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Sample records for laser welded v-4cr-4tl

  1. Mechanical Properties of Laser Weldment of V-4Cr-4Ti Alloy

    International Nuclear Information System (INIS)

    Heo, Nam-Jin; Nagasaka, Takuya; Muroga, Takeo; Nishimura, Arata; Shinozaki, Kenji; Watanabe, Hideo

    2003-01-01

    The effect of the laser welding condition on properties of the weldment, such as bending, tensile and charpy impact properties were investigated in a V-4Cr-4Ti alloy (NIFS-HEAT- 2). The microstructural and microchemical development in the weldment was also investigated for mechanistic study of the impurity behavior during the welding. Increase in hardness occurred in the weld zone. The hardening was due to the dissolution of the large and small precipitates existed in the base metal before welding. The degree of hardening varied with a distance from the bead center. The absorption energy by the impact test increased with the decrease in the input power density during the laser welding. The impact absorption energy of the weld, which is similar to that of the base metal, was obtained by optimizing the welding condition

  2. The effect of laser welding process parameters on the mechanical and microstructural properties of V-4CR-4TI structural materials

    International Nuclear Information System (INIS)

    Reed, C. B.; Natesan, K.; Xu, Z.; Smith, D. L.

    1999-01-01

    V-Cr-Ti alloys are among the leading candidate materials for the frost wall and other structural materials applications in fusion power reactors because of several important advantages including inherently low irradiation-induced activity, good mechanical properties, good compatibility with lithium, high thermal conductivity and good resistance to irradiation-induced swelling and damage [1]. However, weldability of these alloys in general must be demonstrated, and laser welding, specifically, must be developed. Laser welding is considered to be an attractive process for construction of a reactor due to its high penetrating power and potential flexibility. This paper reports on a systematic study which was conducted to examine the use of a pulsed Nd:YAG laser to weld sheet materials of V-Cr-Ti alloys and to characterize the microstructural and mechanical properties of the resulting joints. Deep penetration and defect-free welds were achieved under an optimal combination of laser parameters including focal length of lens, pulse energy, pulse repetition rate, beam travel speed, and shielding gas arrangement. The key for defect-free welds was found to be the stabilization of the keyhole and providing an escape path for the gas trapped in the weld. An innovative method was developed to obtain deep penetration and oxygen contamination free welds. Oxygen and nitrogen uptake were reduced to levels only a few ppm higher than the base metal by design and development of an environmental control box. The effort directed at developing an acceptable postwelding heat treatment showed that five passes of a diffuse laser beam over the welded region softened the weld material, especially in the root region of the weld

  3. The effect of laser welding process parameters on the mechanical and microstructural properties of V-4Cr-4Ti structural materials

    International Nuclear Information System (INIS)

    Reed, C.; Natesan, K.; Xu, Z.; Smith, D.

    2000-01-01

    This paper reports on a systematic study which was conducted to examine the use of a pulsed Nd:YAG laser to weld sheet materials of V-Cr-Ti alloys and to characterize the microstructural and mechanical properties of the resulting joints. Deep penetration and defect-free welds were achieved under an optimal combination of laser parameters including focal length of lens, pulse energy, pulse repetition rate, beam travel speed, and shielding gas arrangement. The key for defect-free welds was found to be the stabilization of the keyhole and providing an escape path for the gas trapped in the weld. An innovative method was developed to obtain deep penetration and oxygen contamination free welds. Oxygen and nitrogen uptake were reduced to levels only a few ppm higher than the base metal by design and development of an environmental control box. Effort directed at developing an acceptable postwelding heat treatment showed that five passes of a diffuse laser beam over the welded region softened the weld material, especially in the root region of the weld

  4. Residual stresses in 2 1/4Cr1Mo welds

    International Nuclear Information System (INIS)

    Fidler, R.; Jerram, K.

    1978-01-01

    Two separate investigations, initiated in an attempt to explain the large amount of residual stress scatter previously observed in the weld metal of eighteen nominally identical thick-section 2 1/4Cr1Mo butt welds, are described in this paper. The first examined the detailed surface residual stress distributions in 2 1/4Cr1Mo manual arc circumferential butt welds in 80mm and 100mm thick 1/2Cr1/2Mo1/4V steam pipe. High residual stresses were found in the regions of overlap between adjacent weld beads, with low values in virgin weld metal. The second utilised single pass manual metal arc bead-in-groove welds to investigate the effects of preheat and weld metal composition on weld metal residual stresses. In four weld metals, mild steel, 1/2Cr1/2Mo1/4V, 1Cr1/2Mo, and 2 1/4Cr1Mo, the residual stresses were very similar, becoming less tensile (or more compressive) with increase of preheat, while the residual stresses in the fifth weld metal (12Cr) were significantly different, being compressive and less affected by preheat. In both investigations the effects have been described in terms of the basic metallurgical phenomena occurring in the weld metal. (author)

  5. A comparative study of pulsed Nd:YAG laser welding and TIG welding of thin Ti6Al4V titanium alloy plate

    International Nuclear Information System (INIS)

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

    2013-01-01

    This paper reports on a study aiming at comparing properties of the Ti6Al4V titanium alloy joints between pulsed Nd:YAG laser welding and traditional fusion welding. To achieve the research purpose, Ti6Al4V titanium alloy plates with a thickness of 0.8 mm were welded using pulsed Nd:YAG laser beam welding (LBW) and gas tungsten arc welding (TIG), respectively. Residual distortions, weld geometry, microstructure and mechanical properties of the joints produced with LBW and TIG welding were compared. During the tensile test, with the aid of a high speed infrared camera, evolution of the plastic strain within tensile specimens corresponding to LBW and TIG welding were recorded and analyzed. Compared with the TIG, the welded joint by LBW has the characters of small overall residual distortion, fine microstructure, narrow heat-affected zone (HAZ), high Vickers hardness. LBW welding method can produce joints with higher strength and ductility. It can be concluded that Pulsed Nd:YAG laser welding is much more suitable for welding the thin Ti6Al4V titanium alloy plate than TIG welding.

  6. Ti-6Al-4V electron beam weld qualification using laser scanning confocal microscopy

    International Nuclear Information System (INIS)

    Wanjara, P.; Brochu, M.; Jahazi, M.

    2005-01-01

    Processing conditions for manufacturing Ti-6Al-4V components by welding using an electron beam source are known to influence the transformation microstructure in the narrow fusion and heat-affected zones of the weld region. This work examined the effect of multiple-sequence welding on the characteristics of the transformed beta microstructure, using laser scanning confocal microscopy to resolve the Widmanstaetten alpha-beta structure in the fusion zone. The evolution in the alpha interlamellar spacing and plate thickness with processing was then related to microhardness measurements in the weld region

  7. Metallurgical Bonding Development of V-4Cr-4Ti Alloy for the DIII-D Radiative Divertor Program

    International Nuclear Information System (INIS)

    Smith, J.P.; Johnson, W.R.; Trester, P.W.

    1998-01-01

    General Atomics (GA), in conjunction with the Department of Energy's (DOE) DIII-D Program, is carrying out a plan to utilize a vanadium alloy in the DIII-D tokamak as part of the DIII-D Radiative Divertor (RD) upgrade. The V-4Cr-4Ti alloy has been selected in the U.S. as the leading candidate vanadium alloy for fusion applications. This alloy will be used for the divertor fabrication. Manufacturing development with the V-4Cr-4Ti alloy is a focus of the DIII-D RD Program. The RD structure, part of which will be fabricated from V-4Cr-4Ti alloy, will require many product forms and types of metal/metal bonded joints. Metallurgical bonding methods development on this vanadium alloy is therefore a key area of study by GA. Several solid state (non-fusion weld) and fusion weld joining methods are being investigated. To date, GA has been successful in producing ductile, high strength, vacuum leak tight joints by all of the methods under investigation. The solid state joining was accomplished in air, i.e., without the need for a vacuum or inert gas environment to prevent interstitial impurity contamination of the V-4Cr-4Ti alloy

  8. Investigation and Optimization of Disk-Laser Welding of 1 mm Thick Ti-6Al-4V Titanium Alloy Sheets

    Directory of Open Access Journals (Sweden)

    Fabrizia Caiazzo

    2015-01-01

    Full Text Available Ti-6Al-4V joints are employed in nuclear engineering, civil industry, military, and space vehicles. Laser beam welding has been proven to be promising, thanks to increased penetration depth and reduction of possible defects of the welding bead; moreover, a smaller grain size in the fusion zone is better in comparison to either TIG or plasma arc welding, thus providing an increase in tensile strength of any welded structures. In this frame, the regression models for a number of crucial responses are discussed in this paper. The study has been conducted on 1 mm thick Ti-6Al-4V plates in square butt welding configuration; a disk-laser source has been used. A three-level Box-Behnken experimental design is considered. An optimum condition is then suggested via numerical optimization with the response surface method using desirability functions with proper weights and importance of constraints. Eventually, Vickers microhardness testing has been conducted to discuss structural changes in fusion and heat affected zone due to welding thermal cycles.

  9. Development of laser welding techniques for vanadium alloys

    International Nuclear Information System (INIS)

    Strain, R.V.; Leong, K.H.; Smith, D.L.

    1996-01-01

    Laser welding is potentially advantageous because of its flexibility and the reduced amount of material affected by the weld. Bead-on-plate and butt welds were previously performed to depths of about 4 mm with a 6-kW CO 2 laser on V-4%Cr-4%Ti and V-5%Cr-5%Ti alloys. These welds were made at a speed of 0.042 m/s using argon purging at a flow rate of 2.8 m 3 /s. The purge was distributed with a diffuser nozzle aimed just behind the laser beam during the welding operation. The fusion zones of welds made under these conditions consisted of very fine, needle-shaped grains and were also harder than the bulk metal (230-270 dph, compared to ∼180 dph for the bulk metal). A limited number of impact tests showed that the as-welded ductile-brittle transition temperatures (DBTT) was above room temperature, but heat treatment at 1000 degrees C for 1 h in vacuum reduced the DBTT to <-25 degrees C. Activities during this reporting period focused on improvements in the purging system and determination of the effect of welding speed on welds. A 2-kW continuous YAG laser at Lumonics Corp. in Livonia, MI, was used to make 34 test welds for this study

  10. A Comparative Study on the Laser Welding of Ti6Al4V Alloy Sheets in Flat and Horizontal Positions

    Directory of Open Access Journals (Sweden)

    Baohua Chang

    2017-04-01

    Full Text Available Laser welding has been increasingly utilized to manufacture a variety of components thanks to its high quality and speed. For components with complex shapes, the welding position needs be continuously adjusted during laser welding, which makes it necessary to know the effects of the welding position on the quality of the laser welds. In this paper, the weld quality under two (flat and horizontal welding positions were studied comparatively in the laser welding of Ti6Al4V titanium alloy, in terms of weld profiles, process porosity, and static tensile strengths. Results show that the flat welding position led to better weld profiles, less process porosity than that of the horizontal welding position, which resulted from the different actions of gravity on the molten weld metals and the different escape routes for pores under different welding positions. Although undercuts showed no association with the fracture positions and tensile strengths of the welds, too much porosity in horizontal laser welds led to significant decreases in the strengths and specific elongations of welds. Higher laser powers and travel speeds were recommended, for both flat and horizontal welding positions, to reduce weld porosity and improve mechanical properties.

  11. Flexural strength of pure Ti, Ni-Cr and Co-Cr alloys submitted to Nd:YAG laser or TIG welding.

    Science.gov (United States)

    Rocha, Rick; Pinheiro, Antônio Luiz Barbosa; Villaverde, Antonio Balbin

    2006-01-01

    Welding of metals and alloys is important to Dentistry for fabrication of dental prostheses. Several methods of soldering metals and alloys are currently used. The purpose of this study was to assess, using the flexural strength testing, the efficacy of two processes Nd:YAG laser and TIG (tungsten inert gas) for welding of pure Ti, Co-Cr and Ni-Cr alloys. Sixty cylindrical specimens were prepared (20 of each material), bisected and welded using different techniques. Four groups were formed (n=15). I: Nd:YAG laser welding; II- Nd:YAG laser welding using a filling material; III- TIG welding and IV (control): no welding (intact specimens). The specimens were tested in flexural strength and the results were analyzed statistically by one-way ANOVA. There was significant differences (pTIG and laser welding and also between laser alone and laser plus filling material. In conclusion, TIG welding yielded higher flexural strength means than Nd:YAG laser welding for the tested Ti, Co-Cr and Ni-Cr alloys.

  12. Feasibility of correlating V-Cr-Ti alloy weld strength with weld chemistry. CRADA final report

    International Nuclear Information System (INIS)

    Grossbeck, M.L.; Odom, R.W.

    1998-06-01

    The mechanical properties of refractory metals such as vanadium are determined to a large extent by the interstitial impurities in the alloy. In the case of welding, interstitial impurities are introduced in the welding process from the atmosphere and by dissolution of existing precipitates in the alloy itself. Because of the necessity of having an ultra-pure atmosphere, a vacuum chamber or a glove box is necessary. In the V-Cr-Ti system, the titanium serves as a getter to control the concentration of oxygen and nitrogen in solid solution in the alloy. In this project the secondary ion mass spectrometry (SIMS) technique was used to detect, measure, and map the spacial distribution of impurity elements in welds in the alloy V-4Cr-4Ti. An attempt was then made to correlate the concentrations and distributions of the impurities with mechanical properties of the welds. Mechanical integrity of the welds was determined by Charpy V-notch testing. Welds were prepared by the gas-tungsten-arc (GTA) method. Charpy testing established a correlation between weld impurity concentration and the ductile to brittle transition temperature (DBTT). Higher concentrations of oxygen resulted in a higher DBTT. An exception was noted in the case of a low-oxygen weld which had a high hydrogen concentration resulting in a brittle weld. The concentrations and distributions of the impurities determined by SIMS could not be correlated with the mechanical properties of the welds. This research supports efforts to develop fusion reactor first wall and blanket structural materials

  13. 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.

  14. Correlation of microstructure and fracture toughness of advanced 9Cr/CrMoV dissimilarly welded joint

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Qian [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Lu, Fenggui, E-mail: Lfg119@sjtu.edu.cn [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Liu, Xia [Shanghai Turbine Plant of Shanghai Electric Power Generation Equipment Co. Ltd., Shanghai 200240 (China); Yang, Renjie [Shanghai Turbine Works Company, Shanghai 200240 (China); Cui, Haichao [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Gao, Yulai, E-mail: ylgao@shu.edu.cn [State Key Laboratory of Advanced Special Steels, Shanghai University, Shanghai 200072 (China)

    2015-06-25

    In this paper, the fracture toughness and the related microstructure characteristics of dissimilarly welded joint manufactured by advanced 9Cr and CrMoV steels were systematically investigated. The dissimilarly welded joint was fabricated by narrow gap submerged arc welding (NG-SAW) applying multi-layer and multi-pass technique. Fracture toughness, as one of the most important property to assess the reliability of welded joint, was studied for different regions including CrMoV base metal (CrMoV-BM), heat affected zone (HAZ) of CrMoV side (CrMoV-HAZ), weld metal (WM), heat affected zone of 9Cr side (9Cr-HAZ) and 9Cr base metal (9Cr-BM). It was found that the fracture toughness of CrMoV-BM, CrMoV-HAZ and WM was better than that of 9Cr-HAZ and 9Cr-BM. In order to illustrate these results, the microstructure of the whole welded joint was observed by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM) detailedly. It was found that the fine high-temperature tempered martensite and bainite in WM, CrMoV-BM and CrMoV-HAZ contribute to the higher fracture toughness, while lower fracture toughness for 9Cr-BM and HAZ was caused by coarse tempered lath-martensite. Furthermore, the fracture morphology showed that ductile fracture occurred in WM and CrMoV side, while brittle fracture appeared in BM and HAZ of 9Cr side.

  15. Effect of the overlapping factor on the microstructure and mechanical properties of pulsed Nd:YAG laser welded Ti6Al4V sheets

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Xiao-Long; Liu, Jing; Zhang, Lin-Jie, E-mail: zhanglinjie@mail.xjtu.edu.cn; Zhang, Jian-Xun

    2014-07-01

    The effect of the overlapping factor on the microstructures and mechanical properties of pulsed Nd:YAG laser welded Ti6Al4V alloy sheets was investigated by microstructural observations, microhardness tests, tensile tests and fatigue tests. A microstructural examination shows that by increasing the overlapping factor, the grains in the fusion zone become coarser, and the width of the heat affected zone increases. As overlapping factor increases, the width of region composed completely of martensite α′ and the secondary α phase in the heat affected zone increases, consequently the gradient of microstructure along the direction from the fusion zone to base metal decreases, so does the gradient of microhardness. The results of tensile and fatigue tests reveal that the joints made using medium overlapping factor exhibit better mechanical properties than those welded with low and high overlapping factors. Based on the experimental results, it can be stated that a sound weld of Ti6Al4V alloy can be obtained if an appropriate overlapping factor is used. - Highlights: • The weld quality of Ti6Al4V alloy under various overlapping factors was assessed. • Tensile and fatigue tests were conducted with as-welded specimen. • Localized strain across the weld was measured using DIC photogrammetry system. • A sound weld of Ti6Al4V alloy is obtained by using right overlapping factor.

  16. Deformation behavior of laser welds in high temperature oxidation resistant Fe-Cr-Al alloys for fuel cladding applications

    Science.gov (United States)

    Field, Kevin G.; Gussev, Maxim N.; Yamamoto, Yukinori; Snead, Lance L.

    2014-11-01

    Ferritic-structured Fe-Cr-Al alloys are being developed and show promise as oxidation resistant accident tolerant light water reactor fuel cladding. This study focuses on investigating the weldability and post-weld mechanical behavior of three model alloys in a range of Fe-(13-17.5)Cr-(3-4.4)Al (wt.%) with a minor addition of yttrium using modern laser-welding techniques. A detailed study on the mechanical performance of bead-on-plate welds using sub-sized, flat dog-bone tensile specimens and digital image correlation (DIC) has been carried out to determine the performance of welds as a function of alloy composition. Results indicated a reduction in the yield strength within the fusion zone compared to the base metal. Yield strength reduction was found to be primarily constrained to the fusion zone due to grain coarsening with a less severe reduction in the heat affected zone. For all proposed alloys, laser welding resulted in a defect free weld devoid of cracking or inclusions.

  17. Low temperature heat treatments of AA5754-Ti6Al4V dissimilar laser welds: Microstructure evolution and mechanical properties

    Science.gov (United States)

    Leo, P.; D'Ostuni, S.; Casalino, G.

    2018-03-01

    This paper presents the effects of the post welding heat treatments (PWHT) performed at 350 °C and 450 °C on the microstructure evolution and mechanical properties of AA5754 and Ti6Al4V dissimilar laser welds. The microstructure and tensile properties of the welds before and after low temperature treatment were analyzed. The off-set welding technique was applied to limit the formation of brittle intermetallic compounds during the welding process. The laser beam was directed onto the titanium side at a small distance from the aluminum edge. The keyhole formed and the full penetration was reached in the titanium side of the weld. Thereafter, the aluminum side melted as the heat that formed the keyhole transferred from the titanium fused zone. Two different energy lines (32 J/mm and 76 J/mm) were used. In this manner, a fused and a heat affected zones was revealed on both sides of the weld. Several intermetallic compounds formed in the intermetallic layer between the two metals. The thickness and the composition of the intermetallic layer depended on the welding parameters and the post welding heat treatment. The hardness and tensile properties of the welds before and after the post welding heat treatment were measured and analyzed.

  18. Dissimilar laser welding of AISI 316L stainless steel to Ti6–Al4–6V alloy via pure vanadium interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Tomashchuk, I., E-mail: iryna.tomashchuk@u-bourgogne.fr; Grevey, D.; Sallamand, P.

    2015-01-12

    Successful continuous laser joining of AISI 316L stainless steel with Ti6Al4V titanium alloy through pure vanadium interlayer has been performed. Three welding configurations were tested: one-pass welding involving all three materials and two pass and double spot welding involving creation of two melted zones separated by remaining solid vanadium. For the most relevant welds, the investigation of microstructure, phase content and mechanical properties has been carried out. In case of formation of a single melted zone, the insertion of steel elements into V-based solid solution embrittles the weld. In case of creation of two separated melted zones, the mechanical resistance of the junction is determined by annealing of remaining vanadium interlayer, which can be witnessed by observing the increase of grain size and decrease of UTS. The two pass configuration allows attain highest mechanical resistance: 367 MPa or 92% of UTS of annealed vanadium. Double spot configuration produces excessive heat supply to vanadium interlayer, which results in important decrease of tensile strength down to 72% of UTS of annealed vanadium. It was found that undesirable σ phase which forms between Fe and V is not created during the laser welding process because of high cooling rates. However, the zones whose composition corresponds to σ homogeneity range are crack-susceptible, so the best choice is to reduce the V content in steel/vanadium melted zone below σ phase formation limit. In the same time, the proportion between V and Ti in Ti6Al4V/vanadium melted zones does not influence mechanical properties as these elements form ideal solid solution.

  19. Fatigue failure analysis of V-4Ti-4Cr alloy

    International Nuclear Information System (INIS)

    Aglan, H.; Gan, Y.X.; Grossbeck, M.

    1999-01-01

    In the present work, the fatigue fracture and failure behavior of a V-4Ti-4Cr has been studied. Static tests were conducted to study the overloading behavior and to select the magnitude of the stress level for the fatigue studies. Fatigue tests were performed using single edge notched (SEN) specimens under tension-tension load control conditions. Fatigue crack propagation (FCP) data such as the crack length, number of cycles, and hysteresis loops were recorded to calculate the crack speed, the energy release rate, and the change in work expended on damage formation and dissipative processes within the material. Parameters characterizing the fatigue fracture resistance of V-4Ti-4Cr alloy, namely the specific energy of damage (γ'), and the dissipative coefficient (β'), were determined from the fatigue data using the modified crack layer (MCL) theory. Fracture surface examination using scanning electron microscopy (SEM) revealed ductile failure mechanisms under tensile overloading conditions. The fatigue fracture surface of the V-4Ti-4Cr consists of three distinct regions, corresponding to the threshold, stable and unstable crack propagation stages. (orig.)

  20. Atom-probe field-ion microscopy investigation of CMSX-4 Ni-base superalloy laser beam welds

    International Nuclear Information System (INIS)

    Babu, S.S.; David, S.A.; Vitek, J.M.; Miller, M.K.

    1996-01-01

    CMSX-4 superalloy laser beam welds were investigated by transmission electron microscopy and atom probe field-ion microscopy (APFIM). The weld microstructure consisted of fine (10- to 50-nm) irregularly shaped γ' precipitates (0.65 to 0.75 volume fraction) within the γ matrix. APFIM compositions of the γ and γ' phases were found to be different from those in the base metal. Concentration profiles across the γ and γ' phases showed extensive variations of Cr, Co and Al concentrations as a function of distance within the γ phase. Calculated lattice misfits near the γ/γ' interface in the welds are positive values compared to the negative values for base metal. (orig.)

  1. The effect of post-weld heat treatment on the microstructure and notched tensile fracture of Ti–15V–3Cr–3Al–3Sn to Ti–6Al–4V dissimilar laser welds

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, C.T.; Shiue, R.K. [Department of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan, ROC (China); Huang, R.-T. [Institute of Materials Engineering, National Taiwan Ocean University, Keelung 202, Taiwan, ROC (China); Tsay, L.W., E-mail: b0186@mail.ntou.edu.tw [Institute of Materials Engineering, National Taiwan Ocean University, Keelung 202, Taiwan, ROC (China)

    2016-01-20

    A CO{sub 2} laser was applied for dissimilar welding of Ti–15V–3Cr–3Al–3Sn (Ti–15–3) to Ti–6Al–4V (Ti–6–4) alloys. The microstructures and notched tensile strength (NTS) of the dissimilar welds were investigated in the as-welded and post-weld heat treatment (PWHT) conditions, and the results were compared with Ti–6–4 and Ti–15–3 homogeneous laser welds with the same PWHT. The results indicated that predominant α″ with a few α and β phases was formed in the as-welded fusion zone (FZ). Furthermore, the FZ hardness was susceptible to the PWHT and showed a plateau for the specimens aged in the temperature range from 426 to 482 °C/4 h. In comparison with the homogeneous Ti–15–3 weld under the same PWHT conditions, the dilution of Ti–15–3 with Ti–6–4 caused a slight increase in the Al equivalent (Al{sub EQ}) of the FZ, resulting in a further rise in FZ hardness. With the PWHT at/below 538 °C, the dissimilar welds were associated with low NTS or high notch brittleness.

  2. Development of laser welded appendages to Zircaloy-4 fuel tubing (sheath/cladding)

    Energy Technology Data Exchange (ETDEWEB)

    Livingstone, S., E-mail: steve.livingstone@cnl.ca [Canadian Nuclear Laboratories Limited, Chalk River, ON, Canada K0J 1J0 (Canada); Xiao, L. [Canadian Nuclear Laboratories Limited, Chalk River, ON, Canada K0J 1J0 (Canada); Corcoran, E.C.; Ferrier, G.A.; Potter, K.N. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, ON, Canada K7K 7B4 (Canada)

    2015-04-01

    Highlights: • Examines feasibility of laser welding appendages to Zr-4 tubing. • Laser welding minimizes the HAZ and removes toxic Be. • Mechanical properties of laser welds appear competitive with induction brazed joints. • Work appears promising and lays the foundation for further investigations. - Abstract: Laser welding is a potential alternative to the induction brazing process commonly used for appendage attachment in CANDU{sup ®} fuel fabrication that uses toxic Be as a filler metal, and creates multiple large heat affected zones in the sheath. For this work, several appendages were laser welded to tubing using different laser heat input settings and then examined with a variety of techniques: visual examination, metallography, shear strength testing, impact testing, and fracture surface analysis. Where possible, the examination results are contrasted against production induction brazed joints. The work to date looks promising for laser welded appendages. Further work on joint optimization, corrosion testing, irradiation testing, and post-irradiation examination will be performed in the future.

  3. Thermal and x-ray studies on Tl2U(MoO4)3 and Tl4U(MoO4)4

    International Nuclear Information System (INIS)

    Dahale, N.D.; Keskar, Meera; Kulkarni, N.K.; Singh Mudher, K.D.

    2006-01-01

    In the quaternary Tl-U(IV)-Mo-O system, two new compounds namely Tl 2 U(MoO 4 ) 3 and Tl 4 U(MoO 4 ) 4 were prepared and characterized by powder X-ray diffraction and thermal methods. These compounds were prepared by solid state reactions of Tl 2 MoO 4 , UMoO 5 and MoO 3 in the required stoichiometric ratio at 500 deg C in evacuated sealed quartz ampoule. The XRD data of Tl 2 U(MoO 4 ) 3 and Tl 4 U(MoO 4 ) 4 were indexed on orthorhombic cell. TG curves of Tl 2 U(MoO 4 ) 3 and Tl 4 U(MoO 4 ) 4 did not show any weight change up to 700 deg C in an inert atmosphere. During heating in an inert atmosphere, Tl 2 U(MoO 4 ) 3 and Tl 4 U(MoO 4 ) 4 showed endothermic Dta peaks due to melting of the compounds at 519 and 565 deg C, respectively. (author)

  4. Substitution of indium for chromium in TlIn5−xCrxSe8: crystal structure of TlIn4.811(5Cr0.189(5Se8

    Directory of Open Access Journals (Sweden)

    Robin Lefèvre

    2017-04-01

    Full Text Available The new thallium penta(indium/chromium octaselenide, TlIn4.811(5Cr0.189(5Se8, has been synthesized by solid-state reaction. It crystallizes isotypically with TlIn5Se8 in the space group C2/m. Although the two Tl positions are disordered and only partially occupied, no Tl deficiency was observed. The insertion of chromium in the structure has been confirmed by EDS analysis. Chromium substitutes indium exclusively at one of three In sites, viz. at one of the positions with site symmetry 2/m (Wyckoff position 2a. In the crystal structure, edge-sharing InSe6 octahedra, and (In,CrSe6 octahedra and InSe4 tetrahedra make up two types of columns that are linked into a framework in which two different types of channels parallel to [010] are present. The Tl atoms are located in the larger of the channels, whereas the other, smaller channel remains unoccupied.

  5. X-ray radiography of Ti6Al4V welded by plasma tungsten arc (PTA) welding

    Energy Technology Data Exchange (ETDEWEB)

    Dikbas, Halil; Caligulu, Ugur; Taskin, Mustafa; Turkmen, Mustafa [Firat Univ., Elazig (Turkey). Metallurgy Dept.

    2013-03-01

    In this study, X-ray radiographic tests of Ti6Al4V alloys welded by plasma tungsten arc welding (PTA) were investigated. PTA welding experiments were carried out under argon shielding gas atmosphere, at 1400-1600 W and 1800 W welding powers as well as 1 m/min, 0.75 m/min, and 0.50 m/min welding speeds. After this process, radiography of the welded joints was performed by X-ray diffraction. The result of the radiographic tests indicated that by increasing welding power the widths of deep penetration increased in all specimens. On the contrary, increasing welding speeds decreases the widths deep penetration. The best properties of Ti6Al4V joints were observed for specimens welded at 1800 W welding power and at 0.50 m/min welding speed. (orig.)

  6. Trithallium tetraselenophosphate Tl3PSe4, and trithallium tetrathioarsenate, Tl3AsS4, by neutron time-of-flight diffraction

    International Nuclear Information System (INIS)

    Alkire, R.W.; Vergamini, P.J.; Larson, A.C.; Morosin, B.

    1984-01-01

    Room-temperature (293 K) single-crystal structure determinations of the isostructural materials Tl 3 PSe 4 and Tl 3 AsS 4 were performed at the Los Alamos National Laboratory Pulsed Neutron Facility. For Tl 3 PSe 4 : Msub(r) = 959.92, Pcmn, a = 9.276 (1), b = 11.036 (2), c = 9.058 (1) A, V = 927.27 A 3 , Z = 4, Dsub(m) = 6.87 (2), Dsub(x) = 6.876 Mg m -3 , lambdasub(neutron) = 0.5 → 5.2 A, F(000) = 252.5 fm. For Tl 3 AsS 4 : Msub(r) = 816.29, Pcmn, a = 9.084 (3), b = 10.877 (3), c = 8.877 (3) A, V = 877.11 A 3 , Z = 4, Dsub(m) = 6.18 (2), Dsub(x) = 6.181 Mg m -3 , lambdasub(neutron) = 0.5 → 5.2 A, F(000) = 177.2 fm. For Tl 3 PSe 4 (Tl 3 AsS 4 ), 1929 (1013) reflections were measured with I > 3sigma(I) and refined by full-matrix least squares to R(F) = 0.061 (0.063). Results on atomic refinement from this study represent an order of magnitude increase in precision over previous single-crystal X-ray structural work using Mo Kα radiation. The PSe 4 3- (AsS 4 3- ) groups have essentially tetrahedral configurations and one Tl + ion shows large anisotropic thermal motion which is structure related. (Auth.)

  7. Effect of Cr4+ impurities in Nd:Cr:GSGG and Nd:Cr:YAG laser materials on parameters of lasers at solar pumping

    International Nuclear Information System (INIS)

    Payziyev, Sh.D.; Bakhramov, S.A.; Shayimov, F.F.; Fayziev, A.Sh.

    2015-01-01

    The analysis of an effect of Cr 4+ impurity ions, existent in Nd 3+ :Cr 3+ :GSGG and Nd 3+ :Cr 3+ :YAG laser materials on output parameters of solar pumped lasers is carried out by modeling of lasing process at solar pumping. (authors)

  8. Measurement of hydrogen solubility and desorption rate in V-4Cr-4Ti and liquid lithium-calcium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.H.; Erck, R.; Park, E.T. [Argonne National Lab., IL (United States)] [and others

    1997-04-01

    Hydrogen solubility in V-4Cr-4Ti and liquid lithium-calcium was measured at a hydrogen pressure of 9.09 x 10{sup {minus}4} torr at temperatures between 250 and 700{degrees}C. Hydrogen solubility in V-4Cr-4Ti and liquid lithium decreased with temperature. The measured desorption rate of hydrogen in V-4Cr-4Ti is a thermally activated process; the activation energy is 0.067 eV. Oxygen-charged V-4Cr-4Ti specimens were also investigated to determine the effect of oxygen impurity on hydrogen solubility and desorption in the alloy. Oxygen in V-4Cr-4Ti increases hydrogen solubility and desorption kinetics. To determine the effect of a calcium oxide insulator coating on V-4Cr-4Ti, hydrogen solubility in lithium-calcium alloys that contained 0-8.0 percent calcium was also measured. The distribution ratio R of hydrogen between liquid lithium or lithium-calcium and V-4Cr-4Ti increased as temperature decreased (R {approx} 10 and 100 at 700 and 250{degrees}C, respectively). However at <267{degrees}C, solubility data could not be obtained by this method because of the slow kinetics of hydrogen permeation through the vanadium alloy.

  9. Measurement of hydrogen solubility and desorption rate in V-4Cr-4Ti and liquid lithium-calcium alloys

    International Nuclear Information System (INIS)

    Park, J.H.; Erck, R.; Park, E.T.

    1997-01-01

    Hydrogen solubility in V-4Cr-4Ti and liquid lithium-calcium was measured at a hydrogen pressure of 9.09 x 10 -4 torr at temperatures between 250 and 700 degrees C. Hydrogen solubility in V-4Cr-4Ti and liquid lithium decreased with temperature. The measured desorption rate of hydrogen in V-4Cr-4Ti is a thermally activated process; the activation energy is 0.067 eV. Oxygen-charged V-4Cr-4Ti specimens were also investigated to determine the effect of oxygen impurity on hydrogen solubility and desorption in the alloy. Oxygen in V-4Cr-4Ti increases hydrogen solubility and desorption kinetics. To determine the effect of a calcium oxide insulator coating on V-4Cr-4Ti, hydrogen solubility in lithium-calcium alloys that contained 0-8.0 percent calcium was also measured. The distribution ratio R of hydrogen between liquid lithium or lithium-calcium and V-4Cr-4Ti increased as temperature decreased (R ∼ 10 and 100 at 700 and 250 degrees C, respectively). However at <267 degrees C, solubility data could not be obtained by this method because of the slow kinetics of hydrogen permeation through the vanadium alloy

  10. Characteristics of Resistance Spot Welded Ti6Al4V Titanium Alloy Sheets

    Directory of Open Access Journals (Sweden)

    Xinge Zhang

    2017-10-01

    Full Text Available Ti6Al4V titanium alloy is applied extensively in the aviation, aerospace, jet engine, and marine industries owing to its strength-to-weight ratio, excellent high-temperature properties and corrosion resistance. In order to extend the application range, investigations on welding characteristics of Ti6Al4V alloy using more welding methods are required. In the present study, Ti6Al4V alloy sheets were joined using resistance spot welding, and the weld nugget formation, mechanical properties (including tensile strength and hardness, and microstructure features of the resistance spot-welded joints were analyzed and evaluated. The visible indentations on the weld nugget surfaces caused by the electrode force and the surface expulsion were severe due to the high welding current. The weld nugget width at the sheets’ faying surface was mainly affected by the welding current and welding time, and the welded joint height at weld nugget center was chiefly associated with electrode force. The maximum tensile load of welded joint was up to 14.3 kN in the pullout failure mode. The hardness of the weld nugget was the highest because of the coarse acicular α′ structure, and the hardness of the heat-affected zone increased in comparison to the base metal due to the transformation of the β phase to some fine acicular α′ phase.

  11. Exploring the thermoelectric and magnetic properties of uranium selenides: Tl2Ag2USe4 and Tl3Cu4USe6

    International Nuclear Information System (INIS)

    Azam, Sikander; Khan, Saleem Ayaz; Din, Haleem Ud; Khenata, Rabah; Goumri-Said, Souraya

    2016-01-01

    The electronic, magnetic and thermoelectric properties of Tl 2 Ag 2 USe 4 and Tl 3 Cu 4 USe 6 compounds were investigated using the full potential linear augmented plane wave (FP-LAPW) method based on the density functional theory (DFT). The exchange correlation was treated with the generalized gradient approximation plus optimized effective Hubbard parameter and spin–orbit coupling (GGA+U+SOC). The present uranium selenides show narrow direct energy band gap values of 0.7 and 0.875 eV for Tl 2 Ag 2 USe 4 and Tl 3 Cu 4 USe 6 respectively. For both selenides U-d/f states are responsible for electrical transport properties. Uranium atoms were the most contributors in the magnetic moment compared to other atoms and show ferromagnetic nature. The spin density isosurfaces show the polarization of neighboring atoms of Uranium, such as silver/copper and selenium. Thermoelectric calculations reveal that Tl 3 Cu 4 USe 6 is more suitable for thermoelectric device applications than Tl 2 Ag 2 USe 4 . - Highlights: • Electronic, magnetic and thermoelectric properties of uranium selenides are investigated with DFT. • They show a narrow direct energy band gap of 0.7 and 0.875 eV. • U-d/f states are responsible for electrical transport properties. • Tl 3 Cu 4 USe 6 is more suitable for thermoelectric device applications than Tl 2 Ag 2 USe 4 .

