Welded Joints of Al/Cu Clad Plates

    Directory of Open Access Journals (Sweden)

    QIAO Ke

    2017-10-01

    Full Text Available Al/Cu clad plates were joined by friction stir welding (FSW, and the effect of rotation rate on microstructure and mechanical properties of joints was investigated. The results show that the laminar structure of aluminum and copper is generated in the weld. With increase the of rotation rate, the grain sizes of aluminum and copper are increased respectively. The average microhardness of the Al/Cu plates exceeds that of the as-received metal of 33.0 HV, and ultimate tensile strength is 127.21 MPa in the nugget zone when rotation rate is 1180 r/min. The microhardness of copper in the nugget zone is 99.7 HV, reached 82.05% of the microhardness of received metal, and void defect is main reason responsible for the decrease of mechanical properties of joints.

  16. Studi Perbandingan Proses Pengelasan Smaw Pada Lingkungan Darat dan Bawah Air Terhadap Ketahanan Uji Bending Weld Joint Material A36

    OpenAIRE

    Safira Dwi Anggraeni; Herman Pratikno; Yoyok Setyo Hadiwidodo

    2017-01-01

    Penelitian ini bertujuan untuk mengetahui perbedaan nilai kekuatan uji bending,  dan kekerasan pada sambungan weld joint plat baja A36 pada proses pengelasan SMAW di lingkungan darat dan bawah air. Penelitian ini menggunakan Baja A36 dengan variasi lingkungan pengelasan yakni di darat dan di bawah air dengan menggunakan las SMAW dan memakai elektroda E7018 diameter 3,2 mm. Spesimen dilakukan pengujian bending berupa face bend dan root bend, pengujian kekerasan dan foto mikro. Pada pengujian b...

  17. Corrosion Resistance and Mechanical Properties of TIG and A-TIG Welded Joints of Lean Duplex Stainless Steel S82441 / 1.4662

    Directory of Open Access Journals (Sweden)

    Brytan Z.

    2016-06-01

    Full Text Available This paper presents results of pitting corrosion resistance of TIG (autogenous and with filler metal and A-TIG welded lean duplex stainless steel S82441/1.4662 evaluated according to ASTM G48 method, where autogenous TIG welding process was applied using different amounts of heat input and shielding gases like pure Ar and Ar+N2 and Ar+He mixtures. The results of pitting corrosion resistance of the welded joints of lean duplex stainless steel S82441 were studied in as weld conditions and after different mechanical surface finish treatments. The results of the critical pitting temperature (CPT determined according to ASTM G48 at temperatures of 15, 25 and 35°C were presented. Three different surface treatment after welding were applied: etching, milling, brushing + etching. The influence of post weld surface treatment was studied in respect to the pitting corrosion resistance, basing on CPT temperature.

  18. Microstructure and Mechanical Properties of Dissimilar Welded Ti3Al/Ni-Based Superalloy Joint Using a Ni-Cu Filler Alloy

    Science.gov (United States)

    Chen, Bing-Qing; Xiong, Hua-Ping; Guo, Shao-Qing; Sun, Bing-Bing; Chen, Bo; Tang, Si-Yi

    2015-02-01

    Dissimilar welding of a Ti3Al-based alloy and a Ni-based superalloy (Inconel 718) was successfully carried out using gas tungsten arc welding technology in this study. With a Ni-Cu alloy as filler material, sound joints have been obtained. The microstructure evolution along the cross section of the dissimilar joint has been revealed based on the results of scanning electron microscopy and X-ray energy dispersive spectroscopy as well as X-ray diffractometer. It is found that the weld/Ti3Al interface is composed of Ti2AlNb matrix dissolved with Ni and Cu, Al(Cu, Ni)2Ti, (Cu, Ni)2Ti, (Nb, Ti) solid solution, and so on. The weld and In718/weld interface mainly consist of (Cu, Ni) solid solutions. The weld exhibits higher microhardness than the two base materials. The average room-temperature tensile strength of the joints reaches 242 MPa and up to 73.6 pct of the value can be maintained at 873 K (600 °C). The brittle intermetallic phase of Ti2AlNb matrix dissolved with Ni and Cu at the weld/Ti3Al interface is the weak link of the joint.

  19. Parametric optimization of inverse trapezoid oleophobic surfaces

    DEFF Research Database (Denmark)

    Cavalli, Andrea; Bøggild, Peter; Okkels, Fridolin

    2012-01-01

    In this paper, we introduce a comprehensive and versatile approach to the parametric shape optimization of oleophobic surfaces. We evaluate the performance of inverse trapezoid microstructures in terms of three objective parameters: apparent contact angle, maximum sustainable hydrostatic pressure...

  20. Numerical Evaluation of Temperature Field and Residual Stresses in an API 5L X80 Steel Welded Joint Using the Finite Element Method

    Directory of Open Access Journals (Sweden)

    Jailson A. Da Nóbrega

    2016-01-01

    Full Text Available Metallic materials undergo many metallurgical changes when subjected to welding thermal cycles, and these changes have a considerable influence on the thermo-mechanical properties of welded structures. One method for evaluating the welding thermal cycle variables, while still in the project phase, would be simulation using computational methods. This paper presents an evaluation of the temperature field and residual stresses in a multipass weld of API 5L X80 steel, which is extensively used in oil and gas industry, using the Finite Element Method (FEM. In the simulation, the following complex phenomena were considered: the variation in physical and mechanical properties of the material as a function of the temperature, welding speed and convection and radiation mechanisms. Additionally, in order to characterize a multipass weld using the Gas Tungsten Arc Welding process for the root pass and the Shielded Metal Arc Welding process for the filling passes, the analytical heat source proposed by Goldak and Chakravarti was used. In addition, we were able to analyze the influence of the mesh refinement in the simulation results. The findings indicated a significant variation of about 50% in the peak temperature values. Furthermore, changes were observed in terms of the level and profile of the welded joint residual stresses when more than one welding pass was considered.

  1. Optimization and Characterization of the Friction Stir Welded Sheets of AA 5754-H111: Monitoring of the Quality of Joints with Thermographic Techniques.

    Science.gov (United States)

    De Filippis, Luigi Alberto Ciro; Serio, Livia Maria; Palumbo, Davide; De Finis, Rosa; Galietti, Umberto

    2017-10-11

    Friction Stir Welding (FSW) is a solid-state welding process, based on frictional and stirring phenomena, that offers many advantages with respect to the traditional welding methods. However, several parameters can affect the quality of the produced joints. In this work, an experimental approach has been used for studying and optimizing the FSW process, applied on 5754-H111 aluminum plates. In particular, the thermal behavior of the material during the process has been investigated and two thermal indexes, the maximum temperature and the heating rate of the material, correlated to the frictional power input, were investigated for different process parameters (the travel and rotation tool speeds) configurations. Moreover, other techniques (micrographs, macrographs and destructive tensile tests) were carried out for supporting in a quantitative way the analysis of the quality of welded joints. The potential of thermographic technique has been demonstrated both for monitoring the FSW process and for predicting the quality of joints in terms of tensile strength.

  2. Study of residual stresses in welded joints of dual phase HSLA steel used in automotive industry; Estudo das tensoes residuais em juntas soldadas de aco ARBL bifasico usado na industria automobilistica

    Energy Technology Data Exchange (ETDEWEB)

    Barbato, D.S.; Fonseca, M.P. Cindra; Marques Junior, A.S.; Chuvas, T.C.; Pardal, J.M., E-mail: mcindra@vm.uff.b [Universidade Federal Fluminense (PGMEC/UFF), Niteroi, RJ (Brazil). Programa de Pos-graduacao em Engenharia Mecanica; Berretta, J.R. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2010-07-01

    One way of weight reduction in automotive vehicles is through the use of high strength and low alloy (HSLA) steels, which enables the use of small thickness plates. Whereas the appearance of residual stresses is intrinsic to the welding process, this study evaluates the residual stresses generated in welded joints obtained by TIG and LASER welding processes and comparing them. Residual stresses were measured by X-rays diffraction technique, using a portable device with Cr{kappa}{alpha} radiation applying the double exposure method. It also evaluates the influence of shot peening treatment applied after welding, in the bend tests conducted for both welding conditions and TIG welded joints showed higher stability of compressive stresses after welding. The metallographic analysis by optical microscopy complemented the welded joints characterization. (author)

  3. First industrial application of the auto-adaptative MAG STT welding technique with laser joint tracking; Premiere application industrielle du soudage MAG STT avec suivi de joint auto-adaptatif au laser

    Energy Technology Data Exchange (ETDEWEB)

    Tran Tien, Th. [Institut de Soudure, 93 - Villepinte (France)

    2007-05-15

    The Welding Institute has participated to the plan of construction of the Large Hadron Collider. The hoops of the dipolar magnets are composed of two half cylinders 15 m in length in 10 mm 316LN austenitic stainless steel and are assembled around the magnet in a horizontal-vertical position. The Welding Institute has developed a software for carrying out the auto-adaptative welding technique with laser joint tracking, in using the MAG STT (Surface Tension Transfer) process. The modelling of the welding laws and the strategy of filling the joints in multi-paths absorb the physical tolerances of the preparation (clearance, poor alignment, root..) in dynamic welding condition too. (O.M.)

  4. Optimization of Resistance Spot Weld Condition for Single Lap Joint of Hot Stamped 22MnB5 by Taking Heating Temperature and Heating Time into Consideration

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hong Seok; Kim, Byung Min; Park, Geun Hwan [Pusan National University, Busan (Korea, Republic of); Lim, Woo Seung [Keimyung University, Daegu (Korea, Republic of)

    2010-10-15

    In this study, optimization of the process parameters of the resistance spot welding of a sheet of aluminum-coated boron alloyed steel, 22MnB5, used in hot stamping has been performed by a Taguchi method to increase the strength of the weld joint. The process parameters selected were current, electrode force, and weld time. The heating temperature and heating time of 22MnB5 are considered to be noise factors. It was known that the variation in the thickness of the intermetallic compound layer between the aluminum-coated layer and the substrate, which influences on the formation of nugget, was generated due to the difference of diffusion reaction according to heating conditions. From the results of spot weld experiment, the optimum weld condition was determined to be when the current, electrode force, and weld time were 8kA, 4kN, and 18 cycles, respectively. The result of a test performed to verify the optimized weld condition showed that the tensile strength of the weld joint was over 32kN, which is considerably higher than the required strength, i.e., 23kN.

  5. An Assessment of the Mechanical Properties and Microstructural Analysis of Dissimilar Material Welded Joint between Alloy 617 and 12Cr Steel

    Directory of Open Access Journals (Sweden)

    Hafiz Waqar Ahmad

    2016-10-01

    Full Text Available The most effective method to reduce CO2 gas emission from the steam power plant is to improve its performance by elevating the steam temperature to more than 700 °C. For this, it is necessary to develop applicable materials at high temperatures. Ni-based Alloy 617 and 12Cr steel are used in steam power plants, due to their remarkable mechanical properties, high corrosion resistance, and creep strength. However, since Alloy 617 and 12Cr steel have different chemical compositions and thermal and mechanical properties, it is necessary to develop dissimilar material welding technologies. Moreover, in order to guarantee the reliability of dissimilar material welded structures, the assessment of mechanical and metallurgical properties, fatigue strength, fracture mechanical analysis, and welding residual stress analysis should be conducted on dissimilar material welded joints. In this study, first, multi-pass dissimilar material welding between Alloy 617 and 12Cr steel was performed under optimum welding conditions. Next, mechanical properties were assessed, including the static tensile strength, hardness distribution, and microstructural analysis of a dissimilar material welded joint. The results indicated that the yield strength and tensile strength of the dissimilar metal welded joint were higher than those of the Alloy 617 base metal, and lower than those of the 12Cr steel base metal. The hardness distribution of the 12Cr steel side was higher than that of Alloy 617 and the dissimilar material weld metal zone. It was observed that the microstructure of Alloy 617 HAZ was irregular austenite grain, while that of 12Cr steel HAZ was collapsed martensite grain, due to repeatable heat input during multi-pass welding.

  6. The structure and properties of filler metal-free laser beam welded joints in steel S700MC subjected to TMCP

    Science.gov (United States)

    Górka, Jacek; Stano, Sebastian

    2016-12-01

    The research-related tests aimed to determine the effect of filer-metal free laser beam welding on the structure and properties of 10 mm thick steel S700MC subjected to the Thermo-Mechanical Control Process (TMCP). The nondestructive tests revealed that the welded joints represented quality level B according to the requirements of standard 13919-1. The destructive tests revealed that the joints were characterised by tensile strength being by approximately 5% lower than that of the base material. The tests of thin foils performed using a high-resolution scanning transmission electron microscope revealed that filler metal-free welding led to the increased amount of alloying microagents (Ti and Nb) in the weld (particularly near fusion line) in comparison with welding performed using a filler metal. The significant content of hardening phases in the welds during cooling resulted in considerable precipitation hardening through finedispersive (Ti,Nb)(C,N) type precipitates (several nm in size) leading to the deterioration of plastic properties. The destructive tests revealed that the joints were characterised by tensile strength being by approximately 5% lower than that of the base material. The increase in the concentration of microagents responsible for steel hardening (Ti and Nb) also contributed to the decrease in weld toughness being below the allowed value of 25 J/cm2.

  7. THE ROLE OF SHIELDING GAS ON MECHANICAL, METALLURGICAL AND CORROSION PROPERTIES OF CORTEN STEEL WELDED JOINTS OF RAILWAY COACHES USING GMAW

    Directory of Open Access Journals (Sweden)

    Byju John

    2016-12-01

    Full Text Available This analysis lays emphasis on finding a suitable combination of shielding gas for welding underframe members such as sole bar of Railway Coaches made of corten steel; for improved mechanical, metallurgical and corrosion properties of welds using copper coated solid MIG/MAG welding filler wire size 1.2 mm conforming to AWS/SFA 5.18 ER 70 S in Semi-automatic GMAW process. Solid filler wire is preferred by welders due to less fumes, practically no slag and easy manipulation of welding torch with smooth wire flow during corrosion repair attention, when compared to Flux cored wire. Three joints using Gas metal arc welding (GMAW with shielding gases viz., Pure CO2, (80% Ar – 20% CO2 and (90% Ar – 10% CO2 were made from test pieces cut from Sole bar material of Railway Coach. Study of Mechanical properties such as tensile strength, hardness and toughness revealed that welded joint made using shielding gas (80% Ar – 20% CO2 has better Mechanical properties compared to the other two shielding gases and comparable to that of Parent metal. Type of Shielding gas used has influence on the chemical composition and macro & micro structures. The Tafel extrapolation study of freshly ground samples in 3.5% NaCl solution revealed that the welded joint made using shielding gas (80% Ar – 20% CO2 has also better corrosion resistance which is comparable to the Parent metal as well as similar commercial steels.

  8. Microstructures and Mechanical Properties of Dissimilar Al/Steel Butt Joints Produced by Autogenous Laser Keyhole Welding

    Directory of Open Access Journals (Sweden)

    Li Cui

    2017-11-01

    Full Text Available Dissimilar Al/steel butt joints of 6.0 mm thick plates have been achieved using fiber laser keyhole welding autogenously. The cross sections, interface microstructures, hardness and tensile properties of Al/steel butt joints obtained under different travel speeds and laser beam offsets were investigated. The phase morphology and thickness of the intermetallic compound (IMC layers at the interface were analyzed by scanning electronic microscopes (SEM using the energy-dispersive spectrometry (EDS and electron back-scattered diffraction (EBSD techniques. The results show that travel speeds and laser beam offsets are of considerable importance for the weld shape, morphology and thickness of IMC layers, and ultimate tensile strength (UTS of Al/steel butt joints. This proves that the IMC layers consist of Fe2Al5 phases and Fe4Al13 phases by EBSD phase mapping. Increasing laser beam offsets from 0.3 mm to 0.7 mm significantly decreases the quantity of Fe4Al13 phases and the thickness of Fe2Al5 layers at the interface. During tensile processing, the Fe2Al5 layer with the weakest bonding strength is the most brittle region at the interface. However, an intergranular fracture that occurred at Fe2Al5 layers leads to a relatively high UTS of Al/steel butt joints.

  9. Missed joint induced by thermoelectric magnetic field in electron-beam welding dissimilar metals—Experiment and scale analysis

    Science.gov (United States)

    Wei, P. S.; Wen, Chih-Wei

    2002-10-01

    A missed joint, resulting from an induced thermoelectric magnetism in welding dissimilar metals with a high-intensity electron beam, is experimentally and analytically investigated. Election-beam welding is a very useful process for joining a wide range of dissimilar metals, which may be difficult or impossible to weld by other techniques. Certain combinations of materials, unfortunately, readily give rise to a missed-joint defect because of thermoelectric-magnetic deflection of the beam. Combinations of dissimilar metals chosen for this study are low-carbon steel and type 304 stainless steel, low-carbon steel and Ni-Cu alloy, and type 304 stainless steel and Ni-Cu alloy. The experimental results find agreement with a previous study showing that the electron beam deflects toward the metal with a larger Seebeck coefficient (denoted by metal 1). A general and algebraic expression for predicting deflection angle as a function of dimensionless beam power, accelerating voltage-to-Seebeck electromotive force (EMF) parameter, Peclet and Prandtl numbers, and electrical conductivity ratio between metals 1 and 2 has been derived from a scale analysis for the first time. The predicted results agree well with experimental data obtained from the literature, this work, and three-dimensional theoretical prediction.