  12. Prediction of half-metallic properties in TlCrS{sub 2} and TlCrSe{sub 2} based on density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Hashimzade, F.M.; Huseinova, D.A. [Institute of Physics, National Academy of Sciences of Azerbaijan, AZ 1143 Baku (Azerbaijan); Jahangirli, Z.A. [Institute of Physics, National Academy of Sciences of Azerbaijan, AZ 1143 Baku (Azerbaijan); Institute of Radiation Problems, National Academy of Sciences of Azerbaijan, AZ 1143 Baku (Azerbaijan); Mehdiyev, B.H., E-mail: bachschi@yahoo.de [Institute of Physics, National Academy of Sciences of Azerbaijan, AZ 1143 Baku (Azerbaijan)

    2017-08-01

    Highlights: • Half-metallic properties of TlCrS2, TlCrSe2 and hypothetical TlCrSSe have been investigated by first-principles all-electron full-potential linearized augmented plane wave plus local orbital (FP-LAPW+lo) method based on density functional theory (DFT). • Total magnetic moment keeps its integer value on a relatively wide range of changes in volume (−10% ÷ 10%) for TlCrS2 and TlCrSSe, while total magnetic moment TlCrSe2 decreases with increasing volume, approaching to integer value 3 μB. • The states at the Fermi level in the case of spin-up channel consist of a hybridization of p-states of the atom S(Se) with d-states of Cr. - Abstract: Half-metallic properties of TlCrS{sub 2}, TlCrSe{sub 2} and hypothetical TlCrSSe have been investigated by first-principles all-electron full-potential linearized augmented plane wave plus local orbital (FP-LAPW+lo) method based on density functional theory (DFT). The results of calculations show that TlCrS{sub 2} and TlCrSSe are half-metals with energy gap (E{sub g}) ∼0.12 eV for spin-down channel. Strong hybridization of p-state of chalchogen and d-state of Cr leads to bonding and antibonding states and subsequently to the appearance of a gap in spin-down channel of TlCrS{sub 2} and TlCrSSe. In the case of TlCrSe{sub 2}, there is a partial hybridization and p-state is partially present in the DOS at Fermi level making this compound nearly half-metallic. The present calculations revealed that total magnetic moment keeps its integer value on a relatively wide range of changes in volume (−10% ÷ 10%) for TlCrS{sub 2} and TlCrSSe, while total magnetic moment of TlCrSe{sub 2} decreases with increasing volume approaching to integer value 3 μB.

  13. Microstructure characteristics and temperature-dependent high cycle fatigue behavior of advanced 9% Cr/CrMoV dissimilarly welded joint

    International Nuclear Information System (INIS)

    Wu, Qingjun; Lu, Fenggui; Cui, Haichao; Ding, Yuming; Liu, Xia; Gao, Yulai

    2014-01-01

    Advanced 9% Cr and CrMoV steels chosen as candidate materials are first welded by narrow-gap submerged arc welding (NG-SAW) to fabricate the heavy section rotor. The present work focuses on studying the high-cycle fatigue (HCF) behavior of advanced 9% Cr/CrMoV dissimilarly welded joint at different temperatures. Conditional fatigue strength of this dissimilarly welded joint was obtained by HCF tests at room temperature (RT), 400 °C and 470 °C. It was observed that the failure occurred at the side of CrMoV base metal (BM), weld metal (WM) and heat affected zone (HAZ) of CrMoV side over 5×10 7 cycles for the specimens tested at RT, 400 °C and 470 °C. The detailed microstructures of BMs, WMs and HAZs as well as fracture appearance were observed by optical microscopy (OM) and scanning electron microscopy (SEM). Precipitation and aggregation of carbides along the grain boundaries were clearly detected with the increase of temperature, which brought a negative effect on the fatigue properties. It is interesting to note that the inclusion size leading to crack initiation became smaller for the HCF test at higher temperature. Therefore, reduction in the inclusion size in a welded joint helps to improve the HCF performance at high temperature

  14. Microstructure characteristics and temperature-dependent high cycle fatigue behavior of advanced 9% Cr/CrMoV dissimilarly welded joint

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qingjun [Shanghai Key Laboratory of Materials Laser Processing and Modification, Shanghai Jiao Tong University, Shanghai 200240 (China); Lu, Fenggui, E-mail: Lfg119@sjtu.edu.cn [Shanghai Key Laboratory of Materials Laser Processing and Modification, Shanghai Jiao Tong University, Shanghai 200240 (China); Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Cui, Haichao [Shanghai Key Laboratory of Materials Laser Processing and Modification, Shanghai Jiao Tong University, Shanghai 200240 (China); Ding, Yuming; Liu, Xia [Shanghai Turbine Plant of Shanghai Electric Power Generation Equipment Co. Ltd., Shanghai 200240 (China); Gao, Yulai, E-mail: ylgao@shu.edu.cn [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China)

    2014-10-06

    Advanced 9% Cr and CrMoV steels chosen as candidate materials are first welded by narrow-gap submerged arc welding (NG-SAW) to fabricate the heavy section rotor. The present work focuses on studying the high-cycle fatigue (HCF) behavior of advanced 9% Cr/CrMoV dissimilarly welded joint at different temperatures. Conditional fatigue strength of this dissimilarly welded joint was obtained by HCF tests at room temperature (RT), 400 °C and 470 °C. It was observed that the failure occurred at the side of CrMoV base metal (BM), weld metal (WM) and heat affected zone (HAZ) of CrMoV side over 5×10{sup 7} cycles for the specimens tested at RT, 400 °C and 470 °C. The detailed microstructures of BMs, WMs and HAZs as well as fracture appearance were observed by optical microscopy (OM) and scanning electron microscopy (SEM). Precipitation and aggregation of carbides along the grain boundaries were clearly detected with the increase of temperature, which brought a negative effect on the fatigue properties. It is interesting to note that the inclusion size leading to crack initiation became smaller for the HCF test at higher temperature. Therefore, reduction in the inclusion size in a welded joint helps to improve the HCF performance at high temperature.

  15. ¹¹¹In-DOTA-Annexin V for imaging of apoptosis during HSV1-tk/GCV prodrug activation gene therapy in mice with NG4TL4 sarcoma.

    Science.gov (United States)

    Lin, Ming-Hsien; Wu, Shih-Yen; Wang, Hsin-Ell; Liu, Ren-Shyan; Chen, Jyh-Cheng

    2016-02-01

    Apoptosis has been suggested as a cytocidal mechanism of the HSV1-tk-expressing cells when exposed to ganciclovir (GCV). This study evaluated the efficacy of (111)In-labeled Annexin V for monitoring tumor responses during prodrug activation gene therapy with HSV1-tk and GCV. Annexin V was conjugated to DOTA using N-hydroxysulfosuccinimide (sulfo-NHS) and 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (EDC), labeled with (111)In-InCl3 and purified using size exclusion chromatography to give (111)In-DOTA-Annexin V conjugate. The radiochemical yield and the radiochemical purity of (111)In-DOTA-Annexin V were 74±12% and 98±3%, respectively (n=10). (111)In-DOTA-BSA was prepared similarly. An in vitro study to demonstrate the apoptosis of NG4TL4-STK cells after GCV treatment has been performed. Mice bearing NG4TL4-STK and NG4TL4-WT tumors were treated with GCV (10 mg/kg daily) by i.p. injection for 7 consecutive days. Before and during the GCV treatment, biodistribution studies and scintigraphic imaging were performed at 2h post injection of the radiotracers. The uptake of (111)In-DOTA-Annexin V in treated cells (13.41±1.30%) was 4.1 times higher than that in untreated cells (3.21±0.37%). The GCV-induced cell apoptosis in NG4TL4-STK tumor resulted in a significantly increasing accumulation of (111)In-DOTA-Annexin V (1.92±0.32%ID/g at day 0, 4.79±0.86%ID/g at day 2, 4.56±0.58%ID/g at day 4) was observed, but not for that of (111)In-DOTA-BSA. During consecutive GCV treatment, scintigraphic imaging with (111)In-DOTA-Annexin V revealed high uptake in NG4TL4-STK tumor compared with that in NG4TL4-WT tumor. However, no specific (111)In-DOTA-BSA accumulation in NG4TL4-STK and NG4TL4-WT tumors was observed throughout the course of GCV treatment. This study demonstrated that (111)In-DOTA-Annexin V can be used for monitoring tumor cell apoptosis during prodrug activation gene therapy with HSV1-tk and GCV for cancer treatment. Copyright © 2015 Elsevier Ltd. All rights

  16. On the interdiffusion in multilayered silicide coatings for the vanadium-based alloy V-4Cr-4Ti

    Energy Technology Data Exchange (ETDEWEB)

    Chaia, N., E-mail: nabil.chaia@usp.br [Escola de Engenharia de Lorena, Universidade de São Paulo, Pólo Urbo-Industrial Gleba AI-6, 12602-810 Lorena, SP (Brazil); Portebois, L., E-mail: leo.portebois@univ-lorraine.fr [Université de Lorraine, Institut Jean Lamour, UMR7198, Boulevard des Aiguillettes, BP70239, 54506 Vandoeuvre-lès-Nancy, Cedex (France); Mathieu, S., E-mail: stephane.mathieu@univ-lorraine.fr [Université de Lorraine, Institut Jean Lamour, UMR7198, Boulevard des Aiguillettes, BP70239, 54506 Vandoeuvre-lès-Nancy, Cedex (France); David, N., E-mail: nicolas.david@univ-lorraine.fr [Université de Lorraine, Institut Jean Lamour, UMR7198, Boulevard des Aiguillettes, BP70239, 54506 Vandoeuvre-lès-Nancy, Cedex (France); Vilasi, M., E-mail: michel.vilasi@univ-lorraine.fr [Université de Lorraine, Institut Jean Lamour, UMR7198, Boulevard des Aiguillettes, BP70239, 54506 Vandoeuvre-lès-Nancy, Cedex (France)

    2017-02-15

    To provide protection against corrosion at high temperatures, silicide diffusion coatings were developed for the V-4Cr-4Ti alloy, which can be used as the fuel cladding in next-generation sodium-cooled fast breeder reactors. The multilayered coatings were prepared by halide-activated pack cementation using MgF{sub 2} as the transport agent and pure silicon (high activity) as the master alloy. Coated pure vanadium and coated V-4Cr-4Ti alloy were studied and compared as substrates. In both cases, the growth of the silicide layers (V{sub 3}Si, V{sub 5}Si{sub 3}, V{sub 6}Si{sub 5} and VSi{sub 2}) was controlled exclusively by solid-state diffusion, and the growth kinetics followed a parabolic law. Wagner's analysis was adopted to calculate the integrated diffusion coefficients for all silicides. The estimated values of the integrated diffusion coefficients range from approximately 10{sup −9} to 10{sup −13} cm{sup 2} s{sup −1}. Then, a diffusion-based numerical approach was used to evaluate the growth and consumption of the layers when the coated substrates were exposed at critical temperatures. The estimated lifetimes of the upper VSi{sub 2} layer were 400 h and 280 h for pure vanadium and the V-4Cr-4Ti alloy, respectively. The result from the numeric simulation was in good agreement with the layer thicknesses measured after aging the coated samples at 1150 °C under vacuum. - Highlights: • The pack cementation technique is implemented to study interdiffusion in V/Si and V-4Cr-4Ti/Si couples. • Interdiffusion coefficients of vanadium silicides were experimentally determined within the range 1100–1250 °C. • For either V/Si or V-4Cr-4Ti/Si couples, the VSi{sub 2} layer has the highest growth rate. • The Cr and Ti alloying elements mainly modified the V{sub 5}Si{sub 3} and V{sub 6}Si{sub 5} growth rate. • Numerical simulation allows for a confident assessment of the VSi{sub 2} coating lifetime on V-4Cr-4Ti.

  17. Standardization of 201Tl and 55Fe radionuclides in a 4 (PC)-NaI(Tl) coincidence system

    International Nuclear Information System (INIS)

    Pires, Carlos Augusto

    2008-01-01

    In the present work the procedure for the standardization of radionuclides using the 4π(PC)-NaI(Tl) coincidence system was developed. The radionuclides selected were 201 Tl, used in nuclear medicine, and 55 Fe primary standard source, used for x-ray spectrometers calibration. The 4π(PC)-NaI(Tl) is composed of a 4 proportional counter operated at 0.1MPa coupled to two NaI(Tl) crystals. The 201 Tl decays by electron capture process followed by a prompt gamma-ray. The disintegration rate was determined by extrapolation technique using two methods: electronic discrimination and external absorbers. The radioactive sources were prepared in a 20 μg cm -2 thick Collodion film. The conventional electronic system was used. The observed events were registered by the TAC method. The 55 Fe decays by electron capture process to the ground state of 55 Mn, emitting x rays with around 6 keV. The standardization was obtained by the tracing method. This technique was applied using two radionuclides, which decay by electron capture process followed by a prompt gamma-ray, namely 51 Cr and 54 Mn, as tracers. Measurements with 1 and 2 aluminum foils, each 150 g cm-2 thick were carried out. The activity was obtained by extrapolation for zero thickness Al foil. The uncertainties were treated by means of matrix covariance methodology and takes into account all correlations involved. (author)

  18. 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.

  19. Optimization of hybrid laser arc welding of 42CrMo steel to suppress pore formation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yan [Hunan University, State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Changsha (China); Hunan Institute of Science and Technology, College of Mechanical Engineering, Yueyang (China); Chen, Genyu; Mao, Shuai; Zhou, Cong; Chen, Fei [Hunan University, State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Changsha (China)

    2017-06-15

    The hybrid laser arc welding (HLAW) of 42CrMo quenched and tempered steel was conducted. The effect of the processing parameters, such as the relative positions of the laser and the arc, the shielding gas flow rate, the defocusing distance, the laser power, the wire feed rate and the welding speed, on the pore formation was analyzed, the morphological characteristics of the pores were analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results showed that the majority of the pores were invasive. The pores formed at the leading a laser (LA) welding process were fewer than those at the leading a arc (AL) welding process. Increasing the shielding gas flow rate could also facilitate the reduction of pores. The laser power and the welding speed were two key process parameters to reduce the pores. The flow of the molten pool, the weld cooling rate and the pore escaping rate as a result of different parameters could all affect pore formation. An ideal pore-free weld was obtained for the optimal welding process parameters. (orig.)

  20. Copper interactions in TlCu7S4 and TlCu7Se4

    International Nuclear Information System (INIS)

    Noren, L.; Delaplane, R.G.; Berger, R.

    1999-01-01

    Complete text of publication follows. The copper chalcogenides ACu 7 S 4 (A=NH 4 + , Tl + , Rb + ) are quasi-one-dimensional metals at ambient and higher temperatures which is due to the high mobility of copper in these structures. TlCu 7 S 4 and TlCu 7 Se 4 are isostructural compounds, space group I4/m, which can be described on the basis of a TlX 8 cube with two different Cu sites, Cu(1) and Cu(2). Cu(2)-Cu(2) zigzag chains run along the c axis with only 3/4 occupation of the Cu(2) sites. However, these two compounds differ in behaviour on cooling. The sulphide shows a polymorphic first-order transition to the CsAg 7 S 4 type (P4/n) owing to ordering of the vacancies in the Cu(2)-Cu(2) chains. In order to study the nature of the Cu(2) order/disorder in the two title compounds, a series of neutron diffraction measurements (both Bragg and diffuse scattering) were made at several temperatures from 40 to 713 K on the instrument SLAD at Studsvik. The structure at each temperature was modelled using RMC techniques. The resulting configuration show that as the temperature increases, there is a marked increase in the mobility of the Cu atoms in the Cu(2)-Cu(2) chains for TlCu 7 S 4 but not for TlCu 7 Se 4 . This is due to the initial difference in the Cu(2)-Cu(2) distances, only 2.2A for the thiocuprate, but 2.7A in the selenocuprate which explains the relative ease for Cu(2) ordering in the latter case. (author)

  1. Creep properties and simulation of weld repaired low alloy heat resistant CrMo and Mo steels at 540 deg C. Sub-project 2 - Ex-serviced 2.25Cr1M0 weld metal and cross weld repairs

    Energy Technology Data Exchange (ETDEWEB)

    Rui Wu; Storesund, Jan; Borggreen, Kjeld; Feilitzen, Carl von

    2007-12-15

    Weld repair has been carried out in an ex-serviced 10 CrMo 9 10 pipe by using 10 CrMo 9 10, 13 CrMo 4 4 and 15 Mo 3 consumables. Application of current welding procedure and consumables results in an over matched weld repair. This is verified by both creep tests and the creep simulations at even lower stresses than tested. Creep specimens have been extracted from ex-serviced 10 CrMo 9 10 parent metal (PM) and weld metal (WM), from virgin 10 CrMo 9 10 WM, from virgin 13 CrMo 4 4 WM, and from virgin 15 Mo 3 WM. In addition, cross weld specimens including weld metal, heat affected zone (HAZ) and parent metal have been taken from the ex-serviced 10 CrMo 9 10 weld joint, and from three weld repairs. In total, there are nine test series. The sequence of creep lifetime at 540 deg C at given stresses is; virgin 10 CrMo 9 10 weld metal > virgin 15 Mo 3 weld metal approx virgin 13 CrMo 4 4 weld metal approx ex-serviced 10 CrMo 9 10 weld metal >> ex-serviced 10 CrMo 9 10 parent metal > ex-serviced 10 CrMo 9 10 cross weld approx 10 CrMo 9 10 cross weld repair approx 13 CrMo 4 4 cross weld repair approx and 15 Mo 3 cross weld repair. All the series show good creep ductility. The ex-serviced 10 CrMo 9 10 parent metal shows a creep lifetime about one order of magnitude shorter than that for both the virgin parent metal and the ex-serviced 10 CrMo 9 10 weld metal, independent of stresses. Differences in creep lifetime among the ex-serviced 10 CrMo 9 10 cross weld and other cross weld repairs are negligible, simply because rupture always occurred in the ex-serviced 10 CrMo 9 10 parent metal, approximately 10 mm from HAZ, for all the cross welds. Necking is frequently observed in the ex-serviced 10 CrMo 9 10 parent metal at the opposite side of the fracture. Creep damage to a large and a small extend is found adjacent to the fracture and at the necking area, respectively. Other parts of the weld joint like weld metal and HAZ are damage-free, independent of stress, weld metal and

  2. Hydrogen release from vanadium alloy V-4Cr-4Ti

    International Nuclear Information System (INIS)

    Klepikov, A.Kh; Kulsartov, T.V.; Chikhray, E.V.; Romanenko, O.G.; Tazhibaeva, I.L.; Shestakov, V.P.

    1999-01-01

    The experiments on hydrogen loading of vanadium alloy with the following thermodesorption spectroscopy (TDS) measurements were carried out with the sample of the V-4Cr-4Ti vanadium alloy (Russia production). Hydrogen solubility was calculated from experimental TDS curves, obtained after equilibrium loading of the sample at the temperatures 673, 773, 873, 973, and 1073 K. The range of loading pressures was 10-100 Pa. The experiments carried out had an objective to determine the regimes (loading time, temperatures and pressures) for the experiment on in-pile loading of the vanadium alloy. (author)

  3. A Comparison Between Mechanical And Electrochemical Tests on Ti6Al4V Welded By LBW

    Science.gov (United States)

    Serroni, G.; Bitondo, C.; Astarita, A.; Scala, A.; Gloria, A.; Prisco, U.; Squillace, A.; Bellucci, F.

    2011-05-01

    Titanium and its alloys are nowadays widely used in many sectors: in the medical field (orthopedic and dental ones), in the architectural field, in the chemical plants field and in aeronautic. In this last field it is more and more used both for its contribution to make lightweight and time durable structures and for its compatibility with new materials, first of all Carbon Fiber Reinforced Plastics (CFRP). To this aim, lots of researches are now focusing on new and emerging technologies capable to make titanium objects and, at the same time, reducing the scrap, since titanium alloys for aeronautic application are very expensive. This paper examines Grade 5 Titanium Alloy (Ti6Al4V) welded by Laser Beam (LBW) in butt-joint configuration. The source was Nd:YAG laser, moreover two inert gases were used, in order to provide a shield both on the top and on the bottom of the weld bead. The joints were studied by varying two process parameters: welding speed and power of the laser beam. It was not possible to realize a full experimental plan, due to technological limits in making titanium laser beam welds. The joints were tested to measure their mechanical properties and the corrosion resistance. The process parameters do not significantly affect the maximum static strength of the joints. Microscopic analysis showed that welds made with high power and low welding speed have a uniform weld bead, and no macroscopic defect occurs. Fatigue test results, instead, show a marked influence of the morphology of the weld bead: the occurrence of some defects, such as the undercut, both on the top and on the bottom of the weld bead, dramatically reduced fatigue resistance of the joints. Corrosion resistance was studied using the electrochemical micro cell technique, which allows to distinguish electrochemical properties of each zone of the weld bead, even when, as in this case, they are very narrow. By a general point of view, it has been demonstrated that the joints showing the best

  4. Internal-bore-welding of 2 1/4 Cr--1 Mo steel tube-to-tubesheet joints

    International Nuclear Information System (INIS)

    Moorhead, A.J.; Slaughter, G.M.

    1976-01-01

    In order to avoid the disadvantages of the conventional face-side tube-to-tubesheet weld, the steam generators for the Clinch River Breeder Reactor Plant (a power-producing demonstration LMFBR) will be built using a relatively new technique known as internal-bore-welding (IBW). In IBW the tube does not pass through the tubesheet but rather is welded to a short stub machined on the tube side of the tubesheet. This joint has the important advantages of being inspectable by radiography and eliminating the crevice; however, it is much more difficult to weld than is the face-side design. Because of the close proximity of the tubes, there is not room for an orbiting-arc welding head on the outside of the tube. Consequently, this weld must be made by welding from the inside- or bore-side of the tube. The results are presented of the initial phases of a program undertaken at ORNL to develop improved bore-side welding equipment, to gain further understanding of this technique, and to develop mechanical property data for autogeneous welds in 2 1/4 Cr-1 Mo steel tube and tubesheet materials

  5. Performance of V-4Cr-4Ti material exposed to DIII-D tokamak environment

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, H.; Chung, H.M.; Smith, D.L. [Argonne National Lab., IL (United States)] [and others

    1997-04-01

    Test specimens made with the 832665 heat of V-4Cr-4Ti alloy were exposed in the DIII-D tokamak environment to support the installation of components made of a V-4Cr-4Ti alloy in the radiative divertor of the DIII-D. Some of the tests were conducted with the Divertor Materials Evaluation System (DiMES) to study the short-term effects of postvent bakeout, when concentrations of gaseous impurities in the DIII-D chamber are the highest. Other specimens were mounted next to the chamber wall behind the divertor baffle plate, to study the effects of longer-term exposures. By design, none of the specimens directly interacted with the plasma. Preliminary results from testing the exposed specimens indicate only minor degradation of mechanical properties. Additional testing and microstructural characterization are in progress.

  6. Computational model of dual q-switching and lasing processes of the pulsed Cr4+:YAG laser pumped by Nd-glass laser

    International Nuclear Information System (INIS)

    Abdul Ghani, B.; Hammadi, M.

    2007-01-01

    A mathematical model describing the absorption and oscillation processes of intracavity Cr 4+ : YAG crystal pumped by Nd-glass laser has been developed, in order to describe the temporal behavior of laser-absorber system. The model has been assumed that the Cr 4+ ions excited to a higher level by excited state absorption, followed by relaxation directly to the upper laser level through fast channel, and indirectly through slow proposed intermediate channel at different lifetimes. The model offers simple kinetic mechanisms for pulsed solid state lasers and also the influence of the variations of the laser input parameters (pumping rate, maximum amplification coefficient and loss coefficient) on the output pulse characteristics of the passive Q-switched Nd-glass and pulsed Cr 4+ : YAG lasers. The model estimates the temporal behavior of the population densities of different levels and laser beam densities as well as predicts the nanosecond output laser pulses of passive Q-switched Nd-glass laser and pulsed Cr 4+ : YAG laser. The calculated results are in good agreement with the available experimental and theoretical data in the literature. (author)

  7. Manufacture of semifinished items of alloys V-4Ti-4Cr and V-10Ti-5Cr for use as a structural material in fusion applications

    International Nuclear Information System (INIS)

    Potapenko, M.M.; Drobishev, V.A.; Filkin, V.Y.; Gubkin, I.N.; Myasnikov, V.V.; Nikulin, A.D.; Shingarev, E.N.; Vedernikov, G.P.; Votinov, S.N.; Zurabov, V.S.; Zolotarev, A.B.

    1996-01-01

    Vanadium-titanium-chromium alloys are considered as structural materials with the most appropriate properties for fusion applications. However, the final ratio V-Ti-Cr in an alloy is not yet determined. On the one hand, it is offered to optimize structure on the basis of an alloy V-4Ti-4Cr. On the other hand, it is proposed that the optimum of total Ti and Cr content should be near 15%, and the Ti to Cr ratio should be 2:1. Melting, casting and processing by pressure of ingots of vanadium alloys V-4Ti-4Cr and V-10Ti-5Cr weighing as much as 50 kg are considered in the report. The ingots in diameters up to 130 mm were obtained by melting in vacuum-arc furnaces. Results on chemical uniformity and structure of the ingots are presented. A basic scheme of semifinished items manufacture is submitted. Rod and tube hot extrusion conditions are presented. A new technology for protection of ingot and billet surface from gases during hot processing is used to discard application of protective stainless steel and to lower temperature of processing. Sheet and tube products were made from extruded billets by cold rolling with intermediate heat treatment. The list of obtained products, including sheets 0.5-5 mm thick, rods 10-18 mm in diameter and tubes from 50 mm up to 6.0 mm in diameter is presented. The availability of large-scale ingots processing with weight above 300 kg is discussed. (orig.)

  8. Synthesis, structural, X-ray photoelectron spectroscopy (XPS) studies and IR induced anisotropy of Tl{sub 4}HgI{sub 6} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Parasyuk, O.V. [Department of Inorganic and Physical Chemistry, Lesya Ukrainka Eastern European National University, Voli Ave. 13, Lutsk, 43025 (Ukraine); Khyzhun, O.Y. [Frantsevych Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 3 Krzhyzhanivsky St., 03142, Kyiv (Ukraine); Piasecki, M. [Institute of Physics, J. Dlugosz University Częstochowa, Armii Krajowej 13/15, Częstochowa (Poland); Kityk, I.V., E-mail: iwank74@gmail.com [Electrical Engineering Department, Czestochowa University Technology, Armii Krajowej 17, PL-42-217, Czestochowa (Poland); Lakshminarayana, G. [Wireless and Photonic Networks Research Centre, Faculty of Engineering, Universiti Putra Malaysia, 43400, Serdang, Selangor (Malaysia); Luzhnyi, I. [Frantsevych Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 3 Krzhyzhanivsky St., 03142, Kyiv (Ukraine); Fochuk, P.M. [Yuriy Fed’kovych Chernivtsi National University, 2 Kotziubynskoho Str., 58012, Chernivtsi (Ukraine); Fedorchuk, A.O. [Department of Inorganic and Organic Chemistry, Lviv National University of Veterinary Medicine and Biotechnologies, Pekarska Street 50, 79010, Lviv (Ukraine); Levkovets, S.I.; Yurchenko, O.M.; Piskach, L.V. [Department of Inorganic and Physical Chemistry, Lesya Ukrainka Eastern European National University, Voli Ave. 13, Lutsk, 43025 (Ukraine)

    2017-02-01

    In the present work, we report on the synthesis and structural properties including X-ray protoelectron spectroscopy (XPS) analysis of Tl{sub 4}HgI{sub 6} crystals that were grown by Bridgman-Stockbarger method up to 80 mm in length and 18 mm in diameter. The existence of the ternary compound Tl{sub 4}HgI{sub 6} that melts incongruently at 641 K was confirmed. Phase equilibria and structural properties for the TlI–HgI{sub 2} system were investigated by differential thermal analysis (DTA) and X-ray diffraction (XRD) methods. X-ray photoelectron spectra were measured for both pristine and Ar{sup +} ion-bombarded Tl{sub 4}HgI{sub 6} single crystal surfaces. The data reveal that the Tl{sub 4}HgI{sub 6} single crystal is sensitive with respect to Ar{sup +} ion-bombardment as 3.0 keV Ar{sup +} irradiation over 5 min at an ion current density 14 μA/cm{sup 2} induces changes to the elemental stoichiometry of the Tl{sub 4}HgI{sub 6} surface, leading to a decrease of the mercury content in the topmost surface layers. X-ray photoelectron spectroscopy (XPS) measurements indicate very low hygroscopic nature of the Tl{sub 4}HgI{sub 6} single crystal surface. The IR coherent bicolor laser treatment at wavelengths 10.6/5.3 μm has shown an occurrence of anisotropy at wavelengths 1540 nm of Er:glass laser. This may open the applications of Tl{sub 4}HgI{sub 6} as a material for IR laser triggering. - Highlights: • Phase diagram of the HgI{sub 2}–TlI system was built. • Tl{sub 4}HgI{sub 6} single crystals were grown by Bridgman Stockbarger method. • XRD, XPS analysis was done. • Ir induced anisotropy was established. • The compounds may be proposed as Ir laser operated polarizers.

  9. Welding of zircalloy-2 and zircalloy-4 by CO2 laser and by TIG

    International Nuclear Information System (INIS)

    Ram, V.

    1990-01-01

    This study deals with the welding of zircaloy-2 and zircaloy-4 by means of two techniqes, namely tungsten inert gas welding and CO 2 laser welding. Suitable devices and jigs were developed and manufactured to allow the welding of flat specimens and cylindrical specimens. The optimal welding parameters for the two welding methods were determined. The quality of the welds was determined by tensile strength tests at room temperature and by determining the corrosion resistance to steam at temprature of 450 deg C, 550 deg C, and at 650 deg C. The influence of the weld on the microstructure of the material, on its composition and its crystallographic structure was investigated. Analysis of fracture surfaces of the tensile specimens was carried out with a scanning electron microscope. (author)

  10. Study of Gravity Effects on Titanium Laser Welding in the Vertical Position.

    Science.gov (United States)

    Chang, Baohua; Yuan, Zhang; Pu, Haitao; Li, Haigang; Cheng, Hao; Du, Dong; Shan, Jiguo

    2017-09-08

    To obtain satisfactory welds in positional laser beam welding, it is necessary to know how process parameters will influence the quality of welds in different welding positions. In this study, the titanium alloy Ti6Al4V sheets were laser welded in two vertical welding positions (vertical up and vertical down), and the appearance, porosity, strength, and ductility of the laser joints were evaluated. Results show that undercuts of the vertical up welds were greater than that of vertical down welds, while the porosity contents were much higher in vertical down welds than that in vertical up welds. When welding with a higher heat input, the vertical up welding position resulted in poor weld profiles (undercuts and burn-through holes), whereas the vertical down welding position led to excessive porosity contents in welds. Both severe undercut and excessive porosity were detrimental to the tensile properties of the welds. Weld appearance was improved and porosity contents were reduced by using a lower heat input, achieving better weld quality. Therefore, it is suggested that process parameter settings with relatively high laser powers and welding speeds, which can result in lower heat inputs, are used when laser welding the Ti6Al4V titanium alloys vertically.

  11. Electrically insulating films deposited on V-4%Cr-4%Ti by reactive CVD

    International Nuclear Information System (INIS)

    Park, J.H.

    1998-04-01

    In the design of liquid-metal blankets for magnetic fusion reactors, corrosion resistance of structural materials and the magnetohydrodynamic forces and their influence on thermal hydraulics and corrosion are major concerns. Electrically insulating CaO films deposited on V-4%Cr-4%Ti exhibit high-ohmic insulator behavior even though a small amount of vanadium from the alloy become incorporated into the film. However, when vanadium concentration in the film is > 15 wt.%, the film becomes conductive. When the vanadium concentration is high in localized areas, a calcium vanadate phase that exhibits semiconductor behavior can form. The objective of this study is to evaluate electrically insulating films that were deposited on V-4%Cr-4%Ti by a reactive chemical vapor deposition (CVD) method. To this end, CaO and Ca-V-O coatings were produced on vanadium alloys by CVD and by a metallic-vapor process to investigate the electrical resistance of the coatings. The authors found that the Ca-V-O films exhibited insulator behavior when the ratio of calcium concentration to vanadium concentration R in the film > 0.9, and semiconductor or conductor behavior when R 0.98 were exposed in liquid lithium. Based on these studies, they conclude that semiconductor behavior occurs if a conductive calcium vanadate phase is present in localized regions in the CaO coating

  12. Exploring the thermoelectric and magnetic properties of uranium selenides: Tl{sub 2}Ag{sub 2}USe{sub 4} and Tl{sub 3}Cu{sub 4}USe{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Azam, Sikander; Khan, Saleem Ayaz [New Technologies – Research Center, University of West Bohemia, Univerzitni 8, 30614 Pilsen (Czech Republic); Din, Haleem Ud [Department of Physics, Hazara University, Mansehra (Pakistan); Khenata, Rabah [Laboratoire de Physique Quantique et de Modélisation Mathématique (LPQ3M), Département de Technologie, Université de Mascara, Mascara 29000 (Algeria); Goumri-Said, Souraya, E-mail: sosaid@alfaisal.edu [College of Science, Physics department, Alfaisal University, P.O. Box 50927, Riyadh 11533 (Saudi Arabia)

    2016-09-01

    The electronic, magnetic and thermoelectric properties of Tl{sub 2}Ag{sub 2}USe{sub 4} and Tl{sub 3}Cu{sub 4}USe{sub 6} compounds were investigated using the full potential linear augmented plane wave (FP-LAPW) method based on the density functional theory (DFT). The exchange correlation was treated with the generalized gradient approximation plus optimized effective Hubbard parameter and spin–orbit coupling (GGA+U+SOC). The present uranium selenides show narrow direct energy band gap values of 0.7 and 0.875 eV for Tl{sub 2}Ag{sub 2}USe{sub 4} and Tl{sub 3}Cu{sub 4}USe{sub 6} respectively. For both selenides U-d/f states are responsible for electrical transport properties. Uranium atoms were the most contributors in the magnetic moment compared to other atoms and show ferromagnetic nature. The spin density isosurfaces show the polarization of neighboring atoms of Uranium, such as silver/copper and selenium. Thermoelectric calculations reveal that Tl{sub 3}Cu{sub 4}USe{sub 6} is more suitable for thermoelectric device applications than Tl{sub 2}Ag{sub 2}USe{sub 4}. - Highlights: • Electronic, magnetic and thermoelectric properties of uranium selenides are investigated with DFT. • They show a narrow direct energy band gap of 0.7 and 0.875 eV. • U-d/f states are responsible for electrical transport properties. • Tl{sub 3}Cu{sub 4}USe{sub 6} is more suitable for thermoelectric device applications than Tl{sub 2}Ag{sub 2}USe{sub 4}.

  13. Thermodynamical study of the vanadium-hydrogen system. The hydrogen effect on the mechanical properties of V-4Cr-4Ti and V-5Cr-5Ti alloys; Etude thermodynamique du systeme vanadium-hydrogene. Effets de l'hydrogene sur les proprietes mecaniques des alliages V-4Cr-4Ti et V-5Cr-5Ti

    Energy Technology Data Exchange (ETDEWEB)

    Coulombeaux, O

    1998-07-01

    In the framework of the international research programs on fusion reactors, the vanadium alloys are among the most appropriate candidate to constitute the first wall. The author deals with the specific alloys V-4Cr-4Ti and V-5Cr-5Ti and study the hydrogen diffusion. Experimental results show that the induced hydrogen concentration in the sample by diffusion is higher, for the same partial pressure of exposure, in the case of the alloy than for the pure vanadium. He shows that this result can be explainedby the trapping for which the hydrogen is trapped by the titanium. (A.L.B.)

  14. Laser Powder Cladding of Ti-6Al-4V α/β Alloy

    OpenAIRE

    Samar Reda Al-Sayed Ali; Abdel Hamid Ahmed Hussein; Adel Abdel Menam Saleh Nofal; Salah Elden Ibrahim Hasseb Elnaby; Haytham Abdelrafea Elgazzar; Hassan Abdel Sabour

    2017-01-01

    Laser cladding process was performed on a commercial Ti-6Al-4V (α + β) titanium alloy by means of tungsten carbide-nickel based alloy powder blend. Nd:YAG laser with a 2.2-KW continuous wave was used with coaxial jet nozzle coupled with a standard powder feeding system. Four-track deposition of a blended powder consisting of 60 wt % tungsten carbide (WC) and 40 wt % NiCrBSi was successfully made on the alloy. The high content of the hard WC particles is intended to enhance the abrasion resist...

  15. Synthesis and microstructure characterization of Ni-Cr-Co-Ti-V-Al high entropy alloy coating on Ti-6Al-4V substrate by laser surface alloying

    International Nuclear Information System (INIS)

    Cai, Zhaobing; Jin, Guo; Cui, Xiufang; Liu, Zhe; Zheng, Wei; Li, Yang; Wang, Liquan

    2016-01-01

    Ni-Cr-Co-Ti-V-Al high-entropy alloy coating on Ti-6Al-4V was synthesized by laser surface alloying. The coating is composed of a B2 matrix and (Co, Ni)Ti 2 compounds with few β-Ti phases. Focused ion beam technique was utilized to prepare TEM sample and TEM observations agree well with XRD and SEM results. The formation of HEA phases is due to high temperature and rapid cooling rate during laser surface alloying. The thermodynamic parameters, ΔH mix , ΔS mix and δ as well as Δχ, should be used to predict the formation of the BCC solid solution, but they are not the strict criteria. Especially when Δχ reaches a high value (≥ 10%), BCC HEA will be partially decomposed, leading to the formation of (Co, Ni)Ti 2 compound phases. - Highlights: •Preparing HEA coating on Ti-6Al-4V by laser surface alloying is successful. •The synthesized HEA coating mainly consists of BCC HEA and (Co, Ni)Ti 2 compounds. •FIB technology was used to prepare the sample for TEM analysis. • ΔH mix , ΔS mix and δ as well as Δχ, should be all used to predict the formation of solid solution.

  16. Laser Welding of Shape Memory Alloys

    Science.gov (United States)

    Oliveira, Joao Pedro de Sousa

    Joining of shape memory alloys is of great importance for both functional and structural applications as it can provide an increased design flexibility. In this work similar NiTi/NiTi, CuAlMn/CuAlMn and dissimilar NiTi/Ti6Al4V joints were produced by Nd:YAG laser. For the NiTi/NiTi joints the effect of process parameters (namely the heat input) on the superelastic and shape memory effects of the joints was assessed and correlated to its microstructure. Microstructural analysis was performed by means of X-ray diffraction using synchrotron radiation, which allowed for fine probing of the welded material. It was noticed the presence of martensite in the thermally affected regions, while the base material remained fully austenitic. The mechanisms for the formation of martensite, at room temperature, due to the welding procedure are presented and the influence of this phase on the functional properties of the joints is discussed. Additionally, the residual stresses were determined using synchrotron X-ray diffraction. For the dissimilar NiTi/Ti6Al4V joints, a Niobium interlayer was used to prevent the formation undesired brittle intermetallic compounds. Additionally, it was observed that positioning of the laser beam was of significant importance to obtain a sound joint. The mechanisms responsible for the joint formation are discussed based on observations with advanced characterization techniques, such as transmission electron microscopy. At the NiTi/Nb interface, an eutectic reaction promotes joining of the two materials, while at the Ti6Al4V/Nb interface fusion and, subsequent solidification of the Ti6Al4V was responsible for joining. Short distance diffusion of Nb to the fusion zone of Ti6Al4V was observed. Although fracture of the dissimilar welded joints occurred at a stress lower than the minimum required for the stress induced transformation, an improvement on the microstructure and mechanical properties, relatively to existing literature, was obtained. Finally

  17. Phase equilibria in the Tl2MoO4–R2(MoO43–Zr(MoO42 (R = Al, Cr systems: synthesis, structure and properties of new triple molybdates Tl5RZr(MoO46 and TlRZr0.5(MoO43

    Directory of Open Access Journals (Sweden)

    V. G. Grossman

    2017-12-01

    Full Text Available The Tl2MoO4–R2(MoO43–Zr(MoO42 (R = Al, Cr systems were studied in the subsolidus region using X-ray powder diffraction and differential scanning calorimetric (DSC analysis. Quasi-binary joins were revealed, and triangulation was carried out. New ternary molybdates: Tl5RZr(MoO46 (5:1:2 and TlRZr0.5(MoO43 (1:1:1 (R = Al, Cr were prepared. The unit cell parameters for the new compounds were calculated.

  18. A PASSIVELY MODE-LOCKED CR4+:FORSTERITE LASER WITH ELEСTRONICALLY CONTROLLED OUTPUT CHARACTERISTICS

    Directory of Open Access Journals (Sweden)

    S. A. Zolotovskaya

    2011-01-01

    Full Text Available Applicability of electronic control of laser output parameters to bulk solid-state laser sources is demonstrated. A single laser source with variable pulse duration for novel imaging and manipulation systems is presented. Stable passive mode-locking of a Cr4+:forsterite laser using a voltage controlled p-n junction quantum dot saturable absorber was achieved. Output shortening from 17,4 to 6,4 ps near-transform limited pulses was obtained by applying reverse bias.

  19. Effects of Nd:YAG laser pulse frequency on the surface treatment of Ti 6Al 4V alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gursel, Ali [International University of Sarajevo (Bosnia and Herzegovina). Dept. of Mechanical Engineering

    2016-07-01

    The desirable properties of titanium and titanium alloys, including excellent corrosion resistance, high strength to weight ratio and high operating temperature, have led to their successful application in various fields such as the medical and aerospace industries. Among the reliable treatment techniques, laser welding can provide significant advantages for the titanium alloys because of its precision, rapid processing capability and ability to control the welding parameters and their effects. The morphology and the quality of pulsed seam welds are directly or synergistically influenced by the Nd:YAG laser parameters of pulse shape, energy, duration, travel speed, peak power and frequency of repetition. In this study, a 1.5 mm thick Ti-6Al-4V alloy sheet surface was treated by SigmaLaser {sup registered} 300 Nd:YAG pulsed laser. The influence of the pulse frequency on seam morphology and surface effects was then investigated. The seam and surface quality were characterized in terms of weld morphology and microhardness. The results showed that, for Nd:YAG laser seams used for surface treatment, pulse repetition was more effective on the cooling rate than had been expected.

  20. Up to 30 mW of broadly tunable CW green-to-orange light, based on sum-frequency mixing of Cr4+:forsterite and Nd:YVO4 lasers

    DEFF Research Database (Denmark)

    Mortensen, Jesper Liltorp; McWilliam, Allan; G. Leburn, Christopher

    2006-01-01

    Efficient generation of continuous-wave (CW) tunable light in the yellow region is reported. The method is based on sum-frequency mixing of a tunable Cr4+:forsterite laser with a Nd:YVO4 laser. A periodically poled lithium niobate crystal was placed intra-cavity in a Nd:YVO4 laser, and the Cr4...

  1. Welding of heat-resistant 20% Cr-5% Al steels

    International Nuclear Information System (INIS)

    Tusek, J.; Arbi, D.; Kosmac, A.; Nartnik, U.

    2002-01-01

    The paper treats welding of heat-resistant ferritic stainless steels alloyed with approximately 20% Cr and 5% Al. The major part of the paper is dedicated to welding of 20% Cr-5% Al steel with 3 mm in thickness. Welding was carried out with five different welding processes, i. e., manual metal-arc, MIG, TIG, plasma arc, and laser beam welding processes, using a filler material and using no filler material, respectively. The welded joints obtained were subjected to mechanical tests and the analysis of microstructure in the weld metal and the transition zone. The investigations conducted showed that heat-resistant ferritic stainless 20% Cr-5% Al steel can be welded with fusion welding processes using a Ni-based filler material. (orig.)

  2. Heat treatment effects on tensile properties of V-(4-5) wt.% Cr-(4-5) wt.% Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Soppet, W.K. [Argonne National Lab., IL (United States)

    1997-08-01

    Effects of thermomechanical treatments on microstructures and mechanical properties are of interest for long term application of V-Cr-Ti alloys in fusion reactor systems. Influence of thermal annealing at 1050{degrees}C on stress/strain behavior, maximum engineering strength, and uniform and total elongation were evaluated. The results show that multiple annealing has minimal effect on the tensile properties of V-(4-5)Cr-(4-5)Ti alloys tested at room temperature and at 500{degrees}C.

  3. Microstructure and mechanical properties of friction stir welded and laser welded high entropy alloy CrMnFeCoNi

    Science.gov (United States)

    Jo, Min-Gu; Kim, Han-Jin; Kang, Minjung; Madakashira, Phaniraj P.; Park, Eun Soo; Suh, Jin-Yoo; Kim, Dong-Ik; Hong, Sung-Tae; Han, Heung Nam

    2018-01-01

    The high entropy alloy CrMnFeCoNi has been shown to have promising structural properties. For a new alloy to be used in a structural application it should be weldable. In the present study, friction stir welding (FSW) and laser welding (LW) techniques were used to butt weld thin plates of CrMnFeCoNi. The microstructure, chemical homogeneity and mechanical behavior of the welds were characterized and compared with the base metal. The tensile stress-strain behavior of the welded specimens were reasonable when compared with that of the base metal. FSW refined the grain size in the weld region by a factor of ˜14 when compared with the base metal. High-angle annular dark field transmission electron microscopy in combination with energy dispersive X-ray spectroscopy showed chemical inhomogeneity between dendritic and interdendritic regions in the fusion zone of LW. Large fluctuations in composition (up to 15 at%) did not change the crystal structure in the fusion zone. Hardness measurements were carried out in the weld cross section and discussed in view of the grain size, low angle grain boundaries and twin boundaries in FSW specimens and the dendritic microstructure in LW specimens.

  4. Effects of V and Cr on Laser Cladded Fe-Based Coatings

    Directory of Open Access Journals (Sweden)

    Haiyang Wang

    2018-03-01

    Full Text Available Fe-based coatings with high V and Cr content were obtained by laser cladding using Fe-based powder with different Cr3C2 and FeV50 content. The results showed that Fe-based coatings were uniform and dense. The constituent phases were mainly composed of α-Fe solid solution with the increase of Cr3C2 and FeV50, γ-Fe and V8C7 phases were achieved. The microstructure of the coatings exhibited a typical dendrite structure. The concentration of C, V and Cr were saturated in dendritic areas, and the other alloying elements were mainly dissolved in the interdendritic areas. The hardness and wear resistance of Fe-based coatings were enhanced with the Cr3C2 and FeV50 addition. The specimen with 15% Cr3C2 and 16% FeV50 had the highest hardness of 66.1 ± 0.6 HRC, which was 1.05 times higher than the sample with 4.5% Cr3C2 and 5% FeV50, and the wear resistance of the former was three times greater than the latter.

  5. Role of butter layer in low-cycle fatigue behavior of modified 9Cr and CrMoV dissimilar rotor welded joint

    International Nuclear Information System (INIS)

    Wu, Qingjun; Lu, Fenggui; Cui, Haichao; Liu, Xia; Wang, Peng; Tang, Xinhua

    2014-01-01

    Highlights: • Modified 9Cr–CrMoV dissimilar turbine rotor was successfully welded by NG-SAW. • LCF properties of both welded joints were approximate at smaller strain amplitude. • Tempered martensite with amounts of carbides in HAZ contributed to weakest zones. • Matched BL determined LCF properties of whole joint for dissimilar welded rotor. - Abstract: The present work aims at studying the role of butter layer (BL) in low-cycle fatigue (LCF) behavior of modified 9Cr steel and CrMoV steel dissimilar welded joint. The significant difference of the chemical composition of base metals (BMs) makes it a challenge to achieve sound welded joint. Therefore, buttering was considered to obtain a transition layer between the dissimilar steels. The LCF tests of two kinds of specimens without and with butter layer were performed applying strain-controlled cyclic load with different axial strain amplitudes. The test results indicated that the number of cycles at higher strain amplitudes of welded joint without butter layer was greatly higher than that of the joint with butter layer, while the fatigue lifetime to crack initiation (2N f ) became closer to each other at low and middle strain amplitudes. The failure was in the tempered heat affected zone (HAZ) at the CrMoV side for specimens without BL, while the fracture occurred at the tempered HAZ in the BL for specimens with BL. The microstructure details of BM, BL, HAZ and weld metals (WMs) were revealed by optical microscopy (OM). It was found that the tempered martensite was major microstructure for welded joint and much more carbides were observed in tempered HAZ than other parts due to the repeated tempering. Microhardness test indicated a softest zone existing tempered HAZ of BL and also there was a softer zone in tempered HAZ at the CrMoV side due to repeated tempering during welding and post weld heat treatment (PWHT). And scanning electron microscopy (SEM) was applied to observe the fractography. It was

  6. Microstructure and Oxidation Behavior of CrAl Laser-Coated Zircaloy-4 Alloy

    Directory of Open Access Journals (Sweden)

    Jeong-Min Kim

    2017-02-01

    Full Text Available Laser coating of a CrAl layer on Zircaloy-4 alloy was carried out for the surface protection of the Zr substrate at high temperatures, and its microstructural and thermal stability were investigated. Significant mixing of CrAl coating metal with the Zr substrate occurred during the laser surface treatment, and a rapidly solidified microstructure was obtained. A considerable degree of diffusion of solute atoms and some intermetallic compounds were observed to occur when the coated specimen was heated at a high temperature. Oxidation appears to proceed more preferentially at Zr-rich region than Cr-rich region, and the incorporation of Zr into the CrAl coating layer deteriorates the oxidation resistance because of the formation of thermally unstable Zr oxides.

  7. Novel laser-processed CsI:Tl detector for SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Sabet, H., E-mail: hsabet@mgh.harvard.edu; Uzun-Ozsahin, D.; El-Fakhri, G. [Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02129 (United States); Bläckberg, L. [Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02129 and Department of Physics and Astronomy, Uppsala University, Uppsala 75120 (Sweden)

    2016-05-15

    Purpose: The aim of this work is to demonstrate the feasibility of a novel technique for fabrication of high spatial resolution CsI:Tl scintillation detectors for single photon emission computed tomography systems. Methods: The scintillators are fabricated using laser-induced optical barriers technique to create optical microstructures (or optical barriers) inside the CsI:Tl crystal bulk. The laser-processed CsI:Tl crystals are 3, 5, and 10 mm in thickness. In this work, the authors focus on the simplest pattern of optical barriers in that the barriers are created in the crystal bulk to form pixel-like patterns resembling mechanically pixelated scintillators. The monolithic CsI:Tl scintillator samples are fabricated with optical barrier patterns with 1.0 × 1.0 mm{sup 2} and 0.625 × 0.625 mm{sup 2} pixels. Experiments were conducted to characterize the fabricated arrays in terms of pixel separation and energy resolution. A 4 × 4 array of multipixel photon counter was used to collect the scintillation light in all the experiments. Results: The process yield for fabricating the CsI:Tl arrays is 100% with processing time under 50 min. From the flood maps of the fabricated detectors exposed to 122 keV gammas, peak-to-valley (P/V) ratios of greater than 2.3 are calculated. The P/V values suggest that regardless of the crystal thickness, the pixels can be resolved. Conclusions: The results suggest that optical barriers can be considered as a robust alternative to mechanically pixelated arrays and can provide high spatial resolution while maintaining the sensitivity in a high-throughput and cost-effective manner.

  8. Novel laser-processed CsI:Tl detector for SPECT

    International Nuclear Information System (INIS)

    Sabet, H.; Uzun-Ozsahin, D.; El-Fakhri, G.; Bläckberg, L.

    2016-01-01

    Purpose: The aim of this work is to demonstrate the feasibility of a novel technique for fabrication of high spatial resolution CsI:Tl scintillation detectors for single photon emission computed tomography systems. Methods: The scintillators are fabricated using laser-induced optical barriers technique to create optical microstructures (or optical barriers) inside the CsI:Tl crystal bulk. The laser-processed CsI:Tl crystals are 3, 5, and 10 mm in thickness. In this work, the authors focus on the simplest pattern of optical barriers in that the barriers are created in the crystal bulk to form pixel-like patterns resembling mechanically pixelated scintillators. The monolithic CsI:Tl scintillator samples are fabricated with optical barrier patterns with 1.0 × 1.0 mm"2 and 0.625 × 0.625 mm"2 pixels. Experiments were conducted to characterize the fabricated arrays in terms of pixel separation and energy resolution. A 4 × 4 array of multipixel photon counter was used to collect the scintillation light in all the experiments. Results: The process yield for fabricating the CsI:Tl arrays is 100% with processing time under 50 min. From the flood maps of the fabricated detectors exposed to 122 keV gammas, peak-to-valley (P/V) ratios of greater than 2.3 are calculated. The P/V values suggest that regardless of the crystal thickness, the pixels can be resolved. Conclusions: The results suggest that optical barriers can be considered as a robust alternative to mechanically pixelated arrays and can provide high spatial resolution while maintaining the sensitivity in a high-throughput and cost-effective manner.

  9. Determination of P, Cu, Cr, Va and Ti in samples of welded joint No.4 of Kozloduy-1 reactor pressure vessel; Opredelenie soderzhanya fosfora, medi, nikelya, khroma, vanadya i titana v struzhkakh 4 shva 1 bloka AEhS `Kozloduy`

    Energy Technology Data Exchange (ETDEWEB)

    Taskaev, E [Kombinat Atomna Energetika, Kozloduj (Bulgaria); Penev, I; Taskaeva, M [Bylgarska Akademiya na Naukite, Sofia (Bulgaria). Inst. za Yadrena Izsledvaniya i Yadrena Energetika; Aleksieva, L [Sofia Univ. (Bulgaria); Tsokov, P [Kombinat Atomna Energetika, Kozloduj (Bulgaria)

    1996-12-31

    An analysis of reactor steel composition has been carried out in 1989 in order to determine metal embrittlement. The samples consist of shavings taken at 3-4 mm depth from the 4-th welded joint of Unit 1 of the Kozloduy NPP. The shavings have been gradually dissolved in a mixture of acids and the solution evaporated. Quantitative analysis has been carried out by spectrophotometry and by ICP emission spectroscopy. The following element concentrations have been found: P - from 0.0462 to 0.052% by weight; Ni - 0.25 - 0.26% (passport data 0.29%); Cr - 1.47 - 1.54 (passport 1.58%); V - 0.1% (passport 0.15%); Cu - 0.11-0.13% (passport 0.12); Ti - 0.002. The data have been used to calculate metal embrittlement. 4 refs., 8 tabs.

  10. Improvement of the corrosion property of Cr4Mo4V bearing steel using plasma immersion ion implantation

    International Nuclear Information System (INIS)

    Wang, S.Y.; Chu, P.K.

    1997-01-01

    The working conditions of aerospace bearings such as engine bearings are quite harsh and prolonging the life span of these components is thus very important to the aerospace industry. Previous results have shown that the main failure mechanism of aerospace bearings is corrosion, and enhancing their corrosion resistance is a key. Cr4Mo4V, which is equivalent to AISI M50 bearing steel, is usually used in aerospace bearings in China. In this study, Cr4Mo4V components are treated in a new generation plasma immersion ion implanter in which ion implantation and sputter deposition can be carried out in the same chamber without breaking vacuum. Three treatment processes involving Cr, Mo, and N are evaluated. Our test results indicate that Cr is the main element enhancing the corrosion resistance and the addition of nitrogen improves the properties further. The non line-of-sight advantage of PIII is important to the processing of complex-shaped samples such as engine bearings. (orig.)

  11. Laser beam welding of Waspaloy: Characterization and corrosion behavior evaluation

    Science.gov (United States)

    Shoja Razavi, Reza

    2016-08-01

    In this work, a study on Nd:YAG laser welding of Waspaloy sheets has been made. Microstructures, phase changes and hardness of the laser joint were investigated using optical microscopy, scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD) and vickers microhardness (HV0.3). Corrosion behavior of the weldment at low temperature in 3.5%wt NaCl solution at room temperature was also investigated using open circuit potential and cyclic potentiodynamic polarization tests. Hot corrosion studies were conducted on samples in the molten salt environment (Na2SO4-60%V2O5) at 900 °C for 50 h. Results indicated that the microstructure of weld zone was mainly dendritic grown epitaxially in the direction perpendicular to the weld boundary and heat transfer. Moreover, the Ti-Mo carbide particles were observed in the structure of the weld zone and base metal. The average size of carbides formed in the base metal (2.97±0.5 μm) was larger than that of the weld zone (0.95±0.2 μm). XRD patterns of the weld zone and base metal showed that the laser welding did not alter the phase structure of the weld zone, being in γ-Ni(Cr) single phase. Microhardness profile showed that the hardness values of the weld zone (210-261 HV) were lower than that of the base metal (323-330 HV). Electrochemical and hot corrosion tests indicated that the corrosion resistance of the weld metal was greater than the base metal in both room and high temperatures.

  12. Structure-property investigations on a laser beam welded dissimilar joint of aluminium AA6056 and titanium Ti6Al4V for aeronautical applications. Part II: resistance to fatigue crack propagation and fracture

    Energy Technology Data Exchange (ETDEWEB)

    Horstmann, M.; Ventzke, V.; Petrovski, B.; Kocak, M. [GKSS Research Centre Geesthacht, Institute of Materials Research, Materials Mechanics, Geesthacht (Germany); Kocik, R.; Tempus, G. [AIRBUS Deutschland GmbH, Metal Technology, Bremen (Germany); Vaidya, W.V.

    2009-10-15

    Investigations were continued on the dissimilar laser beam welds of AA6056 and Ti6Al4V, fabricated by inserting Ti-sheet into the profiled Al-sheet and melting AA6056 alone. By using microstructure, hardness and strength as the criteria, sites exhibiting non-uniform microstructure and localized plastic deformation due to strength mismatch were investigated in two orientations: crack parallel to the weld and crack perpendicular to the weld for fatigue crack propagation and fracture toughness at room temperature. Effect of temper of AA6056 on these properties was studied for two conditions; welding in T4 followed by post weld heat treatment T6, and welding in T6 and naturally aged for a defined period. The orientation ''crack parallel to the weld'' was investigated in 3 locations on the side of AA6056: the interface and the two changeovers on the Al-side. Firstly, between the fusion zone and the heat affected zone (3 mm from the interface) and secondly, between (primary) heat affected zone and towards the base material (7 mm from the interface). Although brittle intermetallic TiAl{sub 3} had been formed at the interface, uncontrolled separation or debonding at the interface was not observed. Insofar the bond quality of the weld was good. However, the ranking of interface was the lowest since fatigue crack propagation was relatively faster than that in the fusion zone and heat affected zone, and fracture toughness was low. Therefore, unstable fatigue crack propagation is observed when the crack propagates perpendicular to the weld from AA6056 towards Ti6Al4V. The results have shown that the dissimilar joints exhibit improved performance when laser beam welded in the T6 condition. (Abstract Copyright [2009], Wiley Periodicals, Inc.) [German] Teil II: Widerstand gegen Ermuedungsrissausbreitung und Bruch Die Untersuchungen an der laserstrahlgeschweissten Mischverbindung aus AA6056 und Ti6Al4V wurden fortgesetzt. Fuer die Ermuedungsrissausbreitungs

  13. Effect of laser absorption on picosecond laser ablation of Cr12MoV mold steel, 9Cr18 stainless steel and H13A cemented carbide

    Science.gov (United States)

    Wu, Baoye; Liu, Peng; Wang, Xizhao; Zhang, Fei; Deng, Leimin; Duan, Jun; Zeng, Xiaoyan

    2018-05-01

    Due to excellent properties, Cr12MoV mold steel, 9Cr18 stainless steel and H13A cemented carbide are widely used in industry. In this paper, the effect of absorption of laser light on ablation efficiency and roughness have been studied using a picosecond pulse Nd:YVO4 laser. The experimental results reveal that laser wavelength, original surface roughness and chemical composition play an important role in controlling ablation efficiency and roughness. Firstly, higher ablation efficiency with lower surface roughness is achieved on the ablation of 9Cr18 at 532, comparing with 1064 nm. Secondly, the ablation efficiency increases while the Ra of the ablated region decreases with the decrease of original surface roughness on ablation of Cr12MoV mold steel at 532 nm. Thirdly, the ablation efficiency of H13A cemented carbide is much higher than 9Cr18 stainless steel and Cr12MoV mold steel at 1064 nm. Scanning electron microscopy images reveals the formation of pores on the surface of 9Cr18 stainless steel and Cr12MoV mold steel at 532 nm while no pores are formed at 1064 nm. As to H13A cemented carbide, worm-like structure is formed at 1064 nm. The synergetic effects of the heat accumulation, plasma shielding and ablation threshold on laser ablation efficiency and machining quality were analyzed and discussed systematically in this paper.

  14. Effect on fast neutron irradiation to 4 dpa at 400{degrees}C on the properties of V-(4-5)Cr-(4-5)Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J.; Alexander, D.J.; Robertson, J.P. [Oak Ridge National Lab., TN (United States)] [and others

    1997-04-01

    Tensile, Charpy impact and electrical resistivity measurements have been performed at ORNL on V-4Cr-4Ti and V-5Cr-5Ti specimens that were prepared at ANL and irradiated in the lithium-bonded X530 experiment in the EBR-II fast reactor. All of the specimens were irradiated to a damage level of about 4 dpa at a temperature of {approximately}400{degrees}C. A significant amount of radiation hardening was evident in both the tensile and Charpy impact tests. The irradiated V-4Cr-4Ti yield strength measured at {approximately}390{degrees}C was >800 MPa, which is more than three times as high as the unirradiated value. The uniform elongations of the irradiated tensile specimens were typically {approximately}1%, with corresponding total elongations of 4-6%. The ductile to brittle transition temperature of the irradiated specimens was less than the unirradiated resistivity, which suggests that hardening associated with interstitial solute pickup was minimal.

  15. Hydrogen release from irradiated vanadium alloy V-4Cr-4Ti

    Energy Technology Data Exchange (ETDEWEB)

    Klepikov, A.Kh. E-mail: klepikov@ietp.alma-ata.su; Romanenko, O.G.; Chikhray, Y.V.; Tazhibaeva, I.L.; Shestakov, V.P.; Longhurst, G.R. E-mail: gxl@inel.gov

    2000-11-01

    The present work is an attempt to obtain data concerning the influence of neutron and {gamma} irradiation upon hydrogen retention in V-4Cr-4Ti vanadium alloy. The experiments on in-pile loading of vanadium alloy specimens at the neutron flux density 10{sup 14} n/cm{sup 2} s, hydrogen pressure of 80 Pa, and temperatures of 563, 613 and 773 K were carried out using the IVG.1M reactor of the Kazakhstan National Nuclear Center. A preliminary set of loading/degassing experiments with non-irradiated material has been carried out to obtain data on hydrogen interaction with vanadium alloy. The, data presented in this work are related both to non-irradiated and irradiated samples.

  16. Hydrogen release from irradiated vanadium alloy V-4Cr-4Ti

    International Nuclear Information System (INIS)

    Klepikov, A.Kh.; Romanenko, O.G.; Chikhray, Y.V.; Tazhibaeva, I.L.; Shestakov, V.P.; Longhurst, G.R.

    2000-01-01

    The present work is an attempt to obtain data concerning the influence of neutron and γ irradiation upon hydrogen retention in V-4Cr-4Ti vanadium alloy. The experiments on in-pile loading of vanadium alloy specimens at the neutron flux density 10 14 n/cm 2 s, hydrogen pressure of 80 Pa, and temperatures of 563, 613 and 773 K were carried out using the IVG.1M reactor of the Kazakhstan National Nuclear Center. A preliminary set of loading/degassing experiments with non-irradiated material has been carried out to obtain data on hydrogen interaction with vanadium alloy. The, data presented in this work are related both to non-irradiated and irradiated samples

  17. The Effect of Friction Stir Welding on Corrosion Behavior of Ti-6Al-4V

    Science.gov (United States)

    Nasresfahani, Ali Reza; Soltanipur, Abdol Reza; Farmanesh, Khosro; Ghasemi, Ali

    2017-09-01

    Fusion welding can deteriorate corrosion behavior of Ti-6Al-4V alloy. However, the use of friction stir welding leads to a more appropriate corrosion resistance. In this study, the corrosion resistance of welded zones of Ti-6Al-4V alloy using friction stir welding technique is evaluated. For these purposes, the study of structural characteristics using SEM and FESEM equipped with EDS micro-analyses was conducted. Micro-hardness test was also employed to estimate the hardness of welded zones. Corrosion behavior was investigated by a potentiostat instrument. SEM micrographs, EDS and XRD analyses confirmed non-uniformity of chemical composition within the welded zones. The results reveal that the stir zone contains typical alpha and prior beta phases. Nevertheless, thermomechanical zone included equiaxed and bimodal lamellae structure. Furthermore, the presence of different types of phases and microstructure in the thermomechanical zone led to reduced corrosion resistance. The corresponding values of corrosion current density in the stir zone, thermomechanical zone and base metal were 0.048, 0.55 and 0.032 µA, respectively. Corresponding corrosion potential for these zones was estimated as -207, -110 and -157 mV. Evidently, the results show that corrosion resistance of thermomechanical zone is less than that of the stir zone and both zones have lower value than the base metal.

  18. High-Pressure Phase Relations and Crystal Structures of Postspinel Phases in MgV2O4, FeV2O4, and MnCr2O4: Crystal Chemistry of AB2O4 Postspinel Compounds.

    Science.gov (United States)

    Ishii, Takayuki; Sakai, Tsubasa; Kojitani, Hiroshi; Mori, Daisuke; Inaguma, Yoshiyuki; Matsushita, Yoshitaka; Yamaura, Kazunari; Akaogi, Masaki

    2018-06-04

    We have investigated high-pressure, high-temperature phase transitions of spinel (Sp)-type MgV 2 O 4 , FeV 2 O 4 , and MnCr 2 O 4 . At 1200-1800 °C, MgV 2 O 4 Sp decomposes at 4-7 GPa into a phase assemblage of MgO periclase + corundum (Cor)-type V 2 O 3 , and they react at 10-15 GPa to form a phase with a calcium titanite (CT)-type structure. FeV 2 O 4 Sp transforms to CT-type FeV 2 O 4 at 12 GPa via decomposition phases of FeO wüstite + Cor-type V 2 O 3 . MnCr 2 O 4 Sp directly transforms to the calcium ferrite (CF)-structured phase at 10 GPa and 1000-1400 °C. Rietveld refinements of CT-type MgV 2 O 4 and FeV 2 O 4 and CF-type MnCr 2 O 4 confirm that both the CT- and CF-type structures have frameworks formed by double chains of edge-shared B 3+ O 6 octahedra (B 3+ = V 3+ and Cr 3+ ) running parallel to one of orthorhombic cell axes. A relatively large A 2+ cation (A 2+ = Mg 2+ , Fe 2+ , and Mn 2+ ) occupies a tunnel-shaped space formed by corner-sharing of four double chains. Effective coordination numbers calculated from eight neighboring oxygen-A 2+ cation distances of CT-type MgV 2 O 4 and FeV 2 O 4 and CF-type MnCr 2 O 4 are 5.50, 5.16, and 7.52, respectively. This implies that the CT- and CF-type structures practically have trigonal prism (six-coordinated) and bicapped trigonal prism (eight-coordinated) sites for the A 2+ cations, respectively. A relationship between cation sizes of VIII A 2+ and VI B 3+ and crystal structures (CF- and CT-types) of A 2+ B 2 3+ O 4 is discussed using the above new data and available previous data of the postspinel phases. We found that CF-type A 2+ B 2 3+ O 4 crystallize in wide ionic radius ranges of 0.9-1.4 Å for VIII A 2+ and 0.55-1.1 Å for VI B 3+ , whereas CT-type phases crystallize in very narrow ionic radius ranges of ∼0.9 Å for VIII A 2+ and 0.6-0.65 Å for VI B 3+ . This would be attributed to the fact that the tunnel space of CT-type structure is geometrically less flexible due to the smaller coordination

  19. Effects of irradiation at low temperature on V-4Cr-4Ti

    International Nuclear Information System (INIS)

    Alexander, D.J.; Snead, L.L.; Zinkle, S.J.

    1996-01-01

    Irradiation at low temperatures (100 to 275 degrees C) to 0.5 dpa causes significant embrittlement and changes in the subsequent room temperature tensile properties of V-4Cr-4Ti. The yield strength and microhardness at room temperature increase with increasing irradiation temperature. The tensile flow properties at room temperature show large increases in strength and a complete loss of work hardening capacity with no uniform ductility. Embrittlement, as measured by an increase in the ductile-to-brittle transition temperature, increases with increasing irradiation temperature, at least up to 275 degrees C. This embrittlement is not due to pickup of O or other interstitial solutes during the irradiation

  20. Effects of irradiation at low temperature on V-4Cr-4Ti

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, D.J.; Snead, L.L.; Zinkle, S.J. [Oak Ridge National Lab., TN (United States)] [and others

    1996-10-01

    Irradiation at low temperatures (100 to 275{degrees}C) to 0.5 dpa causes significant embrittlement and changes in the subsequent room temperature tensile properties of V-4Cr-4Ti. The yield strength and microhardness at room temperature increase with increasing irradiation temperature. The tensile flow properties at room temperature show large increases in strength and a complete loss of work hardening capacity with no uniform ductility. Embrittlement, as measured by an increase in the ductile-to-brittle transition temperature, increases with increasing irradiation temperature, at least up to 275{degrees}C. This embrittlement is not due to pickup of O or other interstitial solutes during the irradiation.

  1. Systems Tl2MoO4-E(MoO4)2, where E=Zr or Hf, and the crystal structure of Tl8Hf(MoO4)6

    International Nuclear Information System (INIS)

    Bazarov, B.G.; Bazarova, Ts.T.; Fedorov, K.N.; Bazarova, Zh.G.; Chimitova, O.D.; Klevtsova, R.F.; Glinskaya, L.A.

    2006-01-01

    Systems Tl 2 MoO 4 -E(MoO 4 ) 2 (E=Zr, Hf) were studied by X-ray diffraction, differential thermal analysis and IR spectroscopy. Formation of Tl 8 E(MoO 4 ) 6 and Tl 2 E(MoO 4 ) 2 compounds was established. Phase T-x diagrams of the Tl 2 MoO 4 -Zr(MoO 4 ) 2 system were constructed. Monocrystals were grown, and structure of Tl 8 Hf(MoO 4 ) 6 was studied. The compound is crystallized in monoclinic syngony with elementary cell parameters a=9.9688(6), b=18.830(1), c=7.8488(5) A, β=108.538(1) Deg, Z=2, sp. gr. C2/m. The isolated group [HfMo 6 O 24 ] 8- is responsible for fundamental fragment of the structure. Three varieties of crystallographically independent Tl-polyhedra fill space evenly between fragments [HfMo 6 O 24 ] 8- forming three-dimensional form [ru

  2. Microstructural changes of Y-doped V-4Cr-4Ti alloys after ion and neutron irradiation

    Directory of Open Access Journals (Sweden)

    H. Watanabe

    2016-12-01

    Full Text Available High-purity Y-doped V-4Cr-4Ti alloys (0.1–0.2wt. % Y, manufactured by the National Institute for Fusion Science (NIFS, were used for this study. Heavy-ion and fission-neutron irradiation was carried out at temperatures 673–873K. During the ion irradiation at 873K, the microstructure was controlled by the formation of Ti(C,O,N precipitates lying on the (100 plane. Y addition effectively suppressed the growth of Ti(C,O,N precipitates, especially at lower dose irradiation to up to 4 dpa. However, at higher dose levels (12.0 dpa, the number density was almost at the same levels irrespective of the presence of Y. After neutron irradiation at 873K, fine titanium oxides were also observed in all V alloys. However, smaller oxide sizes were observed in the Y-doped samples under the same irradiation conditions. The detailed analysis of EDS showed that the center of the Ti(C,O,N precipitates was mainly enriched by nitrogen. The results showed that the contribution of not only oxygen atoms picked up from the irradiation environment but also nitrogen atoms is essential to understand the microstructural evolution of V-4Cr-4Ti-Y alloys.