  10. Influence of Zn Interlayer on Interfacial Microstructure and Mechanical Properties of TIG Lap-Welded Mg/Al Joints

    Science.gov (United States)

    Gao, Qiong; Wang, Kehong

    2016-03-01

    This study explored 6061 Al alloy and AZ31B Mg alloy joined by TIG lap welding with Zn foils of varying thicknesses, with the additional Zn element being imported into the fusion zone to alloy the weld seam. The microstructures and chemical composition in the fusion zone near the Mg substrate were examined by SEM and EDS, and tensile shear strength tests were conducted to investigate the mechanical properties of the Al/Mg joints, as well as the fracture surfaces, and phase compositions. The results revealed that the introduction of an appropriate amount of Zn transition layer improves the microstructure of Mg/Al joints and effectively reduces the formation of Mg-Al intermetallic compounds (IMCs). The most common IMCs in the fusion zone near the Mg substrate were Mg-Zn and Mg-Al-Zn IMCs. The type and distribution of IMCs generated in the weld zone differed according to Zn additions; Zn interlayer thickness of 0.4 mm improved the sample's mechanical properties considerably compared to thicknesses of less than 0.4 mm; however, any further increase in Zn interlayer thickness of above 0.4 mm caused mechanical properties to deteriorate.

  11. Characterization of Mg/Al butt joints welded by gas tungsten arc filling with Zn–29.5Al–0.5Ti filler metal

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Fei; Wang, Hongyang; Liu, Liming, E-mail: liulm@dlut.edu.cn

    2014-04-01

    The multivariate alloying design of a welding joint is used in the Mg to Al welding process. A Zn–29.5Al–0.5Ti alloy is added as filler metal in gas tungsten arc welding of Mg and Al alloy joint based on the analysis of Al and Mg alloy characteristics. The tensile strength, microstructure, and phase constitution of the weld seam are analyzed. The formation of brittle and hard Mg–Al intermetallic compounds is avoided because of the effects of Zn, Al, and Ti. The average tensile strength of the joint is 148 MPa. Al{sub 3}Ti is first precipitated and functions as the nucleus of heterogeneous nucleation during solidification. Moreover, the precipitated Al–MgZn{sub 2} hypoeutectic phase exhibited a feather-like structure, which enhances the property of the Mg–Al dissimilar joint. - Highlights: • Mg alloy AZ31B and Al alloy 6061 are butt welded by fusion welding. • The effect of Ti in filler metal is investigated. • The formation of Mg–Al intermetallic compounds is avoided.

  12. Structure and mechanical properties of Cresco-Ti laser-welded joints and stress analyses using finite element models of fixed distal extension and fixed partial prosthetic designs.

    Science.gov (United States)

    Uysal, Hakan; Kurtoglu, Cem; Gurbuz, Riza; Tutuncu, Naki

    2005-03-01

    The Cresco-Ti System uses a laser-welded process that provides an efficient technique to achieve passive fit frameworks. However, mechanical behavior of the laser-welded joint under biomechanical stress factors has not been demonstrated. This study describes the effect of Cresco-Ti laser-welding conditions on the material properties of the welded specimen and analyzes stresses on the weld joint through 3-dimensional finite element models (3-D FEM) of implant-supported fixed dentures with cantilever extensions and fixed partial denture designs. Twenty Grade III (ASTM B348) commercially pure titanium specimens were machine-milled to the dimensions described in the EN10002-1 tensile test standard and divided into test (n = 10) and control (n = 10) groups. The test specimens were sectioned and laser-welded. All specimens were subjected to tensile testing to determine yield strength (YS), ultimate tensile strength (UTS), and percent elongation (PE). The Knoop micro-indentation test was performed to determine the hardness of all specimens. On welded specimens, the hardness test was performed at the welded surface. Data were analyzed with the Mann-Whitney U test and Student's t test (alpha=.05). Fracture surfaces were examined by scanning electron microscopy to characterize the mode of fracture and identify defects due to welding. Three-dimensional FEMs were created that simulated a fixed denture with cantilever extensions supported by 5 implants (M1) and a fixed partial denture supported by 2 implants (M2), 1 of which was angled 30 degrees mesio-axially. An oblique load of 400 N with 15 degrees lingual-axial inclinations was applied to both models at various locations. Test specimens fractured between the weld and the parent material. No porosities were observed on the fractured surfaces. Mean values for YS, UTS, PE, and Knoop hardness were 428 +/- 88 MPa, 574 +/- 113 MPa, 11.2 +/- 0.4%, 270 +/- 17 KHN, respectively, for the control group and 642 +/- 2 MPa, 772 +/- 72

  13. Acoustic determination of cracks in welded joints. [by resonant structural vibration measurements

    Science.gov (United States)

    Baltanoiu, M.; Criciotoiu, E.

    1974-01-01

    The acoustic analysis method permits detection of any cracks that might take place and their manner of propagation. The study deals with the cracks produced in experiments to determine the welding technology for a welded gray cast iron workpiece by using piezoelectric transducers to determine vibration acceleration.

  14. Definition of the Mathematical Model Coefficients on the Weld Size of Butt Joint Without Edge Preparation

    Science.gov (United States)

    Sidorov, Vladimir P.; Melzitdinova, Anna V.

    2017-10-01

    This paper represents the definition methods for thermal constants according to the data of the weld width under the normal-circular heat source. The method is based on isoline contouring of “effective power – temperature conductivity coefficient”. The definition of coefficients provides setting requirements to the precision of welding parameters support with the enough accuracy for an engineering practice.

  15. The Segregation and Liquation Crackings in the HAZ of Multipass Laser-Welded Joints for Nuclear Power Plants

    Science.gov (United States)

    Li, Gang; Lu, Xiaofeng; Zhu, Xiaolei; Huang, Jian; Liu, Luwei; Wu, Yixiong

    2017-08-01

    The segregation and liquation crackings in the heat-affected zone (HAZ) beside Inconel 52M overlays of multipass laser-welded joints are investigated for nuclear power plants. The results indicate that Nb-rich precipitates are distributed in chains and some aggregate together as coarse particles in the local regions at the interface. With increasing heat input, the transition width becomes widened and the fraction of the precipitates at the interface significantly increases. Closely associated to Nb segregation, liquation crackings occur along columnar dendrites in the HAZ beside Inconel 52M overlays. Due to no deformation coordination of the columnar dendrites with Nb-rich segregates in Inconel 52M overlays, liquation crackings occur in thermal cycle of multipass laser welding. The enrichment of Nb element in the interdendritic regions increases favorable factors of liquation crackings at grain boundaries.

  16. Microstructural Characterization and Mechanical Properties of Electron Beam Welded Joint of High Strength Steel Grade S690QL

    Directory of Open Access Journals (Sweden)

    Błacha S.

    2016-06-01

    Full Text Available In the paper the results of metallographic examination and mechanical properties of electron beam welded joint of quenched and tempered steel grade S690QL are presented. Metallographic examination revealed that the concentrated electron beam significantly affect the changes of microstructure in the steel. Parent material as a delivered condition (quenched and tempered had a bainitic-martensitic microstructure at hardness about 290 HV0.5. After welding, the microstructure of heat affected zone is composed mainly of martensite (in the vicinity of the fusion line of hardness 420 HV0.5. It should be noted, however, that the microstructure of steel in the heat affected zone varies with the distance from the fusion line. The observed microstructural changes were in accordance with the CCT-S transformation diagram for the examined steel.

  17. Mechanical Characteristics of 9% Ni Steel Welded Joint for Lng Storage Tank at Cryogenic

    Science.gov (United States)

    Yoon, Yong-Keun; Kim, Jae-Hoon; Shim, Kyu-Taek; Kim, Young-Kyun

    To confirm the safety performance of LNG storage tank, the change in fatigue crack growth rate and fracture toughness within X-grooved weld heat-affected zone (HAZ) of newly developed 9% Ni steel, which was SMAW welded, was investigated. These materials were produced by QT (quenching, tempering) heat treatment. The weld metal specimens were prepared by taking the same weld procedure applied in actual inner shell of LNG storage tank. All tests were performed in the temperature ranging from R.T. and -162°C. The fatigue crack growth behavior was carried out using CT specimen. Investigation has been carried out to study the influence of temperature and weld effect on fatigue crack growth behavior. Also, Fracture surfaces after tests were observe by scanning electron microscope (SEM).

  18. Novos paradigmas para especificação de juntas soldadas New paradigms for specification of welded joints

    Directory of Open Access Journals (Sweden)

    Ivan Guerra Machado

    2012-09-01

    Full Text Available O fim último da Tecnologia da Soldagem é a especificação da junta que será produzida. Isto inclui o seu dimensionamento, bem como a adequação de diversos fatores, tais como a tenacidade e outras propriedades mecânicas e metalúrgicas, o ambiente no qual ela está, além da sua finalidade. Porém, adicionalmente há uma nova tendência mundial ―através de Códigos, normas etc.― de considerar a especificação da junta soldada como fruto de complexas interações entre os fenômenos metalúrgicos, os aspectos relativos aos mecanismos das conexões e o comportamento mecânico de todos os materiais envolvidos. Apesar de neste artigo considerarmos como metais base os aços estruturais, não há absolutamente perda de generalidade e com esta relativamente nova perspectiva, deverão sofrer profundas mudanças o nível e a qualidade da informação usualmente acessível aos engenheiros de soldagem e aos projetistas de estruturas soldadas. Portanto, buscando alertar estes profissionais para os novos paradigmas, apresentaremos questões relativas ao projeto das estruturas soldadas (ou produzidas por brasagem, principalmente sob o ponto de vista do apoio que o engenheiro de soldagem pode oferecer ao projetista.The paramount aim of Welding Technology is the specification of the joint that will be produced. This includes its dimensioning, as well as the suitability of many factors, such as toughness and other mechanical and metallurgical properties, the environment in which it is, besides its fitness for purpose. However, additionally there is a new world-wide trend ―through Codes, standards etc.― in to consider the welded joint specification as a result of complex interactions among the metallurgical phenomena, the aspects related to connections mechanisms and the mechanical behaviour of all materials involved. In despite of in this paper we consider structural steels as base metals, absolutely there is not lack of generality and with this

  19. Analysis of features of stainless steels in dissimilar welded joints in chloride inducted corrosion

    Science.gov (United States)

    Topolska, S.; Łabanowski, J.

    2017-08-01

    Stainless steels of femtic-austenitic microstructure that means the duplex Cr-Ni-Mo steels, in comparison with austenitic steel includes less expensive nickel and has much better mechanical properties with good formability and corrosion resistance, even in environments containing chloride ions. Similar share of high chromium ferrite and austenite, which is characterized by high ductility, determines that the duplex steels have good crack resistance at temperatures up to approximately -40°C. The steels containing approximately 22% Cr, 5% Ni, 3% Mo and 0.2% N crystallizes as a solid solution δ, partially transforming from the temperature of about 1200°C to 850°C into the phase α. The stable structure of considered steels, at temperatures above 850°C, is ferrite, and at lower temperatures the mixture of phase γ+α +σ. The two-phase structure α+γ the duplex steel obtains after hyperquenching at the temperature of stability of the mixture of α+γ phases, and the share of the phases depends on the hyper quenching attributes. Hyperquenching in water, with a temperature close to 1200°C, ensures the instance in the microstructure of the steel a large share of ferrite and a small share of the high chromium austenite. This causes the increase of strength properties and reducing the plasticity of the steel and its resistance ability to cracking and corrosion. Slower cooling from the mentioned temperature, for example in the air, enables the partial transformation of the a phase into the γ one (α → γ) and increasing the share of austenite in the steel structure. It leads to improvement of plasticity properties. In the paper are presented the results of investigations of heteronymous welded joints of duplex steel and austenitic one. The results include the relation between the chemical composition of steels and their weldability.

  20. Microstructural Properties and Four-Point Bend Fatigue Behavior of Ti-6.5Al-2Zr-1Mo-1V Welded Joints by Electron Beam Welding

    Science.gov (United States)

    Liu, Peng; Zhai, T.; Zhang, Yuanbin

    2016-06-01

    With the help of a four-point-bend of fatigue rig, high-cycle fatigue tests were carried out on an Ti-6.5Al-2Zr-1Mo-1V titanium alloy at room temperature, 20 Hz and R = 0.1 in ambient air. The test results indicated that the fatigue strength of base metal, 888 MPa, is about 120% of yield strength. The fatigue strength of joints is 814 MPa. It is about 110% of yield strength of base metal. When the loading stress is higher, the fatigue failure region is located in middle weld zone of weld face, which the cracks are propagated along coarse β phase's grain boundary. When the loading stress is lower, the fatigue failure region is located between the incomplete recrystallization zone and base metal. The crack nucleation resistance gradually increases from the WN to HAZ with the variable of loading stress and β phase (little α' phases)→ α + β phase→ α phase.

  1. Rare isolated trapezoid fracture: a case report.

    Science.gov (United States)

    Sadowski, Rita M; Montilla, Richard D

    2008-12-01

    Isolated fractures of the trapezoid are rare. Of all of the fractures of the carpus, the most common is the scaphoid, which represents 68.2% of all carpal fractures (Papp, Orthop Clin N Am 38:251-60, 2007). In contrast, trapezoid fractures represent 0.4% of all carpal injuries. Because it is an infrequently fractured carpal bone, there is a wide variety of treatment plans, including rest, immobilization, and surgery (Green and Pederson, Green's Operative Hand Surgery, Elsevier, Philadelphia, 759 pp, 2005). In this report, we describe a patient who presented with an isolated fracture of the trapezoid that was successfully treated with cast immobilization and had a full functional recovery.

  2. Influence of Joint Configuration on the Strength of Laser Welded Presshardened Steel

    Science.gov (United States)

    Kügler, H.; Mittelstädt, C.; Vollertsen, F.

    Presshardened steel is used in nowadays automotive production. Due to its high strength, sheet thicknesses can be reduced which results in decreasing weight of car body components. However, because of microstructure softening and coating agglomerations in the seam, welding is still a challenge. In this paper laser beam welding of 22MnB5 with varying energy input per irradiated area is presented. It is found that increasing energy input per seam length reduces tensile strength. Using a small spot size of 200 μm, tensile strength of 1434 N/mm2 can be reached in bead on plate welds. In lap welds tensile strength is limited because of coating particles agglomerating at the melt pool border line. However, the resulting strength is higher when using several small weld seams than using one seam with the same total seam width. With three weld seams, each 0.5mm in width, tensile strength of 911N/mm2 is reached in lap welding.

  3. Estimation of Fatigue Life of Laser Welded AISI304 Stainless Steel T-Joint Based on Experiments and Recommendations in Design Codes

    DEFF Research Database (Denmark)

    Lambertsen, Søren Heide; Damkilde, Lars; Kristensen, Anders Schmidt

    2013-01-01

    of specimens are used, two of these are non-welded and the third is welded with a transverse welding (T-Joint). The 13 laser welded specimens are cut out with a milling cutter. The non-welded specimens are divided in 13 specimens cut out with a milling cutter and 10 specimens cut out by a plasma cutter......In this paper the fatigue behavior of laser welded T-joints of stainless steel AISI304 is investigated experimentally. In the fatigue experiments 36 specimens with a sheet thickness of 1 mm are exposed to one-dimensional cyclic loading. Three different types of specimens are adopted. Three groups....... The non-welded specimens are used to study the influence of heat and surface effects on the fatigue life. The fatigue life from the experiments is compared to fatigue life calculated from the guidelines in the standards DNV-RP-C203 and EUROCODE 3 EN-1993-1-9. Insignificant differences in fatigue life...

  4. Microstructural Characterization of Internal Welding Defects and Their Effect on the Tensile Behavior of FSW Joints of AA2198 Al-Cu-Li Alloy

    Science.gov (United States)

    Le Jolu, Thomas; Morgeneyer, Thilo F.; Denquin, Anne; Sennour, Mohamed; Laurent, Anne; Besson, Jacques; Gourgues-Lorenzon, Anne-Françoise

    2014-11-01

    Internal features and defects such as joint line remnant, kissing bond, and those induced by an initial gap between the two parent sheets were investigated in AA2198-T851 friction stir welded joints. They were compared with the parent material and to defect-free welds obtained using a seamless sheet. The cross-weld tensile strength was reduced by the defects by less than 6 pct. The fracture elongation was not significantly affected in view of experimental scatter. Fracture location, however, changed from the thermomechanically affected zone (retreating side) to the defect in the weld nugget for the welds bearing a kissing bond and for some of the gap welds. The kissing bond was shown by EBSD to be an intergranular feature; it fractured under a normal engineering stress close to 260 MPa during an in situ SEM tensile test. Synchrotron tomography after interrupted tensile testing confirmed opening of the kissing bond. For an initial gap of 23 pct of the sheet thickness, intergranular fracture of copper-enriched or oxide-bearing grain boundaries close to the nugget root was evidenced. The stress and strain state of cross-weld specimens loaded under uniaxial tension was assessed using a 3D finite element, multi-material model, determined on the basis of experimental data obtained on the same specimens using digital image correlation.

  5. Dual wire welding torch and method

    Science.gov (United States)

    Diez, Fernando Martinez; Stump, Kevin S.; Ludewig, Howard W.; Kilty, Alan L.; Robinson, Matthew M.; Egland, Keith M.

    2009-04-28

    A welding torch includes a nozzle with a first welding wire guide configured to orient a first welding wire in a first welding wire orientation, and a second welding wire guide configured to orient a second welding wire in a second welding wire orientation that is non-coplanar and divergent with respect to the first welding wire orientation. A method of welding includes moving a welding torch with respect to a workpiece joint to be welded. During moving the welding torch, a first welding wire is fed through a first welding wire guide defining a first welding wire orientation and a second welding wire is fed through a second welding wire guide defining a second welding wire orientation that is divergent and non-coplanar with respect to the first welding wire orientation.