  3. Microstructural Evolution in Friction Stir Welding of Ti-6Al-4V

    Science.gov (United States)

    Rubisoff, H.; Querin, J.; Magee, D.; Schneider, J.

    2008-01-01

    Friction stir welding (FSW) is a thermo-mechanical process that utilizes a nonconsumable rotating pin tool to consolidate a weld joint. In the conventional FSW process, the pin tool is responsible for generating both the heat required to soften the material and the forces necessary to deform and combine the weld seam. As such, the geometry of the pin tool is important to the quality of the weld and the process parameters required to produce the weld. Because the geometry of the pin tool is limitless, a reduced set of pin tools was formed to systematically study their effect on the weldment with respect to mechanical properties and resultant microstructure. In this study 0deg, 15deg, 30deg, 45deg, and 60deg tapered, microwave sintered, tungsten carbide (WC) pin tools were used to FSW Ti-6Al-4V. Transverse sections of the weld were used to test for mechanical properties and to document the microstructure using optical microscopy. X-ray diffraction (XRD) was also used to characterize the microstructure in the welds. FSW results for the 45deg and 60deg pin tools are reported in this paper.

  4. Creep properties and simulation of weld repaired low alloy heat resistant CrMo and Mo steels at 540 deg C. Sub project 1 - Ex-serviced parent metal and virgin weld metals

    Energy Technology Data Exchange (ETDEWEB)

    Rui Wu; Storesund, Jan; Borggreen, Kjeld; Weilin Zang

    2006-10-15

    Many existing power generating and process plants, where low alloy heat resistant CrMo(V) steels are extensively used for critical components, have exceeded their design lifetime of usually 100,000 hours. Assessment of residual lifetime and extension of economic life by weld repair have become increasingly important and attractive. This project aims at i) performing weld repair and determining the degree of mismatching, ii) evaluating the creep properties of weld repairs, iii) analysing creep behaviour of weld repair and providing necessary data for further reliable simulations of weld repair creep behaviour in long term service, and iv), simulating and assessing lifetime and creep damage evolution of weld repair. Weld repair using 10 CrMo 9 10, 13 CrMo 4 4 and 15 Mo 3 consumables has been carried out in a service-exposed 10 CrMo 9 10 pipe. Creep specimens have been extracted from the service-exposed 10 CrMo 9 10 parent metal (PM), from the virgin 10 CrMo 9 10 weld metal (WM), from the virgin 13 CrMo 4 4 WM as well as from the virgin 15 Mo 3 WM. Iso-thermal uniaxial creep tests have been performed at 540 deg C in air. Pre- and post-metallography are carried out on the selected samples. FEM simulations using obtained creep data are executed. Pre-test metallography shows normal and acceptable weld repairs at given welding conditions. Creep tests demonstrate that the virgin 10 CrMo 9 10, 13 CrMo 4 4 and 15 Mo 3 WMs have apparently longer creep lifetime than the service-exposed CrMo 9 10 PM at higher stresses than 110 MPa. Among the weld metals, the longest creep lifetime is found in 10 CrMo 9 10. Higher creep strength and lower creep strain rate in the weld metals indicate an overmatch weld. At 95 MPa, however, lifetime of 13 CrMo 4 4 WM is surprisingly short (factors which may shorten lifetime are discussed and one more test will start to verify creep strength at low stress) and tests are still running for other two weld metals. More results regarding low stress

  5. Microstructure of V-4Cr-4Ti alloy after low-temperature irradiation by ions and neutrons

    International Nuclear Information System (INIS)

    Gazda, J.; Meshii, M.; Chung, H.M.

    1998-01-01

    Mechanical properties of V-4Cr-4Ti alloy were investigated after low-temperature ( ++ ) and dual ion beams (350-keV He + simultaneously with 4.5-MeV Ni ++ ). TEM observations showed the formation of a high density of point-defect clusters and dislocation loops (<30 nm diameter) distributed uniformly in the specimens. Mechanical-property testing showed embrittlement of the alloy. TEM investigations of deformed microstructures were used to determine the causes of embrittlement and yielded observation of dislocation channels propagating through the undeformed matrix. Channels are the sole slip paths and cause early onset of necking and loss of work-hardening in this alloy. Based on a review of the available literature, suggestions are made for further research of slip localization in V-base alloys

  6. Effect of trace solute hydrogen on the fatigue life of electron beam welded Ti-6Al-4V alloy joints

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Junhui; Hu, Shubing, E-mail: 187352581@qq.com; Ji, Longbo

    2017-01-27

    This paper describes an experimental hydrogenating treatment on a Ti-6Al-4V fatigue specimen containing an electron beam welding joint. The effect of trace solute hydrogen on the microstructures and fatigue behavior of welded Ti-6Al-4V alloy joints was investigated using an optical microscope, X-ray diffractometer, scanning electron microscope, transmission electron microscope and other methodologies. The results demonstrated that no hydride formed in the hydrogenated weld joint at a hydrogen concentration of less than 0.140 wt%. Internal hydrogen, which was present in the alloy in the form of solid solution atoms, caused lattice distortion in the β phase. The fatigue properties of the Ti-6Al-4V weld joint hydrogenated with trace solute hydrogen decreased significantly. The solute hydrogen led to an increase in the brittleness of the hydrogenated weld joint. The dislocation densities in the secondary α and β phase were higher. Fatigue cracks nucleated at the α/β interfaces. The effect of solute hydrogen accelerated the separation of the persistent slip bands, which decreased the threshold required for fatigue crack growth. Solute hydrogen also accelerated the fatigue crack growth rate. These two factors contributed to the degradation of the fatigue life in the electron beam welded Ti-6Al-4V alloy joints.

  7. Comparison between pulsed Nd:YAG laser superficial treatment and ceramic coating in creep test of Ti-6Al-4V alloy

    International Nuclear Information System (INIS)

    Reis, A.G.; Reis, D.A.P.; Moura Neto, C.; Oliveira, H.S.; Couto, A.A.

    2009-01-01

    The objective of this work was evaluating the creep resistance of the Ti-6Al-4V alloy with superficial treatment of pulsed Nd:YAG laser and ceramic coating in creep test of Ti-6Al-4V alloy. It was used Ti-6Al-4V alloy as cylindrical bars under forged and annealing of 190 deg C by 6 hours condition and cooled by air. The Ti-6Al-4V alloy after the superficial treatment of pulsed Nd:YAG laser and ceramic coating was submitted to creep tests at 600°C and 125 at 319 MPa, under constant load mode. In the Nd:YAG pulsed laser treatment was used an environment of 40 % N and 60 % Ar, with 2.1 W of power and 10 m/s of speed. Yttria (8 wt.%) stabilized zirconia (YSZ) with a CoNiCrAlY bond coat was atmospherically plasma sprayed on Ti-6Al-4V substrates by Sulzer Metco Type 9 MB. The obtained results suggest the laser treatment on Ti-6Al-4V alloy improved its creep resistance. (author)

  8. High-pressure single-crystal X-ray diffraction of Tl2SeO4

    International Nuclear Information System (INIS)

    Grzechnik, Andrzej; Breczewski, Tomasz; Friese, Karen

    2008-01-01

    The effect of pressure on the crystal structure of thallium selenate (Tl 2 SeO 4 ) (Pmcn, Z=4), containing the Tl + cations with electron lone pairs, has been studied with single-crystal X-ray diffraction in a diamond anvil cell up to 3.64 GPa at room temperature. No phase transition has been observed. The compressibility data are fitted by a Murnaghan equation of state with the zero-pressure bulk modulus B 0 =29(1) GPa and the unit-cell volume at ambient pressure V 0 =529.6(8) A 3 (B'=4.00). Tl 2 SeO 4 is the least compressible in the c direction, while the pressure-induced changes of the a and b lattice parameters are quite similar. These observations can be explained by different pressure effects on the nine- and 11-fold coordination polyhedra around the two non-equivalent Tl atoms. The SeO 4 2- tetrahedra are not rigid units and become more distorted. Their contribution to the compressibility is small. The effect of pressure on the isotypical oxide materials A 2 TO 4 with the β-K 2 SO 4 structure is discussed. It appears that the presence of electron lone pairs on the Tl + cation does not seem to influence the compressibility of Tl 2 SeO 4 . - Graphical abstract: Pressure dependence of normalized lattice parameters and unit-cell volumes in Tl 2 SeO 4 (Pmcn, Z=4). The solid line is the Murnaghan equation of state

  9. Effect of Pulse Laser Welding Parameters and Filler Metal on Microstructure and Mechanical Properties of Al-4.7Mg-0.32Mn-0.21Sc-0.1Zr Alloy

    Directory of Open Access Journals (Sweden)

    Irina Loginova

    2017-12-01

    Full Text Available The effect of pulse laser welding parameters and filler metal on microstructure and mechanical properties of the new heat-treatable, wieldable, cryogenic Al-4.7Mg-0.32Mn-0.21Sc-0.1Zr alloy were investigated. The optimum parameters of pulsed laser welding were found. They were 330–340 V in voltage, 0.2–0.25 mm in pulse overlap with 12 ms duration, and 2 mm/s speed and ramp-down pulse shape. Pulsed laser welding without and with Al-5Mg filler metal led to the formation of duplex (columnar and fine grains as-cast structures with hot cracks and gas porosity as defects in the weld zone. Using Al-5Ti-1B filler metal for welding led to the formation of the fine grain structure with an average grain size of 4 ± 0.2 µm and without any weld defects. The average concentration of Mg is 2.8%; Mn, 0.2%; Zr, 0.1%; Sc, 0.15%; and Ti, 2.1% were formed in the weld. The ultimate tensile strength (UTS of the welded alloy with AlTiB was 260 MPa, which was equal to the base metal in the as-cast condition. The UTS was increased by 60 MPa after annealing at 370 °C for 6 h that was 85% of UTS of the base alloy.

  10. Welding repair of the high-intermediate pressure steam casings made of Cr-Mo and Cr-Mo-V steel

    International Nuclear Information System (INIS)

    Mazur, Z.; Cristalinas, V.; Kubiak, J.

    1996-01-01

    An analysis of typical failure causes and their location at high-intermediate pressure steam turbine casing, and weldability analysis of the Cr-Mo and Cr-Mo-V steels, is carried out. basing on the steam turbine of 158 MW capacity, the internal high pressure casing failures and development of in situ repair welding technology is described. After repair, the casing was put back into service

  11. Survey of welding processes for field fabrication of 2 1/4 Cr-1 Mo steel pressure vessels. [128 references

    Energy Technology Data Exchange (ETDEWEB)

    Grotke, G.E.

    1980-04-01

    Any evaluation of fabrication methods for massive pressure vessels must consider several welding processes with potential for heavy-section applications. These include submerged-arc and shielded metal-arc, narrow-joint modifications of inert-gas metal-arc and inert-gas tungsten-arc processes, electroslag, and electron beam. The advantage and disadvantages of each are discussed. Electroslag welding can be dropped from consideration for joining of 2 1/4 Cr-1 Mo steel because welds made with this method do not provide the required mechanical properties in the welded and stress relieved condition. The extension of electron-beam welding to sections as thick as 4 or 8 inches (100 or 200 mm) is too recent a development to permit full evaluation. The manual shielded metal-arc and submerged-arc welding processes have both been employed, often together, for field fabrication of large vessels. They have the historical advantage of successful application but present other disadvantages that make them otherwise less attractive. The manual shielded metal-arc process can be used for all-position welding. It is however, a slow and expensive technique for joining heavy sections, requires large amounts of skilled labor that is in critically short supply, and introduces a high incidence of weld repairs. Automatic submerged-arc welding has been employed in many critical applications and for welding in the flat position is free of most of the criticism that can be leveled at the shielded metal-arc process. Specialized techniques have been developed for horizontal and vertical position welding but, used in this manner, the applications are limited and the cost advantage of the process is lost.

  12. Study of the impact of treatment modes on hardness, deformability and microstructure of VT6 (Ti-6Al-4V and VV751P (Ni-15Co-10Cr alloy samples after selective laser sintering

    Directory of Open Access Journals (Sweden)

    Galkina Natalia V.

    2017-01-01

    Full Text Available Selective laser sintering is an advanced method for obtaining sophisticated products and assembly permanent joints. This is particularly relevant for heat resistant alloys employed in aviation equipment. Heat treatment modes traditionally applied to the products are chosen in accordance with conditions of further product operation. In this paper there are given the results of experimental study of hardness, deformability and microstructure of samples after selective laser sintering of Ni-15Co-10Cr and Ti–6Al–4V alloy powders. It has been determined that Ni-15Co-10Cr alloy ageing increases the hardness and deformability of samples; these characteristics decrease if the ageing lasts for 9-19 hours. Annealing of Ti–6Al–4V alloy samples results in preserving original hardness. After complete annealing, the hardness of samples decreases from 32 … 33HRC to 24 … 26HRC. Microstructural studies showed that there are cracks between layers in the surface of Ti–6Al–4V alloy samples after sintering and not complete annealing. After full annealing, cracks' width and length decreased. Cracks in Ni-15Co-10Cr alloy samples' microstructure were not detected.

  13. The effects of microhardnesses and friction coefficients of GCr15 and Cr4Mo4V bearing materials by ion implantation

    International Nuclear Information System (INIS)

    Yang Qifa; Xiang Deguang; Lu Haolin

    1988-01-01

    Some experimental results of microhardnesses and friction coefficients of GCr15 and Cr4Mo4V bearing materials which were implanted with Cr, Mo, N and B ions are reported in this paper. It is found that the microhardnesses are increased and the friction coefficients are reduced by Cr, Mo, N and B ion implantation for two materials. The friction coefficients of Cr + Mo + N , Cr + Mo + B ion implanted samples are reduced to 1/3 of the unimplanted samples

  14. Laser Welding-Brazing of Immiscible AZ31B Mg and Ti-6Al-4V Alloys Using an Electrodeposited Cu Interlayer

    Science.gov (United States)

    Zhang, Zequn; Tan, Caiwang; Wang, Gang; Chen, Bo; Song, Xiaoguo; Zhao, Hongyun; Li, Liqun; Feng, Jicai

    2018-03-01

    Metallurgical bonding between immiscible system AZ31B magnesium (Mg) and Ti-6Al-4V titanium (Ti) was achieved by adding Cu interlayer using laser welding-brazing process. Effect of the laser power on microstructure evolution and mechanical properties of Mg/Cu-coated Ti joints was studied. Visually acceptable joints were obtained at the range of 1300 to 1500 W. The brazed interface was divided into three parts due to temperature gradient: direct irradiation zone, intermediate zone and seam head zone. Ti3Al phase was produced along the interface at the direct irradiation zone. Ti-Al reaction layer grew slightly with the increase in laser power. A small amount of Ti2(Cu,Al) interfacial compounds formed at the intermediate zone and the ( α-Mg + Mg2Cu) eutectic structure dispersed in the fusion zone instead of gathering when increasing the laser power at this zone. At the seam head zone, Mg-Cu eutectic structure was produced in large quantities under all cases. Joint strength first increased and then decreased with the variation of the laser power. The maximum fracture load of Mg/Cu-coated Ti joint reached 2314 N at the laser power of 1300 W, representing 85.7% joint efficiency when compared with Mg base metal. All specimens fractured at the interface. The feature of fracture surface at the laser power of 1100 W was characterized by overall smooth surface. Obvious tear ridge and Ti3Al particles were observed at the fracture surface with increase in laser power. It suggested atomic diffusion was accelerated with more heat input giving rise to the enhanced interfacial reaction and metallurgical bonding in direct irradiation zone, which determined the mechanical properties of the joint.

  15. Phase diagrams of novel Tl{sub 4}SnSe{sub 4}–TlSbSe{sub 2}–Tl{sub 2}SnSe{sub 3} quasi-ternary system following DTA and X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Barchiy, I.E.; Tatzkar, A.R. [Department of Chemistry, Uzhgorod National University, Pidgirna St., 46, Uzhgorod 88000 (Ukraine); Fedorchuk, A.O. [Department of Inorganic and Organic Chemistry, Lviv National University of Veterinary Medicine and Biotechnologies, Pekarska St., 50, Lviv 79010 (Ukraine); Plucinski, K., E-mail: kpluc2006@wp.pl [Electronics Department, Military University Technology, Warsaw, Kaliskiego 2, Warsaw 00-908 (Poland)

    2016-06-25

    Phase relation in the Tl{sub 4}SnSe{sub 4}–TlSbSe{sub 2}–Tl{sub 2}SnSe{sub 3} quasiternary system were studied by the DTA and X-ray diffraction in combination with mathematical modeling. The phase diagrams of the Tl{sub 4}SnSe{sub 4}–TlSbSe{sub 2} and Tl{sub 2}SnSe{sub 3}–TlSbSe{sub 2} systems, the perspective views of the phase interaction in the ternary system, the liquidus surface projection, the isothermal section at 423 K were built for the first time. The Tl{sub 4}SnSe{sub 4}–TlSbSe{sub 2}–Tl{sub 2}SnSe{sub 3} system is of the invariant eutectic type and is characterized by the formation of limited solid solutions following initial ternary compounds. New complex compounds are not formed. - Highlights: • Two Tl{sub 4}SnSe{sub 4}–TlSbSe{sub 2},Tl{sub 2}SnSe{sub 3}–TlSbSe{sub 2} systems were explored. • Invariant processes in the ternary system were determined. • New complex compounds were not observed in ternary system.

  16. Type IIIa cracking at 2CrMo welds in 1/2CrMoV pipework

    Energy Technology Data Exchange (ETDEWEB)

    Brett, S J; Smith, P A [National Power plc, Swindon (United Kingdom)

    1999-12-31

    The most common form of in-service defect found today on the welds of National Power`s 1/2CrMoV pipework systems is Type IV cracking which occurs in intercritically transformed material at the edge of the heat affected zone. However an alternate form of cracking, termed IIIa, which occurs close to the weld fusion line in fully grain refined heat affected zones, has also been observed. The incidence of Type IIIa cracking has increased in recent years and these defects now constitute a significant part of the total recorded crack population. This presentation describes Type IIIa cracking and compares and contrasts it with the better documented Type IV cracking. Particular reference is made to the role of carbon diffusion at the weld fusion line in promoting Type IIIa damage in preference to Type IV. (orig.) 5 refs.

  17. Type IIIa cracking at 2CrMo welds in 1/2CrMoV pipework

    Energy Technology Data Exchange (ETDEWEB)

    Brett, S.J.; Smith, P.A. [National Power plc, Swindon (United Kingdom)

    1998-12-31

    The most common form of in-service defect found today on the welds of National Power`s 1/2CrMoV pipework systems is Type IV cracking which occurs in intercritically transformed material at the edge of the heat affected zone. However an alternate form of cracking, termed IIIa, which occurs close to the weld fusion line in fully grain refined heat affected zones, has also been observed. The incidence of Type IIIa cracking has increased in recent years and these defects now constitute a significant part of the total recorded crack population. This presentation describes Type IIIa cracking and compares and contrasts it with the better documented Type IV cracking. Particular reference is made to the role of carbon diffusion at the weld fusion line in promoting Type IIIa damage in preference to Type IV. (orig.) 5 refs.

  18. An empirical-statistical model for laser cladding of Ti-6Al-4V powder on Ti-6Al-4V substrate

    Science.gov (United States)

    Nabhani, Mohammad; Razavi, Reza Shoja; Barekat, Masoud

    2018-03-01

    In this article, Ti-6Al-4V powder alloy was directly deposited on Ti-6Al-4V substrate using laser cladding process. In this process, some key parameters such as laser power (P), laser scanning rate (V) and powder feeding rate (F) play important roles. Using linear regression analysis, this paper develops the empirical-statistical relation between these key parameters and geometrical characteristics of single clad tracks (i.e. clad height, clad width, penetration depth, wetting angle, and dilution) as a combined parameter (PαVβFγ). The results indicated that the clad width linearly depended on PV-1/3 and powder feeding rate had no effect on it. The dilution controlled by a combined parameter as VF-1/2 and laser power was a dispensable factor. However, laser power was the dominant factor for the clad height, penetration depth, and wetting angle so that they were proportional to PV-1F1/4, PVF-1/8, and P3/4V-1F-1/4, respectively. Based on the results of correlation coefficient (R > 0.9) and analysis of residuals, it was confirmed that these empirical-statistical relations were in good agreement with the measured values of single clad tracks. Finally, these relations led to the design of a processing map that can predict the geometrical characteristics of the single clad tracks based on the key parameters.

  19. Investigation of TL, OSL and PTTL properties of Mg2SiO4:Tb dosimeters

    International Nuclear Information System (INIS)

    Oguz, K. F.; Goekce, M.; Karali, T.; Harmansah, C.

    2010-01-01

    In this study thermoluminescence (TL) and optically stimulated luminescence (OSL) properties of Mg 2 SiO 4 :Tb in the form of sintered pellets were investigated. Mg 2 SiO 4 :Tb is a recently developed dosimetric material which offers high sensitivity for TL and OSL in dosimetric applications. Thermoluminescence glow curve of Tb doped Mg 2 SiO 4 samples show a glow peak at about 200 degree Celsius with two small peaks at about 275 and 330 degree Celsius, respectively. OSL experiments showed that blue light (470 nm) is six times more efficient than green light (532 nm) to stimulate the OSL emission. The aim of this study was to determine the TL and OSL fading properties of Mg 2 SiO 4 : Tb using OSL and TL methods. In addition, PTTL properties of the Mg 2 SiO 4 : Tb was investigated by using blue LEDs, UV lamp and blue laser. Investigations on the fading properties also showed that the TL signal fades % 10 in a period of 1 month and OSL signal fades % 10 in a period of 3 month, which then the signal remains relatively stable for longer periods.

  20. Effects of B4C Addition on the Laser Beam Welding Characteristics of Al/SiC MMCs Produced By P/M

    Directory of Open Access Journals (Sweden)

    Serdar KARAOĞLU

    2011-01-01

    Full Text Available Fusion weldability characteristics of metal matrix composites (MMC produced by powder metallurgy (P/M are usually insufficient due to unwanted micro-structural changes that occur during welding. This study aims to investigate the effects of B4C addition as reinforcement on the weld quality of Al/SiC MMCs. After the production of Al/SiC MMCs by P/M with or without the addition of B4C, laser beam welding (LBW characteristics of the materials were investigated by focusing on the integrity of the welds. Optical microscopy (OM, scanning electron microscopy (SEM, and energy dispersive X-ray analysis (EDX were utilized for the characterization of the welds. Results show that Al/SiC MMCs produced by P/M can not be easily welded by LBW, but weldability characteristics of the material can be improved by the addition of B4C.

  1. Fabrication of a 1200 kg Ingot of V-4Cr-4Ti for the DIII-D Radiative Divertor Program

    International Nuclear Information System (INIS)

    Johnson, W.R.; Smith, J.P.

    1998-01-01

    Vanadium chromium titanium alloys are attractive materials for fusion reactors because of their high temperature capability and their potential for low neutron active and rapid activation decay. A V-4Cr-4Ti alloy has been selected in the U.S. as the current leading candidate vanadium alloy for future use in fusion reactor structural applications. General Atomics (GA), in conjunction with the Department of Energy's (DOE) DIII-D Program, is carrying out a plan for the utilization of this vanadium alloy in the DIII-D tokamak. The plan will culminate in the fabrication, installation, and operation of a V-4Ti alloy structure in the DIII-D Radiative Divertor (RD) upgrade. The deployment of vanadium alloy will provide a meaningful step in the development and technology acceptance of this advanced material for future fusion power devices. Under a GA contract and material specification, an industrial scale 1200 kg heat (ingot) of a V-4Cr-4Ti alloy has been produced and converted into product forms by Wah Chang of Albany, Oregon (WCA). To assure the proper control of minor and trace impurities which affect the mechanical and activation behavior of this vanadium alloy, selected lots of raw vanadium base metal were processed by aluminothermic reduction of high purity vanadium oxide, and were then electron beam melted into two high purity vanadium ingots. The ingots were then consolidated with high purity Cr and Ti, and double vacuum-arc melted to obtain a 1200 kg V-4Cr-4Ti alloy ingot. Several billets were extruded from the ingot, and were then fabricated into plate, sheet, and rod at WCA. Tubing was subsequently processed from plate material. The chemistry and fabrication procedures for the product forms were specified on the basis of experience and knowledge gained from DOE Fusion Materials Program studies on previous laboratory scale heats and a large scale ingot (500 kg)

  2. Investigation of Laser Welding of Ti Alloys for Cognitive Process Parameters Selection

    Directory of Open Access Journals (Sweden)

    Fabrizia Caiazzo

    2018-04-01

    Full Text Available Laser welding of titanium alloys is attracting increasing interest as an alternative to traditional joining techniques for industrial applications, with particular reference to the aerospace sector, where welded assemblies allow for the reduction of the buy-to-fly ratio, compared to other traditional mechanical joining techniques. In this research work, an investigation on laser welding of Ti–6Al–4V alloy plates is carried out through an experimental testing campaign, under different process conditions, in order to perform a characterization of the produced weld bead geometry, with the final aim of developing a cognitive methodology able to support decision-making about the selection of the suitable laser welding process parameters. The methodology is based on the employment of artificial neural networks able to identify correlations between the laser welding process parameters, with particular reference to the laser power, welding speed and defocusing distance, and the weld bead geometric features, on the basis of the collected experimental data.

  3. Investigation of Laser Welding of Ti Alloys for Cognitive Process Parameters Selection.

    Science.gov (United States)

    Caiazzo, Fabrizia; Caggiano, Alessandra

    2018-04-20

    Laser welding of titanium alloys is attracting increasing interest as an alternative to traditional joining techniques for industrial applications, with particular reference to the aerospace sector, where welded assemblies allow for the reduction of the buy-to-fly ratio, compared to other traditional mechanical joining techniques. In this research work, an investigation on laser welding of Ti⁻6Al⁻4V alloy plates is carried out through an experimental testing campaign, under different process conditions, in order to perform a characterization of the produced weld bead geometry, with the final aim of developing a cognitive methodology able to support decision-making about the selection of the suitable laser welding process parameters. The methodology is based on the employment of artificial neural networks able to identify correlations between the laser welding process parameters, with particular reference to the laser power, welding speed and defocusing distance, and the weld bead geometric features, on the basis of the collected experimental data.

  4. Laser cladding Ni-base composite coating on titanium alloy with pre-placed B4C+NiCoCrAlY

    International Nuclear Information System (INIS)

    Qingwu Meng; Lin Geng; Zhenzhu Zheng

    2005-01-01

    Using a CO 2 laser, a process of cladding Ni-base composite coating on Ti6Al4V with pre-placed B 4 C and NiCoCrAlY was studied. A good metallurgical bonding coating without cracks and pores was obtained in reasonable ratio of components and low energy laser process. Morphology and microstructure of the coating were analyzed with OM, XRD, SEM and EDS. It is certain that there was a reaction between B 4 C and Ti during in-situ producing TiB 2 and TiC. The Ni-base composite coating is strengthened with TiB 2 and TiC reinforcement phases. Vickers hardness tester measured that the average microhardness of the coating is HV1200 and it is 3.5 times of the Ti6Al4V substrate. The high hard coating containing several reinforcement phases greatly enhances wear resistance of titanium alloy. (orig.)

  5. Structure of Ti-6Al-4V nanostructured titanium alloy joint obtained by resistance spot welding

    Energy Technology Data Exchange (ETDEWEB)

    Klimenov, V. A., E-mail: klimenov@tpu.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); National Research Tomsk Polytechnic University, 30 Lenin Av., Tomsk, 634050 (Russian Federation); Kurgan, K. A., E-mail: kirill-k2.777@mail.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); Chumaevskii, A. V., E-mail: tch7av@gmail.com [Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Sciences, 2/4 Akademicheskii pr., Tomsk, 634021 (Russian Federation); Klopotov, A. A., E-mail: klopotovaa@tsuab.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); National Research Tomsk State University, 36 Lenin Ave., Tomsk, 634050 (Russian Federation); Gnyusov, S. F., E-mail: gnusov@rambler.ru [National Research Tomsk Polytechnic University, 30 Lenin Av., Tomsk, 634050 (Russian Federation)

    2016-01-15

    The structure of weld joints of the titanium alloy Ti-6Al-4V in the initial ultrafine-grained state, obtained by resistance spot welding, is studied using the optical and scanning electron microscopy method and the X-ray structure analysis. The carried out studies show the relationship of the metal structure in the weld zone with main joint zones. The structure in the core zone and the heat affected zone is represented by finely dispersed grains of needle-shaped martensite, differently oriented in these zones. The change in the microhardness in the longitudinal section of the weld joint clearly correlates with structural changes during welding.

  6. Microstructural examination of V-(4-5%) Cr-(4-5%)Ti irradiated in X530

    Energy Technology Data Exchange (ETDEWEB)

    Gelles, D.S. [Pacific Northwest National Lab., Richland, WA (United States); Chung, H.M. [Argonne Natinonal Lab., IL (United States)

    1997-08-01

    Microstructural examination results are reported for two heats of V-(4-5%)Cr-(4-5%)Ti irradiated in the X530 experiment to {approximately}400{degrees}C to provide an understanding of the microstructural evolution that may be associated with degradation of mechanical properties. Fine precipitates were observed in high density intermixed with small defect clusters for all conditions examined following the irradiation. The irradiation-induced precipitation does not appear to be affected by preirradiation heat treatment at 950-1125{degrees}C. There was no evidence for a significant density of large (diameter >10 nm) dislocation loops or network dislocations.

  7. Development of remote laser welding technology

    International Nuclear Information System (INIS)

    Kim, Soo-Sung; Kim, Woong-Ki; Lee, Jung-Won; Yang, Myung-Seung; Park, Hyun-Soo

    1999-01-01

    Various welding processes are now available for end cap closure of nuclear fuel element such as TIG(Tungsten Inert Gas) welding, magnetic resistance welding and laser welding. Even though the resistance and TIG welding process are widely used for manufacturing of the commercial fuel elements, it can not be recommended for the remote seal welding of fuel element at PIE facility due to its complexity of the electrode alignment, difficulty in the replacement of parts in the remote manner and its large heat input for thin sheath. Therefore, Nd:YAG laser system using the optical fiber transmission was selected for Zircaloy-4 end cap welding. Remote laser welding apparatus is developed using a pulsed Nd:YAG laser of 500 watt average power with optical fiber transmission. The laser weldability is satisfactory in respect of the microstructures and mechanical properties comparing with the TIG and resistance welding. The optimum operation processes of laser welding and the optical fiber transmission system for hot cell operation in remote manner have been developed. (author)

  8. Closing the weld gap with laser/mig hybrid welding process

    DEFF Research Database (Denmark)

    Bagger, Claus; Olsen, Flemming Ove; Wiwe, Bjarne David

    2003-01-01

    In this article, laboratory tests are demonstrated that systematically accesses the critical gap distance when welding CMn 2.13 mm steel with a 2.6 kW CO2 laser, combined with a MIG energy source. In the work, the welding speed is varied at gap distances from 0 to 0.8 mm such that the limits...... for obtaining sound welds are identified. The welds are quality assessed according to ISO 13.919-1 and EN25817, transversal hardness measurements are made and the heat input to the workpiece is calculated. The results show that the critical gap is 0.1 mm for a laser weld alone. With hybrid welding, this can...... be increased to 0.6 mm, even at a welding speed of 3.5 m/min. The maximum welding speed with the hybrid process is comparable to laser welding alone, 4.5 m/min. The measured hardness is comparable to MIG welding, and this corresponds to a 33 percent reduction compared to laser welding alone. The heat input...

  9. Tl, Bi, and Pb doping in Ba4BiPb2TlO12-δ

    International Nuclear Information System (INIS)

    Sutto, T.E.; Averill, B.A.

    1992-01-01

    To determine the effects of different 6s metal concentrations on the superconducting nature of Ba 4 BiPb 2 TlO 12-δ , materials produced via four doping schemes were examined: Ba 4 Bi(Pb, Tl) 3 O 12-δ , Ba 4 -(BiPb) 3 TlO 12-δ , Ba 4 (Bi,Tl) 2 Pb 2 O 12-δ , and Ba 4 Bi x Pb 4-2x Tl x O 12-δ . For the parent compound a value of δ = 0.91 was observed, indicating that approximately 1/4 oxygen atom was missing per cubic subsection of the unit cell. For all samples, the symmetry of the parent compound changed from orthorhombic to tetragonal as the system moved away from the ideal composition. This was usually accompanied by the loss of superconductivity, which exhibited a maximum T c of 10.5 K for the parent compound Ba 4 BiPb 2 TlO 12-δ . Also reported are high-temperature magnetic susceptibility results, which are used to determine the effect of metal substitution on the density of states at the Fermi level. For each set of variants on the parent composition, the onset of superconductivity was accompanied by a significant decrease in the size of the Pauli paramagnetic signal. 16 refs., 6 figs

  10. Characterization of laser deposited Ti6Al4V/TiC composite powders on a Ti6Al4V substrate

    CSIR Research Space (South Africa)

    Mahamood, RM

    2014-01-01

    Full Text Available This paper reports the material characterization of Ti6Al4V/TiC composite produced by laser metal deposition. The Ti6Al4V/TiC composites were deposited with a composition ratio of 50 wt.% Ti64l4V and 50 wt.% TiC. The depositions were achieved...

  11. Laser cladding of Ti-6Al-4V with various carbide powders

    International Nuclear Information System (INIS)

    Folkes, J.A.; Shibata, K.

    1994-01-01

    Laser cladding Ti-6Al-4V can be achieved with various weight percentages of different carbide powders. The microstructure and morphology of the clad layer is determined by the cladding powder composition, for a given set of laser parameters, such that 10 and 20 wt% Cr 3 C 2 results in a β + TiC clad microstructure; 10 and 20 wt% WC results in an α + TiC clad microstructure (plus some original WC); and Mo 2 C gives an α + β + TiC or β + TiC structure, depending on the weight percentage of Mo 2 C. The morphology of the TiC in all cases is dendritic or feathery, depending on the carbide content. The microstructure observed in all cases agreed well with that theoretically predicted from the energetics of carbide formation and β-stabilizing properties of each element

  12. Investigation on fracture toughness of laser beam welded steels

    International Nuclear Information System (INIS)

    Riekehr, S.; Cam, G.; Santos, J.F. dos; Kocak, M.; Klein, R.M.; Fischer, R.

    1999-01-01

    Laser beam welding is currently used in the welding of a variety of structural materials including hot and cold rolled steels, high strength low alloy and stainless steels, aluminium and titanium alloys, refractory and high temperature alloys and dissimilar materials. This high power density welding process has unique advantages of cost effectiveness, low distortion, high welding speed, easy automation, deep penetration, narrow bead width, and narrow HAZ compared to the conventional fusion welding processes. However, there is a need to understand the deformation and fracture properties of laser beam weld joints in order to use this cost effective process for fabrication of structural components fully. In the present study, an austenitic stainless steel, X5CrNi18 10 (1.4301) and a ferritic structural steel, RSt37-2 (1.0038), with a thickness of 4 mm were welded by 5 kW CO 2 laser process. Microhardness measurements were conducted to determine the hardness profiles of the joints. Flat micro-tensile specimens were extracted from the base metal, fusion zone, and heat affected zone of ferritic joint to determine the mechanical property variation across the joint and the strength mismatch ratio between the base metal and the fusion zone. Moreover, fracture mechanics specimens were extracted from the joints and tested at room temperature to determine fracture toughness, Crack Tip Opening Displacement (CTOD), of the laser beam welded specimens. The effect of the weld region strength mis-matching on the fracture toughness of the joints have been evaluated. Crack initiation, crack growth and crack deviation processes have also been examined. These results were used to explain the influence of mechanical heterogeneity of the weld region on fracture behaviour. This work is a part of the ongoing Brite-Euram project Assessment of Quality of Power Beam Weld Joints (ASPOW). (orig.)

  13. Characterization on the Microstructure Evolution and Toughness of TIG Weld Metal of 25Cr2Ni2MoV Steel after Post Weld Heat Treatment

    Directory of Open Access Journals (Sweden)

    Xia Liu

    2018-03-01

    Full Text Available The microstructure and toughness of tungsten inert gas (TIG backing weld parts in low-pressure steam turbine welded rotors contribute significantly to the total toughness of the weld metal. In this study, the microstructure evolution and toughness of TIG weld metal of 25Cr2Ni2MoV steel low-pressure steam turbine welded rotor under different post-weld heat treatment (PWHT conditions are investigated. The fractography and microstructure of weld metal after PWHT are characterized by optical microscope, SEM, and TEM, respectively. The Charpy impact test is carried out to evaluate the toughness of the weld. The optical microscope and SEM results indicate that the as-welded sample is composed of granular bainite, acicular ferrite and blocky martensite/austenite (M-A constituent. After PWHT at 580 °C, the blocky M-A decomposes into ferrite and carbides. Both the number and size of precipitated carbides increase with holding time. The impact test results show that the toughness decreases dramatically after PWHT and further decreases with holding time at 580 °C. The precipitated carbides are identified as M23C6 carbides by TEM, which leads to the dramatic decrease in the toughness of TIG weld metal of 25Cr2Ni2MoV steel.

  14. Latest MIG, TIG arc-YAG laser hybrid welding systems for various welding products

    Science.gov (United States)

    Ishide, Takashi; Tsubota, Shuho; Watanabe, Masao

    2003-03-01

    Laser welding is capable of high-efficiency low-strain welding, and so its applications are started to various products. We have also put the high-power YAG laser of up to 10 kW to practical welding use for various products. On the other hand the weakest point of this laser welding is considered to be strict in the welding gap aiming allowance. In order to solve this problem, we have developed hybrid welding of TIG, MIG arc and YAG laser, taking the most advantages of both the laser and arc welding. Since the electrode is coaxial to the optical axis of the YAG laser in this process, it can be applied to welding of various objects. In the coaxial MIG, TIG-YAG welding, in order to make irradiation positions of the YAG laser beams having been guided in a wire or an electrode focused to the same position, the beam transmitted in fibers is separated to form a space between the separated beams, in which the laser is guided. With this method the beam-irradiating area can be brought near or to the arc-generating point. This enables welding of all directions even for the member of a three-dimensional shape. This time we carried out welding for various materials and have made their welding of up to 1 mm or more in welding groove gap possible. We have realized high-speed 1-pass butt welding of 4m/min in welding speed with the laser power of 3 kW for an aluminum alloy plate of approximately 4 mm thick. For a mild steel plate also we have realized butt welding of 1m/min with 5 kW for 6 mm thick. Further, in welding of stainless steel we have shown its welding possibility, by stabilizing the arc with the YAG laser in the welding atmosphere of pure argon, and shown that this welding is effective in high-efficiency welding of various materials. Here we will report the fundamental welding performances and applications to various objects for the coaxial MIG, TIG-YAG welding we have developed.

  15. Prediction of residual stresses in electron beam welded Ti-6Al-4V plates

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Lianyong; Ge, Keke; Jing, Hongyang; Zhao, Lei; Lv, Xiaoqing [Tianjin Univ. (China); Han, Yongdian [Tianjin Univ. (China). Key Lab. of Advanced Joining Technology

    2017-05-01

    A thermo-metallurgical procedure based on the SYSWELD code was developed to predict welding temperature field, microstructure and residual stress in butt-welded Ti-6Al-4V plate taking into account phase transformation. The formation of martensite was confirmed by the CCT diagram and microstructure in the weld joint, which significantly affects the magnitude of residual stress. The hole drilling procedure was utilized to measure the values of residual stress at the top surface of the specimen, which are in well agreement with the numerical results. Both simulated and test results show that the magnitude and distribution of residual stress on the surface of the plate present a large gradient feature from the weld joint to the base metal. Moreover, the distribution law of residual stresses in the plate thickness was further analyzed for better understanding of its generation and evolution.

  16. Characteristics of Ni-Cr-Fe laser clad layers on EA4T steel

    Science.gov (United States)

    Chen, Wenjing; Chen, Hui; Wang, Yongjing; Li, Congchen; Wang, Xiaoli

    2017-07-01

    The Ni-Cr-Fe metal powder was deposited on EA4T steel by laser cladding technology. The microstructure and chemical composition of the cladding layer were analyzed by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The bonding ability between the cladding layer and the matrix was measured. The results showed that the bonding between the cladding layer and the EA4T steel was metallurgical bonding. The microstructure of cladding layer was composed of planar crystals, columnar crystals and dendrite, which consisted of Cr2Ni3, γ phase, M23C6 and Ni3B phases. When the powder feeding speed reached 4 g/min, the upper bainite occurred in the heat affected zone (HAZ). Moreover, the tensile strength of the joint increased, while the yield strength and the ductility decreased.

  17. The effect of advanced ultrasonic forging on fatigue fracture mechanisms of welded Ti-6A1-4V alloy

    Science.gov (United States)

    Smirnova, A.; Pochivalov, Yu.; Panin, V.; Panin, S.; Eremin, A.; Gorbunov, A.

    2017-12-01

    The current study is devoted to application of advanced postwelding ultrasonic forging to joints formed by laser welding of Ti-6A1-4V alloy in order to enhance their mechanical properties and fatigue durability. Low cycle fatigue tests were performed via digital image correlation technique used to obtain strain fields and in situ characterization of deformation, crack growth and fracture. Fracture surfaces were studied by SEM analysis accompanied with calculation of fracture patterns percentage. The fatigue tests demonstrate the high increase in the number of cycles until fracture (from 17 000 to 32 000 cycles) which could be explained by high ductility of welded material after treatment. This leads to lower fatigue crack growth rate due to higher energy dissipation. The obtained effect is attributable only for small cracks on micro-/mesoscales and fails to play a significant role for macro cracks.

  18. Evaluating mechanical properties of hybrid laser arc girth welds

    Energy Technology Data Exchange (ETDEWEB)

    Pussegoda, L. N.; Begg, D.; Holdstock, R.; Jodoin, A. [BMT Fleet Technology Ltd Techonology, Kanata, ON, (Canada); Ligh, K.; Rondeau, D. [Appliead Thermal Sciences Inc., Sanford, ME, (United States); Hansen, E. [ESAB, Florence, SC, (United States)

    2010-07-01

    Hybrid laser arc welding (HLAW) is a promising new process for making girth welds on steel pipelines. This study investigated the mechanical properties of overmatched X80 and X100 pipeline steel girth welds made using the HLAW process. The testing of this process was conducted on NPS36 pipes of 10.4 mm and 14.3 mm thickness, respectively. Various weld positions were produced on X80 and X100 pipes. Laser inspection data were collected during the whole welding process. Also standard tests for girth welds, Charpy V-notch impact tests, CTOD tests, all weld metal (AWM) tension tests, were carried out. The results showed that the fracture transition temperature is higher at the 3 and 9 o'clock positions than at the 9 and 12 o'clock positions. The effect of clock position on fracture toughness is currently being explored; a modified CTOD has been developed to reduce the possibility of crack deviation.

  19. Electron beam welding of heavy section 3Cr-1.5Mo alloy

    International Nuclear Information System (INIS)

    King, J.F.; David, S.A.; Nasreldin, A.

    1986-01-01

    Welding of thick section steels is a common practice in the fabrication of pressure vessels for energy systems. The fabrication cost is strongly influenced by the speed at which these large components can be welded. Conventional welding processes such as shielded metal arc (SMA) and submerged arc (SA) are time-consuming and expensive. Hence there is a great need to reduce welding time and the tonnage of weld metal deposited. Electron beam welding (EBW) is a process that potentially could be used to achieve dramatic reduction in the welding time and costs. The penetrating ability of the beam produces welds with high depth-to-width ratios at relatively high travel speeds, making it possible to weld thick sections with one or two passes without filler metals and other consumables. The paper describes a study that was undertaken to investigate the feasibility of using a high power electron beam welding machine to weld heavy section steel. The main emphasis of this work was concentrated on determining the mechanical properties of the resulting weldment, characterizing the microstructure of the various weldment regions, and comparing these results with those from other processes. One of the steels selected for the heavy section electron beam welding study was a new 3 Cr-1.5 Mo-0.1 V alloy. The steel was developed at the AMAX Materials Research Center by Wada and co-workers for high temperature, high pressure hydrogen service as a possible improved replacement for 2-1/4 Cr-1 Mo steels. The excellent strength and toughness of this steel make it a promising candidate for future pressure vessels such as those for coal gasifiers. The work was conducted on 102 mm (4 in.) thick plates of this material in the normalized-and-tempered condition

  20. Development and characterization of laser clad high temperature self-lubricating wear resistant composite coatings on Ti–6Al–4V alloy

    International Nuclear Information System (INIS)

    Liu, Xiu-Bo; Meng, Xiang-Jun; Liu, Hai-Qing; Shi, Gao-Lian; Wu, Shao-Hua; Sun, Cheng-Feng; Wang, Ming-Di; Qi, Long-Hao

    2014-01-01

    Highlights: • A novel high temperature self-lubricating anti-wear composite coating was fabricated. • Reinforced carbides as well as self-lubricating sulfides were in situ synthesized. • Microhardness of the Ti–6Al–4V substrate was significantly improved. • Friction coefficient and wear rate of the composite coating were greatly reduced. - Abstract: To enhance the wear resistance and friction-reducing capability of titanium alloy, a process of laser cladding γ-NiCrAlTi/TiC + TiWC 2 /CrS + Ti 2 CS coatings on Ti–6Al–4V alloy substrate with preplaced NiCr/Cr 3 C 2 –WS 2 mixed powders was studied. A novel coating without cracks and few pores was obtained in a proper laser processing. The composition and microstructure of the fabricated coating were examined by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) techniques, and tribological properties were evaluated using a ball-on-disc tribometer under dry sliding wear test conditions at 20 °C (room-temperature), 300 °C, 600 °C, respectively. The results show that the coating has unique microstructure consisting of α-Ti, TiC, TiWC 2 , γ-NiCrAlTi, Ti 2 CS and CrS phases. Average microhardness of the composite coating is 1005 HV 0.2 , which is about 3-factor higher than that of Ti–6Al–4V substrate (360 HV 0.2 ). The friction coefficient and wear rate of the coating are greatly decreased due to the combined effects of the dominating anti-wear capabilities of reinforced TiC and TiWC 2 carbides and the CrS and Ti 2 CS sulfides which have excellent self-lubricating property

  1. The development of the rotational friction welding process for the welding of γ-TiAl-casting alloy Ti-47Al-3.5(Mn+Cr+Nb)-0.8(B+Si) to Ti6Al4V. Pt. II; Prozessentwicklung zum Rotationsreibschweissen der γ-TiAl-Feingusslegierung Ti-47Al-3.5(Mn+Cr+Nb)-0.8(B+Si) mit Ti6Al4V. T. II

    Energy Technology Data Exchange (ETDEWEB)

    Ventzke, Volker; Riekehr, Stefan; Horstmann, Manfred; Kashaev, Nikolai; Brokmeier, Heinz-Guenter; Huber, Norbert [Helmholtz-Zentrum Geesthacht GmbH, Zentrum fuer Material- und Kuestenforschung, Geesthacht (Germany). Inst. fuer Werkstoffforschung, Werkstoffmechanik

    2014-07-01

    At process temperatures of T > T{sub β}, the globular and fine grained microstructure of the Titanium alloy Ti6Al4V supports the occurrence of super-plasticity and deformation within the β phase region. This led to one sided shortening of the welded joints combined with the formation of weld flash. As a result of this no evening out of temperature across the forging surface between the γ-TAB cast alloy and Ti6Al4V alloy sides of the joint was able to take place, as a result of which the friction weld seam produced became symmetrically wedge shaped about the axis of rotation. Thereby the γ-TAB cast alloy side of the joint became only slightly compressed exhibiting no appreciable signs of deformation. In the radial direction on the γ-TAB side of the joint close to the forged surface neither the hardness nor the microstructure were homogeneous. Without pre-heating the fine ground, lapped and homogenised γ-TAB weld specimens at a temperature of 800 C above the brittle - ductile transformation transition temperature it was not possible to prevent the occurrence of boundary surface cracking on the outside, micro-voids and inter-lamellar cracking on the γ-TAB side solely by varying the welding parameters. The pre-heating of the γ-TAB friction weld specimens was a necessary pre-requisite to support the deformation of the γ-TAB side of the welded joint and the formation of weld flash during the friction welding process. (orig.)

  2. Characterizing and improving the toughness of thick-sectioned 2 1/4 Cr-1 Mo electroslag weldments

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, G.R.; Frost, R.H.

    1980-09-01

    Efforts to improve the toughness of electroslag weldments consisted of four endeavors: process control, changes caused in 2 1/4 Cr-1 Mo steel by electroslag welding and post-weld heat treatment, electrochemical reactions during the electroslag welding, and toughness testing.

  3. Parameter optimization for selective laser melting of TiAl6V4 alloy by CO2 laser

    Science.gov (United States)

    Baitimerov, R. M.; Lykov, P. A.; Radionova, L. V.; Safonov, E. V.

    2017-10-01

    TiAl6V4 alloy is one of the widely used materials in powder bed fusion additive manufacturing technologies. In recent years selective laser melting (SLM) of TiAl6V4 alloy by fiber laser has been well studied, but SLM by CO2-lasers has not. SLM of TiAl6V4 powder by CO2-laser was studied in this paper. Nine 10×10×10 mm cubic specimens were fabricated using different SLM process parameters. All of the fabricated specimens have a good dense structure and a good surface finish quality without dimensional distortion. The lowest porosity that was achieved was about 0.5%.

  4. Performance of V-4Cr-4Ti Alloy Exposed to the JFT-2M Tokamak Environment

    International Nuclear Information System (INIS)

    Johnson, W.R.; Trester, P.W.; Sengoku, S.; Ishiyama, S.; Fukaya, K.; Eto, M.; Oda, T.; Hirohata, Y.; Hino, T.; Tsai, H.

    1999-01-01

    A long-term test has been conducted in the JFT-2M tokamak fusion device to determine the effects of environmental exposure on the mechanical and chemical behavior of a V-4Cr-4Ti alloy. Test specimens of the alloy were exposed in the outward lower divertor chamber of JFT-2M in a region away from direct contact with the plasma and were preheated to 300 C just prior to and during selected plasma discharges. During their nine-month residence time in JFT-2M, the specimens experienced approximately 200 lower single-null divertor shots at 300 C, during which high energy particle fluxes to the preheated test specimens were significant, and approximately 2,010 upper single-null divertor shots and non-diverter shots at room temperature, for which high energy particle fluxes to and expected particle retention in the test specimens were very low. Data from post-exposure tests have indicated that the performance of the V-4Cr-4Ti alloy would not be significantly affected by environmental exposure to gaseous species at partial pressures typical for tokamak operation. Deuterium retention in the exposed alloy was also low (<2 ppm). Absorption of interstitial by the alloy was limited to the very near surface, and neither the strength nor the Charpy impact properties of the alloy appeared to be significantly changed from the exposure to the JFT-2M tokamak environment

  5. Early evaluation of hydrogen isotopes separation by V4Cr4Ti-based sorbents at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Kulsartov, Timur, E-mail: tima@physics.kz [Institute of Experimental and Theoretical Physics of Kazakh National University, 050038 Almaty (Kazakhstan); Institute of Atomic Energy of National Nuclear Center, 071100 Kurchatov (Kazakhstan); Shestakov, Vladimir; Chikhray, Yevgen; Kenzhina, Inesh; Askerbekov, Saulet [Institute of Experimental and Theoretical Physics of Kazakh National University, 050038 Almaty (Kazakhstan); Gordienko, Yuriy; Ponkratov, Yuriy; Zaurbekova, Zhanna [Institute of Atomic Energy of National Nuclear Center, 071100 Kurchatov (Kazakhstan)

    2016-12-15

    This paper presents the results of experiments on hydrogen isotopes sorption with V4Cr4Ti vanadium alloys from a mixture of hydrogen isotopes. The studies were carried out at temperatures of 353 K, 393 K, 423 K; and pressures of 10{sup 3}–10{sup 4} Pa in gas mixture of hydrogen isotopes. The α-phase domain of V-H (D) system was studied, where the concentration of hydrogen isotopes atoms should not exceed 0.015H (D) atoms per metal atom. The separation parameters were derived for several saturation conditions accordingly to registered time dependences of hydrogen isotopes partial pressure drop. The conclusion was made about the prospects of using vanadium alloys in hydrogen isotopes separation and purification systems.

  6. Cryogen spray cooling during laser tissue welding.

    Science.gov (United States)

    Fried, N M; Walsh, J T

    2000-03-01

    Cryogen cooling during laser tissue welding was explored as a means of reducing lateral thermal damage near the tissue surface and shortening operative time. Two centimetre long full-thickness incisions were made on the epilated backs of guinea pigs, in vivo. India ink was applied to the incision edges then clamps were used to appose the edges. A 4 mm diameter beam of 16 W, continuous-wave, 1.06 microm, Nd:YAG laser radiation was scanned over the incisions, producing approximately 100 ms pulses. There was a delay of 2 s between scans. The total irradiation time was varied from 1-2 min. Cryogen was delivered to the weld site through a solenoid valve in spurt durations of 20, 60 and 100 ms. The time between spurts was either 2 or 4 s, corresponding to one spurt every one or two laser scans. Histology and tensile strength measurements were used to evaluate laser welds. Total irradiation times were reduced from 10 min without surface cooling to under 1 min with surface cooling. The thermal denaturation profile showed less denaturation in the papillary dermis than in the mid-dermis. Welds created using optimized irradiation and cooling parameters had significantly higher tensile strengths (1.7 +/- 0.4 kg cm(-2)) than measured in the control studies without cryogen cooling (1.0 +/- 0.2 kg cm(-2)) (p laser welding results in increased weld strengths while reducing thermal damage and operative times. Long-term studies will be necessary to determine weld strengths and the amount of scarring during wound healing.

  7. Property Investigation of Laser Cladded, Laser Melted and Electron Beam Melted Ti-Al6-V4

    Science.gov (United States)

    2006-05-01

    UNCLASSIFIED/UNLIMITED UNCLASSIFIED/UNLIMITED Figure 3: Examples of electron beam melted net shape parts; powder bed [3]. 1.4 Laser Cladding ...description, www.arcam.com. [4] K.-H. Hermann, S. Orban, S. Nowotny, Laser Cladding of Titanium Alloy Ti6242 to Restore Damaged Blades, Proceedings...Property Investigation of Laser Cladded , Laser Melted and Electron Beam Melted Ti-Al6-V4 Johannes Vlcek EADS Deutschland GmbH Corporate Research

  8. Correlation of fatigue properties and microstructure in investment cast Ti-6Al-4V welds

    International Nuclear Information System (INIS)

    Oh, Jinkeun; Kim, Nack J.; Lee, Sunghak; Lee, Eui W.

    2003-01-01

    The effect of microstructural characteristics on high-cycle fatigue properties and fatigue crack propagation behavior of welded regions of an investment cast Ti-6Al-4V were investigated. High-cycle fatigue and fatigue crack propagation tests were conducted on the welded regions, which were processed by two different welding methods: tungsten inert gas (TIG) and electron beam (EB) welding. Test data were analyzed in relation to microstructure, tensile properties, and fatigue fracture mode. The base metal was composed of an alpha plate colony structure transformed to a basket-weave structure with thin α platelets after welding and annealing. High-cycle fatigue results indicated that fatigue strength of the EB weld was lower than that of the base metal or the TIG weld because of the existence of large micropores formed during welding, although it had the highest yield strength. In the case of the fatigue crack propagation, the EB weld composed of thinner α platelets had a faster crack propagation rate than the base metal or the TIG weld. The effective microstructural feature determining the fatigue crack propagation rate was found to be the width of α platelets because it was well matched with the reversed cyclic plastic zone size calculated in the threshold ΔK regime

  9. Experimental study on the resistance to hydrogen embrittlement of NIFS-V4Cr4Ti alloy

    International Nuclear Information System (INIS)

    Chen Jiming; Xu Zengyu; Den Ying; Muroga, T.

    2002-01-01

    SWIP (Southwestern Institute of Physics) has joined an international collaboration on the hydrogen embrittlement resistance evaluation of the vanadium alloy. This paper presents some experiments on the tensile properties and Charpy impact properties of the NIFS-V4Cr4Ti alloy with high-level hydrogen concentration. The experiment results show different properties against hydrogen embrittlement in static tension and impact load. The critical hydrogen concentration required to embrittle the alloy was about 215 - 310 mg·kg -1 on static tension load, but less than 130 mg·kg -1 on impact loading

  10. Stress distribution in Co-Cr implant frameworks after laser or TIG welding.

    Science.gov (United States)

    de Castro, Gabriela Cassaro; de Araújo, Cleudmar Amaral; Mesquita, Marcelo Ferraz; Consani, Rafael Leonardo Xediek; Nóbilo, Mauro Antônio de Arruda

    2013-01-01

    Lack of passivity has been associated with biomechanical problems in implant-supported prosthesis. The aim of this study was to evaluate the passivity of three techniques to fabricate an implant framework from a Co-Cr alloy by photoelasticity. The model was obtained from a steel die simulating an edentulous mandible with 4 external hexagon analog implants with a standard platform. On this model, five frameworks were fabricated for each group: a monoblock framework (control), laser and TIG welding frameworks. The photoelastic model was made from a flexible epoxy resin. On the photoelastic analysis, the frameworks were bolted onto the model for the verification of maximum shear stress at 34 selected points around the implants and 5 points in the middle of the model. The stresses were compared all over the photoelastic model, between the right, left, and center regions and between the cervical and apical regions. The values were subjected to two-way ANOVA, and Tukey's test (α=0.05). There was no significant difference among the groups and studied areas (p>0.05). It was concluded that the stresses generated around the implants were similar for all techniques.

  11. Analysis of High Temperature Deformed Structure and Dynamic Precipitation in W9Mo3Cr4V Steel

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    With TEM、SEM, various high-temperature deformed structures inW9Mo3Cr4V steel were investigated. The sub-structures,recrystallized nuclei, as well as the dynamic precipitation were also studied and analyzed. The relationship between recrystallized structures and dynamic precipitation was discussed. The results showed that the deformed structures in W9Mo3Cr4V steel are more complicated than those in low alloy steels. Because W9Mo3Cr4V steel is a high-speed steel, there are a large number of residual carbides on the matrix. Also, much dynamic precipitating carbides will precipitate during deformation at high temperature.

  12. Ti–6Al–4V welded joints via electron beam welding: Microstructure, fatigue properties, and fracture behavior

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiaoguang [School of Energy and Power Engineering, Beihang University, Beijing 100191 (China); Co-Innovation Center for Advanced Aero-Engine, Beijing 100191 (China); Li, Shaolin [School of Energy and Power Engineering, Beihang University, Beijing 100191 (China); Qi, Hongyu, E-mail: qhy@buaa.edu.cn [School of Energy and Power Engineering, Beihang University, Beijing 100191 (China); Co-Innovation Center for Advanced Aero-Engine, Beijing 100191 (China)

    2014-03-01

    The effect of microstructural characteristics on the fatigue properties of electron beam-welded joints of forged Ti–6Al–4V and its fracture behavior were investigated. Tensile tests and fatigue tests were conducted at room temperature in air atmosphere. The test data were analyzed in relation to microstructure, high-cycle fatigue properties, low-cycle fatigue properties, and fatigue crack propagation properties. The high-cycle fatigue test results indicated that the fatigue strength of the joint welded via electron beam welding was higher than that of the base metal because the former had a high yield strength and all high-cycle fatigue specimens were fractured in the base metal. Although the joint specimens had a lower low-cycle fatigue life than the base metal, they mainly ruptured at the fusion zone of the joint specimen and their crack initiation mechanism is load-dependent. The fatigue crack propagation test results show that the joint had a slower crack propagation rate than the base metal, which can be attributed to the larger grain in the fusion zone.

  13. Experimental investigation of Ti–6Al–4V titanium alloy and 304L stainless steel friction welded with copper interlayer

    Directory of Open Access Journals (Sweden)

    R. Kumar

    2015-03-01

    Full Text Available The basic principle of friction welding is intermetallic bonding at the stage of super plasticity attained with self-generating heat due to friction and finishing at upset pressure. Now the dissimilar metal joints are especially popular in defense, aerospace, automobile, bio-medical, refinery and nuclear engineerings. In friction welding, some special alloys with dual phase are not joined successfully due to poor bonding strength. The alloy surfaces after bonding also have metallurgical changes in the line of interfacing. The reported research work in this area is scanty. Although the sound weld zone of direct bonding between Ti–6Al–4V and SS304L was obtained though many trials, the joint was not successful. In this paper, the friction welding characteristics between Ti–6Al–4V and SS304L into which pure oxygen free copper (OFC was introduced as interlayer were investigated. Box–Behnken design was used to minimize the number of experiments to be performed. The weld joint was analyzed for its mechanical strength. The highest tensile strength between Ti–6Al–4V and SS304L between which pure copper was used as insert metal was acquired. Micro-structural analysis and elemental analysis were carried out by EDS, and the formation of intermetallic compound at the interface was identified by XRD analysis.

  14. Microstructure of Ti-6Al-4V produced by selective laser melting

    International Nuclear Information System (INIS)

    Simonelli, M; Tse, Y Y; Tuck, C

    2012-01-01

    Ti-6Al-4V is the most widely used titanium alloy. Manufacturing of Ti-6Al-4V components using novel additive processing techniques such as selective laser melting is of great interest. This study focuses on the microstructure characterisation of Ti-6Al-4V components produced by selective laser melting (SLM) with full (Ti-6Al-4V base plate) and partial (Ti-6Al-4V needle-shaped bed) support. The starting material, a plasma atomised powder, and the component products are studied using various microscopy techniques including optical, scanning electron and transmission electron microscopy and electron backscattered diffraction (EBSD). Powder particles are fully dense, possess a spherical shape and are composed of acicular α phase. The as-built material shows oriented acicular martensitic phase with well defined columnar grains. The morphology of martensitic phase and microstructural evolution will be discussed in relation to the SLM processing parameters employed and the different cooling rates experienced by the components.

  15. Low-Cycle Fatigue Behavior of 10CrNi3MoV High Strength Steel and Its Undermatched Welds.

    Science.gov (United States)

    Song, Wei; Liu, Xuesong; Berto, Filippo; Razavi, S M J

    2018-04-24

    The use of high strength steel allows the design of lighter, more slender and simpler structures due to high strength and favorable ductility. Nevertheless, the increase of yield strength does not guarantee the corresponding improvement of fatigue resistance, which becomes a major concern for engineering structure design, especially for the welded joints. The paper presents a comparison of the low cycle fatigue behaviors between 10CrNi3MoV high strength steel and its undermatched weldments. Uniaxial tension tests, Push-pull, strain-controlled fatigue tests were conducted on base metal and weldments in the strain range of 0.2⁻1.2%. The monotonic and cyclic stress-strain curves, stress-life, strain-life and energy-life in terms of these materials were analyzed for fatigue assessment of materials discrepancy. The stress-life results of base metal and undermatched weld metal exhibit cyclic softening behaviors. Furthermore, the shapes of 10CrNi3MoV steel hysteresis loops show a satisfactory Masing-type behavior, while the weld metal shows a non-Masing type behavior. Strain, plastic and total strain energy density amplitudes against the number of reversals to failure results demonstrate that the undermatched weld metal presents a higher resistance to fatigue crack initiation than 10CrNi3MoV high strength steel. Finally, fatigue fracture surfaces of specimens were compared by scanning electron microscopy to identify the differences of crack initiation and the propagation between them.

  16. Low-Cycle Fatigue Behavior of 10CrNi3MoV High Strength Steel and Its Undermatched Welds

    Directory of Open Access Journals (Sweden)

    Wei Song

    2018-04-01

    Full Text Available The use of high strength steel allows the design of lighter, more slender and simpler structures due to high strength and favorable ductility. Nevertheless, the increase of yield strength does not guarantee the corresponding improvement of fatigue resistance, which becomes a major concern for engineering structure design, especially for the welded joints. The paper presents a comparison of the low cycle fatigue behaviors between 10CrNi3MoV high strength steel and its undermatched weldments. Uniaxial tension tests, Push-pull, strain-controlled fatigue tests were conducted on base metal and weldments in the strain range of 0.2–1.2%. The monotonic and cyclic stress-strain curves, stress-life, strain-life and energy-life in terms of these materials were analyzed for fatigue assessment of materials discrepancy. The stress-life results of base metal and undermatched weld metal exhibit cyclic softening behaviors. Furthermore, the shapes of 10CrNi3MoV steel hysteresis loops show a satisfactory Masing-type behavior, while the weld metal shows a non-Masing type behavior. Strain, plastic and total strain energy density amplitudes against the number of reversals to failure results demonstrate that the undermatched weld metal presents a higher resistance to fatigue crack initiation than 10CrNi3MoV high strength steel. Finally, fatigue fracture surfaces of specimens were compared by scanning electron microscopy to identify the differences of crack initiation and the propagation between them.

  17. Thallous chalcogenide (Tl 6I 4Se) for radiation detection at X-ray and γ-ray energies

    Science.gov (United States)

    Liu, Zhifu; Peters, John A.; Wessels, Bruce W.; Johnsen, Simon; Kanatzidis, Mercouri G.

    2011-12-01

    The optical and charge transport properties of the thallous chalcogenide compound Tl6I4Se were characterized. The semiconductor crystals are grown by the modified Bridgman method. We have measured the refractive index, and absorption coefficient of the compound ranging from 300 to 1500 nm by analysis of the UV-vis-near IR transmission and reflection spectra. The band gap is 1.8 eV. For the evaluation of detector performance, the mobility-lifetime products for both the electron and hole carriers were measured. Tl6I4Se has mobility-lifetime products of 7.1×10-3 and 5.9×10-4 cm2/V for electron and hole carriers, respectively, which are comparable to those of Cd0.9Zn0.1Te. The γ-ray spectrum for a Tl6I4Se detector was measured. Its response to the 122 keV of 57Co source is comparable to that of Cd0.9Zn0.1Te.

  18. Laser Powder Cladding of Ti-6Al-4V α/β Alloy

    Science.gov (United States)

    Al-Sayed Ali, Samar Reda; Hussein, Abdel Hamid Ahmed; Nofal, Adel Abdel Menam Saleh; Elgazzar, Haytham Abdelrafea; Sabour, Hassan Abdel

    2017-01-01

    Laser cladding process was performed on a commercial Ti-6Al-4V (α + β) titanium alloy by means of tungsten carbide-nickel based alloy powder blend. Nd:YAG laser with a 2.2-KW continuous wave was used with coaxial jet nozzle coupled with a standard powder feeding system. Four-track deposition of a blended powder consisting of 60 wt % tungsten carbide (WC) and 40 wt % NiCrBSi was successfully made on the alloy. The high content of the hard WC particles is intended to enhance the abrasion resistance of the titanium alloy. The goal was to create a uniform distribution of hard WC particles that is crack-free and nonporous to enhance the wear resistance of such alloy. This was achieved by changing the laser cladding parameters to reach the optimum conditions for favorable mechanical properties. The laser cladding samples were subjected to thorough microstructure examinations, microhardness and abrasion tests. Phase identification was obtained by X-ray diffraction (XRD). The obtained results revealed that the best clad layers were achieved at a specific heat input value of 59.5 J·mm−2. An increase by more than three folds in the microhardness values of the clad layers was achieved and the wear resistance was improved by values reaching 400 times. PMID:29036935

  19. Laser Powder Cladding of Ti-6Al-4V α/β Alloy.

    Science.gov (United States)

    Al-Sayed Ali, Samar Reda; Hussein, Abdel Hamid Ahmed; Nofal, Adel Abdel Menam Saleh; Hasseb Elnaby, Salah Elden Ibrahim; Elgazzar, Haytham Abdelrafea; Sabour, Hassan Abdel

    2017-10-15

    Laser cladding process was performed on a commercial Ti-6Al-4V (α + β) titanium alloy by means of tungsten carbide-nickel based alloy powder blend. Nd:YAG laser with a 2.2-KW continuous wave was used with coaxial jet nozzle coupled with a standard powder feeding system. Four-track deposition of a blended powder consisting of 60 wt % tungsten carbide (WC) and 40 wt % NiCrBSi was successfully made on the alloy. The high content of the hard WC particles is intended to enhance the abrasion resistance of the titanium alloy. The goal was to create a uniform distribution of hard WC particles that is crack-free and nonporous to enhance the wear resistance of such alloy. This was achieved by changing the laser cladding parameters to reach the optimum conditions for favorable mechanical properties. The laser cladding samples were subjected to thorough microstructure examinations, microhardness and abrasion tests. Phase identification was obtained by X-ray diffraction (XRD). The obtained results revealed that the best clad layers were achieved at a specific heat input value of 59.5 J·mm -2 . An increase by more than three folds in the microhardness values of the clad layers was achieved and the wear resistance was improved by values reaching 400 times.

  20. Genesis of Microstructures in Friction Stir Welding of Ti-6Al-4V

    Science.gov (United States)

    Tchein, Gnofam Jacques; Jacquin, Dimitri; Coupard, Dominique; Lacoste, Eric; Girot Mata, Franck

    2018-03-01

    This paper is focused on the genesis of microstructures in friction stir welding (FSW) of the Ti-6Al-4V alloy. Several titanium joints, initially prepared with four different preheat treatments, were processed by FSW. Detailed microstructural analyses were performed in order to investigate change in the microstructure during the process. In this work, the FSW processing allows a controlled and stable microstructure to be produced in the stirring zone, regardless of the initial heat treatment or the welding conditions. The welded material undergoes a severe thermomechanical treatment which can be divided into two steps. First, the friction in the shoulder and the plastic strain give rise to the necessary conditions to allow a continuous dynamic recrystallization of the β phase. This operation produces a fine and equiaxed β grain structure. Second, once the pin has moved away, the temperature decreases, and the material undergoes a heat treatment equivalent to air quenching. The material thus exhibits a β → β + α transformation with germination of a fine intergranular Widmanstätten phase within the ex-fully-recrystallized-β grains.

  1. Genesis of Microstructures in Friction Stir Welding of Ti-6Al-4V

    Science.gov (United States)

    Tchein, Gnofam Jacques; Jacquin, Dimitri; Coupard, Dominique; Lacoste, Eric; Girot Mata, Franck

    2018-06-01

    This paper is focused on the genesis of microstructures in friction stir welding (FSW) of the Ti-6Al-4V alloy. Several titanium joints, initially prepared with four different preheat treatments, were processed by FSW. Detailed microstructural analyses were performed in order to investigate change in the microstructure during the process. In this work, the FSW processing allows a controlled and stable microstructure to be produced in the stirring zone, regardless of the initial heat treatment or the welding conditions. The welded material undergoes a severe thermomechanical treatment which can be divided into two steps. First, the friction in the shoulder and the plastic strain give rise to the necessary conditions to allow a continuous dynamic recrystallization of the β phase. This operation produces a fine and equiaxed β grain structure. Second, once the pin has moved away, the temperature decreases, and the material undergoes a heat treatment equivalent to air quenching. The material thus exhibits a β → β + α transformation with germination of a fine intergranular Widmanstätten phase within the ex-fully-recrystallized- β grains.

  2. Fatigue strength of welds and welded materials of high-temperature steels resistant to pressurized hydrogen of the type 2.25% Cr/1% Mo

    International Nuclear Information System (INIS)

    Burlat, J.; Cheviet, A.; Million, A.

    1986-01-01

    The aim of the study is to examine systematically the creep strength of welded joints (base material, heat influence zone and welded seam) and of pure welding materials of the type 2 1/4-3% Cr/1% Mo. According to the AD standard rules, the rule which stipulates that the creep strength of welded seams under full stress be calculated with the strength characteristic value reduced by 20% applies to all heat-resistant steels, if no rupture stress values for the welded joints are available. Manufacturers of steel and weld fillers together with the Union of Technical Control Associations (VdTUeV) have prepared a test programme according to which on the one hand welded joints are tested at right angles to their seams, and on the other pure welding material is tested with respect to its creep strength. The development of the testes and their results have been described. The first results are available as VdTUeV material performance sheets, for 2 materials, and as provisional VdTUeV specification sheets, for 3 weld fillers. With the tested materials, it becomes practically feasible to reduce the creep strength of longitudinally welded pressure-bearing components by about 20% of wall thickness. (orig.) [de

  3. Effect of tempering temperature on microstructure and sliding wear property of laser quenched 4Cr13 steel

    NARCIS (Netherlands)

    Ouyang, J.H.; Pei, Y.T.; Li, X.D.; Lei, T.C.

    1994-01-01

    4Cr13 martensite stainless steel was quenched by a CO2 laser and tempered for 2 h at different temperatures in the range 200 °C to 550 °C. The microstructure of treated layer was observed by SEM, XRD and TEM. Tempering leads to the decomposition of a large number of retained austenites in laser

  4. The use of extraction and electronic diffraction replicas for precipitates characterization in welded Cr-Mo Steels

    International Nuclear Information System (INIS)

    Gutierrez de Saiz-Solabarria, S.; San Juan Nunez, J.M.