  6. Predicting failure response of spot welded joints using recent extensions to the Gurson model

    DEFF Research Database (Denmark)

    Nielsen, Kim Lau

    2010-01-01

    to their approximate description of the nucleation, growth and coalescence of microvoids. Using the void shape factor of the GLD-model, a simple approach for approximating void nucleation by either particle fracture or particle-matrix decohesion is applied and a study of the subsequent void shape evolution...... is presented. The models are applied to predict failure of specimens containing a fully intact weld nugget as well as a partly removed weld nugget to address the problems of shrinkage voids or larger weld defects. All analysis are carried out by full 3D finite element modelling....

  7. Manufacturing of hybrid aluminum copper joints by electromagnetic pulse welding - Identification of quantitative process windows

    Science.gov (United States)

    Psyk, Verena; Scheffler, Christian; Linnemann, Maik; Landgrebe, Dirk

    2017-10-01

    Compared to conventional joining techniques, electromagnetic pulse welding offers important advantages especially when it comes to dissimilar material connections as e.g. copper aluminum welds. However, due to missing guidelines and tools for process design, the process has not been widely implemented in industrial production, yet. In order to contribute to overcoming this obstacle, a combined numerical and experimental process analysis for electromagnetic pulse welding of Cu-DHP and EN AW-1050 was carried out and the results were consolidated in a quantitative collision parameter based process window.

  8. Microstructure and mechanical properties of similar and dissimilar joints of aluminium alloy and pure copper by friction stir welding

    Directory of Open Access Journals (Sweden)

    V.C. Sinha

    2016-09-01

    Full Text Available In the present study, the microstructure and mechanical properties of similar and dissimilar friction stir welded joints of aluminium alloy (AlA and pure copper (Cu were evaluated at variable tool rotational speeds from 150 to 900 rpm in steps of 150 rpm at 60 mm/min travel speed and constant tilt angle 2°. The interfacial microstructures of the joints were characterised by optical and scanning electron microscopy. The Al4Cu9, AlCu, Al2Cu and Al2Cu3 intermetallic compounds have been observed at the interface and stir zone region of dissimilar Al/Cu FSWed joints. Variation in the grain size was observed in the stir zone depending upon the heat input value. Axial force, traverse force and torque value were analysed with variation in tool rotational speed. Residual stresses were measured at the stir zone by X-ray diffraction technique. Maximum ultimate tensile strength of ∼75% of AlA strength for AlA–AlA joints has been obtained at 750 rpm and for Cu–Cu joint tensile strength of ∼100% of tensile strength of Cu was obtained at 300 rpm. However, for Cu–AlA joint when processed at 600 rpm tool rotational speed achieved maximum ultimate tensile strength of ∼77% of AlA.

  9. Hot cracking of welded joints of the 7CrMoVTiB 10-10 (T/P24) steel

    Science.gov (United States)

    Adamiec, J.

    2011-05-01

    Bainitic steel 7CrMoVTiB10-10 is one the newest steels for waterwalls of modern industrial boilers [1]. In Europe, attempts have been made to make butt welded joints of pipes made of this steel of the diameter up to 51 mm and thickness up to 8 mm. Many cracks have been observed in the welded joint, both during welding and transport and storage [2-4]. The reasons of cracking and the prevention methods have not been investigated. No comprehensive research is carried out in Europe in order to automate the welding process of the industrial boiler elements made of modern bainitic steel, such as 7CrMoVTiB10-10. There is no information about its overall, operative and local weldability, influence of heat treatment, as well as about resistance of the joints to cracking during welding and use. The paper presents experience of Energoinstal SA from development of technology and production of waterwalls of boilers made of the 7CrMoVTiB 10-10 steel on a multi-head automatic welder for submerged arc welding.

  10. Evaluation of mechanical vibration effect on the residual stresses levels in steel welded joints using an Interface Matlab based on Norm API 579

    Directory of Open Access Journals (Sweden)

    R Rodrigues

    2016-10-01

    Full Text Available Nowadays with the high growth of petrochemical welding technology a great development due to high manufacturing offshore structures, storage tanks of petroleum, boilers and pressure vessels for refining plants have been done. Due to various metallurgical changes and restrictions to contraction and expansion undergone by materials when subjected to welding thermal cycle, internal stresses are generated in welded joint which are nominated residual stresses. It is generally undesirable because it can lead to several problems, such as cracks, cold stress fracture, stress corrosion, among others. Although several studies involving residual stresses have been developed in recent years, few information about the variation of the residual stresses level in welded joints when subjected to stress relief treatment by mechanical vibration have been done. Likewise, there are few information related to the comparison between the degree of efficiency by using the post-weld heat treatment and those treatment. Therefore, the goal of this work was to apply the relieve residual stresses treatment by mechanical vibration in steel welded joints used in oil industry, and compare the results with those obtained by post heat treatment and evaluate the efficiency level of this technique In addition, this works also hope to contribute for a better understanding of this technique and to find which parameters have a greater influence on the results.

  11. Fiber laser welding of dissimilar titanium (Ti-6Al-4V/cp-Ti) T-joints and their laser forming process for aircraft application

    Science.gov (United States)

    Froend, M.; Fomin, F.; Riekehr, S.; Alvarez, P.; Zubiri, F.; Bauer, S.; Klusemann, B.; Kashaev, N.

    2017-11-01

    The weldability of dissimilar T-joints between commercially pure titanium (cp-Ti) Grade 2 skin and Ti-6Al-4V Grade 5 stringer using a continuous wave 8 kW ytterbium fiber laser as well as the possibility of subsequent laser straightening process of these joints were investigated. Based on the industrial standards ISO 4578:2011 and AWS D17.1:200, process development to compensate inherent angular distortion after welding by laser heating with the same equipment as for welding was carried out. The obtained results were effectively transferred to a 6-stringer-demonstrator with a length up to 500 mm. To investigate the shape and morphology of the welding seam as well as to verify its freedom from defects using the defined process parameters, metallographic transverse cross-sections and X-ray analyses were realized. In addition, the behavior of the welding seam geometry and the bending behavior of the specimens for varied process parameters were elucidated. For the welding process special attention to the shielding conditions and to the local and angular laser beam positioning was payed. To straighten the welded joints, laser straightening parameters inducing no microstructural changes were identified.

  12. THE EFFECT OF THE ANNEALING TEMPERATURE ON THE CORROSION RESISTANCE OF WELD JOINT OF AISI 310 STEEL - SHORT COMMUNICATION

    Directory of Open Access Journals (Sweden)

    Pavel Kovačócy

    2011-10-01

    Full Text Available The article presents samples of weld joint of AISI 310 austenitic steel which were subjected to solution annealing at various temperature - time exposures. The objective of the experiment was to determine the annealing temperature so that the steel should not be sensitized. Tendency to intercrystalline corrosion was analysed by means of a corrosion test in 10 % oxalic acid according to ASTM A 262. At the temperatures of 1000 and 1100°C held for 15 min. the steel was not sensitized. At the temperature of 850°C the steel was sensitized, i.e. susceptible to intercrystalline corrosion.

  13. THE EFFECT OF THE ANNEALING TEMPERATURE ON THE CORROSION RESISTANCE OF WELD JOINT OF AISI 310 STEEL - SHORT COMMUNICATION

    Directory of Open Access Journals (Sweden)

    Martina Nerádová

    2012-02-01

    Full Text Available The article presents samples of weld joint of AISI 310 austenitic steel which were subjected to solution annealing at various temperature - time exposures. The objective of the experiment was to determine the annealing temperature so that the steel should not be sensitized. Tendency to intercrystalline corrosion was analysed by means of a corrosion test in 10 % oxalic acid according to ASTM A 262. At the temperatures of 1000 and 1100°C held for 15 min. the steel was not sensitized. At the temperature of 850°C the steel was sensitized, i.e. susceptible to intercrystalline corrosion.

  14. A study on an efficient prediction of welding deformation for T-joint laser welding of sandwich panel Part II: Proposal of a method to use shell element model

    Directory of Open Access Journals (Sweden)

    Jae Woong Kim

    2014-06-01

    Full Text Available I-core sandwich panel that has been used more widely is assembled using high power CO2 laser welding. Kim et al. (2013 proposed a circular cone type heat source model for the T-joint laser welding between face plate and core. It can cover the negative defocus which is commonly adopted in T-joint laser welding to provide deeper penetration. In part I, a volumetric heat source model is proposed and it is verified thorough a comparison of melting zone on the cross section with experiment results. The proposed model can be used for heat transfer analysis and thermal elasto-plastic analysis to predict welding deformation that occurs during laser welding. In terms of computational time, since the thermal elasto-plastic analysis using 3D solid elements is quite time consuming, shell element model with multi-layers have been employed instead. However, the conventional layered approach is not appropriate for the application of heat load at T-Joint. This paper, Part II, suggests a new method to arrange different number of layers for face plate and core in order to impose heat load only to the face plate.

  15. A study on an efficient prediction of welding deformation for T-joint laser welding of sandwich panel Part II : Proposal of a method to use shell element model

    Directory of Open Access Journals (Sweden)

    Kim Jae Woong

    2014-06-01

    Full Text Available I-core sandwich panel that has been used more widely is assembled using high power CO₂laser welding. Kim et al. (2013 proposed a circular cone type heat source model for the T-joint laser welding between face plate and core. It can cover the negative defocus which is commonly adopted in T-joint laser welding to provide deeper penetration. In part I, a volumetric heat source model is proposed and it is verified thorough a comparison of melting zone on the cross section with experiment results. The proposed model can be used for heat transfer analysis and thermal elasto-plastic analysis to predict welding deformation that occurs during laser welding. In terms of computational time, since the thermal elasto-plastic analysis using 3D solid elements is quite time consuming, shell element model with multi-layers have been employed instead. However, the conventional layered approach is not appropriate for the application of heat load at T-Joint. This paper, Part II, suggests a new method to arrange different number of layers for face plate and core in order to impose heat load only to the face plate.

  16. The Influence Of Repair Welded Joint On The Life Of Steam Pipeline Made Of Cr-Mo Steel Serviced Beyond The Calculated Working Time

    Directory of Open Access Journals (Sweden)

    Zieliński A.

    2015-06-01

    Full Text Available The aim of the paper was to examine the influence of repair welded joints on the service life of steam pipelines for over 220 000 hours of service in creep conditions. The research included the study of the microstructure using scanning microscopy, the tests on mechanical properties at room and elevated temperature, determining the nil ductility transition temperature, and short-time creep tests to determine the residual life of the material. The tests allowed determining the time of further safe operation of elements of the steam pipeline with a repair welded joint, with reference to the base material, and the welded joint after service. The assessment of residual life and disposable residual life, and at the same time determining the possible time of further safe operation, has an essential meaning in the case of elements serviced considerably beyond the calculated working time.

  17. Finite element modelling and characterization of friction welding on UNS S31803 duplex stainless steel joints

    Directory of Open Access Journals (Sweden)

    Mohammed Asif. M

    2015-12-01

    Full Text Available Solid state joining techniques are increasingly employed in joining duplex stainless steel materials due to their high integrity. Continuous drive friction welding is a solid state welding technique which is used to join similar and dissimilar materials. This joining technique is characterized by short cycle time, low heat input and narrow heat affected zones. The simulation becomes an important tool in friction welding because of short welding cycle. In the present work, a three dimensional non-linear finite element model was developed. The thermal history and axial shortening profiles were predicted using ANSYS, a software tool. This numerical model was validated using experimental results. The results show that the frictional heating stage of the process has more influence on temperature and upsetting stage has more impact on axial shortening. The knowledge of these parameters would lead to optimization of input parameters and improvement of design and machine tools.

  18. Multiple Crack Growth Prediction in AA2024-T3 Friction Stir Welded Joints, Including Manufacturing Effects

    DEFF Research Database (Denmark)

    Carlone, Pierpaolo; Citarella, Roberto; Sonne, Mads Rostgaard

    2016-01-01

    boundary element method (FEM-DBEM) procedure, coupling the welding process simulation to the subsequent crack growth assessment, is proposed and applied to simulate multiple crack propagation, with allowance for manufacturing effects. The friction stir butt welding process of the precipitation hardened AA......A great deal of attention is currently paid by several industries toward the friction stir welding process to realize lightweight structures. Within this aim, the realistic prediction of fatigue behavior of welded assemblies is a key factor. In this work an integrated finite element method - dual......2024-T3 alloy was simulated using a thermo-mechanical FEM model to predict the process induced residual stress field and material softening. The computed stress field was transferred to a DBEM environment and superimposed to the stress field produced by a remote fatigue traction load applied...

  19. Effects of LSP on micro-structures and residual stresses in a 4 mm CLAM steel weld joints

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xizhang, E-mail: chenxizhang@wzu.edu.cn [School of Mechanical and Electrical Engineering, Wenzhou University., Wenzhou 325035 (China); School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu (China); Fang, Yuanyuan [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu (China); Zhang, Shuyan; Kelleher, Joe F. [ISIS, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); Zhou, Jianzhong [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu (China)

    2015-05-15

    The effects of laser shock processing (LSP) on the distribution of residual stress and micro-structure of China Low Activation Martensitic (CLAM) steel weldment were investigated via neutron diffraction and optical microscope (OM). A pair of 4 mm CLAM steel plates joined by GTA welding. Special attention is paid to the generation of high level compressive residual stresses introduced by LSP. Residual stress in longitudinal, normal and transversal direction at weldment surface and longitudinal stress through thickness are evaluated via neutron diffraction. Compressive residual stress after LSP occurred at more than 90% areas within the weld joint, it is almost double the areas of compressive stress compare to weldment surface before LSP. The maximum compressive normal residual stress becomes to −183 MPa after LSP from −63 MPa before LSP. The Modification of surface micro-structures including weld zone (WZ), heat affected zone (HAZ) and base metal (BM) are also discussed. Results to date demonstrate that laser shock processing has been a great potential method for the improvement of mechanical performance of components.

  20. Experimental study of cyclic creep and high-cycle fatigue of welded joints of St3 steel by the DIC technique

    Energy Technology Data Exchange (ETDEWEB)

    Kibitkin, Vladimir V., E-mail: vvk@ispms.tsc.ru; Solodushkin, Andrey I., E-mail: s.ai@sibmail.com; Pleshanov, Vasily S., E-mail: vsp@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation)

    2015-10-27

    In the paper the mechanisms of plastic deformation and fracture of welded joints of steel St3 were investigated at high-cycle fatigue and cyclic creep by the digital image correlation (DIC) technique. The evolution of strain rate is studied for the following regions: base metal, HAZ, and fusion zone. This strain rate evolution can be considered as a mechanical response of material. Three stages of deformation evolution are shown: deformation hardening (I), fatigue crack initiation (II), and the last stage is related to main crack (III). Two criteria are offered to evaluate the current mechanical state of welded joints.

  1. Effect of Thread and Rotating Speed on Material Flow Behavior and Mechanical Properties of Friction Stir Lap Welding Joints

    Science.gov (United States)

    Ji, Shude; Li, Zhengwei; Zhou, Zhenlu; Wu, Baosheng

    2017-10-01

    This study focused on the effects of thread on hook and cold lap formation, lap shear property and impact toughness of alclad 2024-T4 friction stir lap welding (FSLW) joints. Except the traditional threaded pin tool (TR-tool), three new tools with different thread locations and orientations were designed. Results showed that thread significantly affected hook, cold lap morphologies and lap shear properties. The tool with tip-threaded pin (T-tool) fabricated joint with flat hook and cold lap, which resulted in shear fracture mode. The tools with bottom-threaded pin (B-tool) eliminated the hook. The tool with reverse-threaded pin (R-tool) widened the stir zone width. When using configuration A, the joints fabricated by the three new tools showed higher failure loads than the joint fabricated by the TR-tool. The joint using the T-tool owned the optimum impact toughness. This study demonstrated the significance of thread during FSLW and provided a reference to optimize tool geometry.

  2. Studi Perbandingan Proses Pengelasan Smaw Pada Lingkungan Darat dan Bawah Air Terhadap Ketahanan Uji Bending Weld Joint Material A36

    Directory of Open Access Journals (Sweden)

    Safira Dwi Anggraeni

    2017-01-01

    Full Text Available Penelitian ini bertujuan untuk mengetahui perbedaan nilai kekuatan uji bending,  dan kekerasan pada sambungan weld joint plat baja A36 pada proses pengelasan SMAW di lingkungan darat dan bawah air. Penelitian ini menggunakan Baja A36 dengan variasi lingkungan pengelasan yakni di darat dan di bawah air dengan menggunakan las SMAW dan memakai elektroda E7018 diameter 3,2 mm. Spesimen dilakukan pengujian bending berupa face bend dan root bend, pengujian kekerasan dan foto mikro. Pada pengujian bending pengelasan di darat tidak menghasilkan cacat yang berarti, sedangkan untuk hasil pengujian bending face dan root pada pengelasan bawah air terdapat cacat sepanjang daerah lasan sebesar 38 mm, hal ini tidak dapat diterima karena ukuran cacat lebih besar dari persyaratan yang ada pada ASME Section IX edisi 2015. Pada pengujian kekerasan, nilai kekerasan tertinggi pada pengelasan di darat adalah 200,5 HVN sedangkan nilai kekerasan teritinggi pada pengelasan bawah air adalah 290,2 HVN. Hasil pengujian kekerasan tertinggi pada pengelasan bawah air lebih rendah dari persyaratan AWS D3.6M – Underwater Welding Code, sehinga nilai kekerasan memenuhi persyaratan standar. Hasil foto mikro pada pengelasan di darat pada daerah base metal, persentase struktur mikro untuk ferit adalah 75,44% dan perlit adalah 24,56%. Pada daerah HAZ, persentase struktur mikro untuk ferit adalah 70,11% dan perlit adalah 28,89%. Pada daerah weld metal, persentase struktur mikro untuk ferit adalah 61,11% dan perlit adalah 38,89%. Sedangkan untuk hasil foto mikro pada pengelasan di bawah air pada daerah base metal, persentase struktur mikro untuk ferit adalah 74,89% dan perlit adalah 25,11%. Pada daerah HAZ, persentase struktur mikro untuk martensit adalah 46,11%,   struktur mikro ferit adalah 18,22% dan struktur mikro perlit adalah 35,67%. Pada daerah weld metal, persentase struktur mikro untuk ferit adalah 48,9% dan struktur mikro perlit adalah 51,1%. 