    1997-01-01

    The precipitates and phases found in the structure of welded joints of Heat Interchanges Tubes were studied and identified. The base material satisfied the requirements of ASME Sec II, SA 213 Gr T22 (2 1/4 Cr 1 Mo). Compositions of Filler Metals were: 2 1/4 Cr 1 Mo and 2 1/4 Cr 1 Mo 1/4 Nb. The chemical composition of base and weld materials were analyzed by atomic emission spectroscopy in high vacuum electric discharge and by inductive plasma coupled. For the constituents characterization extraction and diffraction microscopy replicas were used. (Author) 65 refs

  5. Correlation of Weld Appearance with Microstructure and Mechanical Properties of 2024-T4 Aluminum Alloy Welded by Fiber Laser with Filler Wire

    Directory of Open Access Journals (Sweden)

    XU Fei

    2017-11-01

    Full Text Available Two typical cross-section of welds, including nail shape and near X shape, are obtained in the process of fiber laser welding 2024-T4 Al alloy with filler wire. The correlations of the two weld appearances and other elements (such as microstructure, microhardness, and joint's tensile properties were analyzed. The results show that the weld with near X shape cross-section during the welding process is more stable than that with nail shape cross-section, and the welding spatter of the former is smaller than that of the latter. The microstructure of the weld zone is columnar grains and equiaxed grains, the columnar grains are formed near the fusion line and growing along the vertical direction of the fusion line, the equiaxed grains are distributed in the center of the weld zone. The secondary dendrite of the grains in the center of the weld with nail shape cross-section grows better, and gradually forms to equiaxed dendrite, while the grains size of the weld with near X shape cross-section is relatively finer, exhibiting equiaxed cellular grain. Compared with the joint with nail shape cross-section of the weld, the joint with near X shape cross-section of the weld have some different characteristics, the precipitation strengthening phase θ(Al2Cu content in weld zone of the latter is more than that of the former, the average microhardness value of the weld zone of the latter is higher than that of the former, the softening phenomenon of heat affect zone (HAZ of the latter is weaker than that of the former, and the joint's tensile strength and plasticity of the latter are lower than that of the former slightly.

  6. Numerical modeling of keyhole dynamics in laser welding

    Science.gov (United States)

    Zhang, Wen-Hai; Zhou, Jun; Tsai, Hai-Lung

    2003-03-01

    Mathematical models and the associated numerical techniques have been developed to study the following cases: (1) the formation and collapse of a keyhole, (2) the formation of porosity and its control strategies, (3) laser welding with filler metals, and (4) the escape of zinc vapor in laser welding of galvanized steel. The simulation results show that the formation of porosity in the weld is caused by two competing mechanisms: one is the solidification rate of the molten metal and the other is the speed that molten metal backfills the keyhole after laser energy is terminated. The models have demonstrated that porosity can be reduced or eliminated by adding filler metals, controlling laser tailing power, or applying an electromagnetic force during keyhole collapse process. It is found that a uniform composition of weld pool is difficult to achieve by filler metals due to very rapid solidification of the weld pool in laser welding, as compared to that in gas metal arc welding.

  7. Syntheses, crystal structures, and characterization of two new Tl{sup +}-Cu{sup 2+}-Te{sup 6+} oxides: Tl{sub 4}CuTeO{sub 6} and Tl{sub 6}CuTe{sub 2}O{sub 10}

    Energy Technology Data Exchange (ETDEWEB)

    Yeon, Jeongho; Kim, Sang-Hwan [Department of Chemistry, University of Houston, 136 Fleming Building, Houston, TX 77204-5003 (United States); Green, Mark A. [Department of Materials Science and Engineering, University of Maryland, College Park, MD, 20742-2115 and NIST Center for Neutron Research, National Institute of Standard and Technology, 100 Bureau Drive, Gaithersburg, MD 20899-6103 (United States); Bhatti, Kanwal Preet; Leighton, C. [Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455-0132 (United States); Shiv Halasyamani, P., E-mail: psh@uh.edu [Department of Chemistry, University of Houston, 136 Fleming Building, Houston, TX 77204-5003 (United States)

    2012-12-15

    Crystals and polycrystalline powders of two new oxide materials, Tl{sub 4}CuTeO{sub 6} and Tl{sub 6}CuTe{sub 2}O{sub 10}, have been synthesized by hydrothermal and solid-state methods. The materials were structurally characterized by single-crystal X-ray diffraction. Tl{sub 4}CuTeO{sub 6} and Tl{sub 6}CuTe{sub 2}O{sub 10} exhibit one dimensional anionic slabs of [CuTeO{sub 6}]{sup 4-} and [CuTe{sub 2}O{sub 10}]{sup 6-}, respectively. Common to both slabs is the occurrence of Cu{sup 2+}O{sub 4} distorted squares and Te{sup 6+}O{sub 6} octahedra. The slabs are separated by Tl{sup +} cations. For Tl{sub 4}CuTeO{sub 6}, magnetic measurements indicate a maximum at {approx}8 K in the temperature dependence of the susceptibility. Low temperature neutron diffraction data confirm no long-range magnetic ordering occurs and the susceptibility was adequately accounted for by fits to a Heisenberg alternating chain model. For Tl{sub 6}CuTe{sub 2}O{sub 10} on the other hand, magnetic measurements revealed paramagnetism with no evidence of long-range magnetic ordering. Infrared, UV-vis spectra, thermogravimetric, and differential thermal analyses are also reported. Crystal data: Tl{sub 4}CuTeO{sub 6}, Triclinic, space group P-1 (No. 2), a=5.8629(8) A, b=8.7848(11) A, c=9.2572(12) A, {alpha}=66.0460(10), {beta}=74.2010(10), {gamma}=79.254(2), V=417.70(9) A{sup 3}, and Z=2; Tl{sub 6}CuTe{sub 2}O{sub 10}, orthorhombic, space group Pnma (No. 62), a=10.8628(6) A, b=11.4962(7) A, c=10.7238(6) A, V=1339.20(13) A{sup 3}, and Z=4. - Graphical Abstract: Two new oxide materials, Tl{sub 4}CuTeO{sub 6} and Tl{sub 6}CuTe{sub 2}O{sub 10}, have been synthesized and characterized. The materials exhibit one dimensional crystal structures consisting of CuO{sub 4} and TeO{sub 6} polyhedra. Highlights: Black-Right-Pointing-Pointer Two New Tl-Te-Cu-oxides have been synthesized and structurally characterized. Black-Right-Pointing-Pointer For Tl{sub 4}CuTeO{sub 6}, magnetic measurements indicate a

  8. Laser Powder Cladding of Ti-6Al-4V α/β Alloy

    Directory of Open Access Journals (Sweden)

    Samar Reda Al-Sayed Ali

    2017-10-01

    Full Text Available Laser cladding process was performed on a commercial Ti-6Al-4V (α + β titanium alloy by means of tungsten carbide-nickel based alloy powder blend. Nd:YAG laser with a 2.2-KW continuous wave was used with coaxial jet nozzle coupled with a standard powder feeding system. Four-track deposition of a blended powder consisting of 60 wt % tungsten carbide (WC and 40 wt % NiCrBSi was successfully made on the alloy. The high content of the hard WC particles is intended to enhance the abrasion resistance of the titanium alloy. The goal was to create a uniform distribution of hard WC particles that is crack-free and nonporous to enhance the wear resistance of such alloy. This was achieved by changing the laser cladding parameters to reach the optimum conditions for favorable mechanical properties. The laser cladding samples were subjected to thorough microstructure examinations, microhardness and abrasion tests. Phase identification was obtained by X-ray diffraction (XRD. The obtained results revealed that the best clad layers were achieved at a specific heat input value of 59.5 J·mm−2. An increase by more than three folds in the microhardness values of the clad layers was achieved and the wear resistance was improved by values reaching 400 times.

  9. Optimisation of laser welding parameters for welding of P92 material using Taguchi based grey relational analysis

    Directory of Open Access Journals (Sweden)

    Shanmugarajan B.

    2016-08-01

    Full Text Available Creep strength enhanced ferritic (CSEF steels are used in advanced power plant systems for high temperature applications. P92 (Cr–W–Mo–V steel, classified under CSEF steels, is a candidate material for piping, tubing, etc., in ultra-super critical and advanced ultra-super critical boiler applications. In the present work, laser welding process has been optimised for P92 material by using Taguchi based grey relational analysis (GRA. Bead on plate (BOP trials were carried out using a 3.5 kW diffusion cooled slab CO2 laser by varying laser power, welding speed and focal position. The optimum parameters have been derived by considering the responses such as depth of penetration, weld width and heat affected zone (HAZ width. Analysis of variance (ANOVA has been used to analyse the effect of different parameters on the responses. Based on ANOVA, laser power of 3 kW, welding speed of 1 m/min and focal plane at −4 mm have evolved as optimised set of parameters. The responses of the optimised parameters obtained using the GRA have been verified experimentally and found to closely correlate with the predicted value.

  10. Examination of structure and mechanical properties of hard-to-weld metal joints obtained with the laser method

    International Nuclear Information System (INIS)

    Czujko, T.; Przetakiewicz, W.; Jozwiak, S.; Hoffman, J.; Kalita, W.

    1995-01-01

    Metal joints of stainless of type X6CrNiMoTi1722 (according to DIN) and high conductivity (HC) copper, and joints of transformer steel containing about 3.5% of silicon were obtained using metal sheets 2 mm in thickness. The microstructure and the distribution of microhardness in the area of the joint, and the changes of the strength and elongation caused by the process of laser welding were examined with reference to the properties of the native metal; and, in the case of transformer steel-joints, the effects of welding by means of the TIG method were also analyzed. A probable mechanism of the formation of the steel-copper joint was presented, the strength of which is comparable with that of copper. The superiority of laser welding over TIG welding was also demonstrated. (author). 11 refs, 4 figs, 1 tab

  11. Finite element simulation of laser transmission welding of dissimilar ...

    African Journals Online (AJOL)

    user

    materials between polyvinylidene fluoride and titanium ... finite element (FE) thermal model is developed to simulate the laser ... Keywords: Laser transmission welding, Temperature field, Weld dimension, Finite element analysis, Thermal modeling. 1. .... 4) The heating phenomena due to the phase changes are neglected.

  12. Stress corrosion cracking in repair-welded 3.5 NiCrMoV steel in an actual turbine environment

    International Nuclear Information System (INIS)

    Hitomi, Itoh; Takashi, Shige; Takashi, Momoo

    2001-01-01

    Temporary welding repairs are sometimes needed when damage occurs at the teeth of blade grooves in a low-pressure turbine rotor operated at the dry/wet boundary region. When repair welding has been performed for the 3,5 NiCrMoV steel used in low-pressure turbines, the soundness of the weld must be confirmed. For this reason, a laboratory investigation of susceptibility for stress corrosion cracking (SCC) was conducted for test specimens taken from simulated welds, and then an exposure test was conducted in an actual turbine environment for approximately 7,000 hours. As no SCC initiation was detected and also the propagation was extremely small, repair welding is deemed to be applicable. (author)

  13. Interface and properties of the friction stir welded joints of titanium alloy Ti6Al4V with aluminum alloy 6061

    International Nuclear Information System (INIS)

    Wu, Aiping; Song, Zhihua; Nakata, Kazuhiro; Liao, Jinsun; Zhou, Li

    2015-01-01

    Highlights: • Friction stir butt welding of titanium alloy Ti6Al4V and aluminum alloy A6061-T6. • Welding parameters affect interfacial microstructure of the joint. • Welding parameters affect the mechanical property of joint and fracture position. • Joining mechanism of Ti6Al4V/A6061 dissimilar alloys by FSW is investigated. - Abstract: Titanium alloy Ti6Al4V and aluminum alloy 6061 dissimilar material joints were made with friction stir welding (FSW) method. The effects of welding parameters, including the stir pin position, the rotating rate and the travel speed of the tool, on the interface and the properties of the joints were investigated. The macrostructure of the joints and the fracture surfaces of the tensile test were observed with optical microscope and scanning electron microscope (SEM). The interface reaction layer was investigated with transmission electron microscopy (TEM). The factors affecting the mechanical properties of the joints were discussed. The results indicated that the tensile strength of the joints and the fracture location are mainly dependent on the rotating rate, and the interface and intermetallic compound (IMC) layer are the governing factor. There is a continuous 100 nm thick TiAl 3 IMC at the interface when the rotating rate is 750 rpm. When the welding parameters were appropriate, the joints fractured in the thermo-mechanically affected zone (TMAZ) and the heat affected zone (HAZ) of the aluminum alloy and the strength of the joints could reach 215 MPa, 68% of the aluminum base material strength, as well as the joint could endure large plastic deformation

  14. Experimental investigation and finite element simulation of laser beam welding induced residual stresses and distortions in thin sheets of AA 6056-T4

    International Nuclear Information System (INIS)

    Zain-ul-abdein, Muhammad; Nelias, Daniel; Jullien, Jean-Francois; Deloison, Dominique

    2010-01-01

    Laser beam welding has recently found its application in the fabrication of aircraft structures where fuselage panels, made of thin sheets of AA 6056-T4 (an aluminium alloy), are welded with stiffeners of the same material in a T-joint configuration. The present work simulates laser beam welding induced residual stresses and distortions using industrially employed thermal and mechanical boundary conditions. Various measurements performed on small-scale welded test specimens provide a database of experimental results that serves as a benchmark for qualification of the simulation results. The welding simulation is performed with the commercial finite element software Abaqus and a Fortran programme encoding a conical heat source with Gaussian volumetric distribution of flux. A sequentially coupled temperature-displacement analysis is undertaken to simulate the weld pool geometry, transient temperature and displacement fields. The material is assumed to follow an elasto-plastic law with isotropic hardening behaviour (von Mises plasticity model). A comparison between the experimental and simulation results shows a good agreement. Finally, the residual stress and strain states in a T-joint are predicted.

  15. Dye-enhanced laser welding for skin closure.

    Science.gov (United States)

    DeCoste, S D; Farinelli, W; Flotte, T; Anderson, R R

    1992-01-01

    The use of a laser to weld tissue in combination with a topical photosensitizing dye permits selective delivery of energy to the target tissue. A combination of indocyanine green (IG), absorption peak 780 nm, and the near-infrared (IR) alexandrite laser was studied with albino guinea pig skin. IG was shown to bind to the outer 25 microns of guinea pig dermis and appeared to be bound to collagen. The optical transmittance of full-thickness guinea pig skin in the near IR was 40% indicating that the alexandrite laser should provide adequate tissue penetration. Laser "welding" of skin in vivo was achieved at various concentrations of IG from 0.03 to 3 mg/cc using the alexandrite at 780 nm, 250-microseconds pulse duration, 8 Hz, and a 4-mm spot size. A spectrum of welds was obtained from 1- to 20-W/cm2 average irradiance. Weak welds occurred with no thermal damage obtained at lower irradiances: stronger welds with thermal damage confined to the weld site occurred at higher irradiances. At still higher irradiances, local vaporization occurred with failure to "weld." Thus, there was an optimal range of irradiances for "welding," which varied inversely with dye concentration. Histology confirmed the thermal damage results that were evident clinically. IG dye-enhanced laser welding is possible in skin and with further optimization may have practical application.

  16. Study of simultaneous q-switching and mode-locking in ND:YVO4 laser with Cr4+:YAG crystal

    International Nuclear Information System (INIS)

    Al-Sous, M. B.

    2009-01-01

    A numerical model of rate equations for a four-level solid-state laser with Cr 4+ :YAG saturable absorber including excited state absorption ESA is presented. The cavity is divided into a large number of disks and the model is solved for each disk and its local corresponding photon flux. The flux array is shifted for each recurrence simulating the movement of photons inside the cavity during the round trip. This simulator can describe the mode locking phenomenon and can be used to simulate the simultaneous mode locking and Q-switching with a saturable absorber. (author)

  17. Study of simulations q-switching and mode-locking in Nd:YVO4 laser with Cr4+:YAG crystal

    International Nuclear Information System (INIS)

    Al-Sous, M. B.

    2007-12-01

    A numerical model of rate equations for a four-level solid-state laser with Cr 4+ :YAG saturable absorber including excited state absorption ESA is presented. The cavity is divided into a large number of disks and the model is solved for each disk and its local corresponding photon flux. The flux array is shifted for each recurrence simulating the movement of photons inside the cavity during the round trip. This simulator can describe the mode locking phenomenon and can be used to simulate the simultaneous mode locking and Q-switching with a saturable absorber.(author)

  18. Laser metal deposition of Ti6Al4V: A study on the effect of laser power on microstructure and microhardness

    CSIR Research Space (South Africa)

    Mahamood, RM

    2013-03-01

    Full Text Available The effect of laser power on the resulting microstructure and microhardness of laser metal deposited Ti6Al4V powder on Ti6Al4V substrate has been investigated. The tracks were deposited using 99.6 % pure Ti6Al4V powder of particle size ranging...

  19. The effects of welding parameters on ultra-violet light emissions, ozone and CrVI formation in MIG welding.

    Science.gov (United States)

    Dennis, J H; Mortazavi, S B; French, M J; Hewitt, P J; Redding, C R

    1997-01-01

    This paper describes the relationships between ultra-violet emission, ozone generation and CrVI production in MIG welding which were measured as a function of shield gas flow rate, welding voltage, electrode stick-out and shield gas composition using an automatic welding rig that permitted MIG welding under reproducible conditions. The experimental results are interpreted in terms of the physico-chemical processes occurring in the micro- and macro-environments of the arc as part of research into process modification to reduce occupational exposure to ozone and CrVI production rates in MIG welding. We believe the techniques described here, and in particular the use of what we have termed u.v.-ozone measurements, will prove useful in further study of ozone generation and CrVI formation and may be applied in the investigation of engineering control of occupational exposure in MIG and other welding process such as Manual Metal Arc (MMA) and Tungsten Inert Gas (TIG).

  20. Pressure-induced transition in Tl2MoO4

    International Nuclear Information System (INIS)

    Machon, Denis; Friese, Karen; Breczewski, Tomasz; Grzechnik, Andrzej

    2010-01-01

    Tl 2 MoO 4 has been studied under high-pressure by X-ray diffraction, Raman spectroscopy, and optical absorption measurements. A first-order phase transition is observed at 3.5±0.5 GPa. The nature (ordered vs. disordered) of the high-pressure phase strongly depends on the local hydrostatic conditions. Optical absorption measurements tend to show that this transition is concomitant with an electronic structure transformation. Prior to the transition, single crystal X-ray diffraction shows that pressure induces interactions between MoO 4 fragments and the Mo coordination number tends to increase. In addition, the stereoactivity of the lone-pair electrons on the three symmetrically independent Tl-sites is not uniform; while for two sites the stereoactivity decreases with increasing pressures for the third site the stereoactivity increases. - Graphical Abstract: (up) Structural evolutions of Tl 2 MoO 4 in the low-pressure phase. (Down) Optical properties of the high-pressure phase as a function of pressure. Display Omitted

  1. Development of nitronic 50 fusion welding techniques for 4 K service

    International Nuclear Information System (INIS)

    Dalder, E.N.C.; Juhas, M.C.

    1981-01-01

    The Mirror Fusion Test Facility (MFTF-B) is a large magnetic fusion energy experiment in the tandem mirror configuration. The requirement that each pair of Yin-Yang magnets, one pair at each end of the experiment, not undergo excessive lateral motion during seismic events was found to require excessively thick (> 12.7 mm) walled tubing in the support-struts, which accelerated the flow of heat inward to the 4 K magnet case from the nearby 300 K wall of the rector vessel, when any of the Cr-Ni austenite stainless steels, such as Type 304 with a 300 K yield-strength (sigma y) of 307 mpa (min.) was considered. Since the cold end of the lateral restraining strut was to be at or near 4 K, the additional constraints of good austenite stability and resistance to brittle fracture at 4 K existed. After consideration of these constraints against available information on Cr-Ni and Cr-Mn-Ni-N 2 austenitic stainless steels, grade XM-19 (Fe-22 Cr-12 Ni-5 Mn-.04 C-.02 N 2 was chosen. The mechanical properties of these welds were studied

  2. Laser beam-plasma plume interaction during laser welding

    Science.gov (United States)

    Hoffman, Jacek; Moscicki, Tomasz; Szymanski, Zygmunt

    2003-10-01

    Laser welding process is unstable because the keyhole wall performs oscillations which results in the oscillations of plasma plume over the keyhole mouth. The characteristic frequencies are equal to 0.5-4 kHz. Since plasma plume absorbs and refracts laser radiation, plasma oscillations modulate the laser beam before it reaches the workpiece. In this work temporary electron densities and temperatures are determined in the peaks of plasma bursts during welding with a continuous wave CO2 laser. It has been found that during strong bursts the plasma plume over the keyhole consists of metal vapour only, being not diluted by the shielding gas. As expected the values of electron density are about two times higher in peaks than their time-averaged values. Since the plasma absorption coefficient scales as ~N2e/T3/2 (for CO2 laser radiation) the results show that the power of the laser beam reaching the metal surface is modulated by the plasma plume oscillations. The attenuation factor equals 4-6% of the laser power but it is expected that it is doubled by the refraction effect. The results, together with the analysis of the colour pictures from streak camera, allow also interpretation of the dynamics of the plasma plume.

  3. A quasi-in-situ EBSD observation of the transformation from rolling texture to recrystallization texture in V-4Cr-4Ti alloy

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Lixia [Institute of Materials Research, China Academy of Engineering Physics, Jiangyou, Sichuan Province 621908 (China); Li, Xiongwei [Institute of Metal Research, China Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Fan, Zhijian [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, Sichuan Province 621900 (China); Jiang, Chunli; Zhou, Ping [Institute of Materials Research, China Academy of Engineering Physics, Jiangyou, Sichuan Province 621908 (China); Lai, Xinchun, E-mail: laixinchun@caep.cn [Institute of Materials Research, China Academy of Engineering Physics, Jiangyou, Sichuan Province 621908 (China)

    2017-04-15

    Recrystallization texture evolution of rolled V-4Cr-4Ti alloy has been investigated by quasi-in-situ EBSD (electron back-scattering diffraction) method. Concurrently, the precipitates were characterized by SEM (Scanning Electron Microscopy). It was found that both the initial rolling textures and the distribution of the precipitates affected the formation of the recrystallization texture. It was revealed that the texture transformations of (558) 〈110〉 + (665) 〈110〉 to (334) 〈483〉 + (665) 〈1 1 2.4〉 were possibly attributed to the selective drag induced by the sparsely dispersed Ti-rich precipitates. While the densely distributed Ti-rich precipitates were responsible for the randomized recrystallization texture. Finally, when the precipitates were absent, the orientation changes from (112) 〈110〉 and (558) 〈110〉 to (111) 〈112〉 and (001) <110> to (001) <520> were observed. - Highlights: • Micro recrystallization texture evolution in V-4Cr-4Ti alloys is reported for the first time. • The volume fraction of Ti-rich precipitates has significant effect on the recrystallization texture evolution. • The dissolution of the Ti-rich precipitates above 1100 °C induces the strengthening of (111) <112> texture.

  4. Research on Heat Source Model and Weld Profile for Fiber Laser Welding of A304 Stainless Steel Thin Sheet

    Directory of Open Access Journals (Sweden)

    Peizhi Li

    2018-01-01

    Full Text Available A heat source model is the key issue for laser welding simulation. The Gaussian heat source model is not suitable to match the actual laser weld profile accurately. Furthermore, fiber lasers are widely recognized to result in good-quality laser beam output, a narrower weld zone, less distortion, and high process efficiency, compared with other types of lasers (such as CO2, Nd : YAG, and diode lasers. At present, there are few heat source models for fiber laser welding. Most of researchers evaluate the weld profile only by the bead width and depth of penetration, which is not suitable for the laser keyhole welding nail-like profile. This paper reports an experimental study and FEA simulation of fiber laser butt welding on 1 mm thick A304 stainless steel. A new heat source model (cylindrical and cylindrical is established to match the actual weld profile using Marc and Fortran software. Four bead geometry parameters (penetration depth, bead width, waist width, and depth of the waist are used to compare between the experimental and simulation results. The results show that the heat source model of cylindrical and cylindrical can match the actual shape of the fiber laser welding feasibly. The error range of the penetration depth, bead width, waist width, and depth of the waist between experimental and simulation results is about 4.1 ± 1.6%, 2.9 ± 2.0%, 13.6 ± 7.4/%, and 18.3 ± 8.0%, respectively. In addition, it is found that the depth of penetration is more sensitive to laser power rather than bead width, waist width, and depth of the waist. Welding speed has a similar influence on the depth of penetration, weld width, waist width, and depth of the waist.

  5. Laser-welded ureteral anastomoses: experimental studies with three techniques.

    Science.gov (United States)

    Gürpinar, T; Gürer, S; Kattan, M W; Wang, L; Griffith, D P

    1996-01-01

    Tissue welding with laser energy is a new technique for reconstructive surgery. The potential advantages of laser welding are (a) lack of foreign body reaction, (b) decreased operative time, (c) less tissue manipulation, and (d) effective union of tissues equivalent to sutured anastomoses. We have performed ureteral anastomoses in adult mongrel dogs using a KTP 532 nm laser at an intensity of 1.4 W. Multiple "spot welds" of 1-s duration were utilized in a single layer anastomosis. Laser-welded anastomoses were performed with and without protein solder (33% and 50% human albumin) and were compared to sutured anastomoses. The laser-welded anastomoses required less operative time and provided bursting pressure levels similar to those of traditional sutured anastomoses. There was no advantage or disadvantage to the addition of human albumin as a solder in these experimental studies.

  6. Inverse Thermal Analysis of Ti-6Al-4V Friction Stir Welds Using Numerical-Analytical Basis Functions with Pseudo-Advection

    Science.gov (United States)

    Lambrakos, S. G.

    2018-04-01

    Inverse thermal analysis of Ti-6Al-4V friction stir welds is presented that demonstrates application of a methodology using numerical-analytical basis functions and temperature-field constraint conditions. This analysis provides parametric representation of friction-stir-weld temperature histories that can be adopted as input data to computational procedures for prediction of solid-state phase transformations and mechanical response. These parameterized temperature histories can be used for inverse thermal analysis of friction stir welds having process conditions similar those considered here. Case studies are presented for inverse thermal analysis of friction stir welds that use three-dimensional constraint conditions on calculated temperature fields, which are associated with experimentally measured transformation boundaries and weld-stir-zone cross sections.

  7. Tribocorrosion Study of Ordinary and Laser-Melted Ti6Al4V Alloy

    Directory of Open Access Journals (Sweden)

    Danillo P. Silva

    2016-10-01

    Full Text Available Titanium alloys are used in biomedical implants, as well as in other applications, due to the excellent combination of corrosion resistance and mechanical properties. However, the tribocorrosion resistance of titanium alloy is normally not satisfactory. Therefore, surface modification is a way to improve this specific performance. In the present paper, laser surface-modified samples were tested in corrosion and pin-on-disk tribocorrosion testing in 0.90% NaCl under an average Hertzian pressure of 410 MPa against an alumina sphere. Laser-modified samples of Ti6Al4V were compared with ordinary Ti6Al4V alloy. Electrochemical impedance showed higher modulus for laser-treated samples than for ordinary Ti6Al4V ones. Moreover, atomic force microscopy revealed that laser-treated surfaces presented less wear than ordinary alloy for the initial exposure. For a further exposure to wear, i.e., when the wear depth is beyond the initial laser-affected layer, both materials showed similar corrosion behavior. Microstructure analysis and finite element method simulations revealed that the different behavior between the initial and the extensive rubbing was related to a fine martensite-rich external layer developed on the irradiated surface of the fusion zone.

  8. Crack growth behavior of low-alloy bainitic 51CrV4 steel

    OpenAIRE

    Canadinç, Demircan; Lambers, H. G.; Gorny B.; Tschumak, S.; Maier, H.J.

    2010-01-01

    The crack growth behavior of low-alloy bainitic 51CrV4 steel was investigated. The current results indicate that the stress state present during the isothermal bainitic transformation has a strong influence on the crack propagation behavior in the near threshold regime, when the crack growth direction is perpendicular to the loading axis of the original sample undergoing phase transformation. However, the influence of stresses superimposed during the bainitic transformation on the crack growt...

  9. Some tests of explosion welding in Zry 4 - Zry 4 and other materials

    International Nuclear Information System (INIS)

    Badino, N.S.; Nashmias, J.L.

    1993-01-01

    The possibility of welding explosion for nuclear industry materials is studied. In this case, difficulties to join them by fusion welding are presented. The following pairs are selected: Zry 4-Zry 4, Zry 4-Incoloy, Zry 4-stainless steel, Zry 4-Inconel. Good results in Zry 4-Zry 4 and not so clear results are obtained in other cases. Other possible tests are now being studied and thought about. (Author)

  10. Laser power coupling efficiency in conduction and keyhole welding ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    tomacrograph showing grain orientation ... steep columnar grains of the fusion .... viz. pre-oxidation of metal surface by laser heating in air, chemical ... 4.1b Sheets of 0.5 mm thickness: Laser welds of 0.5-mm thick sheets exhibited steep angles ... boundaries of solidifying weld metal which leads to intergranular cracking ...

  11. Hybrid laser-arc welding

    DEFF Research Database (Denmark)

    Hybrid laser-arc welding (HLAW) is a combination of laser welding with arc welding that overcomes many of the shortfalls of both processes. This important book gives a comprehensive account of hybrid laser-arc welding technology and applications. The first part of the book reviews...... the characteristics of the process, including the properties of joints produced by hybrid laser-arc welding and ways of assessing weld quality. Part II discusses applications of the process to such metals as magnesium alloys, aluminium and steel as well as the use of hybrid laser-arc welding in such sectors as ship...... building and the automotive industry. With its distinguished editor and international team of contributors, Hybrid laser-arc welding, will be a valuable source of reference for all those using this important welding technology. Professor Flemming Ove Olsen works in the Department of Manufacturing...

  12. Stable polarization short pulse passively Q-switched monolithic microchip laser with [110] cut Cr4+:YAG

    International Nuclear Information System (INIS)

    Wang, Y; Gong, M; Yan, P; Huang, L; Li, D

    2009-01-01

    A monolithic Nd:YAG microchip laser with [110] cut Cr 4+ :YAG is presented. The output beam is linearly polarized with polarization ratio higher than 100:1. The polarization direction is stable, independent of pump power, crystal temperature, LD temperature. In single longitudinal mode operation, stable 259 ps pulses at 2.5 kHz with 82 kW peak power and diffraction limited beam mode are output. With a simple and compact one-pass Nd:YVO 4 amplifier, 144 kW peak power is achieved. Single longitudinal and fundamental transverse mode is kept after passing through the amplifier stage. The microchip laser can be operated in two longitudinal modes with two sets of output pulses by increasing the pump power

  13. Adhesion property and high-temperature oxidation behavior of Cr-coated Zircaloy-4 cladding tube prepared by 3D laser coating

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun-Gil, E-mail: hgkim@kaeri.re.kr; Kim, Il-Hyun; Jung, Yang-Il; Park, Dong-Jun; Park, Jeong-Yong; Koo, Yang-Hyun

    2015-10-15

    A 3D laser coating technology using Cr powder was developed for Zr-based alloys considering parameters such as: the laser beam power, inert gas flow, cooling of Zr-based alloys, and Cr powder control. This technology was then applied to Zr cladding tube samples to study the effect of Cr coating on the high-temperature oxidation of Zr-based alloys in a steam environment of 1200 °C for 2000s. It was revealed that the oxide layer thickness formed on the Cr-coated tube surface was about 25-times lower than that formed on a Zircaloy-4 tube surface. In addition, both the ring compression and the tensile tests were performed to evaluate the adhesion properties of the Cr-coated sample. Although some cracks were formed on the Cr-coated layer, the Cr-coated layer had not peeled off after the two tests.

  14. Electronic, Magnetic, and Redox Properties of [MFe(3)S(4)] Clusters (M = Cd, Cu, Cr) in Pyrococcus furiosus Ferredoxin.

    Science.gov (United States)

    Staples, Christopher R.; Dhawan, Ish K.; Finnegan, Michael G.; Dwinell, Derek A.; Zhou, Zhi Hao; Huang, Heshu; Verhagen, Marc F. J. M.; Adams, Michael W. W.; Johnson, Michael K.

    1997-12-03

    The ground- and excited-state properties of heterometallic [CuFe(3)S(4)](2+,+), [CdFe(3)S(4)](2+,+), and [CrFe(3)S(4)](2+,+) cubane clusters assembled in Pyrococcus furiosus ferredoxin have been investigated by the combination of EPR and variable-temperature/variable-field magnetic circular dichroism (MCD) studies. The results indicate Cd(2+) incorporation into [Fe(3)S(4)](0,-) cluster fragments to yield S = 2 [CdFe(3)S(4)](2+) and S = (5)/(2) [CdFe(3)S(4)](+) clusters and Cu(+) incorporation into [Fe(3)S(4)](+,0) cluster fragments to yield S = (1)/(2) [CuFe(3)S(4)](2+) and S = 2 [CuFe(3)S(4)](+) clusters. This is the first report of the preparation of cubane type [CrFe(3)S(4)](2+,+) clusters, and the combination of EPR and MCD results indicates S = 0 and S = (3)/(2) ground states for the oxidized and reduced forms, respectively. Midpoint potentials for the [CdFe(3)S(4)](2+,+), [CrFe(3)S(4)](2+,+), and [CuFe(3)S(4)](2+,+) couples, E(m) = -470 +/- 15, -440 +/- 10, and +190 +/- 10 mV (vs NHE), respectively, were determined by EPR-monitored redox titrations or direct electrochemistry at a glassy carbon electrode. The trends in redox potential, ground-state spin, and electron delocalization of [MFe(3)S(4)](2+,+) clusters in P. furiosus ferredoxin are discussed as a function of heterometal (M = Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Tl).

  15. Numerical simulation of the laser welding process for the prediction of temperature distribution on welded aluminium aircraft components

    Science.gov (United States)

    Tsirkas, S. A.

    2018-03-01

    The present investigation is focused to the modelling of the temperature field in aluminium aircraft components welded by a CO2 laser. A three-dimensional finite element model has been developed to simulate the laser welding process and predict the temperature distribution in T-joint laser welded plates with fillet material. The simulation of the laser beam welding process was performed using a nonlinear heat transfer analysis, based on a keyhole formation model analysis. The model employs the technique of element ;birth and death; in order to simulate the weld fillet. Various phenomena associated with welding like temperature dependent material properties and heat losses through convection and radiation were accounted for in the model. The materials considered were 6056-T78 and 6013-T4 aluminium alloys, commonly used for aircraft components. The temperature distribution during laser welding process has been calculated numerically and validated by experimental measurements on different locations of the welded structure. The numerical results are in good agreement with the experimental measurements.

  16. Development of remote welding technology for nuclear fuel end capping (A study on the weldability of Zircaloy-4)

    Energy Technology Data Exchange (ETDEWEB)

    Kho, Jin Hyun; Sung, Ho Hyun; Hyun, Yong Kyu; Suh, Hee Kang [Korea University of Technology and Education, Cheonan (Korea)

    1998-03-01

    The integrity of nuclear fuel end cap welds is essential to the nuclear fuel performance and safety as well as the usability of power plant. The first aim of this project is to obtain experimental data on the nuclear fuel cladding materials of Zircaloy-4 with welding processes such as plasma arc, gas tungsten arc and laser beam welding. the data obtained in this study will be applicable to the nuclear fuel design, fabrication and nuclear fuel quality control. In addition, the welding processes applicable to the Zircaloy-4 welding were compared and contrasted. The weldability of Zircaloy-4 was evaluated from the metallurgical and mechanical standpoints. 88 refs., 57 figs., 16 tabs. (Author)

  17. Photo-TL in CaSO4:Dy: high exposure dosimetry

    International Nuclear Information System (INIS)

    Caldas, L.V.E.; Mayhugh, M.R.

    1974-01-01

    CaSO 4 :Dy exposed to 10 3 to 10 8 R then annealed in the range 280 to 400 0 C displays little TL in the major dosimetry peak near 200 0 C. Subsequent illumination with 250 nm light reinduces the 200 0 C TL. This radiation-enabled photo-TL is roughly proportional to the square root of the enabling exposure at least to 10 8 R. (auth)

  18. A physically based constitutive model for a V-4Cr-4Ti alloy

    International Nuclear Information System (INIS)

    Donahue, E.G.; Odette, G.R.; Lucas, G.E.