  3. Evaluation of the welded joints in P92 and P122 pipe steels

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, S.H.; Lee, K.W.; Chi, B.H.; Lee, Y.S.; Kong, B.O. [Doosan Heavy Industries and Construction Co., Ltd., Changwon (Korea); Park, S.H.; Nam, S.W. [Korea Advanced Inst. of Science and Technology, Taejon (Korea); Lim, B.S.; Kim, B.J. [Sungkyunkwan Univ., Suwon (Korea)

    2002-07-01

    SAW and SMAW processes in P92 and P122 pipe steels have been investigated for the application to the main steam pipe and the header components of boiler in the domestic thermal power plant. P92 steel indicated the higher weld metal toughness compared to P122 steel. The double PWHT was more beneficial to the weld metal toughness than the single PWHT with the same tempering parameter. Determined from the weld metal toughness and the economic point of view, the PWHT conditions of the P92 and the P122 steels were 750 C for 5 hrs and 760 C for 5 hrs respectively. The continuous low cycle fatigue (LCF) life was similar for both P92 and P122 irrespective of the test temperatures and the position of cross weld. The continuous LCF and the creep-fatigue interaction (CFI) tests also indicated very similar fatigue life in the base metal regardless of the holding time. On the other hand, in the weld metal, the CFI life caused a reduction in cycles to failure lower by a factor of 2 {proportional_to} 4 than the continuous LCF life, and the extent of reduction was increasing with increasing test temperatures. There was an indication of dependence of crack growth rate on temperature in the P92 and the P122. The slope of the Paris plot (m) had also a trend towards the higher values at the higher temperatures. The crack growth rate in the weld metal was slightly slower than that in the base metal. The HAZ showed the fastest growth rate and the highest value over m {proportional_to} 4 in the cross weld. The crack growth rates in the base metal of the P122 were faster than those of the P92 at temperatures of 600{proportional_to}700 C. (orig.)

  4. New And Existing Bridge Constructions - Increase of Fatigue Strength of Welded Joints by High Frequency Mechanical Impact Treatment

    Directory of Open Access Journals (Sweden)

    Ummenhofer Thomas

    2013-07-01

    Full Text Available Numerous studies at KIT prove that high frequency mechanical impact (HFMI treatment is an efficient method for increasing the fatigue strength of welded steel structures. Within different research projects it was found that HFMI-methods can be used successfully for new and existing structures in order to extend the fatigue life. This paper gives an overview of the current status of existing steel bridges in Germany regarding aspects like bridge age distributions and traffic loads. Based on that overview welded joints susceptible to fatigue failure are identified. Using component-like small scale specimens, HFMI-methods were investigated within the objective of implementing an effective application for new and existing structures. Applying the fatigue test data observed, existing design proposals are evaluated and design recommendations for HFMI-treated joints are given. As a result of the research work, a transfer into practice has been realized and different applications are illustrated using the example of bridge constructions made of steel.

  5. An Evaluation of Global and Local Tensile Properties of Friction-Stir Welded DP980 Dual-Phase Steel Joints Using a Digital Image Correlation Method

    Directory of Open Access Journals (Sweden)

    Hyoungwook Lee

    2015-12-01

    Full Text Available The effect of the microstructure heterogeneity on the tensile plastic deformation characteristic of friction-stir-welded (FSW dual-phase (DP steel was investigated for the potential applications on the lightweight design of vehicles. Friction-stir-welded specimens with a butt joint configuration were prepared, and quasi-static tensile tests were conducted, to evaluate the tensile properties of DP980 dual-phase steels. The friction-stir welding led to the formation of martensite and a significant hardness rise in the stir zone (SZ, but the presence of a soft zone in the heat-affected zone (HAZ was caused by tempering of the pre-existing martensite. Owing to the appearance of severe soft zone, DP980 FSW joint showed almost 93% joint efficiency with the view-point of ultimate tensile strength and relatively low ductility than the base metal (BM. The local tensile deformation characteristic of the FSW joints was also examined using the digital image correlation (DIC methodology by mapping the global and local strain distribution, and was subsequently analyzed by mechanics calculation. It is found that the tensile deformation of the FSW joints is highly heterogeneous, leading to a significant decrease in global ductility. The HAZ of the joints is the weakest region where the strain localizes early, and this localization extends until fracture with a strain near 30%, while the strain in the SZ and BM is only 1% and 4%, respectively. Local constitutive properties in different heterogeneous regions through the friction-stir-welded joint was also briefly evaluated by assuming iso-stress conditions. The local stress-strain curves of individual weld zones provide a clear indication of the heterogeneity of the local mechanical properties.

  6. An Evaluation of Global and Local Tensile Properties of Friction-Stir Welded DP980 Dual-Phase Steel Joints Using a Digital Image Correlation Method.

    Science.gov (United States)

    Lee, Hyoungwook; Kim, Cheolhee; Song, Jung Han

    2015-12-04

    The effect of the microstructure heterogeneity on the tensile plastic deformation characteristic of friction-stir-welded (FSW) dual-phase (DP) steel was investigated for the potential applications on the lightweight design of vehicles. Friction-stir-welded specimens with a butt joint configuration were prepared, and quasi-static tensile tests were conducted, to evaluate the tensile properties of DP980 dual-phase steels. The friction-stir welding led to the formation of martensite and a significant hardness rise in the stir zone (SZ), but the presence of a soft zone in the heat-affected zone (HAZ) was caused by tempering of the pre-existing martensite. Owing to the appearance of severe soft zone, DP980 FSW joint showed almost 93% joint efficiency with the view-point of ultimate tensile strength and relatively low ductility than the base metal (BM). The local tensile deformation characteristic of the FSW joints was also examined using the digital image correlation (DIC) methodology by mapping the global and local strain distribution, and was subsequently analyzed by mechanics calculation. It is found that the tensile deformation of the FSW joints is highly heterogeneous, leading to a significant decrease in global ductility. The HAZ of the joints is the weakest region where the strain localizes early, and this localization extends until fracture with a strain near 30%, while the strain in the SZ and BM is only 1% and 4%, respectively. Local constitutive properties in different heterogeneous regions through the friction-stir-welded joint was also briefly evaluated by assuming iso-stress conditions. The local stress-strain curves of individual weld zones provide a clear indication of the heterogeneity of the local mechanical properties.

  7. Transformation and Precipitation Reactions by Metal Active Gas Pulsed Welded Joints from X2CrNiMoN22-5-3 Duplex Stainless Steels

    Science.gov (United States)

    Utu, Ion-Dragos; Mitelea, Ion; Urlan, Sorin Dumitru; Crăciunescu, Corneliu Marius

    2016-01-01

    The high alloying degree of Duplex stainless steels makes them susceptible to the formation of intermetallic phases during their exposure to high temperatures. Precipitation of these phases can lead to a decreasing of the corrosion resistance and sometimes of the toughness. Starting from the advantages of the synergic Metal Active Gas (MAG) pulsed welding process, this paper analyses the structure formation particularities of homogeneous welded joints from Duplex stainless steel. The effect of linear welding energy on the structure morphology of the welded joints was revealed by macro- and micrographic examinations, X-ray energy dispersion analyses, measurements of ferrite proportion and X-ray diffraction analysis. The results obtained showed that the transformation of ferrite into austenite is associated with the chromium, nickel, molybdenum and nitrogen distribution between these two phases and their redistribution degree is closely linked to the overall heat cycle of the welding process. The adequate control of the energy inserted in the welded components provides an optimal balance between the two microstructural constituents (Austenite and Ferrite) and avoids the formation of undesirable intermetallic phases. PMID:28773727

  8. The defects and microstructure in the fusion zone of multipass laser welded joints with Inconel 52M filler wire for nuclear power plants

    Science.gov (United States)

    Li, Gang; Lu, Xiaofeng; Zhu, Xiaolei; Huang, Jian; Liu, Luwei; Wu, Yixiong

    2017-09-01

    The defects and microstructure in the fusion zone of multipass laser welded joints with Inconel 52M filler wire are investigated for nuclear power plants. Experimental results indicate that the incomplete fusion forms as the deposited metals do not completely cover the groove during multipass laser welding. The dendritic morphologies are observed on the inner surface of the porosity in the fusion zone. Many small cellular are found in the zones near the fusion boundary. With solidification preceding, cellular gradually turn into columnar dendrites and symmetrical columnar dendrites are exhibited in the weld center of the fusion zone. The fine equiaxed grains form and columnar dendrites disappear in the remelted zone of two passes. The dendrite arm spacing in the fusion zone becomes widened with increasing welding heat input. Nb-rich carbides/carbonitrides are preferentially precipitated in the fusion zone of multipass laser welded joints. In respect to high cooling rate during multipass laser welding, element segregation could be insufficient to achieve the component of Laves phase.

  9. Creep-fatigue evaluation method for weld joint of Mod.9Cr-1Mo steel Part II: Plate bending test and proposal of a simplified evaluation method

    Energy Technology Data Exchange (ETDEWEB)

    Ando, Masanori, E-mail: ando.masanori@jaea.go.jp; Takaya, Shigeru, E-mail: takaya.shigeru@jaea.go.jp

    2016-12-15

    Highlights: • Creep-fatigue evaluation method for weld joint of Mod.9Cr-1Mo steel is proposed. • A simplified evaluation method is also proposed for the codification. • Both proposed evaluation method was validated by the plate bending test. • For codification, the local stress and strain behavior was analyzed. - Abstract: In the present study, to develop an evaluation procedure and design rules for Mod.9Cr-1Mo steel weld joints, a method for evaluating the creep-fatigue life of Mod.9Cr-1Mo steel weld joints was proposed based on finite element analysis (FEA) and a series of cyclic plate bending tests of longitudinal and horizontal seamed plates. The strain concentration and redistribution behaviors were evaluated and the failure cycles were estimated using FEA by considering the test conditions and metallurgical discontinuities in the weld joints. Inelastic FEA models consisting of the base metal, heat-affected zone and weld metal were employed to estimate the elastic follow-up behavior caused by the metallurgical discontinuities. The elastic follow-up factors determined by comparing the elastic and inelastic FEA results were determined to be less than 1.5. Based on the estimated elastic follow-up factors obtained via inelastic FEA, a simplified technique using elastic FEA was proposed for evaluating the creep-fatigue life in Mod.9Cr-1Mo steel weld joints. The creep-fatigue life obtained using the plate bending test was compared to those estimated from the results of inelastic FEA and by a simplified evaluation method.

  10. An Analysis of Laser-Welded Nicr-Ir and Nicr-Pt Micro Joints on Spark Plug Electrodes in Biogas-Fuelled Engines

    Directory of Open Access Journals (Sweden)

    Grabas B.

    2016-06-01

    Full Text Available The paper deals with the laser beam welding of tips to central and side spark plug electrodes made of a nickel-chromium alloy. The tips attached to the central electrodes were made from a solid iridium wire 0.8 mm in diameter and 2 mm in length, while the tips connected to the side electrodes were made from a platinum wire 1.5 mm in diameter and 0.25 mm in thickness. In both cases, accurate positioning of the tips was required before they were resistance welded to the electrodes. Then, a fillet weld was produced with an Nd:YAG laser using single, partly overlapping conductive pulses. The laser welding was performed at different laser power levels and pulse durations. Metallographic sections of the joints were prepared to observe changes in the microstructure and determine their correlation with the changes in the process parameters. The results were used to select appropriate welding parameters for the materials joined. The microscopic analysis indicated welding imperfections such as micro cracks at the interface between the elements joined. The tips welded to the spark plug electrodes can help extend the service life of spark plugs in highly corrosive environments.

  11. Influences of Friction Stir Welding Parameters on Microstructural and Mechanical Properties of AA5456 (AlMg5) at Different Lap Joint Thicknesses

    Science.gov (United States)

    Pishevar, M. R.; Mohandesi, J. Aghazadeh; Omidvar, H.; Safarkhanian, M. A.

    2015-10-01

    Friction stir welding is suitable for joining series 5000 alloys because no fusion welding problems arise for the alloys in this process. The present study examined the effects of double-pass welding and tool rotational and travel speeds for the second-pass welding on the mechanical and microstructural properties of friction stir lap welding of AA5456 (AlMg5)-H321 (5 mm thickness) and AA5456 (AlMg5)-O (2.5 mm thickness). The first pass of all specimens was performed at a rotational speed of 650 rpm and a travel speed of 50 mm/min. The second pass was performed at rotational speeds of 250, 450, and 650 rpm and travel speeds of 25, 50, and 75 mm/min. The results showed that the second pass changed the grain sizes in the center of the nugget zone compared with the first pass. It was observed that the size of the hooking defect of the double-pass-welded specimens was higher than that for the single-pass-welded specimen. The size of the hooking defect was found to be a function of the rotational and travel speeds. The optimal joint tensile shear properties were achieved at a rotational speed of 250 rpm and travel a speed of 75 mm/min.

  12. 2D Linear Friction Weld Modelling of a Ti-6Al-4V T-Joint

    Directory of Open Access Journals (Sweden)

    L. A. Lee

    2015-09-01

    Full Text Available Most examples of linear friction weld process models have focused on joining two identically shaped workpieces. This article reports on the development of a 2D model, using the DEFORM finite element package, to investigate the joining of a rectangular Ti-6Al-4V workpiece to a plate of the same material. The work focuses on how this geometry affects the material flow, thermal fields and interface contaminant removal. The results showed that the material flow and thermal fields were not even across the two workpieces. This resulted in more material expulsion being required to remove the interface contaminants from the weld line when compared to joining two identically shaped workpieces. The model also showed that the flash curves away from the weld due to the rectangular upstand “burrowing” into the base plate. Understanding these critical relationships between the geometry and process outputs is crucial for further industrial implementation of the LFW process.

  13. An automatic approach for nondestructive radiographic inspection of pipeline weld joint; Uma abordagem automatica aplicada a inspecao radiografica nao-destrutiva de soldas em tubulacoes

    Energy Technology Data Exchange (ETDEWEB)

    Felisberto, Marcelo K.; Schneider, Guilherme A.; Centeno, Tania M.; Arruda, Lucia V.R. de [Centro Federal de Educacao Tecnologica do Parana, Curitiba, PR (Brazil). CPGEI - Programa de Pos-graduacao em Engenharia Eletrica e Informatica Industrial

    2005-07-01

    The current work contributes to the research in the area of pipelines non-destructive testing by presenting new methodologies for the automatic analysis of welds radiographs. Object recognition techniques based on genetic algorithms were used for the automatic weld bead detection. In addiction, an image digital filter was also tested in the weld bead images and, as a result, supposed defects are highlighted, making them easier to be detected. These methodologies were tested for 120 digital radiographs from carbon steel pipeline welded joints. These images were acquired by a storage phosphor system, using double-wall radiographic exposing technique with single-wall radiographic viewing, according to the ASME V code. As a result, even human vision hard-perceptible defects are automatically highlighted and extracted from the whole image to be separately analyzed. (author)

  14. Increasing Strength and Operational Reliability of Fixed Joints of Tubes by MMA Welding

    Science.gov (United States)

    Il'yaschenko, D. P.; Chinakhov, D. A.; Danilov, V. I.; Schlyakhova, G. V.; Gotovschik, Y. M.

    2015-09-01

    This paper presents peculiar properties of structure formation, phase and chemical composition while welding of low-alloy steel 09MnSi2-l depending on the dynamic characteristics of power sources of different types. Proper selection of power sources enables to decrease burning of alloy elements in metal of weld (Mn by 14% and Si by 17% of the weight ratio), to obtain more homogenous structure of deposited metal, to reduce length of heat-affected zone by 50% and to improve impact strength by 4-9%.

  15. Microstructural investigation of the heat-affected zone of simulated welded joint of P91 steel

    Directory of Open Access Journals (Sweden)

    T. Vuherer

    2013-07-01

    Full Text Available In the process of testing real components exposed to elevated temperature, it is not possible to neglect cracks. The most significant cracks can be induced by welding, which is applied for joining of structural components. Pressure equipment in service is also exposed to high pressure and high stresses. Materials for their manufacturing are designed to resist high stress at elevated temperature, and to meet requirements regarding creep resistance. The objective of this study is to investigate microstructure of different regions of the heat affected zone in T/P91 steels by using thermal simulation instead of welding.

  16. Microstructure of Welded Joints of X5CrNiCuNb16-4 (17-4 PH Martensitic Stainlees Steel After Heat Treatment

    Directory of Open Access Journals (Sweden)

    Ziewiec A.

    2014-10-01

    Full Text Available The paper presents rezults of microstructure (LM, TEM investigation and hardness measurments of welded joints in martensitic precipitation hardened stainless steel containing copper, subjected to heat treatment. For the aging temperature up to 540 °C even for the very long times, the microstructure of the welded joints is similar to this one at lower temerature aging. After aging at 620 °C a distinct change of the microstructure was observed. Non-equilibrium solidification conditions of the weld metal, segregation and the diffusion of copper and the elements stablilizing the austenite cause the occurrence of the reverse transformation of the martensite into austenite as fast as just 1 hour at 620 °C. TEM investigations revealed the differences in dispersion of hardening copper precipitates after aging at temperature 620 °C for 1 and 4 hours.

  17. Experimental and numerical studies on the issues in laser welding of light-weight alloys in a zero-gap lap joint configuration

    Science.gov (United States)

    Harooni, Masoud

    current study a non-destructive evaluation method based on spectroscopy is proposed to detect the presence of pores in the lap joint of laser welded AZ31B magnesium alloy. The electron temperature that is calculated by the Boltzmann plot method is correlated to the presence of pores in the weld bead. A separate series of experiments was performed to evaluate the effect of an oxide coating layer on the dynamic behavior of the molten pool in the laser welding of an AZ31B magnesium alloy in a zero-gap lap joint configuration. A high speed CCD camera assisted with a green laser as an illumination source was selected to record the weld pool dynamics. Another technique used in this study was two-pass laser welding process to join AZ31B magnesium sheet in a zero-gap, lap-shear configuration. Two groups of samples including one pass laser welding (OPLW) and two pass laser welding (TPLW) were studied. In the two pass laser welding procedure, the first pass is performed by a defocused laser beam on the top of the two overlapped sheets in order to preheat the faying surface prior to laser welding, while the second pass is applied to melt and eventually weld the samples. Tensile and microhardness tests were used to measure the mechanical properties of the laser welded samples. A spectrometer was also used in real-time to correlate pore formation with calculated electron temperature using the Boltzmann plot method. The results of calculated electron temperature confirmed the previous results in earlier chapter. Magnesium and aluminum are two alloys which are used in different industries mainly due to their light weight. The main use of these two alloys is in automotive industry. Since different parts of the automobiles can be manufactured with each of these two alloys, it is essential to evaluate the joining feasibility of dissimilar metals such as aluminum to magnesium. A 4 kW fiber laser is used to join AZ31B magnesium alloy to AA 6014 using an overlap joint configuration. Two

  18. Wear characteristics and defects analysis of friction stir welded joint of aluminium alloy 6061-t6

    Czech Academy of Sciences Publication Activity Database

    Kumar, R.; Chattopadhyaya, S.; Hloch, Sergej; Krolczyk, G.; Legutko, S.

    2016-01-01

    Roč. 18, č. 1 (2016), s. 128-135 ISSN 1507-2711 Institutional support: RVO:68145535 Keywords : Friction stir welding (FSW) * grinding machine * Field Emission Scanning Electron Microscope (FESEM) Subject RIV: JQ - Machines ; Tools Impact factor: 1.145, year: 2016 http://www.ein.org.pl/2016-01-17

  19. Automated Variable-Polarity Plasma-Arc Welding

    Science.gov (United States)

    Numes, A. C., Jr.; Bayless, E. O., Jr.; Jones, S. C., III; Munafo, P.; Munafo, A.; Biddle, A.; Wilson, W.

    1984-01-01

    Variable-polarity plasma-arc methods produces better welds at lower cost than gas-shielded tungsten-arc welding in assemblies. Weld porosity very low and costs of joint preparation, depeaking, inspection, and weld repair minimized.

  20. Finite element analysis for three dimensional welding processes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ju Wan; Cho, Young Sam; Kim, Hyun Gyu; Choi, Kang Hyouk; Im, Se Young [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

    2001-07-01

    We propose an implicit numerical implementation for the Leblond's transformation plasticity constitutive equations, which are widely used in welded steel structure. We apply generalized trapezoidal rule to integrate the equations and determine the consistent tangent moduli. The implementation may be used with updated Lagrangian formulation. We test a simple butt-welding process to compare with SYSWELD and discuss the accuracy.

  1. Avaliação do efeito da energia de soldagem sobre as tensões residuais resultantes em juntas soldadas com multipasse Welding energy input evaluation on the final residual stresses in multipass welded joints

    Directory of Open Access Journals (Sweden)

    George Luiz Gomes de Oliveira

    2010-09-01

    Full Text Available A energia de soldagem pode ser ajustada tanto por meio do controle da potência (tensão e corrente de soldagem quanto por meio da velocidade de soldagem. Tais formas de ajustes modificam os efeitos da energia de soldagem sobre a junta, o que pode influenciar de forma distinta as tensões residuais resultantes na mesma. Desta forma, o objetivo deste trabalho é avaliar o efeito da energia de soldagem, considerando seu ajuste através da alteração individual e independente da corrente e da velocidade de soldagem, sobre as tensões residuais resultantes em juntas soldadas com multipasse. Foram empregadas amostras de aço estrutural chanfradas em meio-v e soldadas utilizando eletrodo revestido. Aplicaram-se três energias de soldagem obtidas por meio de três níveis distintos de corrente e de velocidade de soldagem. As amostras foram levadas a um difratômetro de raios-x portátil onde foram levantados os perfis de tensões residuais na superfície das mesmas. Uma verificação importante foi que diferentes parâmetros de soldagem que resultam em aportes térmicos "iguais", geram níveis diferentes de tensões residuais, ou seja, a energia de soldagem não pode ser considerada de forma isolada em análises de níveis de tensões residuais resultantes da soldagem multipasse.The energy input in welding can be adjusted by either control of welding power (voltage and welding current or welding speed. These different ways of changing can result in different residual stress profiles in the welded joint. Then, the aim of this work is to evaluate, in an independent way, the welding energy input, current and speed effect on the final residual stresses of a multipass joint. Semi-v chamfered samples of structural steel and SMAW process was used. Three different levels of welding current and speed was employed in order to get three levels of energy input. The residual stress measurement was accomplished through X-ray diffraction, using a minidiffractometer

  2. Investigation of possible causes for appearance of a crack in the welded joint of the ship winch frame

    Directory of Open Access Journals (Sweden)

    Milos S. Matejic

    2014-11-01

    Full Text Available Ship winches are one of the most important parts of the ship equipment since they perform the most responsible tasks on various ships. In the majority of cases, the ship winches are welded structures. All the necessary calculations according to required standards, that have to be done prior to actual execution of the structure, should also include the verification by the finite elements method. For the high reliability requirements to be met, the welded joints integrity of all the parts must be examined before they are assembled into the winch. After all the tests are conducted and parts are assembled into the winch, the factory acceptance test (FAT must be done. During those tests all the flaws, which can appear during manufacturing, must show. An appearance of a very unusual crack in the ship winch frame, which happened during the FAT, is described in this paper. The simulation by the finite elements method was performed to obtain the stresses at which the crack appeared. The possible causes for that crack appearance are considered. Some measures for reducing appearance of such cracks to a minimum are proposed, as well as certain directions for further research of this problem. 

  3. Nugget formation and its mechanism of resistance spot welded joints in DP600 dual-phase and DC54D ultralow carbon steel

    Science.gov (United States)

    Li, Ci; Yuan, Xinjian; Wu, Kanglong; Wang, Haodong; Hu, Zhan; Pan, Xueyu

    2017-05-01

    Resistance spot welded joints in different configurations of DP600 and DC54D were investigated to elucidate the nugget formation process and mechanical properties of the resultant joints. Results show that, when the welding time was less than 4 cycles, the fusion zone (FZ) was not formed, but the heat-affected zone (HAZ) occurred with a "butterfly" shape. In 4 cycles, the FZ in dissimilar sheets occurred with an "abnormal butterfly" shape because of nugget shift. When the welding time increased to 14 cycles, the FZ exhibited a "bread loaf" shape and the weld shifted to "dog bones." The nugget can be divided into three regions, namely, FZ, HAZ1, and HAZ2, and the FZ consisted of lath martensite. The micro hardness of DP600 FZ was lower than that of HAZ because of the dilution of DC54D. The failure mode of B changed from interfacial failure to plug failure during the nugget formation process. The tensile-shear load of sound weld is 6.375, 6.016, and 19.131 kN.

  4. Wavelets Application in Prediction of Friction Stir Welding Parameters of Alloy Joints from Vibroacoustic ANN-Based Model

    Directory of Open Access Journals (Sweden)

    Emilio Jiménez-Macías

    2014-01-01

    Full Text Available This paper analyses the correlation between the acoustic emission signals and the main parameters of friction stir welding process based on artificial neural networks (ANNs. The acoustic emission signals in Z and Y directions have been acquired by the AE instrument NI USB-9234. Statistical and temporal parameters of discomposed acoustic emission signals using Wavelet Transform have been used as input of the ANN. The outputs of the ANN model include the parameters of tool rotation speed and travel speed, and tool profile, as well as the tensile strength. A multilayer feed-forward neural network has been selected and trained, using Levenberg-Marquardt algorithm for different network architectures. Finally, an analysis of the comparison between the measured and the calculated data is presented. The model obtained can be used to model and develop an automatic control of the parameters of the process and mechanical properties of joint, based on the acoustic emission signals.

  5. Evaluation of Creep Strength of Heterogeneous Welded Joint in HR6W Alloy and Sanicro 25 Steel

    Directory of Open Access Journals (Sweden)

    Zieliński A.

    2017-12-01

    Full Text Available This article presents the results of investigations on HR6W alloy and Sanicro 25 steel and the dissimilar welded joint made of them. The characteristic images of microstructure of the investigated materials in the as-received condition and following the creep test, observed with a scanning electron microscope (SEM, are shown. The X-ray analysis of phase composition of the existing precipitates was carried out. The method for evaluation of creep strength based on abridged creep tests carried out at a temperature higher than the design one is presented. The obtained results do not deviate from the values of creep strength determined in long-term creep tests. The maximum difference in creep strength of the investigated materials is ±20%, which is in compliance with the acceptable scatter band. The methodology presented can be used for verification of creep strength (life time of the material of finished components to be operated under creep conditions.

  6. Prediction of corrosion fatigue crack initiation behavior of A7N01P-T4 aluminum alloy welded joints

    Science.gov (United States)

    An, J.; Chen, J.; Gou, G.; Chen, H.; Wang, W.

    2017-07-01

    Through investigating the corrosion fatigue crack initiation behavior of A7N01P-T4 aluminum alloy welded joints in 3.5 wt.% NaCl solution, corrosion fatigue crack initiation life is formulated as Ni = 6.97 × 1012[Δσeqv1.739 - 491.739]-2 and the mechanism of corrosion fatigue crack initiation is proposed. SEM and TEM tests revealed that several corrosion fatigue cracks formed asynchronously and the first crack does not necessarily develop into the leading crack. The uneven reticular dislocations produced by fatigue loading are prone to piling up and tangling near the grain boundaries or the second phases and form the “high dislocation-density region” (HDDR), which acts as an anode in microbatteries and dissolved to form small crack. Thus the etching pits, HDDR near the grain boundaries and second phases are confirmed as the main causes inducing the initiation of fatigue crack.

  7. Characterization the microstructure of pulsed Nd:YAG welding method in low frequencies; correlation with tensile and fracture behavior in laser-welded nitinol joints

    Science.gov (United States)

    Shojaei Zoeram, Ali; Rahmani, Aida; Asghar Akbari Mousavi, Seyed Ali

    2017-05-01

    The precise controllability of heat input in pulsed Nd:YAG welding method provided by two additional parameters, frequency and pulse duration, has made this method very promising for welding of alloys sensitive to heat input. The poor weldability of Ti-rich nitinol as a result of the formation of Ti2Ni IMC has deprived us of the unique properties of this alloy. In this study, to intensify solidification rate during welding of Ti-rich nitinol, pulsed Nd:YAG laser beam in low frequency was employed in addition to the employment of a copper substrate. Specific microstructure produced in this condition was characterized and the effects of this microstructure on tensile and fracture behavior of samples welded by two different procedures, full penetration and double-sided method with halved penetration depth for each side were investigated. The investigations revealed although the combination of low frequencies, the use of a high thermal conductor substrate and double-sided method eliminated intergranular fracture and increased tensile strength, the particular microstructure, built in the pulsed welding method in low frequencies, results to the formation of the longitudinal cracks during the first stages of tensile test at weld centerline. This degrades tensile strength of welded samples compared to base metal. The results showed samples welded in double-sided method performed much better than samples welded in full penetration mode.

  8. Testing of intergranular and pitting corrosion in sensitized welded joints of austenitic stainless steel

    Directory of Open Access Journals (Sweden)

    Bore V. Jegdic

    2017-06-01

    Full Text Available Pitting corrosion resistance and intergranular corrosion of the austenitic stainless steel X5Cr Ni18-10 were tested on the base metal, heat affected zone and weld metal. Testing of pitting corrosion was performed by the potentiodynamic polarization method, while testing of intergranular corrosion was performed by the method of electrochemical potentiokinetic reactivation with double loop. The base metal was completely resistant to intergranular corrosion, while the heat affected zone showed a slight susceptibility to intergranular corrosion. Indicators of pitting corrosion resistance for the weld metal and the base metal were very similar, but their values are significantly higher than the values for the heat affected zone. This was caused by reduction of the chromium concentration in the grain boundary areas in the heat affected zone, even though the carbon content in the examined stainless steel is low (0.04 wt. % C.

  9. Creep properties in similar weld joint of a thick-walled P92 steel pipe

    Czech Academy of Sciences Publication Activity Database

    Sklenička, Václav; Kuchařová, Květa; Svobodová, M.; Kvapilová, Marie; Král, Petr; Horváth, P.

    2016-01-01

    Roč. 119, č. 1 (2016), s. 1-12 ISSN 1044-5803 R&D Projects: GA ČR(CZ) GA16-09518S; GA MPO FR-TI4/406 Institutional support: RVO:68081723 Keywords : 9–12%Cr steels * Creep testing * High temperature creep * Thick-walled pipe * Welding Subject RIV: JG - Metallurgy Impact factor: 2.714, year: 2016

  10. Stress corrosion cracking behaviour of gas tungsten arc welded super austenitic stainless steel joints

    OpenAIRE

    Vinoth Kumar, M.; Balasubramanian, V.; Rajakumar, S.; Albert, Shaju K.

    2015-01-01

    Super 304H austenitic stainless steel with 3% of copper posses excellent creep strength and corrosion resistance, which is mainly used in heat exchanger tubing of the boiler. Heat exchangers are used in nuclear power plants and marine vehicles which are intended to operate in chloride rich offshore environment. Chloride stress corrosion cracking is the most likely life limiting failure with austenitic stainless steel tubing. Welding may worsen the stress corrosion cracking susceptibility of t...

  11. Surface integrity analysis of abrasive water jet-cut surfaces of friction stir welded joints

    Czech Academy of Sciences Publication Activity Database

    Kumar, R.; Chattopadhyaya, S.; Dixit, A. R.; Bora, B.; Zeleňák, Michal; Foldyna, Josef; Hloch, Sergej; Hlaváček, Petr; Ščučka, Jiří; Klich, Jiří; Sitek, Libor; Vilaca, P.

    2017-01-01

    Roč. 88, č. 5 (2017), s. 1687-1701 ISSN 0268-3768 R&D Projects: GA MŠk(CZ) LO1406; GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : friction stir welding (FSW) * abrasive water jet (AWJ) * optical profilometer * topography * surface roughness Subject RIV: JQ - Machines ; Tools Impact factor: 2.209, year: 2016 http://link.springer.com/article/10.1007/s00170-016-8776-0

  12. Microstructure characteristics and mechanical properties of laser-welded joint of γ-TiAl alloy with pure Ti filler metal

    Science.gov (United States)

    Cai, Xiaolong; Sun, Daqian; Li, Hongmei; Guo, Hongling; Gu, Xiaoyan; Zhao, Zhuo

    2017-12-01

    γ-TiAl alloy was successfully welded using pure Ti filler metal by laser. The microstructures, element distribution and phase composition of the joint were investigated by SEM, EDS and XRD, and the mechanical properties of the joints were evaluated by nanoindentation and tensile strength tests. Crack-free joints were obtained by using Ti filler metal. The weld zone mainly contained of α2-Ti3Al phase and a small amount of Ti2Al phases. The hardness values in the weld zone were higher than that of base metal (BM) due to the formation of α2-Ti3Al phase, but for the modulus values were just the reverse. The tensile strength and elongation of the joints were 288 MPa and 2.19%, respectively, accounting for 74.8% and 94.0% of the BM, respectively. The joint fracture surface exhibited typical brittle fracture morphology, and Ti2Al and TiAl2 particle phases can be seen on the fracture surface.

  13. Combination Effects of Nocolok Flux with Ni Powder on Properties and Microstructures of Aluminum-Stainless Steel TIG Welding-Brazing Joint

    Science.gov (United States)

    He, Huan; Lin, Sanbao; Yang, Chunli; Fan, Chenglei; Chen, Zhe

    2013-11-01

    A flux consisting of Nocolok and nickel powder was first applied for TIG welding-brazing of aluminum-stainless steel. Results of tensile and impact tests illustrated that a significant improvement in mechanical properties of the butt joint was obtained with the flux, tensile strength increased from 116 to 158 MPa, and impact energy increased from 3.2 to 6.7 J. Investigation results on microstructures of interfaces and seams suggested that Ni addition significantly decreased the thickness of intermetallic compound (IMC) layer on the interfaces, but did not change the phase structure of Al13Fe4. Furthermore, precipitate phase in the welded seams changed from Al6Fe to Al9FeNi, and the quantity of precipitate phases decreased from 12 to 9% approximately. Finally, effect of Ni powder's addition on the joint was analyzed and discussed. The reduction in the thickness of IMC and quantity of precipitate phases are beneficial to joint properties.

  14. Optimization and Characterization of the Friction Stir Welded Sheets of AA 5754-H111: Monitoring of the Quality of Joints with Thermographic Techniques

    Directory of Open Access Journals (Sweden)

    Luigi Alberto Ciro De Filippis

    2017-10-01

    Full Text Available Friction Stir Welding (FSW is a solid-state welding process, based on frictional and stirring phenomena, that offers many advantages with respect to the traditional welding methods. However, several parameters can affect the quality of the produced joints. In this work, an experimental approach has been used for studying and optimizing the FSW process, applied on 5754-H111 aluminum plates. In particular, the thermal behavior of the material during the process has been investigated and two thermal indexes, the maximum temperature and the heating rate of the material, correlated to the frictional power input, were investigated for different process parameters (the travel and rotation tool speeds configurations. Moreover, other techniques (micrographs, macrographs and destructive tensile tests were carried out for supporting in a quantitative way the analysis of the quality of welded joints. The potential of thermographic technique has been demonstrated both for monitoring the FSW process and for predicting the quality of joints in terms of tensile strength.