    2000-01-01

    A constitutive model for low-to-intermediate temperatures, strains, and strain rates is developed for the program heat of V-4Cr-4Ti. The basic form of the model is derived from more general dislocation-based models of yield stress and strain hardening. The physically based forms are fit to a database derived from tensile tests carried out over a wide range of temperatures and strain rates. Yield and post-yield strain-hardening contributions to the flow stress are additive. The yield stress has both thermally activated and athermal components. The former is described by a two-mechanism activated dislocation slip model, with contributions that appear to arise from both lattice friction (at lower temperatures) and dislocation pinning by interstitial impurities (at higher temperatures). The yield stress data can be correlated using a strain rate-compensated temperature. The model uses a temperature-weighted average of the two mechanisms. Post-yield strain hardening was found to be approximately athermal. Strain hardening is fit to a two-component modified Voce-type saturating flow stress model. The constitutive model is also used to determine the flow stability limits as estimates of uniform tensile strains. The relatively compact, but mechanism-based, semi-empirical model has a number of both fundamental and practical advantages that are briefly outlined

  19. Thermodynamic properties of CdCr2S4

    International Nuclear Information System (INIS)

    Kesler, Ya.A.; Shchelkotunov, V.A.; Tret'yakov, Yu.D.; Kamyshova, V.K.; Gordeev, I.V.; Alferov, V.A.

    1977-01-01

    The true thermal capacity of ferromagnetic chromium spinel CdCr 2 S 4 has been measured in the temperature range of 172-673 K. Coefficient of linear expansion has been measured in the temperature range of 173-677 K. A change in heat content of the compound has been found by the mixing method (298-750 K). The lattice contribution into thermal capacity, the contribution of thermal expansion, the values of isothermal compressibility factor, and the Crueneisen constants have been calculated from true and mean heat capacity of CdCr 2 S 4 in a wide temperature range. The lattice energy V has been calculated for CdCr 2 S 4 ; it amounts -4226 kcal/mol

  20. Mathematical solutions of rate equations of a laser-diode end-pumped passively Q-switched and mode locked Nd-laser with Cr4+:YAG polarized saturable absorber

    International Nuclear Information System (INIS)

    Abdul Ghani, B.; Hammadi, M.

    2012-01-01

    The intracavity frequency-doubling (IFD) of a simultaneous passively Q-switched mode-locked diode-pumped Nd 3 + - laser is studied with a polarized isotropic Cr 4 +: YAG saturable absorber. A general recurrence formula for the mode-locked pulses under the Q-switched envelope at fundamental wavelength has been reconstructed in order to analyze the temporal shape behavior of a single Q-switched envelope with mode-locking pulse trains. This formula has been derived taking into account the impact of the IFD and polarized Cr 4 +: YAG saturable absorber.The presented mathematical model describes the self-induced anisotropy appeared in the polarized Cr 4 +: YAG in the nonlinear stage of the giant pulse formation. For the anisotropic Nd 3 +: YVO 4 active medium, the generated polarized waves are assumed to be fixed through the lasing cycle. Besides, the maximum absorber initial transmission and the minimum mirror reflectivity values have been determined from the second threshold criterion. The calculated numerical results demonstrate the impact of the variation of the input laser parameters (rotational angle of the polarized crystal, absorber initial transmission and the output mirror reflectivity) on the characteristics of the output laser pulse (SH peak power, pulse width, pulse duration and shift pulse position of central mode). The calculated numerical results in this work is in good qualitative and quantitative agreement with the available experimental data reported in the references. (author)

  1. Investigation on Nd:YAG laser weldability of zircaloy-4 end cap closure for nuclear fuel elements

    International Nuclear Information System (INIS)

    Kim, Soo Sung; Lee, Chul Yung; Yang, Myung Seung

    2001-01-01

    Various welding processes are now available for end cap closure of nuclear fuel element such as TIG(Tungsten Inert Gas) welding, magnetic resistance welding and laser welding. Even though the resistance and TIG welding processes are widely used for manufacturing commercial fuel elements, they can not be recommended for the remote seal welding of a fuel element at a hot cell facility due to the complexity of electrode alignment, difficulty in the replacement of parts in the remote manner and a large heat input for a thin sheath. Therefore, the Nd:YAG laser system using optical fiber transmission was selected for Zircaloy-4 end cap welding inside hot cell. The laser welding apparatus was developed using a pulsed Nd:YAG laser of 500 watt average power with optical fiber transmission. The weldability of laser welding was satisfactory with respect to the microstructures and mechanical properties comparing with TIG and resistance welding. The optimum operation processes of laser welding and the optical fiber transmission system for hot cell operation in a remote manner have been developed. The effects of irradiation on the properties of the laser apparatus were also being studied

  2. Corneal tissue welding with infrared laser irradiation after clear corneal incision.

    Science.gov (United States)

    Rasier, Rfat; Ozeren, Mediha; Artunay, Ozgür; Bahçecioğlu, Halil; Seçkin, Ismail; Kalaycoğlu, Hamit; Kurt, Adnan; Sennaroğlu, Alphan; Gülsoy, Murat

    2010-09-01

    The aim of this study was to investigate the potential of infrared lasers for corneal welding to seal corneal cuts done in an experimental animal model. Full-thickness corneal cuts on freshly enucleated bovine eyes were irradiated with infrared (809-nm diode, 980-nm diode, 1070-nm YLF, and 1980-nm Tm:YAP) lasers to get immediate laser welding. An 809-nm laser was used with the topical application of indocyanine green to enhance the photothermal interaction at the weld site. In total, 60 bovine eyes were used in this study; 40 eyes were used in the first part of the study for the determination of optimal welding parameters (15 eyes were excluded because of macroscopic carbonization, opacification, or corneal shrinkage; 2 eyes were used for control), and 20 eyes were used for further investigation of more promising lasers (YLF and Tm:YAP). Laser wavelength, irradiating power, exposure time, and spot size were the dose parameters, and optimal dose for immediate closure with minimal thermal damage was estimated through histological examination of welded samples. In the first part of the study, results showed that none of the applications was satisfactory. Full-thickness success rates were 28% (2 of 7) for 809-nm and for 980-nm diode lasers and 67% (2 of 3) for 1070-nm YLF and (4 of 6) for 1980-nm Tm:YAP lasers. In the second part of the study, YLF and Tm:YAP lasers were investigated with bigger sample size. Results were not conclusive but promising again. Five corneal incisions were full-thickness welded out of 10 corneas with 1070-nm laser, and 4 corneal incisions were partially welded out of 10 corneas with 1980-nm laser in the second part of the study. Results showed that noteworthy corneal welding could be obtained with 1070-nm YLF laser and 1980-nm Tm:YAP laser wavelengths. Furthermore, in vitro and in vivo studies will shed light on the potential usage of corneal laser welding technique.

  3. Interfacial microstructure and mechanical property of Ti6Al4V/A6061 dissimilar joint by direct laser brazing without filler metal and groove

    International Nuclear Information System (INIS)

    Song, Zhihua; Nakata, Kazuhiro; Wu, Aiping; Liao, Jinsun

    2013-01-01

    Laser brazing of Ti6Al4V and A6061-T6 alloys with 2 mm thickness was conducted by focusing laser beam on aluminum alloy side, and the effect of laser offset distance on microstructure and mechanical properties of the dissimilar butt joint was investigated. Laser offset has a great influence on the thickness of interfacial intermetallic compound (IMC) layer and the mechanical property of joint. The thickness of interfacial IMC layer is less than 500 nm, and the average tensile strength of the joint reaches 64% of aluminum base material strength, when suitable welding conditions are used. The interfacial IMC is TiAl 3 . The formation of interfacial IMC layer and its effect on mechanical property of the joint are discussed in the present study.

  4. Fusion welding studies using laser on Ti-SS dissimilar combination

    Science.gov (United States)

    Shanmugarajan, B.; Padmanabham, G.

    2012-11-01

    Laser welding investigations were carried out on dissimilar Ti-SS combination. The study is aimed to improve the weld strength and ductility by minimizing harmful intermetallics and taking advantage of high cooling rates in laser welding. Results of continuous wave 3.5 kW CO2 laser welding of totally dissimilar combination of Titanium and stainless steel (304) have been discussed. Bead on plate welding experiments were conducted to identify the laser welding parameters using depth of penetration as criteria. The welding of dissimilar combination has been attempted both autogenously and with interlayers such as Vanadium (V) and Tantalum (Ta) in the form of laser cladding as well as strip. Autogenous welds were carried out by varying the laser power, welding speed and position of the laser beam with respect to the joint centre. The resultant welds are characterized by macrostructure analysis, SEM/EDAX and XRD and as welded tensile test in UTM. The autogenous welds have exhibited extensive cracking even when welded at high speeds or by manipulating the beam position with respect to the joint. Similarly Vandaium as interlayer could not achieve crack free joint. A joint with 40 MPa strength could be made with Ta as interlayer. Results and analysis of these variants of laser welded joints are reported and discussed.

  5. Properties of the 4.45 eV optical absorption band in LiF:Mg, Ti

    International Nuclear Information System (INIS)

    Nail, I.; Oster, L.; Horowitz, Y. S.; Biderman, S.; Belaish, Y.

    2006-01-01

    The optical absorption (OA) and thermoluminescence (TL) of dosimetric LiF:Mg,Ti (TLD-100) as well as nominally pure LiF single crystal have been studied as a function of irradiation dose, thermal and optical bleaching in order to investigate the role of the 4.45 eV OA band in low temperature TL. Computerised deconvolution was used to resolve the absorption spectrum into individual gaussian bands and the TL glow curve into glow peaks. Although the 4.45 eV OA band shows thermal decay characteristics similar to the 4.0 eV band its dose filling constant and optical bleaching properties suggest that it cannot be associated with the TL of composite peaks 4 or 5. Its presence in optical grade single crystal LiF further suggests that it is an intrinsic defect or possibly associated with chance impurities other than Mg, Ti. (authors)

  6. Evaluation of 2 1/4 Cr-1 Mo steel for liquid lithium containment. II. Effects of post-weld heat treatment and niobium content. Annual report, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, T.L.; Edwards, G.R.

    1979-01-01

    The lithium corrosion resistance of the regular grade of 2 1/4 Cr-1 Mo steel can be vastly improved with a proper postweld heat treatment, but even greater improvements are needed. Results indicate that if weldments were tempered sufficiently long at 760C to remove all Mo/sub 2/C from the microstructure, even greater resistance to attack by low nitrogen lithium could be achieved. Corrosion tests should eventually be performed on regular grade 2 1/4 Cr-1 Mo steel weldments which have been given a long-term (> 25 h) post-weld temper at 760C. Lithium corrosion resistance of regular grade 2 1/4 Cr-1 Mo steel may also be improved by employing a quench and temper heat treatment. Quenched microstructures have more homogenous distribution of carbides than isothermally annealed microstructures, and if properly tempered, should provide excellent lithium corrosion resistance. Furthermore, the toughness of such a lower bainite microstructure should be better than that of the ferrite-bainitic microstructure created by an isothermal anneal. Numerous parameters, all potentially deleterious to the lithium corrosion resistance of 2 1/4 Cr-1 Mo steel, remain to be investigated; two such variables are velocity effects and lead content in the lithium.

  7. Evaluation of 2 1/4 Cr-1 Mo steel for liquid lithium containment. II. Effects of post-weld heat treatment and niobium content. Annual report, 1979

    International Nuclear Information System (INIS)

    Anderson, T.L.; Edwards, G.R.

    1979-01-01

    The lithium corrosion resistance of the regular grade of 2 1/4 Cr-1 Mo steel can be vastly improved with a proper postweld heat treatment, but even greater improvements are needed. Results indicate that if weldments were tempered sufficiently long at 760C to remove all Mo 2 C from the microstructure, even greater resistance to attack by low nitrogen lithium could be achieved. Corrosion tests should eventually be performed on regular grade 2 1/4 Cr-1 Mo steel weldments which have been given a long-term (> 25 h) post-weld temper at 760C. Lithium corrosion resistance of regular grade 2 1/4 Cr-1 Mo steel may also be improved by employing a quench and temper heat treatment. Quenched microstructures have more homogenous distribution of carbides than isothermally annealed microstructures, and if properly tempered, should provide excellent lithium corrosion resistance. Furthermore, the toughness of such a lower bainite microstructure should be better than that of the ferrite-bainitic microstructure created by an isothermal anneal. Numerous parameters, all potentially deleterious to the lithium corrosion resistance of 2 1/4 Cr-1 Mo steel, remain to be investigated; two such variables are velocity effects and lead content in the lithium

  8. The influence of post-processing on creep and microstructure of rolled Cu-8Cr-4Nb

    Energy Technology Data Exchange (ETDEWEB)

    Walley, J.L.; Heelan, J.L.; Vettraino, L.G.; Groza, J.R. [Department of Chemical Engineering and Materials Science, University of California, One Shields Ave., Davis, CA 95616 (United States); Gibeling, J.C., E-mail: jcgibeling@ucdavis.edu [Department of Chemical Engineering and Materials Science, University of California, One Shields Ave., Davis, CA 95616 (United States)

    2010-10-15

    Research highlights: {yields} A simulated-life heat treatment anneal of 24 h at 773 K reduced the steady-state creep rate and increased the creep life of a rolled powder metallurgy Cu-8Cr-4Nb alloy. {yields} The primary microstructural difference between the rolled form and the annealed form of Cu-8Cr-4Nb is the development of annealing twins during heat treatment causing a decrease in the intensity of the texture. {yields} Friction stir welding of rolled Cu-8Cr-4Nb negatively affected creep ductility, thereby decreasing creep life at the temperature tested. Strain localization in the soft heat-affected zone of the weld is hypothesized to be the cause of the decreased creep ductility. - Abstract: Previous work has shown that rolling of an extruded Cu-8Cr-4Nb (GRCop-84) alloy results in higher steady-state creep rates over a range of stresses, leading to concern that other post-processing methods could have substantial deleterious effects on creep properties. To explore that possibility, constant-stress creep tests were conducted at 773 K on rolled GRCop-84 after it was subjected to either friction stir welding (FSW) or a 24 h 1073 K simulated-life heat treatment. The FSW had no measurable effect on the creep rate of the rolled material, but did have detrimental effects on the creep ductility caused by softening, and thus strain localization, in the heat-affected zone of the weld. The simulated-life heat treatment decreased the steady-state creep rate by approximately 45% as compared to the rolled material, leading to longer creep life at a particular applied stress. Electron backscatter diffraction methods were used to compare the microstructural features of extruded, rolled and annealed material forms. It was determined that the rolling procedure decreased the grain size, and decreased the intensity of the texture as compared to the extruded form. The simulated-life heat treatment allowed for the substantial development of twins along with minor grain growth, and

  9. The influence of post-processing on creep and microstructure of rolled Cu-8Cr-4Nb

    International Nuclear Information System (INIS)

    Walley, J.L.; Heelan, J.L.; Vettraino, L.G.; Groza, J.R.; Gibeling, J.C.

    2010-01-01

    Research highlights: → A simulated-life heat treatment anneal of 24 h at 773 K reduced the steady-state creep rate and increased the creep life of a rolled powder metallurgy Cu-8Cr-4Nb alloy. → The primary microstructural difference between the rolled form and the annealed form of Cu-8Cr-4Nb is the development of annealing twins during heat treatment causing a decrease in the intensity of the texture. → Friction stir welding of rolled Cu-8Cr-4Nb negatively affected creep ductility, thereby decreasing creep life at the temperature tested. Strain localization in the soft heat-affected zone of the weld is hypothesized to be the cause of the decreased creep ductility. - Abstract: Previous work has shown that rolling of an extruded Cu-8Cr-4Nb (GRCop-84) alloy results in higher steady-state creep rates over a range of stresses, leading to concern that other post-processing methods could have substantial deleterious effects on creep properties. To explore that possibility, constant-stress creep tests were conducted at 773 K on rolled GRCop-84 after it was subjected to either friction stir welding (FSW) or a 24 h 1073 K simulated-life heat treatment. The FSW had no measurable effect on the creep rate of the rolled material, but did have detrimental effects on the creep ductility caused by softening, and thus strain localization, in the heat-affected zone of the weld. The simulated-life heat treatment decreased the steady-state creep rate by approximately 45% as compared to the rolled material, leading to longer creep life at a particular applied stress. Electron backscatter diffraction methods were used to compare the microstructural features of extruded, rolled and annealed material forms. It was determined that the rolling procedure decreased the grain size, and decreased the intensity of the texture as compared to the extruded form. The simulated-life heat treatment allowed for the substantial development of twins along with minor grain growth, and a substantial

  10. A comparative study of laser beam welding and laser-MIG hybrid welding of Ti-Al-Zr-Fe titanium alloy

    International Nuclear Information System (INIS)

    Li Ruifeng; Li Zhuguo; Zhu Yanyan; Rong Lei

    2011-01-01

    Research highlights: → Ti-Al-Zr-Fe titanium alloy sheets were welded by LBW and LAMIG methods. → LAMIG welded joints have better combination of strength and ductility. → LAMIG welding is proved to be feasible for the production of titanium sheet joints. - Abstract: Ti-Al-Zr-Fe titanium alloy sheets with thickness of 4 mm were welded using laser beam welding (LBW) and laser-MIG hybrid welding (LAMIG) methods. To investigate the influence of the methods difference on the joint properties, optical microscope observation, microhardness measurement and mechanical tests were conducted. Experimental results show that the sheets can be welded at a high speed of 1.8 m/min and power of 8 kW, with no defects such as, surface oxidation, porosity, cracks and lack of penetration in the welding seam. In addition, all tensile test specimens fractured at the parent metal. Compared with the LBW, the LAMIG welding method can produce joints with higher ductility, due to the improvement of seam formation and lower microhardness by employing a low strength TA-10 welding wire. It can be concluded that LAMIG is much more feasible for welding the Ti-Al-Zr-Fe titanium alloy sheets.

  11. Laser welding engineering

    International Nuclear Information System (INIS)

    Bhieh, N. M.; El Eesawi, M. E.; Hashkel, A. E.

    2007-01-01

    Laser welding was in its early life used mainly for unusual applications where no other welding process would be suitable that was twenty five years ago. Today, laser welding is a fully developed part of the metal working industry, routinely producing welds for common items such as cigarette lighters, which springs, motor/transformer lamination, hermetic seals, battery and pacemaker cans and hybrid circuit packages. Yet very few manufacturing engineering have seriously considers employing lasers in their own operations. Why? There are many reasons, but a main one must be not acquainted with the operation and capabilities of a laser system. Other reasons, such as a relatively high initial cost and a concern about using lasers in the manufacturing environment, also are frequently cited, and the complexity of the component and flexibility of the light delivery system. Laser welding could be used in place of many different standard processes, such as resistance (spot or seam), submerged arc, RF induction, high-frequency resistance, ultrasonic and electronic and electron-beam. while each of these techniques has established an independent function in the manufacturing world, the flexible laser welding approach will operate efficiently and economically in many different applications. Its flexibility will even permit the welding system to be used for other machining function, such as drilling, scribing, sealing and serializing. In this article, we will look at how laser welding works and what benefits it can offer to manufacturing engineers. Some industry observers state that there are already 2,000 laser machine tools being used for cutting, welding and drilling and that the number could reach 30,000 over the next 15 years as manufacturing engineers become more aware of the capabilities of lasers [1). While most laser applications are dedicated to one product or process that involves high-volume, long-run manufacturing, the flexibility of a laser to supply energy to hard

  12. Microstructural Study of 17-4PH Stainless Steel after Plasma-Transferred Arc Welding

    Directory of Open Access Journals (Sweden)

    Dewei Deng

    2015-01-01

    Full Text Available The improvement of the surface qualities and surface hardening of precipitation hardened martensitic stainless steel 17-4PH was achieved by the plasma-transferred arc welding (PTAW process deposited with Co-based alloy. The microstructure of the heat affected zone (HAZ and base metal were characterized by optical microscope (OM, scanning electron microscope (SEM and transmission electron microscope (TEM. The results show that there are obvious microstructural differences between the base metal and HAZ. For example, base material is transformed from lath martensite to austenite due to the heateffect of the welding process. On the other hand, the precipitate in the matrix (bar-like shape Cr7C3 phase with a width of about one hundred nanometres and a length of hundreds of nanometres grows to a rectangular appearance with a width of about two hundred nanometres and a length of about one micron. Stacking fault could also be observed in the Cr7C3 after PTAW. The above means that welding can obviously improve the surface qualities.

  13. Absolute disintegration rate and 320 keV {gamma}-ray emission probability of {sup 51}Cr

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, M.C.M. de [Laboratorio Nacional de Metrologia das Radiacoes Ionizantes /Instituto de Radioprotecao e Dosimetria (LNMRI/ IRD), Avenida Salvador Allende, s/no. Recreio-Rio de Janeiro, CEP 22780-160 (Brazil)], E-mail: candida@ird.gov.br; Iwahara, A.; Poledna, R.; Silva, C.J. da; Delgado, J.U. [Laboratorio Nacional de Metrologia das Radiacoes Ionizantes /Instituto de Radioprotecao e Dosimetria (LNMRI/ IRD), Avenida Salvador Allende, s/no. Recreio-Rio de Janeiro, CEP 22780-160 (Brazil)

    2007-09-21

    This work describes the procedures for determining absolutely the {sup 51}Cr disintegration rate by using the 4{pi}{beta}-{gamma} coincidence and anti-coincidence counting and the sum-peak methods. A 4''x4''-NaI(Tl) scintillation detector was used in the {gamma}- channel of the 4{pi}{beta}-{gamma} coincidence system for {gamma}-ray counting. In the {beta}-channel, a 4{pi} gas flow proportional counter was used for counting of characteristic X-rays and Auger electrons originating from the electron capture events of the {sup 51}Cr decay scheme. Gamma spectrometry measurements by high-pure planar and coaxial germanium detectors were performed in the sum-peak method and in the determination of the 320 keV {gamma}-emission probability of {sup 51}Cr. This latter determined value agrees with the recent values found in the literature, confirming the reliability of the three methods used in this work for the disintegration rate measurements.

  14. Some studies on weld bead geometries for laser spot welding process using finite element analysis

    International Nuclear Information System (INIS)

    Siva Shanmugam, N.; Buvanashekaran, G.; Sankaranarayanasamy, K.

    2012-01-01

    Highlights: → In this study, a 2 kW Nd:YAG laser welding system is used to conduct laser spot welding trials. → The size and shape of the laser spot weld is predicted using finite element simulation. → The heat input is assumed to be a three-dimensional conical Gaussian heat source. → The result highlights the effect of beam incident angle on laser spot welds. → The achieved results of numerical simulation are almost identical with a real weldment. -- Abstract: Nd:YAG laser beam welding is a high power density welding process which has the capability to focus the beam to a very small spot diameter of about 0.4 mm. It has favorable characteristics namely, low heat input, narrow heat affected zone and lower distortions, as compared to conventional welding processes. In this study, finite element method (FEM) is applied for predicting the weld bead geometry i.e. bead length (BL), bead width (BW) and depth of penetration (DP) in laser spot welding of AISI 304 stainless steel sheet of thickness 2.5 mm. The input parameters of laser spot welding such as beam power, incident angle of the beam and beam exposure time are varied for conducting experimental trials and numerical simulations. Temperature-dependent thermal properties of AISI 304 stainless steel, the effect of latent heat of fusion, and the convective and radiative aspects of boundary conditions are considered while developing the finite element model. The heat input to the developed model is assumed to be a three-dimensional conical Gaussian heat source. Finite-element simulations of laser spot welding were carried out by using Ansys Parametric Design Language (APDL) available in finite-element code, ANSYS. The results of the numerical analysis provide the shape of the weld beads for different ranges of laser input parameters that are subsequently compared with the results obtained through experimentation and it is found that they are in good agreement.

  15. Mechanical properties of friction stir welded 11Cr-ferritic/martensitic steel

    International Nuclear Information System (INIS)

    Yano, Y.; Sato, Y.S.; Sekio, Y.; Ohtsuka, S.; Kaito, T.; Ogawa, R.; Kokawa, H.

    2013-01-01

    Friction stir welding was applied to the wrapper tube materials, 11Cr-ferritic/martensitic steel, designed for fast reactors and defect-free welds were successfully produced. The mechanical and microstructural properties of the friction stir welded steel were subsequently investigated. The hardness values of the stir zone were approximately 550 Hv (5.4 GPa) with minimal dependence on the rotational speed, even though they were much higher than those of the base material. However, tensile strengths and elongations of the stir zones were high at 298 K, compared to those of the base material. The excellent tensile properties are attributable to the fine grain formation during friction stir welding

  16. Investigation of plasma arc welding as a method for the additive manufacturing of titanium-(6)aluminum-(4)vanadium alloy components

    Science.gov (United States)

    Stavinoha, Joe N.

    The process of producing near net-shape components by material deposition is known as additive manufacturing. All additive manufacturing processes are based on the addition of material with the main driving forces being cost reduction and flexibility in both manufacturing and product design. With wire metal deposition, metal is deposited as beads side-by-side and layer-by-layer in a desired pattern to build a complete component or add features on a part. There are minimal waste products, low consumables, and an efficient use of energy and feedstock associated with additive manufacturing processes. Titanium and titanium alloys are useful engineering materials that possess an extraordinary combination of properties. Some of the properties that make titanium advantageous for structural applications are its high strength-to-weight ratio, low density, low coefficient of thermal expansion, and good corrosion resistance. The most commonly used titanium alloy, Ti-6Al-4V, is typically used in aerospace applications, pressure vessels, aircraft gas turbine disks, cases and compressor blades, and surgical implants. Because of the high material prices associated with titanium alloys, the production of near net-shape components by additive manufacturing is an attractive option for the manufacturing of Ti-6Al-4V alloy components. In this thesis, the manufacturing of cylindrical Ti-6Al-4V alloy specimens by wire metal deposition utilizing the plasma arc welding process was demonstrated. Plasma arc welding is a cost effective additive manufacturing technique when compared to other current additive manufacturing methods such as laser beam welding and electron beam welding. Plasma arc welding is considered a high-energy-density welding processes which is desirable for the successful welding of titanium. Metal deposition was performed using a constant current plasma arc welding power supply, flow-purged welding chamber, argon shielding and orifice gas, ERTi-5 filler metal, and Ti-6Al

  17. Laser Welding Of Finned Tubes Made Of Austenitic Steels

    Directory of Open Access Journals (Sweden)

    Stolecki M.

    2015-09-01

    Full Text Available This paper describes the technology of welding of finned tubes made of the X5CrNi1810 (1.4301 austenitic steel, developed at Energoinstal SA, allowing one to get high quality joints that meet the requirements of the classification societies (PN-EN 15614, and at the same time to significantly reduce the manufacturing costs. The authors described an automatic technological line equipped with a Trumph disc laser and a tube production technological process. To assess the quality of the joints, one performed metallographic examinations, hardness measurements and a technological attempt to rupture the fin. Analysis of the results proved that the laser-welded finned tubes were performed correctly and that the welded joints had shown no imperfections.

  18. On the excitation spectra of Cr{sup 3+}/Cr{sup 2+} and V{sup 3+} co-doped ZnAl{sub 2}S{sub 4} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Anghel, S., E-mail: anggell@gmail.com [Institute of Applied Physics, Academiei Str 5, Chis,inău MD-2028, Republic of Moldova (Moldova, Republic of); Ruhr-Universität Bochum, Anorganische Chemie III, Universitätsstrasse 150, D-44801 Bochum (Germany); Brik, M.G. [College of Sciences, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Institute of Physics, University of Tartu, Ravila 14 C, Tartu 50411 (Estonia); Institute of Physics, Jan Dlugosz University, Armii Krajowej 13/15, PL-42200 Czestochowa (Poland); Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warsaw (Poland); Ma, C.-G. [College of Sciences, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Sushkevich, K. [State University of Moldova, Mateevici Str 60, Chis,inău MD-2009, Republic of Moldova (Moldova, Republic of); Kulyuk, L. [Institute of Applied Physics, Academiei Str 5, Chis,inău MD-2028, Republic of Moldova (Moldova, Republic of)

    2015-10-15

    The excitation spectra of the ZnAl{sub 2}S{sub 4} spinel crystals codoped with chromium and vanadium are investigated in order to explain some features of the Cr{sup 3+} ions optical spectra and the inconsistency of the experimental absorption/emission bands position with the Tanabe–Sugano diagram, as well as the “missing” band in the absorption spectrum of V{sup 3+} ion although this band should be present as it is due to a spin allowed transition. The unusual high Racah parameters of the C/B ratio for Cr{sup 3+} ions have been induced to recalculate the Tanabe–Sugano diagram for the d{sup 3} electron configuration and the ratio C/B=8 in order to use it for the experimental results interpretation. The presence of Cr{sup 2+} ions in the low spin electron configurations in the octahedral coordination was confirmed; the temperature dependence of the Cr{sup 2+} emission at about 1.9 eV was studied and the Huang–Rhys factors were estimated for different temperatures. Despite the fact that the V{sup 3+}C/B ratio has a different value compared to the case of Cr{sup 3+} ions, the electron–phonon interaction is similar for both ions, with the Huang–Rhys parameter equal to 10 in both cases. Further research into optimizing the ZnAl{sub 2}S{sub 4}:Cr, V system to get an efficient enhancement of the vanadium emission on account on re-absorbing the chromium emission is suggested. - Highlights: • The spectroscopic properties of Cr and V codoped α-ZnAI{sub 2}S{sub 4} have been investigated. • The crystal field calculations have been performed. • The Huang–Rhys factors have been estimated for different temperatures. • The theoretical calculations have been correlated with the excitation spectra.

  19. Calculated energy dependence of CaSO4:Dy TL phosphor and phosphor embedded Teflon for X and gamma rays

    International Nuclear Information System (INIS)

    Chang, J.-K.; Nam, Y.-M.; Kim, J.-L.; Chang, S.-Y.; Kim, B.-H.

    2001-01-01

    The energy dependence of a CaSO 4 :Dy TL phosphor for 21 monoenergetic photons of energy ranging from 0.01 to 3 MeV was calculated by using MCNP4A code. The calculation results show good agreement with those of other authors within ± 5% relative error. Calculations and experiments are also performed to determine the energy dependence of CaSO 4 : Dy phosphor with Dy concentrations from 0.01 to 1.5 mol %, and with the compositions of TL-Teflon from 10 to 90 wt %. The calculated energy responses show good agreement with the experiment results within ± 20% relative error except for a concentration lower than 0.1 mol % Dy and the low energy regions of M30 (Eave.=20 keV) and M60 (Eave.=34 keV). For the TL-Teflon mixture, the energy dependence shows an decreasing trend with the increase of Teflon concentration in MCNP calculation but shows no dependence for TL-Teflon mixture proportions in experiment. These differences are due to the non-homogeneous distribution of Dy concentration and the effect of large grain size in the phosphors. The energy dependence of the 30 wt/o CaSO 4 (0.1 mol%;Dy) and 70 wt/o Teflon that is placed behind the filters of plastic, aluminum, copper, tin and lead with a thickness from 0.1 to 2 mm were calculated, respectively

  20. Femtosecond Cr:LiSAF and Cr:LiCAF lasers pumped by tapered diode lasers.

    Science.gov (United States)

    Demirbas, Umit; Schmalz, Michael; Sumpf, Bernd; Erbert, Götz; Petrich, Gale S; Kolodziejski, Leslie A; Fujimoto, James G; Kärtner, Franz X; Leitenstorfer, Alfred

    2011-10-10

    We report compact, low-cost and efficient Cr:Colquiriite lasers that are pumped by high brightness tapered laser diodes. The tapered laser diodes provided 1 to 1.2 W of output power around 675 nm, at an electrical-to-optical conversion efficiency of about 30%. Using a single tapered diode laser as the pump source, we have demonstrated output powers of 500 mW and 410 mW together with slope efficiencies of 47% and 41% from continuous wave (cw) Cr:LiSAF and Cr:LiCAF lasers, respectively. In cw mode-locked operation, sub-100-fs pulse trains with average power between 200 mW and 250 mW were obtained at repetition rates around 100 MHz. Upon pumping the Cr:Colquiriite lasers with two tapered laser diodes (one from each side of the crystal), we have observed scaling of cw powers to 850 mW in Cr:LiSAF and to 650 mW in Cr:LiCAF. From the double side pumped Cr:LiCAF laser, we have also obtained ~220 fs long pulses with 5.4 nJ of pulse energy at 77 MHz repetition rate. These are the highest energy levels reported from Cr:Colquiriite so far at these repetition rates. Our findings indicate that tapered diodes in the red spectral region are likely to become the standard pump source for Cr:Colquiriite lasers in the near future. Moreover, the simplified pumping scheme might facilitate efficient commercialization of Cr:Colquiriite systems, bearing the potential to significantly boost applications of cw and femtosecond lasers in this spectral region (750-1000 nm).

  1. Creep failure analysis of butt welded tubes

    International Nuclear Information System (INIS)

    Browne, R.J.; Parker, J.D.; Walters, D.J.

    1981-01-01

    As part of a major research programme to investigate the influence of butt welds on the life expectancy of tubular components, a series of internal-pressure, stress-rupture tests have been carried out. Thick walled 1/2Cr 1/2Mo 1/4V tube specimens were welded with mild steel, 1Cr 1/2Mo steel, 2 1/4Cr 1Mo steel or nominally matching 1/2Cr 1/2Mo 1/4V steel to give a wide range of weld metal creep strengths relative to the parent tube. The weldments were tested at 565 0 C at two values of internal pressure, and gave failure lives of up to 44,000 hrs. Finite element techniques have been used to determine the stationary state stress distribution in the weldment which was represented by a three material model. Significant stress redistribution was indicated and these results enabled the position and orientation of cracking and the rupture life to be predicted. The theoretical and experimental results have been used to highlight the limitations of current design methods which are based on the application of the mean diameter hoop stress to the parent material stress rupture data. (author)

  2. Searching for “LiCrIIPO4

    International Nuclear Information System (INIS)

    Mosymow, E.; Glaum, R.; Kremer, R.K.

    2014-01-01

    The two new phosphates LiCr II 4 (PO 4 ) 3 and Li 5 Cr II 2 Cr III (PO 4 ) 4 are discovered as equilibrium phases (ϑ=800 °C) in the quarternary system Li/Cr/P/O. Their crystal structures have been determined from single-crystal X-ray diffraction data (LiCr II 4 (PO 4 ) 3 : violet-blue, Pnma (no. 62), Z=4, a=6.175(1) Å, b=14.316(3) Å, c=10.277(2) Å, 100 parameters, R 1 =0.028, wR 2 =0.08, 2060 unique reflections with F o >4σ(F o ); Li 5 Cr II 2 Cr III (PO 4 ) 4 : greyish-green, P1 ¯ (no. 2), Z=1, a=4.9379(7) Å, b=7.917(2) Å, c=8.426(2) Å, α=109.98(2)°, β=90.71(1)°, γ=104.91(1)°, 131 parameters, R 1 =0.022, wR 2 =0.067, 1594 unique reflections with F o >4σ(F o )). Li 5 Cr II 2 Cr III (PO 4 ) 4 adopts an hitherto unknown structure type. The crystal structure of LiCr II 4 (PO 4 ) 3 is isotypic to that of NaCd II 4 (PO 4 ) 3 and related to that of the mineral silicocarnotite Ca 5 (PO 4 ) 2 (SiO 4 ). Significant disorder between Li + and Cr 2+ is observed for both crystal structures. The oxidation states assigned to chromium in these two phosphates are in agreement with UV/vis/NIR absorption spectra and magnetic susceptibility data recorded for both compounds. Instead of “LiCr II PO 4 ” mixtures of LiCr II 4 (PO 4 ) 3 , Li 5 Cr II 2 Cr III (PO 4 ) 4 , Cr 2 O 3 , and CrP are observed at equilibrium. Instead of “Li 2 Cr II P 2 O 7 ” four-phase mixtures consisting of Li 9 Cr III 3 (P 2 O 7 ) 3 (PO 4 ) 2 , Li 3 Cr III 2 (PO 4 ) 3 , LiCrP 2 O 7 , and CrP were obtained. - Graphical abstract: Investigations on the equilibrium relations in the system Li/Cr/P/O revealed the two hitherto unknown phosphates Li 5 Cr II 2 Cr III (PO 4 ) 4 and LiCr II 4 (PO 4 ) 3 . They form instead of “LiCr II PO 4 ”. The crystal structures, magnetic behavior and optical spectra of these phosphates are reported. - Highlights: • The two new phosphates Li 5 Cr II 2 Cr III (PO 4 ) 4 and LiCr II 4 (PO 4 ) 3 have been characterized. • Optical spectra and paramagnetism of

  3. Evaluating electrically insulating films deposited on V-4% Cr-4% Ti by reactive CVD

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.H.; Cho, W.D. [Argonne National Lab., IL (United States)

    1997-04-01

    Previous CaO coatings on V-4%Cr-4%Ti exhibited high-ohmic insulator behavior even though a small amount of vanadium from the alloy was incorporated in the coating. However, when the vanadium concentration in the coatings is > 15 wt%, the coating becomes conductive. When the vanadium concentration is high in localized areas, a calcium vanadate phase that exhibits semiconductor behavior can form. To explore this situation, CaO and Ca-V-O coatings were produced on vanadium alloys by chemical vapor deposition (CVD) and by a metallic-vapor process to investigate the electrical resistance of the coatings. Initially, the vanadium alloy specimens were either charged with oxygen in argon that contained trace levels of oxygen, or oxidized for 1.5-3 h in a 1% CO-CO{sub 2} gas mixture or in air to form vanadium oxide at 625-650{degrees}C. Most of the specimens were exposed to calcium vapor at 800-850{degrees}C. Initial and final weights were obtained to monitor each step, and surveillance samples were removed for examination by optical and scanning electron microscopy and electron-energy-dispersive and X-ray diffraction analysis; the electrical resistivity was also measured. The authors found that Ca-V-O films exhibited insulator behavior when the ratio of calcium concentration to vanadium concentration R in the film was > 0.9, and semiconductor or conductor behavior for R < 0.8. However, in some cases, semiconductor behavior was observed when CaO-coated samples with R > 0.98 were exposed in liquid lithium. Based on these studies, the authors conclude that semiconductor behavior occurs if a conductive calcium vanadate phase is present in localized regions in the CaO coating.