  15. Prediction of the Vickers Microhardness and Ultimate Tensile Strength of AA5754 H111 Friction Stir Welding Butt Joints Using Artificial Neural Network.

    Science.gov (United States)

    De Filippis, Luigi Alberto Ciro; Serio, Livia Maria; Facchini, Francesco; Mummolo, Giovanni; Ludovico, Antonio Domenico

    2016-11-10

    A simulation model was developed for the monitoring, controlling and optimization of the Friction Stir Welding (FSW) process. This approach, using the FSW technique, allows identifying the correlation between the process parameters (input variable) and the mechanical properties (output responses) of the welded AA5754 H111 aluminum plates. The optimization of technological parameters is a basic requirement for increasing the seam quality, since it promotes a stable and defect-free process. Both the tool rotation and the travel speed, the position of the samples extracted from the weld bead and the thermal data, detected with thermographic techniques for on-line control of the joints, were varied to build the experimental plans. The quality of joints was evaluated through destructive and non-destructive tests (visual tests, macro graphic analysis, tensile tests, indentation Vickers hardness tests and t thermographic controls). The simulation model was based on the adoption of the Artificial Neural Networks (ANNs) characterized by back-propagation learning algorithm with different types of architecture, which were able to predict with good reliability the FSW process parameters for the welding of the AA5754 H111 aluminum plates in Butt-Joint configuration.

  16. Prediction of the Vickers Microhardness and Ultimate Tensile Strength of AA5754 H111 Friction Stir Welding Butt Joints Using Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Luigi Alberto Ciro De Filippis

    2016-11-01

    Full Text Available A simulation model was developed for the monitoring, controlling and optimization of the Friction Stir Welding (FSW process. This approach, using the FSW technique, allows identifying the correlation between the process parameters (input variable and the mechanical properties (output responses of the welded AA5754 H111 aluminum plates. The optimization of technological parameters is a basic requirement for increasing the seam quality, since it promotes a stable and defect-free process. Both the tool rotation and the travel speed, the position of the samples extracted from the weld bead and the thermal data, detected with thermographic techniques for on-line control of the joints, were varied to build the experimental plans. The quality of joints was evaluated through destructive and non-destructive tests (visual tests, macro graphic analysis, tensile tests, indentation Vickers hardness tests and t thermographic controls. The simulation model was based on the adoption of the Artificial Neural Networks (ANNs characterized by back-propagation learning algorithm with different types of architecture, which were able to predict with good reliability the FSW process parameters for the welding of the AA5754 H111 aluminum plates in Butt-Joint configuration.

  17. Prediction of the Vickers Microhardness and Ultimate Tensile Strength of AA5754 H111 Friction Stir Welding Butt Joints Using Artificial Neural Network

    Science.gov (United States)

    De Filippis, Luigi Alberto Ciro; Serio, Livia Maria; Facchini, Francesco; Mummolo, Giovanni; Ludovico, Antonio Domenico

    2016-01-01

    A simulation model was developed for the monitoring, controlling and optimization of the Friction Stir Welding (FSW) process. This approach, using the FSW technique, allows identifying the correlation between the process parameters (input variable) and the mechanical properties (output responses) of the welded AA5754 H111 aluminum plates. The optimization of technological parameters is a basic requirement for increasing the seam quality, since it promotes a stable and defect-free process. Both the tool rotation and the travel speed, the position of the samples extracted from the weld bead and the thermal data, detected with thermographic techniques for on-line control of the joints, were varied to build the experimental plans. The quality of joints was evaluated through destructive and non-destructive tests (visual tests, macro graphic analysis, tensile tests, indentation Vickers hardness tests and t thermographic controls). The simulation model was based on the adoption of the Artificial Neural Networks (ANNs) characterized by back-propagation learning algorithm with different types of architecture, which were able to predict with good reliability the FSW process parameters for the welding of the AA5754 H111 aluminum plates in Butt-Joint configuration. PMID:28774035

  18. Effect of Dwell Time on Joint Interface Microstructure and Strength of Dissimilar Friction Stir Spot-Welded Al-5083 and St-12 Alloy Sheets

    Science.gov (United States)

    Fereiduni, Eskandar; Movahedi, Mojtaba; Kokabi, Amir Hossein; Najafi, Hossein

    2017-04-01

    Joining of Al-5083 alloy sheet to St-12 steel sheet was performed using a new friction stir spot welding (FSSW) technique in which the tool pin tip did not enter lower steel sheet. Effect of dwell time on the microstructure and mechanical properties of the joints was studied by various methods including microhardness measurements, shear test, stereo and light microscopy as well as scanning and transmission electron microscopy (SEM and TEM). Results indicated that compared to the conventional FSSW process, stronger joints can be achieved by this FSSW technique. Cross-sectional observation of the failed specimens indicated the occurrence of final fracture from the circumference of the tool pin where the Al sheet thickness was decreased as a result of the tool pin penetration. However, microhardness measurements introduced these fracture locations as the hardest regions of the Al part of welds. In addition to the Al3Fe and Al5Fe2 intermetallic compounds reported in the literature to form at the interface of dissimilar Al/steel joints, a third layer of AlFe intermetallic compound was also identified adjacent to the steel side of welds. Enhancement of the dwell time from 5 to 15 seconds increased the intermetallic layer thickness from 1.7 to 3 µm and resulted in the formation of harder stirred zone. This consequently increased the strength of the weld.

  19. Quantitative ultrasonic testing of acoustically anisotropic materials with verification on austenitic and dissimilar weld joints

    Science.gov (United States)

    Boller, C.; Pudovikov, S.; Bulavinov, A.

    2012-05-01

    Austenitic stainless steel materials are widely used in a variety of industry sectors. In particular, the material is qualified to meet the design criteria of high quality in safety related applications. For example, the primary loop of the most of the nuclear power plants in the world, due to high durability and corrosion resistance, is made of this material. Certain operating conditions may cause a range of changes in the integrity of the component, and therefore require nondestructive testing at reasonable intervals. These in-service inspections are often performed using ultrasonic techniques, in particular when cracking is of specific concern. However, the coarse, dendritic grain structure of the weld material, formed during the welding process, is extreme and unpredictably anisotropic. Such structure is no longer direction-independent to the ultrasonic wave propagation; therefore, the ultrasonic beam deflects and redirects and the wave front becomes distorted. Thus, the use of conventional ultrasonic testing techniques using fixed beam angles is very limited and the application of ultrasonic Phased Array techniques becomes desirable. The "Sampling Phased Array" technique, invented and developed by Fraunhofer IZFP, allows the acquisition of time signals (A-scans) for each individual transducer element of the array along with fast image reconstruction techniques based on synthetic focusing algorithms. The reconstruction considers the sound propagation from each image pixel to the individual sensor element. For anisotropic media, where the sound beam is deflected and the sound path is not known a-priori, a novel phase adjustment technique called "Reverse Phase Matching" is implemented. By taking into account the anisotropy and inhomogeneity of the weld structure, a ray tracing algorithm for modeling the acoustic wave propagation and calculating the sound propagation time is applied. This technique can be utilized for 2D and 3D real time image reconstruction. The

  20. Modelling of microstructural creep damage in welded joints of 316L stainless steel; Modelisation de l'endommagement a haute temperature dans le metal d'apport des joints soudes d'acier inoxydable austenitique

    Energy Technology Data Exchange (ETDEWEB)

    Bouche, G

    2000-07-01

    Welded joints of 316L stainless steel under service conditions at elevated temperature are known to be preferential sites of creep damage, as compared to the base material. This damage results in the formation of cavities and the development of creep cracks which can lead to a premature failure of welded components. The complex two-phase microstructure of 316L welds was simulated by manually filling a mould with longitudinal deposited weld beads. The moulded material was then aged during 2000 hours at 600 deg. C. High resolution Scanning Electron Microscopy was largely used to examine the microstructure of the simulated material before and after ageing. Smooth and notched creep specimens were cut from the mould and tested at 600 deg. C under various stress levels. A comparison of the lifetime versus nominal stress curves for the base and welded materials shows a greater dependence of the welded material to creep phenomena. Observation and EBSD analysis show that damage is preferentially located along the austenite grain boundaries. The stress and strain fields in the notched specimens were calculated by finite element method. A correlation of this field to the observed damage was made in order to propose a predictive law relating the creep damage to the mechanical conditions applied locally. Further mechanical tests and simulation on CT specimens and mode II tubular specimens allowed validating the model under various multiaxial loading conditions. (author)

  1. Characterization of Explosive Weld Joints by TEM and SEM/EBSD

    Directory of Open Access Journals (Sweden)

    Paul H.

    2014-10-01

    Full Text Available The layers near the interface of explosively welded plates were investigated by means of microscopic observations with the use of transmission electron microscopy (TEM equipped with energy dispersive spectrometry and scanning electron microscopy equipped with electron backscattered diffraction facility (SEM/EBSD. The metal compositions based on carbon or stainless steels (base plate and Ti, Zr and Ta (flyer plate were analyzed. The study was focused on the possible interdiffusion across the interface and the changes in the dislocation structure of bonded plates in the layers near-the-interface.

  2. An Analysis of Microstructure and Mechanical Properties on Friction Stir Welded Joint of Dissimilar 304 Stainless Steel and Commercially Pure Aluminium

    Directory of Open Access Journals (Sweden)

    Balamagendiravarman M.

    2017-09-01

    Full Text Available In this study, friction stir welding of dissimilar 304 stainless steel and commercially pure aluminium was performed under the following condition of tool rotational speed 1000 rpm, traverse speed 60 mm/min and tool tilt angle 2 degree. Microstructural characterisation was carried out by optical microscope, scanning electron microscope (SEM. Optical images shows that the microstructural change is very minimum in steel side when compared to aluminium side due to the difference in mechanical and thermal properties. The intermetallic compound Al3Fe was observed at the interfacial region and stir region of the welded joint. The maximum ultimate tensile strength is 78% of commercially pure aluminium base metal. Microhardness profile was measured across the weld interface and the maximum value reaches at the stir zone due to the formation of intermettalics.

  3. Mechanical properties and microstructure of F-82H welded joints using CO{sub 2} laser beam

    Energy Technology Data Exchange (ETDEWEB)

    Yamanouchi, N.; Shiba, K.

    1996-10-01

    The laser welding of F-82H was successfully conducted. The heat affected zone of the welding, was about 21 mm width. It was quite adequate to make small specimens, such as SS-3 type sheet tensile specimen.

  4. Assessment of Gap and Charging Voltage Influence on Mechanical Behaviour of Joints Obtained by Magnetic Pulse Welding

    OpenAIRE

    Buiron, N.; dos Santos, B; Franz, G; Habak, M.; Haye, D.; Jouaffre, D.; Morel, M; Rachik, M; Raoelison, R.

    2012-01-01

    This work investigates the study of the experimental weldability in magnetic pulse welding process of a one material assembly (aluminium AA6060T6) and a dissimilar metal couple (aluminium6060T6/copper). The weld quality is defined using a destructive process allowing measuring the weld dimension. A diagram charging voltage-air gap is used to establish the variance of weldability. With the criterion of width of the weld, this representation is able to determine the operational w...

  5. Local mechanical properties of Alloy 82/182 dissimilar weld joint between SA508 Gr.1a and F316 SS at RT and 320C

    Energy Technology Data Exchange (ETDEWEB)

    Byun, Thak Sang [ORNL; Kim, Jin Weon [ORNL

    2009-01-01

    This paper presents the variations of local mechanical and microstructural properties in dissimilar metal weld joints consisting of the SA508 Gr.1a ferritic steel, Alloy 82/182 filler metal, and F316 austenitic stainless steel. Flat or round tensile specimens and transmission electron microscopy disks were taken from the base metals, welds, and heat-affected zones (HAZ) of the joints and tested at room temperature (RT) and/or at 320 C. The tensile test results indicated that the mechanical property was relatively uniform within each material zone, but varied considerably between different zones. Further, significant variations were observed both in the austenitic HAZ of F316 SS and in the ferritic HAZ of SA508 Gr.1a. The yield stress (YS) of the weld metal was under-matched with respect to the HAZs of SA508 Gr.1a and F316 SS by 0.78 to 0.92, although the YS was over-matched with respect to both base metals. The minimum ductility occurred in the HAZ of SA508 Gr.1 at both test temperatures. The plastic instability stress also varied considerably in the weld joints, with minimum values occurring in the SA508 Gr.1a base metal at RT and in the HAZ of F316 SS at 320 C, suggesting that the probability of ductile failure caused by a unstable deformation at the Alloy 82/182 buttering layer is low. Within the HAZ of SA508 Gr.1a, the gradient of the YS and ultimate tensile strength (UTS) was significant, primarily because of the different microstructures produced by the phase transformation during the welding process. The increment of YS was unexpectedly high in the HAZ of F316 SS, which was explained by the strain hardening induced by a strain mismatch between the weldment and the base metal. This was confirmed by the transmission electron micrographs showing high dislocation density in the HAZ.

  6. Microstructure and mechanical property in heat affected zone (HAZ in F82H jointed with SUS316L by fiber laser welding

    Directory of Open Access Journals (Sweden)

    S. Kano

    2016-12-01

    Full Text Available This study investigates the microstructure and mechanical property in heat affected zone (HAZ between F82H and SUS316L jointed by 4 kW fiber laser welding at different parameters such as laser scan rate and beam position. OM/FE-SEM observation, EPMA analysis and nano-indentation hardness test were utilized to characterize the microstructure and evaluate the mechanical property. Results show that the HAZ width is dependent on the welding condition. The precipitation of M23C6 particle in HAZ is found to be closely related to the distance from WM/HAZ interface. Decrease in Cr and C concentration in M23C6 depended on the welding condition; the decrease was relatively milder in the case of shifting the beam position to SUS side. Furthermore, the rapid increment in nano-indentation hardness, i.e. ≈2500 MPa, at HAZ/F82H interface was observed regardless of welding parameters. The temperatures at HAZ/F82H interface were estimated from Cr and C concentration change of M23C6 by EPMA. It was revealed that the temperature of HAZ/F82H interface increased with increasing HAZ width, and that the presence of over-tempered HAZ (THAZ region is confirmed only in the specimens welded right on the F82H/SUS interface (no-shift at the laser scan rate of 3 m/min.

  7. Microstructure and Mechanical Properties of an Ultrasonic Spot Welded Aluminum Alloy: The Effect of Welding Energy

    National Research Council Canada - National Science Library

    He Peng; Daolun Chen; Xianquan Jiang

    2017-01-01

    The aim of this study is to evaluate the microstructures, tensile lap shear strength, and fatigue resistance of 6022-T43 aluminum alloy joints welded via a solid-state welding technique-ultrasonic spot welding (USW...

  8. Properties of thick welded joints on superheater collectors made from new generation high alloy martensitic creep-resisting steels for supercritical parameters

    Energy Technology Data Exchange (ETDEWEB)

    Dobrzanski, Janusz; Zielinski, Adam [Institute for Ferrous Metallurgy, Gliwice (Poland); Pasternak, Jerzy [Boiler Engineering Company RAFAKO S.A., Raciborz (Poland)

    2010-07-01

    The continuously developing power generation sector, including boilers with supercritical parameters, requires applications of new creep-resistant steel grades for construction of boilers steam superheater components. This paper presents selected information, experience within the field of research and implementation of a new group of creep-resistant as X10CrMoVNb9-1(P91), X10CrWMoVNb9-2(P92) and X12CrCoWVNb12-2-2(VM12) grades, containing 9-12%Cr. During welding and examination process the results of mechanical properties, requested level for base material and welded joints, as well as: tensile strength, impact strength and technological properties have been evaluated. Additional destructive examinations, with evaluation of structure stability, hardness distribution, for base material and welded joints after welding, heat treatment, again process have been determined. Recommendations due to the implementation influence of operating parameters of the main boiler components are part of this paper. (orig.)

  9. Intermediate layer, microstructure and mechanical properties of aluminum alloy/stainless steel butt joint using laser-MIG hybrid welding-brazing method

    Science.gov (United States)

    Zhu, Zongtao; Wan, Zhandong; Li, Yuanxing; Xue, Junyu; Hui, Chen

    2017-07-01

    Butt joining of AA6061 aluminum (Al) alloy and 304 stainless steel of 2-mm thickness was conducted using laser-MIG hybrid welding-brazing method with ER4043 filler metal. To promote the mechanical properties of the welding-brazing joints, two kinds of intermediate layers (Al-Si-Mg alloy and Ag-based alloy) are used to adjust the microstructures of the joints. The brazing interface and the tensile strength of the joints were characterized. The results showed that the brazing interface between Al alloy and stainless steel consisted of double layers of Fe2Al5 (near stainless steel) and Fe4Al13 intermetallic compounds (IMCs) with a total thickness of 3.7 μm, when using Al-Si-Mg alloy as the intermediate layer. The brazing interface of the joints using Ag-based alloy as intermediate layer also consists of double IMC layers, but the first layer near stainless steel was FeAl2 and the total thickness of these two IMC layers decreased to 3.1 μm. The tensile strength of the joints using Al-Si-Mg alloy as the intermediate layer was promoted to 149 MPa, which was 63 MPa higher than that of the joints using Al-Si-Mg alloy as the intermediate layer. The fractures occurred in the brazing interface between Al alloy and stainless steel.

  10. Enhanced mechanical properties of tungsten inert gas welded AZ31 magnesium alloy joint using two-pass friction stir processing with rapid cooling

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Nan, E-mail: xunan@hhu.edu.cn; Bao, Yefeng

    2016-02-08

    In this study, tungsten inert gas (TIG) welded AZ31 magnesium alloy joint was subjected to two-pass rapid cooling friction stir processing (RC-FSP). The main results show that, two-pass RC-FSP causes the significant dissolution of the coarse eutectic β-Mg{sub 17}Al{sub 12} phase into the magnesium matrix and the remarkable grain refinement in the stir zone. The low-hardness region which frequently located at heat-affected zone was eliminated. The stir zone showed ultrafine grains of 3.1 μm, and exhibited a good combination of ultrahigh tensile strength of 284 MPa and large elongation of 7.1%. This work provides an effective strategy to enhance the strength of TIG welded magnesium alloy joint without ductility loss.

  11. Cálculo de tensiones en uniones soldadas con costuras de filete asimétricas sometidas a flexión. // Bending shear stresses calculation in welded joints with asymmetric welding fillets.

    Directory of Open Access Journals (Sweden)

    H. Hernández Herrera

    2004-09-01

    Full Text Available En el trabajo se presenta el cálculo de las tensiones de cortante en la sección de la garganta para las uniones soldadassometidas a flexión con costuras de filete de sección transversal asimétrica cuando el plano de carga no pasa por el centrode flexión o no coincide con los ejes centroidales principales de inercia. Los resultados obtenidos por las expresiones decálculo propuestas se comparan con los obtenidos por el Método de los Elementos Finitos demostrando de esta manera lavalidez de las mismas.Palabras claves: Flexión, uniones soldadas, soldadura de filete.___________________________________________________________________________Abstract.In this paper is presented the bending shear stresses calculation in the throat area for asymmetric welded joints with filletweldings, when the load plane does not go by the flexion center or it do not coincide with the mains inertia centroidal axes.The results obtained by the proposed expressions are compared with those obtained by the Finite Elements Methoddemonstrating by this way the validity of the same ones.Key words: Bending, welded joints, fillet weldings.

  12. Effect of post-weld heat treatment and neutron irradiation on a dissimilar-metal joint between F82H steel and 316L stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Haiying, E-mail: haigirl1983@gmail.com [SOKENDAI - The Graduated University for Advanced Studies, Toki (Japan); Nagasaka, Takuya [SOKENDAI - The Graduated University for Advanced Studies, Toki (Japan); National Institute for Fusion Science, Toki (Japan); Kometani, Nobuyuki [Nagoya University, Nagoya (Japan); Muroga, Takeo [SOKENDAI - The Graduated University for Advanced Studies, Toki (Japan); National Institute for Fusion Science, Toki (Japan); Guan, Wenhai; Nogami, Shuhei; Yabuuchi, Kiyohiro; Iwata, Takuya; Hasegawa, Akira [Tohoku University, Sendai (Japan); Yamazaki, Masanori [International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University (Japan); Kano, Sho; Satoh, Yuhki; Abe, Hiroaki [Institute for Materials Research, Tohoku University, Sendai (Japan); Tanigawa, Hiroyasu [Japan Atomic Energy Agency, Rokkasho (Japan)

    2015-10-15

    Highlights: • Significant hardening after neutron irradiation at 300 °C for 0.1 dpa was found in the fine-grain HAZ of F82H for the dissimilar-metal joint between F82H and 316L. • The possible hardening mechanism was explained from the viewpoint of carbon behavior. • However, the significant hardening did not degrade the impact property significantly. - Abstract: A dissimilar-metal joint between F82H steel and 316L stainless steel was fabricated by using electron beam welding (EBW). By microstructural analysis and hardness test, the heat-affected zone (HAZ) of F82H was classified into interlayer area, fine-grain area, and coarse-carbide area. Post-weld heat treatment (PWHT) was applied to control the hardness of HAZ. After PWHT at 680 °C for 1 h, neutron irradiation at 300 °C with a dose of 0.1 dpa was carried out for the joint in Belgian Reactor II (BR-II). Compared to the base metals (BMs) and weld metal (WM), significant irradiation hardening up to 450HV was found in the fine-grain HAZ of F82H. However, the impact property of F82H-HAZ specimens, which was machined with the root of the V-notch at HAZ of F82H, was not deteriorated obviously in spite of the significant irradiation hardening.

  13. Evaluation of base material and welded joints designated for membrane wall components made from low-alloy steels in large boilermaker conditions

    Energy Technology Data Exchange (ETDEWEB)

    Dobrzanski, Janusz; Zielinski, Adam [Institute for Ferrous Metallurgy, Gliwice (Poland); Pasternak, Jerzy [Boiler Engineering Company RAFAKO S.A., Raciborz (Poland)

    2010-07-01

    Supercritical operating parameters of lower emission power units require novel creep resisting steels. Therefore, this paper constains selected information, results of collectors made from the new low-alloy bainitic creep-resistant steels as 7CrWVNb9-6(P23) and 7CrMoVTiB10-10(P24) performed in large boilermaker conditions. The research and implementation process includes: - evaluation, comparison of requested properties of base material and welded joints as tensile strength, impact strength and technological properties, - destructive examinations with evaluation of welded joints and HAZ structure and hardness distribution, - evaluation of creep resistance properties and structure stability after heat treatments and again process of base material, HAZ and welded joints, - influence of manufacturing process in large boilermaker conditions and after simulated operation. A new creep-resistant steels to be used, in order to comply with the operational requirements, as to assure the appropriate reliability and safety of the boiler equipment in operation process. (orig.)

  14. Effect of the welding process on the microstructure and microhardness of API 5L X80 steel welded joint used for oil transportation pipeline; Efeito do processo de soldagem sobre a microestrutura e a microdureza de juntas soldadas de aco API 5L X80 usado em tubulacoes para transporte de petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Alves, R.T.P.; Albuquerque, S.F. [Universidade Federal de Campina Grande (UFCG), PB (Brazil); Maciel, T.M.; Almeida, D.M.; Santos, M.A.

    2008-07-01

    This study had as objective to evaluate the microstructure and microhardness of API 5L X80 steel welded joints, used for pipelines to transport oil and gas, using the Shield Metal Arc Welding process with pre- heating temperature of 200 deg C and 400 deg C and the AWS E8010G electrode as filler metal. For this, besides the microhardness of the welded joint, the weld metals percentiles of micro-constituents and of columnar and regenerated grains and the medium size and extension of the heat affected zone were evaluated. The percentage of acicular ferrite in weld metal ranged from 13% to 33% which generated values of microhardness from 114 HV to 309 HV. (author)

  15. Comparison of Welding Residual Stresses of Hybrid Laser-Arc Welding and Submerged Arc Welding in Offshore Steel Structures

    DEFF Research Database (Denmark)

    Andreassen, Michael Joachim; Yu, Zhenzhen; Liu, Stephen

    2016-01-01

    In the offshore industry, welding-induced distortion and tensile residual stresses have become a major concern in relation to the structural integrity of a welded structure. Particularly, the continuous increase in size of welded plates and joints needs special attention concerning welding induced...... residual stresses. These stresses have a negative impact on the integrity of the welded joint as they promote distortion, reduce fatigue life, and contribute to corrosion cracking and premature failure in the weld components. This paper deals with the influence and impact of welding method on the welding...... induced residual stresses. It is also investigated whether the assumption of residual stresses up to yield strength magnitude are present in welded structures as stated in the design guidelines. The fatigue strength for welded joints is based on this assumption. The two welding methods investigated...

  16. Self-Reacting Friction Stir Welding for Aluminum Alloy Circumferential Weld Applications

    Science.gov (United States)

    Bjorkman, Gerry; Cantrell, Mark; Carter, Robert

    2003-01-01

    Friction stir welding is an innovative weld process that continues to grow in use, in the commercial, defense, and space sectors. It produces high quality and high strength welds in aluminum alloys. The process consists of a rotating weld pin tool that plasticizes material through friction. The plasticized material is welded by applying a high weld forge force through the weld pin tool against the material during pin tool rotation. The high weld forge force is reacted against an anvil and a stout tool structure. A variation of friction stir welding currently being evaluated is self-reacting friction stir welding. Self-reacting friction stir welding incorporates two opposing shoulders on the crown and root sides of the weld joint. In self-reacting friction stir welding, the weld forge force is reacted against the crown shoulder portion of the weld pin tool by the root shoulder. This eliminates the need for a stout tooling structure to react the high weld forge force required in the typical friction stir weld process. Therefore, the self-reacting feature reduces tooling requirements and, therefore, process implementation costs. This makes the process attractive for aluminum alloy circumferential weld applications. To evaluate the application of self-reacting friction stir welding for aluminum alloy circumferential welding, a feasibility study was performed. The study consisted of performing a fourteen-foot diameter aluminum alloy circumferential demonstration weld using typical fusion weld tooling. To accomplish the demonstration weld, weld and tack weld development were performed and fourteen-foot diameter rings were fabricated. Weld development consisted of weld pin tool selection and the generation of a process map and envelope. Tack weld development evaluated gas tungsten arc welding and friction stir welding for tack welding rings together for circumferential welding. As a result of the study, a successful circumferential demonstration weld was produced leading

  17. The Structure And Properties Of Mixed Welded Joints Made Of X10NiCrAlTi32-21 And X6CrNiMoTi17-12-2 Steels

    Directory of Open Access Journals (Sweden)

    Sieczkowski K.

    2015-09-01

    Full Text Available This paper describes the welding technology applied for mixed joints of tubes made of austenitic steels in the X10NiCrAlTi32-21 and X6CrNiMoTi17-12-2 grades. One made a butt joint and a multi-run joint, with the inert gas welding method and a non-consumable electrode. The mechanical properties were tested in the following scope: static tensile test, bending test from the side of the face and from the side of the root, impact test of the joint and hardness measurements. The tests were supplemented by the assessment of the macrostructure and microstructure of the joint. The performed non-destructive and structural tests did not reveal any welding imperfections, and the mechanical test results confirmed high properties of the welded joint. On this basis, the joint was classified into the “B” quality level according to PN EN ISO 5817. The mechanical and structural test results constitute the basis for qualification of the welding technology according to PN EN ISO 15614.

  18. Reprocessing weld and method

    Energy Technology Data Exchange (ETDEWEB)

    Killian, M.L.; Lewis, H.E.

    1993-08-03

    A process is described for improving the fatigue resistance of a small primary structural weld at a joint between structural members of a weldment, the weld having been made with the welding energy input of E[sub 1], the process comprising: applying a reprocessing weld on at least a portion of either one or both toes of the primary structural weld, thereby covering said toe portion, the reprocessing weld containing a filler metal and having a cross-sectional area which is less than the corresponding cross-sectional area of the primary structural weld, the reprocessing weld extending onto the face of the primary structural weld at one side of the toe portion covered and onto the structural member at the other side of the toe portion covered, and the total welding energy input, E[sub 2], used in said reprocessing the primary structural weld being less than the welding energy input E[sub 1] of the primary structural weld.

  19. FFLP problem with symmetric trapezoidal fuzzy numbers

    Directory of Open Access Journals (Sweden)

    Reza Daneshrad

    2015-04-01

    Full Text Available The most popular approach for solving fully fuzzy linear programming (FFLP problems is to convert them into the corresponding deterministic linear programs. Khan et al. (2013 [Khan, I. U., Ahmad, T., & Maan, N. (2013. A simplified novel technique for solving fully fuzzy linear programming problems. Journal of Optimization Theory and Applications, 159(2, 536-546.] claimed that there had been no method in the literature to find the fuzzy optimal solution of a FFLP problem without converting it into crisp linear programming problem, and proposed a technique for the same. Others showed that the fuzzy arithmetic operation used by Khan et al. (2013 had some problems in subtraction and division operations, which could lead to misleading results. Recently, Ezzati et al. (2014 [Ezzati, R., Khorram, E., & Enayati, R. (2014. A particular simplex algorithm to solve fuzzy lexicographic multi-objective linear programming problems and their sensitivity analysis on the priority of the fuzzy objective functions. Journal of Intelligent and Fuzzy Systems, 26(5, 2333-2358.] defined a new operation on symmetric trapezoidal fuzzy numbers and proposed a new algorithm to find directly a lexicographic/preemptive fuzzy optimal solution of a fuzzy lexicographic multi-objective linear programming problem by using new fuzzy arithmetic operations, but their model was not fully fuzzy optimization. In this paper, a new method, by using Ezzati et al. (2014’s fuzzy arithmetic operation and a fuzzy version of simplex algorithm, is proposed for solving FFLP problem whose parameters are represented by symmetric trapezoidal fuzzy number without converting the given problem into crisp equivalent problem. By using the proposed method, the fuzzy optimal solution of FFLP problem can be easily obtained. A numerical example is provided to illustrate the proposed method.

  20. Study of sulphate-reducing bacteria corrosion in the weld joint for API X-70 steel

    Energy Technology Data Exchange (ETDEWEB)

    Flores, J. E.; Patino-Carachure, C.; Alfonso, I.; Rodriguez, J. A.; Rosas, G.

    2012-11-01

    The corrosion behavior originated by sulfate-reducing bacteria (SRB) was studied in two regions of welded API X-70 steel pipeline. The studies were focused on base material (BM) and heat affected zone (HAZ), from the internal region of the pipe. SRB were extracted from oil and grown in a Postgate medium. Corrosion was evaluated at 60 degree centigrade for times between 5 and 64 days. Potentiodynamic polarization curves, obtained by electrochemical techniques, indicated surface activation at short times. Structural and morphological characterizations were carried out by scanning electron microscopy (SEM) and optical microscopy (OM). H{sub 2}S concentration and pH were also measured. Results showed an important increase in the corrosion damage up to 20 days, influenced by the SRB activity, which lead to a maximum of H{sub 2}S (pH minimum). It was found a localized corrosion attack in the HAZ in a higher quantity compared to BM; and the formation of a thin film on the steel surface, originated by corrosion products and bacterial activity. (Author) 15 refs.

  1. Effects of laser shock peening on stress corrosion behavior of 7075 aluminum alloy laser welded joints

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J.T., E-mail: jiasqq1225@126.com [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); School of Materials Engineering, Jiangsu University of Technology, Changzhou 213001 (China); Zhang, Y.K. [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); School of Mechanical Engineering, Southeast University, Nanjing 211189 (China); Chen, J.F.; Zhou, J.Y.; Ge, M.Z.; Lu, Y.L.; Li, X.L. [School of Materials Engineering, Jiangsu University of Technology, Changzhou 213001 (China)

    2015-10-28

    7075 aluminum alloy weldments were processed by an intensive process known as laser shock peening (LSP), meanwhile its stress corrosion behaviors were observed by scanning electron microscopy (SEM) and slow strain rate tensile (SSRT) tests. Results showed that the effect of LSP on corrosion behavior of the joint was fairly useful and obvious. With LSP, the elongation, time of fracture and static toughness after the SSRT test were improved by 11.13%, 20% and 100%, respectively. At the same time, the location of the fracture also changed. LSP led to a transition of the fracture type from transgranular to intergranular The reasons for these enhancements of the joint on corrosion behavior were caused by microstructure, residual stress, micro-hardness, and fracture appearance.

  2. Comparison of Welding Residual Stresses of Hybrid Laser-Arc Welding and Submerged Arc Welding in Offshore Steel Structures

    OpenAIRE

    Andreassen, Michael Joachim; Yu, Zhenzhen; Liu, Stephen; Guerrero-Mata, Martha Patricia

    2016-01-01

    In the offshore industry, welding-induced distortion and tensile residual stresses have become a major concern in relation to the structural integrity of a welded structure. Particularly, the continuous increase in size of welded plates and joints needs special attention concerning welding induced residual stresses. These stresses have a negative impact on the integrity of the welded joint as they promote distortion, reduce fatigue life, and contribute to corrosion cracking and premature fail...

  3. Estimation of tensile shear strength of spot welded joint of steel sheets. 1st report. Resistance spot welded joint strength of steel sheets; Usukohan supotto yosetsu tsugite no hippari sendan tsuyosa no suitei. 1st report. Teiko supotto yosetsu tsugite no tsuyosa

    Energy Technology Data Exchange (ETDEWEB)

    Kabasawa, M.; Funakawa, Y.; Ogawa, K. [NKK Corp., Tokyo (Japan); Tamura, M. [Kokan Keisoku Co. Ltd., Tokyo (Japan)

    1996-11-05

    Recently, use of thinner steel sheets was promoted with their higher strength for weight reduction of car body in the car industry, and also use of higher strength steel sheets was proceeded to improve its collision safety. Among such a condition, estimation of strength of the most fundamental single spot welding joint becomes important because body and parts strengths are mainly occupied by the strength of the welded joint. As relationships between shear strength and strength, thickness and nugget diameter of the steel sheets were investigated uptodate and a lot of empirical equations were obtained, a result obtained by numerical analysis was individual, and empirical equations obtained in conventional studies were narrow in their applied regions and could not be forecast for their application limits. In this study, for a joint obtained by a welding condition corresponding to A class of Japan Welding Society standard WES7301, as an object of low carbon steel sheet containing more than 0.03% of carbon widely used for the car body, an experimental equation to estimate tensile shear strength specified in JIS Z3136 from sheet thickness, mother material feature and nugget diameter was induced. 10 refs., 17 figs., 4 tabs.

  4. (AJST) ANALYSIS OF THE WELD STRENGTH OF THE HIGH ...

    African Journals Online (AJOL)

    2013-08-02

    Aug 2, 2013 ... ABSTRACT: An analysis was carried out to determine the strength of welded joints in. High Density Polyethylene (HDPE) dam liners. Samples were collected of welded joints and subjected to tensile tests and creep test. It was observed that the welded joints from field welded samples were much weaker ...

  5. Double-sided laser beam welded T-joints for aluminum-lithium alloy aircraft fuselage panels: Effects of filler elements on microstructure and mechanical properties

    Science.gov (United States)

    Han, Bing; Tao, Wang; Chen, Yanbin; Li, Hao

    2017-08-01

    In the current work, T-joints consisting of 2.0 mm thick 2060-T8/2099-T83 aluminum-lithium alloys for aircraft fuselage panels have been fabricated by double-sided fiber laser beam welding with different filler wires. A new type wire CW3 (Al-6.2Cu-5.4Si) was studied and compared with conventional wire AA4047 (Al-12Si) mainly on microstructure and mechanical properties. It was found that the main combined function of Al-6.2%Cu-5.4%Si in CW3 resulted in considerable improvements especially on intergranular strength, hot cracking susceptibility and hoop tensile properties. Typical non-dendritic equiaxed zone (EQZ) was observed along welds' fusion boundary. Hot cracks and fractures during the load were always located within the EQZ, however, this typical zone could be restrained by CW3, effectively. Furthermore, changing of the main intergranular precipitated phase within the EQZ from T phase by AA4047 to T2 phase by CW3 also resulted in developments on microscopic intergranular reinforcement and macroscopic hoop tensile properties. In addition, bridging caused by richer substructure dendrites within CW3 weld's columnar zone resulted in much lower hot cracking susceptibility of the whole weld than AA4047.

  6. The environmentally-assisted cracking behaviour in the transition region of nickel-base alloy/low-alloy steel dissimilar weld joints under simulated BWR conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ritter, S.; Seifert, H.P.; Leber, H.J. [Paul Scherrer Institute, Nuclear Energy and Safety Research Department, Lab for Nuclear Materials, 5232 Villigen PSI (Switzerland)

    2011-07-01

    The stress corrosion cracking (SCC) behaviour perpendicular to the fusion line in the transition region between the Alloy 182 nickel-base weld metal and the adjacent low-alloy reactor pressure vessel (RPV) steel of simulated dissimilar metal weld joints was investigated under boiling water reactor normal water chemistry conditions at different stress intensities and chloride concentrations. A special emphasis was placed to the question whether a fast growing inter-dendritic SCC crack in the highly susceptible Alloy 182 weld metal can easily cross the fusion line and significantly propagate into the adjacent low-alloy RPV steel. Cessation of inter-dendritic stress corrosion crack growth was observed in high-purity or sulphate-containing oxygenated water under periodical partial unloading or constant loading conditions with stress intensity factors below 60 MPa-m{sup 1/2} for those parts of the crack front, which reached the fusion line. In chloride containing water, on the other hand, the inter-dendritic stress corrosion crack in the Alloy 182 weld metal very easily crossed the fusion line and further propagated with a very high growth rate as a transgranular crack into the heat-affected zone and base material of the adjacent low-alloy steel. (authors)

  7. Effect of prior cold work on the degree of sensitisation of welded joints of AISI 316L austenitic stainless steel studied by using an electrochemical minicell

    Energy Technology Data Exchange (ETDEWEB)

    De Tiedra, Pilar [Ciencia de los Materiales e Ingenieria Metalurgica, Departamento CMeIM/EGI/ICGF/IM/IPF, Universidad de Valladolid, Escuela de Ingenierias Industriales, Paseo del Cauce 59, Valladolid 47011 (Spain); Martin, Oscar, E-mail: oml@eis.uva.es [Ciencia de los Materiales e Ingenieria Metalurgica, Departamento CMeIM/EGI/ICGF/IM/IPF, Universidad de Valladolid, Escuela de Ingenierias Industriales, Paseo del Cauce 59, Valladolid 47011 (Spain); Garcia, Cristina; Martin, Fernando; Lopez, Manuel [Ciencia de los Materiales e Ingenieria Metalurgica, Departamento CMeIM/EGI/ICGF/IM/IPF, Universidad de Valladolid, Escuela de Ingenierias Industriales, Paseo del Cauce 59, Valladolid 47011 (Spain)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer Double loop shows greater sensitivity to interdendritic corrosion than single loop. Black-Right-Pointing-Pointer Fusion line sensitisation is lower than that of weld metal for all prior cold works. Black-Right-Pointing-Pointer Heat affected zone sensitisation is maximum at a prior cold work of 10%. Black-Right-Pointing-Pointer Heat affected zone sensitisation Much-Less-Than base material sensitisation for a prior cold work of 20%. - Abstract: This work aims to assess the effect of prior cold work on the degree of sensitisation of each of the four welding zones of welded joints of AISI 316L subjected to post-welding sensitisation. Electrochemical potentiokinetic reactivation and double loop electrochemical potentiokinetic reactivation tests are performed on each of the four zones by using a small-scale electrochemical cell (minicell). The results show that the degree of sensitisation of heat affected zone, which achieves its maximum at a prior cold work level of 10%, is significantly lower than that of base material for a prior cold work of 20%.

  8. A newly developed snow vehicle (SM100S) for Antarctica. Part 3: Low temperature toughness of the welded joints of the structural steel

    Science.gov (United States)

    Sakui, Shin; Nakajima, Masashi

    1992-11-01

    For the purpose of developing a new snow vehicle (common use at temperature about -50 C) for the deep ice coring project at Dome Fuji, East Antarctica, the low temperature toughness of the welded joints of structural steel was investigated. It is empirically well known that in case of vehicles employed in a cold air temperature of about -50 C, the low temperature brittle fracture of the structural members does not take place, if one uses semi-killed or killed steel, for which 50 percent FATT's (fracture appearance transition temperature) of the Charpy impact test is about -50 C and Charpy impact values at -50 C are 20 to 29 J/sq cm. In the present report, the Charpy impact test has been performed for both single pass SMAW (shield metal arc welding) and CO2 arc welded joints of JIS (Japan Industrial Standards) steels of SS400, SL2N255, STPL380, and STPL450. The test results show that the JIS steels of SL2N255 and STPL450 can be used for the new vehicle, considering their toughness.

  9. Local mechanical properties of Alloy 82/182 dissimilar weld joint between SA508 Gr.1a and F316 SS at RT and 320 °C

    Science.gov (United States)

    Kim, Jin Weon; Lee, Kyoungsoo; Kim, Jong Sung; Byun, Thak Sang

    2009-02-01

    The distributions of mechanical and microstructural properties were investigated for the dissimilar metal weld joints between SA508 Gr.1a ferritic steel and F316 austenitic stainless steel with Alloy 82/182 filler metal using small-size tensile specimens. The material properties varied significantly in different zones while those were relatively uniform within each material. In particular, significant gradient of the mechanical properties were observed near the both heat-affected zones (HAZs) of F316 SS and SA508 Gr.1a. Thus, the yield stress (YS) was under-matched with respect to the both HAZs, although, the YS of the weld metal was over-matched with respect to both base metals. The minimum ductility occurred in the HAZ of SA508 Gr.1a at both test temperatures. The plastic instability stress also varied considerably across the weld joints, with minimum values occurring in the SA508 Gr.1a base metal at RT and in the HAZ of F316 SS at 320 °C. The transmission electron micrographs showed that the strengthening in the HAZ of F316 SS was attributed to the strain hardening, induced by a strain mismatch between the weldment and the base metal, which was evidenced by high dislocation density in the HAZ of F316 SS.

  10. Local mechanical properties of Alloy 82/182 dissimilar weld joint between SA508 Gr.1a and F316 SS at RT and 320 deg. C

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Weon [Department of Nuclear Engineering, Chosun University, 375 Seosuk-dong, Dong-gu, Gwangju 501-759 (Korea, Republic of)], E-mail: jwkim@chosun.ac.kr; Lee, Kyoungsoo [Nuclear Power Laboratory, Korea Electric Power Research Institute, 103-16 Munji-dong, Yusung-gu, Daejon 305-380 (Korea, Republic of); Kim, Jong Sung [Department of Mechanical Engineering, Sunchon National University, 413 Jungangno, Sunchon, Jeonnam 540-742 (Korea, Republic of); Byun, Thak Sang [Oak Ridge Nation Laboratory, Material Science and Technology Division, P.O. Box 2008, MS-6151, Oak Ridge, TN 37831 (United States)

    2009-02-28

    The distributions of mechanical and microstructural properties were investigated for the dissimilar metal weld joints between SA508 Gr.1a ferritic steel and F316 austenitic stainless steel with Alloy 82/182 filler metal using small-size tensile specimens. The material properties varied significantly in different zones while those were relatively uniform within each material. In particular, significant gradient of the mechanical properties were observed near the both heat-affected zones (HAZs) of F316 SS and SA508 Gr.1a. Thus, the yield stress (YS) was under-matched with respect to the both HAZs, although, the YS of the weld metal was over-matched with respect to both base metals. The minimum ductility occurred in the HAZ of SA508 Gr.1a at both test temperatures. The plastic instability stress also varied considerably across the weld joints, with minimum values occurring in the SA508 Gr.1a base metal at RT and in the HAZ of F316 SS at 320 deg. C. The transmission electron micrographs showed that the strengthening in the HAZ of F316 SS was attributed to the strain hardening, induced by a strain mismatch between the weldment and the base metal, which was evidenced by high dislocation density in the HAZ of F316 SS.

  11. Microstructure, local mechanical properties and stress corrosion cracking susceptibility of an SA508-52M-316LN safe-end dissimilar metal weld joint by GTAW

    Energy Technology Data Exchange (ETDEWEB)

    Ming, Hongliang; Zhu, Ruolin [Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning KeyLaboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049 (China); Zhang, Zhiming [Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning KeyLaboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wang, Jianqiu, E-mail: wangjianqiu@imr.ac.cn [Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning KeyLaboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Han, En.-Hou.; Ke, Wei [Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning KeyLaboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Su, Mingxing [Shanghai Research Center for Weld and Detection Engineering Technique of Nuclear Equipment, Shanghai 201306 (China)

    2016-07-04

    The microstructure, local mechanical properties and local stress corrosion cracking susceptibility of an SA508-52M-316LN domestic dissimilar metal welded safe-end joint used for AP1000 nuclear power plant prepared by automatic gas tungsten arc welding was studied in this work by optical microscopy, scanning electron microscopy (with electron back scattering diffraction and an energy dispersive X-ray spectroscopy system), micro-hardness testing, local mechanical tensile testing and local slow strain rate tests. The micro-hardness, local mechanical properties and stress corrosion cracking susceptibility across this dissimilar metal weld joint vary because of the complex microstructure across the fusion area and the dramatic chemical composition change across the fusion lines. Briefly, Type I boundaries and Type II boundaries exist in 52Mb near the SA508-52Mb interface, a microstructure transition was found in SA508 heat affected zone, the residual strain and grain boundary character distribution changes as a function of the distance from the fusion boundary in 316LN heat affected zone, micro-hardness distribution and local mechanical properties along the DMWJ are heterogeneous, and 52Mw-316LN interface has the highest SCC susceptibility in this DMWJ while 316LN base metal has the lowest one.

  12. Prediction of grain size and mechanical properties in friction stir welded pure copper joints using a thermal model

    DEFF Research Database (Denmark)

    Heidarzadeh, A.; Jabbaribehnam, Mirmasoud; Esmaily, M.

    2015-01-01

    In this study, a thermal model was developed and applied to simulate the friction stir welding of pure copper plates with the thickness of 2 mm. The different traverse speeds of 100, 200, 300, and 400 mm min−1 and rotational speeds of 400, 700, 900 rev min−1 were considered as welding parameters...

  13. The effect of temperature on the SCC behavior of AISI301L stainless steel welded joints in 3.5% NaCl solution

    Science.gov (United States)

    Fu, Z. H.; Gou, G. Q.; Xiao, J.; Qiu, S. Y.; Wang, W. J.

    2017-07-01

    The stress corrosion cracking (SCC) behaviors at slow strain rate tensile (SSRT) test of AISI301L stainless steel laser-MIG welded joints in 3.5 wt.% NaCl solution at 20∘C, 40∘C and 60∘C were investigated. The results showed that the weld metal composed of as-cast with δ-Fe and austenite. The base metal (BM) and heat affected zone (HAZ) contained strain-induced M phase. The stress and strain decreased with the increasing temperature. The SCC cracks are initiated by anodic dissolution at 20∘C. Besides the anodic dissolution mechanism, hydrogen-induced SCC mechanism had appeared in 3.5 wt.% NaCl solution at 40∘C and 60∘C.

  14. Microstructural, Micro-hardness and Sensitization Evaluation in HAZ of Type 316L Stainless Steel Joint with Narrow Gap Welds

    Energy Technology Data Exchange (ETDEWEB)

    Islam, Faisal Shafiqul; Jang, Changheui [KAIST, Daejeon (Korea, Republic of); Kang, Shi Chull [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2015-10-15

    From Micro-hardness measurement HAZ zone was found approximately 1-1.5 mm in NGW and DL-EPR test confirmed that 316L NGW HAZ was not susceptible to sensitization as DOS <1% according to sensitization criteria based on reference. In nuclear power plants 316L stainless steels are commonly used material for their metallurgical stability, high corrosion resistance, and good creep and ductility properties at elevated temperatures. Welding zone considered as the weakest and failure initiation source of the components. For safety and economy of nuclear power plants accurate and dependable structural integrity assessment of main components like pressure vessels and piping are need as it joined by different welding process. In similar and dissimilar metal weld it has been observed that weld microstructure cause the variation of mechanical properties through the thickness direction. In the Heat Affected Zone (HAZ) relative to the fusion line face a unique thermal experience during welding.

  15. The effect of post-welding conditions in friction stir welds: From weld simulation to Ductile Failure

    DEFF Research Database (Denmark)

    Hattel, Jesper Henri; Nielsen, Kim Lau; Tutum, Cem Celal

    2012-01-01

    effect of the post-welding conditions when subjecting a friction stir weld to loading transverse to the weld line. The numerical model of the friction stir welded joint, employs a step-wise modeling approach to combine an in-situ weld simulation with a post-welding failure analysis. Using the commercial......The post-welding stress state, strain history and material conditions of friction stir welded joints are often strongly idealized when used in subsequent modeling analyses, typically by neglecting one or more of the features above. But, it is obvious that the conditions after welding do influence...... the weld performance. The objective of this paper is to discuss some of the main conflicts that arise when taking both the post-welding material conditions and stressestrain state into account in a subsequent structural analysis. The discussion is here based on a preliminary numerical study of the possible...

  16. Comparative study of residual stress by table of coordinates and X-ray diffraction in a welded joint; Estudo comparativo das tensoes residuais por mesa de coordenadas e DR-X numa junta soldada

    Energy Technology Data Exchange (ETDEWEB)

    Siqueira Filho, A.V.; Rolim, T.L.; Yadava, Y.P.; Ferreira, R.A.S., E-mail: anibal_siqueira@yahoo.com.b [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Engenharia Mecanica; Cardoso, F.I.B. [Universidade de Pernambuco (POLI/UPE), Recife, PE (Brazil); Guimaraes, P.B. [Instituto Federal de Educacao, Ciencia e Tecnologia de Pernambuco, Recife, PE (Brazil)

    2010-07-01

    Residual stresses in a welded joint of naval steel ASTM AH-32 was measured either by the displacements of referenced points with a coordinated table (CT) or by x-ray diffraction (X-DR) after welding. For all tests, the welding was performed by a certified welder in the SMAW process, using an AWS E 7018 G3 electrode. Before welding, small holes evenly spaced were made in the specimens to be mapped on a coordinated table (CT). After labeling, the specimens were submitted to the welding process and new measurements by (CT) to evaluate the displacements produced by the tensions generated. In parallel, residual stress were measured by DR-X for validation of this new measurement methodology. (author)

  17. Study of sulphate-reducing bacteria corrosion in the weld joint for API X-70 steel

    Directory of Open Access Journals (Sweden)

    Flores, J. E.

    2012-10-01

    Full Text Available The corrosion behavior originated by sulfate-reducing bacteria (SRB was studied in two regions of welded API X-70 steel pipeline. The studies were focused on base material (BM and heat affected zone (HAZ, from the internal region of the pipe. SRB were extracted from oil and grown in a Postgate medium. Corrosion was evaluated at 60 °C for times between 5 and 64 days. Potentiodynamic polarization curves, obtained by electrochemical techniques, indicated surface activation at short times. Structural and morphological characterizations were carried out by scanning electron microscopy (SEM and optical microscopy (OM. H2S concentration and pH were also measured. Results showed an important increase in the corrosion damage up to 20 days, influenced by the SRB activity, which lead to a maximum of H2S (pH minimum. It was found a localized corrosion attack in the HAZ in a higher quantity compared to BM; and the formation of a thin film on the steel surface, originated by corrosion products and bacterial activity.

    El comportamiento ante la corrosión, originada por bacterias sulfato-reductoras (SRB, fue estudiado en dos regiones de un tubo de acero soldado API X-70. Los estudios se enfocaron en el material base (BM y la zona afectada térmicamente (HAZ, en la parte interna del tubo. Las SRB fueron extraídas del petróleo y cultivadas en un medio Postgate. El comportamiento a la corrosión fue evaluado a una temperatura de 60 °C, por periodos comprendidos entre 5 y 64 días. El análisis de las curvas de polarización potenciodinámicas, obtenidas por técnicas electroquímicas, indicó la activación de la superficie para tiempos cortos. La superficie fue caracterizada estructural y morfológicamente mediante microscopia electrónica de barrido (SEM, así como mediante microscopía óptica (OM. La concentración de H2S y el pH también fueron medidos. Los resultados mostraron un aumento importante de la corrosi