  4. Bioceramic hydroxyapatite coating fabricated on TI-6Al-4V using Nd:YAG Laser

    CSIR Research Space (South Africa)

    Tlotleng, Monnamme

    2014-11-01

    Full Text Available Driven Innovation, 15th Annual International Conference, Stellenbosch, South Africa, 6-7 November 2014 Bioceramic hydroxyapatite coating fabricated on TI-6Al-4V using Nd:YAG Laser M. Tlotleng1, 4*, E. Akinlabi1, M. Shukla2, 3, S. Pityana4, T...

  5. Effects of Laser Peening, and Shot Peening, on Friction Stir Welding

    Science.gov (United States)

    Hatamleh, Omar; Hackel, Lloyd; Rankin, Jon; Truong, Chanh; Walter, Matt

    2006-01-01

    A viewgraph presentation describing the effects of laser peening and shot peening on friction stir welding is shown. The topics include: 1) Background; 2) Friction Stir Welding (FSW); 3) Microstructure; 4) Laser & Shot Peening; 5) Residual Stresses; 6) Tensile Behavior; 7) Fatigue Life & Surface Roughness; 8) Crack Growth; and 9) Benefits.

  6. Welding repair of the steam and gas turbines rotors made of Cr-Mo-V steel

    International Nuclear Information System (INIS)

    Mazur, Z.; Kubiak, J.; Hernandez, A.

    1999-01-01

    An analysis of typical steam turbine and gas turbine rotor failures is carried out. On the base of the rotors different failure causes and their mode of occurring, an evaluation of the weldability of the Cr-Mo-V steels and the classification of the common turbine rotors repair possibilities is presented. The developing of specific in-situ welding repair process of the damaged 20.65 MW gas turbine rotor is described. After repair, the rotor was put back into service. (Author) 15 refs

  7. Effects of Laser Power Level on Microstructural Properties and Phase Composition of Laser-Clad Fluorapatite/Zirconia Composite Coatings on Ti6Al4V Substrates

    Science.gov (United States)

    Chien, Chi-Sheng; Liu, Cheng-Wei; Kuo, Tsung-Yuan

    2016-01-01

    Hydroxyapatite (HA) is one of the most commonly used materials for the coating of bioceramic titanium (Ti) alloys. However, HA has poor mechanical properties and a low bonding strength. Accordingly, the present study replaces HA with a composite coating material consisting of fluorapatite (FA) and 20 wt % yttria (3 mol %) stabilized zirconia (ZrO2, 3Y-TZP). The FA/ZrO2 coatings are deposited on Ti6Al4V substrates using a Nd:YAG laser cladding system with laser powers and travel speeds of 400 W/200 mm/min, 800 W/400 mm/min, and 1200 W/600 mm/min, respectively. The experimental results show that a significant inter-diffusion of the alloying elements occurs between the coating layer (CL) and the transition layer (TL). Consequently, a strong metallurgical bond is formed between them. During the cladding process, the ZrO2 is completely decomposed, while the FA is partially decomposed. As a result, the CLs of all the specimens consist mainly of FA, Ca4(PO4)2O (TTCP), CaF2, CaZrO3, CaTiO3 and monoclinic phase ZrO2 (m-ZrO2), together with a small amount of θ-Al2O3. As the laser power is increased, CaO, CaCO3 and trace amounts of tetragonal phase ZrO2 (t-ZrO2) also appear. As the laser power increases from 400 to 800 W, the CL hardness also increases as a result of microstructural refinement and densification. However, at the highest laser power of 1200 W, the CL hardness reduces significantly due to the formation of large amounts of relatively soft CaO and CaCO3 phase. PMID:28773503

  8. Reactive resistance welding of Ti6Al4V alloy with the use of Ni(V)/Al multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Maj, Lukasz; Morgiel, Jerzy [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, Krakow (Poland); Mars, Krzysztof; Godlewska, Elzbieta [Faculty of Materials Science and Ceramics, AGH University of Science and Technology, Krakow (Poland)

    2017-02-15

    The freestanding Ni(V)/Al multilayer foil was applied as a filler material in order to join Ti6Al4V alloy with the use of reactive resistance welding (RRW) technique. Present investigations, performed with the use of transmission electron microscopy (TEM) method, allowed to show that an application of high current (I = 400 A for 2 min in vacuum conditions ∝10{sup -1} mbar) transformed the Ni(V)/Al multilayers into fine grain (<300 nm) NiAl phase. It also showed that the RRW process led to the formation of firm connection with nanoporosity limited only to the original contact plane between base material and the foil. Simultaneously, the formation of a narrow strip of crystallites of Ti{sub 3}Al intermetallic phase elongated along the joint line (average size of ∝200 nm) was observed. The base material was separated from the joint area by a layer of up to ∝2 μm thickness of nearly defect free α-Ti and β-Ti grains from a heat affected zone (HAZ). The performed experiment proved that Ni(V)/Al multilayer could serve as a filler material for joining of Ti6Al4V alloys even without additional solder layer. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. An evaluation of the susceptibility of V-4Cr-4Ti to stress corrosion cracking in room temperature DIII-D water

    Energy Technology Data Exchange (ETDEWEB)

    Kurtz, R.J.; Jones, R.H. [Pacific Northwest National Lab., Richland, WA (United States); Johnson, W.R.

    1997-04-01

    Two fatigue precracked compact tension (CT) specimens of V-4Cr-4Ti were statically loaded to a stress intensity factor of about 30 MPa{radical}m in room temperature DIII-D water. The first specimen was tested for a period of about 30 days and the second specimen for about 54 days. At the conclusion of each test the specimens were fractured, and the fracture surfaces examined with a scanning electron microscope (SEM) to determine if SCC had occurred. No SCC was found in either test specimen.

  10. Development of laser weld monitoring system for PWR space grid

    International Nuclear Information System (INIS)

    Chung, Chin Man; Kim, Cheol Jung; Kim, Min Suk

    1998-06-01

    The laser welding monitoring system was developed to inspect PWR space grid welding for KNFC. The demands for this optical monitoring system were applied to Q.C. and process control in space grid welding. The thermal radiation signal from weld pool can be get the variation of weld pool size. The weld pool size and depth are verified by analyzed wavelength signals from weld pool. Applied this monitoring system in space grid weld, improved the weld productivity. (author). 4 refs., 5 tabs., 31 figs

  11. Joint properties of dissimilar Al6061-T6 aluminum alloy/Ti–6%Al–4%V titanium alloy by gas tungsten arc welding assisted hybrid friction stir welding

    International Nuclear Information System (INIS)

    Bang, HanSur; Bang, HeeSeon; Song, HyunJong; Joo, SungMin

    2013-01-01

    Highlights: • Hybrid friction stir welding for Al alloy and Ti alloy joint has been carried out. • Mechanical strength of dissimilar joint by HFSW and FSW has been compared. • Microstructure of dissimilar joint by HFSW and FSW has been compared. - Abstract: Hybrid friction stir butt welding of Al6061-T6 aluminum alloy plate to Ti–6%Al–4%V titanium alloy plate with satisfactory acceptable joint strength was successfully achieved using preceding gas tungsten arc welding (GTAW) preheating heat source of the Ti alloy plate surface. Hybrid friction stir welding (HFSW) joints were welded completely without any unwelded zone resulting from smooth material flow by equally distributed temperature both in Al alloy side and Ti alloy side using GTAW assistance for preheating the Ti alloy plate unlike friction stir welding (FSW) joints. The ultimate tensile strength was approximately 91% in HFSW welds by that of the Al alloy base metal, which was 24% higher than that of FSW welds without GTAW under same welding condition. Notably, it was found that elongation in HFSW welds increased significantly compared with that of FSW welds, which resulted in improved joint strength. The ductile fracture was the main fracture mode in tensile test of HFSW welds

  12. Laser-Arc Hybrid Welding of Dissimilar Titanium Alloy and Stainless Steel Using Copper Wire

    Science.gov (United States)

    Gao, Ming; Chen, Cong; Wang, Lei; Wang, Zemin; Zeng, Xiaoyan

    2015-05-01

    Laser-arc hybrid welding with Cu3Si filler wire was employed to join dissimilar Ti6Al4V titanium alloy and AISI316 stainless steel (316SS). The effects of welding parameters on bead shape, microstructure, mechanical properties, and fracture behavior were investigated in detail. The results show that cross-weld tensile strength of the joints is up to 212 MPa. In the joint, obvious nonuniformity of the microstructure is found in the fusion zone (FZ) and at the interfaces from the top to the bottom, which could be improved by increasing heat input. For the homogeneous joint, the FZ is characterized by Fe67- x Si x Ti33 dendrites spreading on α-Cu matrix, and the two interfaces of 316SS/FZ and FZ/Ti6Al4V are characterized by a bamboo-like 316SS layer and a CuTi2 layer, respectively. All the tensile samples fractured in the hardest CuTi2 layer at Ti6Al4V side of the joints. The fracture surface is characterized by river pattern revealing brittle cleavage fracture. The bead formation mechanisms were discussed according to the melt flow and the thermodynamic calculation.

  13. Cr3+ and Cr4+ luminescence in glass ceramic silica

    International Nuclear Information System (INIS)

    Martines, Marco A.U.; Davolos, Marian R.; Jafelicci, Miguel Junior; Souza, Dione F. de; Nunes, Luiz A.O.

    2008-01-01

    This paper reports on the effect of glass ceramic silica matrix on [CrO 4 ] 4- and Cr 2 O 3 NIR and visible luminescence. Chromium-containing silica was obtained by precipitation from water-glass and chromium nitrate acid solution with thermal treatment at 1000 deg. C. From XRD results silica and silica-chromium samples are crystalline. The chromium emission spectrum presents two main broad bands: one in the NIR region (1.1-1.7μm) and other in the visible region (0.6-0.7μm) assigned to Cr 4+ and to Cr 3+ , respectively. This thermal treated glass ceramic silica-chromium sample stabilizes the [CrO 4 ] 4- where Cr 4+ substitutes for Si 4+ and also hexacoordinated Cr 3+ group probably as segregated phase in the system. It can be pointed out that luminescence spectroscopy is a powerful tool for detecting the two chromium optical centers in the glass ceramic silica

  14. Initial Parameter Estimation for Inverse Thermal Analysis of Ti-6Al-4V Deep Penetration Welds

    Science.gov (United States)

    2014-05-16

    theory, for the case of deep-penetration welding, is simulation of the coupling of keyhole formation, melting, fluid flow in the weld melt pool and...isothermal boundaires, e.g., TTB and TM. A specific procedure for interpolation, however, has not been considered. For the present study, the close ...Clarendon Press, Oxford, 2nd ed, 374, 1959. 19. R. Rai, J.W. Elmer, T.A. Palmer, T. DebRoy, Heat Transfer and Fluid Flow During Keyhole Mode Laser Welding

  15. Performance of novel materials for radiation detection: Tl3AsSe3, TlGaSe2, and Tl4HgI6

    International Nuclear Information System (INIS)

    Kahler, D.; Singh, N.B.; Knuteson, D.J.; Wagner, B.; Berghmans, A.; McLaughlin, S.; King, M.; Schwartz, K.; Suhre, D.; Gotlieb, M.

    2011-01-01

    In this paper we report on the electrical characteristics of three novel ternary compounds, Tl 3 AsSe 3 (TAS), TlGaSe 2 (TGS), and Tl 4 HgI 6 (THI), pertaining to their use as radiation detectors. The details for growth and material characterization are not presented. A semiconductor based gamma ray detector requires a material with high Z, high density, high resistivity, appropriate bandgap (1.5-2 eV), low energy/electron-hole pair, and a high μτ product. CZT is currently the best semiconductor material for room temperature gamma ray spectroscopy; however, it is extremely difficult to produce large volumes of detector grade material, making it expensive and in limited supply. DNDO/DHS began searching for other materials that might perform as well as CZT but be easier to grow and in the end lower the cost. For this purpose, we investigated the above three materials as possible replacements for CZT as gamma ray detectors. The bulk resistivity, I-V curves, X-ray response, and gamma ray response measurements for doped and undoped crystals are presented and discussed. TAS shows good X-ray and gamma ray response, but has poor resistivity, which results in large dark current and poor spectral response. TGS has good resistivity, but shows poor X-ray and gamma ray response. THI has excellent resistivity, shows some X-ray and gamma ray response, and has great potential as a gamma ray detector.

  16. Fatigue properties of dissimilar metal laser welded lap joints

    Science.gov (United States)

    Dinsley, Christopher Paul

    This work involves laser welding austenitic and duplex stainless steel to zinc-coated mild steel, more specifically 1.2mm V1437, which is a Volvo Truck Coiporation rephosphorised mild steel. The work investigates both tensile and lap shear properties of similar and dissimilar metal laser welded butt and lap joints, with the majority of the investigation concentrating on the fatigue properties of dissimilar metal laser welded lap joints. The problems encountered when laser welding zinc-coated steel are addressed and overcome with regard to dissimilar metal lap joints with stainless steel. The result being the production of a set of guidelines for laser welding stainless steel to zinc-coated mild steel. The stages of laser welded lap joint fatigue life are defined and the factors affecting dissimilar metal laser welded lap joint fatigue properties are analysed and determined; the findings suggesting that dissimilar metal lap joint fatigue properties are primarily controlled by the local stress at the internal lap face and the early crack growth rate of the material at the internal lap face. The lap joint rotation, in turn, is controlled by sheet thickness, weld width and interfacial gap. Laser welded lap joint fatigue properties are found to be independent of base material properties, allowing dissimilar metal lap joints to be produced without fatigue failure occurring preferentially in the weaker parent material, irrespective of large base material property differences. The effects of Marangoni flow on the compositions of the laser weld beads are experimentally characterised. The results providing definite proof of the stirring mechanism within the weld pool through the use of speeds maps for chromium and nickel. Keywords: Laser welding, dissimilar metal, Zinc-coated mild steel, Austenitic stainless steel, Duplex stainless steel, Fatigue, Lap joint rotation, Automotive.

  17. Residual stress in TI6AL4V objects produced by direct metal laser sintering

    Directory of Open Access Journals (Sweden)

    Van Zyl, Ian

    2016-12-01

    Full Text Available Direct Metal Laser Sintering produces 3D objects using a layer-by- layer method in which powder is deposited in thin layers. Laser beam scans over the powder fusing powder particles as well as the previous layer. High-concentration of laser energy input leads to high thermal gradients which induce residual stress within the as- built parts. Ti6Al4V (ELI samples have been manufactured by EOSINT M280 system at prescribed by EOS process-parameters. Residual stresses were measured by XRD method. Microstructure, values and directions of principal stresses inTi6Al4V DMLS samples were analysed.

  18. Study of sup 1 sup 9 sup 4 Tl sup g decay

    CERN Document Server

    Sudarshan, K; Tripathi, R; Goswami, A; Tomar, B S; Reddy, A V R

    2003-01-01

    Absolute gamma ray intensities in the decay of sup 1 sup 9 sup 4 Tl sup g have been measured following the radiochemical separation of sup 1 sup 9 sup 4 Pb produced in the reaction of sup 1 sup 9 F + sup 1 sup 8 sup 1 Ta. The (EC+beta sup +) branching ratios in the decay of sup 1 sup 9 sup 4 Tl sup g to various levels of sup 1 sup 9 sup 4 Hg were deduced. Three new levels are introduced in the decay scheme. A precise value of half life of sup 1 sup 9 sup 4 Pb (10.0+-0.4 min) is reported.

  19. Study of LiF:Mg,Ti and CaSO4:Dy dosimeters TL response to electron beams of 6 MeV applied to radiotherapy using PMMA and solid water phantoms

    International Nuclear Information System (INIS)

    Bravim, A.; Sakuraba, R.K.; Cruz, J.C.; Campos, L.L.

    2011-01-01

    The performance of CaSO 4 :Dy and LiF:Mg,Ti dosimeters to electron beams applied to radiotherapy was investigated. The TL response of these dosimeters was studied for 6 MeV electron beams using PMMA and Solid Water (SW) phantoms. The dosimeters were previously separated in groups according to their TL individual sensitivities to 60 Co gamma-radiation in air under electronic equilibrium conditions. After that, they were irradiated with 6 MeV electron doses of 0.1, 0.5, 1, 5 and 10 Gy using a linear accelerator Clinac 2100C Varian of Hospital Israelita Albert Einstein – HIAE. The electron beam irradiations were performed using a 10 × 10 cm 2 field size, 100 cm source-phantom surface distance and the dosimeters were positioned at the depth of maximum dose (1.2 cm). The TL readings were carried out between 24 and 32 h after irradiation using a Harshaw 3500 TL reader. The TL dose–response of both type of dosimeters and phantoms presented linear behavior on the electron dose range from 0.1 to 5 Gy CaSO 4 :Dy dosimeter is 21 times more sensitive than LiF:Mg,Ti, dosimeter commonly used in clinical dosimetry. The obtained results indicate that the performance of CaSO 4 :Dy dosimeters is similar to LiF:Mg,Ti dosimeters and this material can be an alternative dosimetric material to be used to clinical electron beams dosimetry.

  20. Absolute activity measurements with the windowless 4π-CsI(Tl)-sandwich spectrometer

    International Nuclear Information System (INIS)

    Denecke, B.

    1994-01-01

    The windowless 4π-CsI(Tl)-sandwich spectrometer consists of two scintillation crystals sandwiching radioactive sources deposited on thin plastic foils. This configuration has a solid angle very close to 4π sr. The detectors are sensitive to charged particles with energies > 15 keV and measure photons of 15-200 keV with a probability > 98%. Disintegration rates of samples of radionuclides with complex decay modes can be determined directly from the measured count rates with uncertainties below 0.3%. Radionuclide solutions of 57 Co, 109 Cd, 125 I, 152 Eu and 192 Ir were standardised, partly in the framework of international comparisons. A detailed description of the spectrometer and the measurement procedure is given. (orig.)

  1. Absolute activity measurements with the windowless 4π-CsI(Tl)-sandwich spectrometer

    Science.gov (United States)

    Denecke, B.

    1994-01-01

    The windowless 4π-CsI(Tl)-sandwich spectrometer consists of two scintillation crystals sandwiching radioactive sources deposited on thin plastic foils. This configuration has a solid angle very close to 4π sr. The detectors are sensitive to charged particles with energies > 15 keV and measure photons of 15-200 keV with a probability > 98%. Disintegration rates of samples of radionuclides with complex decay modes can be determined directly from the measured count rates with uncertainties below 0.3%. Radionuclide solutions of 57Co, 109Cd, 125I, 152Eu and 192Ir were standardised, partly in the framework of international comparisons. A detailed description of the spectrometer and the measurement procedure is given.

  2. TL and OSL studies of carbon doped magnesium aluminate (MgAl2O4:C)

    Science.gov (United States)

    Raj, Sanu S.; Mishra, D. R.; Soni, Anuj; Grover, V.; Polymeris, G. S.; Muthe, K. P.; Jha, S. K.; Tyagi, A. K.

    2016-10-01

    The MgAl2O4:C has been synthesized by using two different methods by electron gun and vacuum assisted melting of MgAl2O4 in presence of graphite. The MgAl2O4:C phosphor thus developed by these two different methods have similar types of the TL/OSL defects with multiple overlapping TL glow peaks from 100 °C to 400 °C. The Computerized Curve De-convolution Analysis (CCDA) has been used to measure TL parameters such as thermal trap depth, frequency factor and order of kinetic associated with charge transfer process in TL phenomenon. The investigated TL/OSL results show that these two methods of incorporating carbon in MgAl2O4 have generated closely resemble the defects of similar types in MgAl2O4:C lattice. However, the MgAl2O4:C synthesized by electron gun shows relatively larger concentration of the TL/OSL defects as compared to MgAl2O4:C synthesized using vacuum assisted melting method. The photo-ionization cross-section (PIC) associated with fastest OSL component of MgAl2O4: C is found to be ∼ 0.5 times than that of fastest OSL component of commercially available dosimetric grade α-Al2O3:C. The MgAl2O4:C thus developed shows good dynamic OSL dose linearity from few mGy to 1 Gy. This work reveals that MgAl2O4:C could be developed as potential tissue equivalent OSL / TL material.

  3. Development of automatic laser welding system

    International Nuclear Information System (INIS)

    Ohwaki, Katsura

    2002-01-01

    Laser are a new production tool for high speed and low distortion welding and applications to automatic welding lines are increasing. IHI has long experience of laser processing for the preservation of nuclear power plants, welding of airplane engines and so on. Moreover, YAG laser oscillators and various kinds of hardware have been developed for laser welding and automation. Combining these welding technologies and laser hardware technologies produce the automatic laser welding system. In this paper, the component technologies are described, including combined optics intended to improve welding stability, laser oscillators, monitoring system, seam tracking system and so on. (author)

  4. Laser and Pressure Resistance Weld of Thin-Wall Cladding for LWR Accident-Tolerant Fuels

    Science.gov (United States)

    Gan, J.; Jerred, N.; Perez, E.; Haggard, D. C.

    2018-02-01

    FeCrAl alloy with typical composition of approximately Fe-15Cr-5Al is considered a primary candidate cladding material for light water reactor accident-tolerant fuel because of its superior resistance to oxidation in high-temperature steam compared with Zircaloy cladding. Thin-walled FeCrAl cladding at 350 μm wall thickness is required, and techniques for joining endplug to cladding need to be developed. Fusion-based laser weld and solid-state joining with pressure resistance weld were investigated in this study. The results of microstructural characterization, mechanical property evaluation by tensile testing, and hydraulic pressure burst testing of the welds for the cladding-endplug specimen are discussed.

  5. Structural relaxation and colour in the spinel-magnesiochromite (MgAl2O4-MgCr2O4) and gahnite-zincochromite (ZnAl2O4-ZnCr2O4) solid solution series

    Science.gov (United States)

    Hålenius, U.; Andreozzi, G. B.; Skogby, H.

    2009-04-01

    .5 %, respectively, is determined. Based on a Cr-O bond distance for the CrO6 polyhedron in magnesiochromite and zincochromite of 1.995 and 1.991 Å respectively (O'Neill and Dollase, 1994) and applying the ligand field relationship 10Dq?C×R-5 (R equals the M-O distance of the MO6-polyhedron), Cr-O bond distances in gahnite and spinel with Cr-contents at trace levels are determined to 1.959 and 1.969 Å, respectively. These M-O bond distances are considerably longer than the M-O distances determined for end member gahnite and spinel by XRD-methods (1.9137 and 1.9280 Å, respectively; O'Neill and Dollase, 1994) and shows that there is considerable structural relaxation of M-O bonds in the two present spinel series. The relaxation parameter, ɛ, determined from the optical absorption spectra is 0.59 and 0.63 for the ZnAl2-2xCr2xO4 and MgAl2-2xCr2xO4 and series, respectively. These values are lower than those suggested from X-ray absorption spectroscopy (Juhin et al. 2007), which may be explained by second nearest neighbour interactions. In contrast to what may be expected, the interelectronic repulsion parameter, B, for V ICr3+ decreases with increasing Cr-content and apparent Cr-O bond length in both of the present spinel series . This indicates that interactions between Cr-atoms in neighbouring octahedra become important at increasing Cr-content and result in more covalent Cr-O bonds. This in turn suppresses the energy of 4A2g -4T2g (4F) transition (and calculated 10Dq-values) in octahedrally coordinated Cr3+. Consequently, the values of structural relaxation parameters determined from the optical absorption spectra must be regarded as minimum numbers. Literature Juhin, A., Calas, G., Cabaret, D. and Galoisy, L. (2007): Structural relaxation around Cr3+ in MgAl2O4. Physical Review, B76, 054105. O'Neill, H.St.C. and Dollase, W.A. (1994): Crystal structures and cation distributions in simple spinels from powder XRD structure refinements: MgCr2O4, ZnCr2O4, Fe3O4 and the temperature

  6. Temper-bead repair-welding of neutron-irradiated reactor (pressure) vessel by low-heat-input TIG and YAG laser welding

    International Nuclear Information System (INIS)

    Nakata, Kiyotomo; Ozawa, Masayoshi; Kamo, Kazuhiko

    2006-01-01

    Weldability in neutron-irradiated low alloy steel for reactor (pressure) vessel has been studied by temper-bead repair-welding of low-heat-input TIG and YAG laser welding. A low alloy steel and its weld, and stainless steel clad and nickel (Ni)-based alloy clad were irradiated in a materials test reactor (LVR-15, Czech Republic) up to 1.4 x 10 24 n/m 2 (>1 MeV) at 290degC, which approximately corresponds to the maximum neutron fluence of 60-year-operation plants' vessels. The He concentration in the irradiated specimens was estimated to be up to 12.9 appm. The repair-welding was carried out by TIG and YAG laser welding at a heat input from 0.06 to 0.86 MJ/m. The mechanical tests of tensile, impact, side bend and hardness were carried out after the repair-welding. Cracks were not observed in the irradiated low alloy steel and its weld by temper-bead repair-welding. Small porosities were formed in the first and second layers of the repair-welds of low alloy steel (base metal). However, only a few porosities were found in the repair-welds of the weld of low alloy steel. From the results of mechanical tests, the repair-welding could be done in the irradiated weld of low alloy steel containing a He concentration up to 12.9 appm, although repair-welding could be done in base metal of low alloy steel containing up to only 1.7 appmHe. On the other hand, cracks occurred in the heat affected zones of stainless steel and Ni-based alloy clads by repair-welding, except by YAG laser repair-welding at a heat input of 0.06 MJ/m in stainless steel clad containing 1.7 appmHe. Based on these results, the determination processes were proposed for optimum parameters of repair-welding of low alloy steel and clad used for reactor (pressure) vessel. (author)

  7. Effect of micromorphology at the fatigue crack tip on the crack growth in electron beam welded Ti-6Al-4V joint

    International Nuclear Information System (INIS)

    Tao, Junhui; Hu, Shubing; Ji, Longbo

    2016-01-01

    In this paper, we describe experiments on welded joints of Ti-6Al-4V alloy specimens exhibiting fatigue characteristics in the base metal (BM), hot affected zone (HAZ) and fuse zone (FZ). The effect of micromorphology on crack propagation at the tip of the fatigue crack in joints formed by electron beam welding was investigated using an optical microscope, transmission electron microscope and other methodologies. The results demonstrated that the fatigue crack originated in and propagated along α/β boundaries in the BM. In the HAZ, the fatigue crack occurred at the boundary between martensite laths, and propagated through most irregular-equiaxed α phases and a few martensite laths. In the FZ, the fatigue crack originated at the boundaries between the fine crushing phases among martensite laths, and propagated along a majority of α/β boundaries and several narrow martensite laths. The electron beam welded joint of Ti-6Al-4V alloy showed instances of zigzag fatigue cracks that increased in degree from lowest in the HAZ, moderate in the FZ to greatest in the BM. Conversely, fatigue crack growth rate (FCGR) was greatest in the HAZ, less in the FZ and slowest in the BM. - Highlights: •Ti-6Al-4V welded joint exhibits different fatigue characteristics. •The fatigue crack propagates along α/β boundaries in the BM. •The fatigue crack propagates through α phases and martensite laths in the HAZ. •The fatigue crack propagates along α/β boundaries and martensite laths in the FZ. •Fatigue crack growth rate is fastest in the HAZ, less in the FZ, slowest in the BM.

  8. Modified section method for laser-welding of ill-fitting cp Ti and Ni-Cr alloy one-piece cast implant-supported frameworks.

    Science.gov (United States)

    Tiossi, R; Falcão-Filho, H; Aguiar Júnior, F A; Rodrigues, R C; Mattos, M da G; Ribeiro, R F

    2010-05-01

    This study aimed to verify the effect of modified section method and laser-welding on the accuracy of fit of ill-fitting commercially pure titanium (cp Ti) and Ni-Cr alloy one-piece cast frameworks. Two sets of similar implant-supported frameworks were constructed. Both groups of six 3-unit implant-supported fixed partial dentures were cast as one-piece [I: Ni-Cr (control) and II: cp Ti] and evaluated for passive fitting in an optical microscope with both screws tightened and with only one screw tightened. All frameworks were then sectioned in the diagonal axis at the pontic region (III: Ni-Cr and IV: cp Ti). Sectioned frameworks were positioned in the matrix (10-Ncm torque) and laser-welded. Passive fitting was evaluated for the second time. Data were submitted to anova and Tukey-Kramer honestly significant difference tests (P screws tightened, one-piece cp Ti group II showed significantly higher misfit values (27.57 +/- 5.06 microm) than other groups (I: 11.19 +/- 2.54 microm, III: 12.88 +/- 2.93 microm, IV: 13.77 +/- 1.51 microm) (P screw-tightened test, with readings on the opposite side to the tightened side, Ni-Cr cast as one-piece (I: 58.66 +/- 14.30 microm) was significantly different from cp Ti group after diagonal section (IV: 27.51 +/- 8.28 microm) (P 0.05). Results showed that diagonally sectioning ill-fitting cp Ti frameworks lowers misfit levels of prosthetic implant-supported frameworks and also improves passivity levels of the same frameworks when compared to one-piece cast structures.

  9. Linear Friction Welding of Dissimilar Materials 316L Stainless Steel to Zircaloy-4

    Science.gov (United States)

    Wanjara, P.; Naik, B. S.; Yang, Q.; Cao, X.; Gholipour, J.; Chen, D. L.

    2018-02-01

    In the nuclear industry, there are a number of applications where the transition of stainless steel to Zircaloy is of technological importance. However, due to the differences in their properties there are considerable challenges associated with developing a joining process that will sufficiently limit the heat input and welding time—so as to minimize the extent of interaction at the joint interface and the resulting formation of intermetallic compounds—but still render a functional metallurgical bond between these two alloys. As such, linear friction welding, a solid-state joining technology, was selected in the present study to assess the feasibility of welding 316L stainless steel to Zircaloy-4. The dissimilar alloy welds were examined to evaluate their microstructural characteristics, microhardness evolution across the joint interface, static tensile properties, and fatigue behavior. Microstructural observations revealed a central intermixed region and, on the Zircaloy-4 side, dynamically recrystallized and thermomechanically affected zones were present. By contrast, deformation on the 316L stainless steel side was limited. In the intermixed region a drastic change in the composition was observed along with a local increase in hardness, which was attributed to the presence of intermetallic compounds, such as FeZr3 and Cr2Zr. The average yield (316 MPa) and ultimate tensile (421 MPa) strengths met the minimum strength properties of Zircaloy-4, but the elongation was relatively low ( 2 pct). The tensile and fatigue fracture of the welds always occurred at the interface in the mode of partial cohesive failure.

  10. Effect of pulsed gas tungsten arc welding on corrosion behavior of Ti-6Al-4V titanium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Balasubramanian, M. [Department of Mechanical Engineering, Maamallan Institute of Technology, Anna University, Sriperumpudur 602 105 (India)], E-mail: manianmb@rediffmail.com; Jayabalan, V. [Department of Manufacturing Engineering, Anna University, Guindy, Chennai 600 025 (India)], E-mail: jbalan@annauniv.edu; Balasubramanian, V. [Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar 608 002 (India)], E-mail: visvabalu@yahoo.com

    2008-07-01

    Due to the excellent combination of properties such as elevated strength-to-weight ratio, high toughness and excellent resistance to corrosion, make titanium alloys attractive for many industrial applications. Advantages of pulsed current welding frequently reported in literature include refinement of fusion zone grain size, etc. Hence, in this investigation an attempt has been made to study the effect of pulsed current Gas Tungsten Arc (GTA) welding parameters on corrosion behavior of Ti-6Al-4V titanium alloy. Pulsed current gas tungsten arc welding was used to fabricate the joints. To optimize the number of experiments to be performed, central composite design was used. The investigation revealed increase in corrosion resistance with increase in peak current and pulse frequency up to an optimum value of the same and decrease in corrosion resistance beyond that optimum point. An increase in corrosion resistance with grain refinement was also detected.

  11. Effect of pulsed gas tungsten arc welding on corrosion behavior of Ti-6Al-4V titanium alloy

    International Nuclear Information System (INIS)

    Balasubramanian, M.; Jayabalan, V.; Balasubramanian, V.

    2008-01-01

    Due to the excellent combination of properties such as elevated strength-to-weight ratio, high toughness and excellent resistance to corrosion, make titanium alloys attractive for many industrial applications. Advantages of pulsed current welding frequently reported in literature include refinement of fusion zone grain size, etc. Hence, in this investigation an attempt has been made to study the effect of pulsed current Gas Tungsten Arc (GTA) welding parameters on corrosion behavior of Ti-6Al-4V titanium alloy. Pulsed current gas tungsten arc welding was used to fabricate the joints. To optimize the number of experiments to be performed, central composite design was used. The investigation revealed increase in corrosion resistance with increase in peak current and pulse frequency up to an optimum value of the same and decrease in corrosion resistance beyond that optimum point. An increase in corrosion resistance with grain refinement was also detected

  12. Electron beam welding of dissimilar metals

    International Nuclear Information System (INIS)

    Metzger, G.; Lison, R.

    1976-01-01

    Thirty-three two-memeber combinations of dissimilar metals were electron beam welded as square-groove butt joints in 0.08 and 0.12 in. sheet material. Many joints were ''braze welded'' by offsetting the electron beam about 0.02 in. from the butt joint to achieve fusion of the lower melting point metal, but no significant fusion of the other member of the pair. The welds were evaluated by visual and metallographic examination, transverse tensile tests, and bend tests. The welds Ag/Al, Ag/Ni15Cr7Fe, Cu/Ni15Cr7Fe, Cu/V, Cu20Ni/Ni15Cr7Fe, Fe18Cr8Ni/Ni, Fe18Cr8Ni/Ni15Cr7Fe, Nb/Ti, Nb/V, Ni/Ni15Cr7Fe, and Cb/V10Ti were readily welded and weld properties were excellent. Others which had only minor defects included the Ag/Cu20Ni, Ag/Ti, Ag/V, Cu/Fe18Cr8Ni, Cu/V10Ti, Cu20Ni/Fe18Cr8Ni, and Ti/Zr2Sn welds. The Cu/Ni weld had deep undercut, but was in other respects excellent. The mechanical properties of the Ag/Fe18Cr8Ni weld were poor, but the defect could probably be corrected. Difficulty with cracking was experienced with the Al/Ni and Fe18Cr8Ni/V welds, but sound welds had excellent mechanical properties. The remaining welds Al-Cu, Al/Cu20Ni, Al/Fe18Cr8Ni, Al/Ni15Cr7Fe, Cu20Ni/V, Cu20Ni/V10Ti, Cb/Zr2Sn, Ni/Ti, Ni15Cr7Fe/V, Ni15Cr7Fe/V10Ti, and Ti/V were unsuccessful, due to brittle phases, primarily at the weld metal-base metal interface. In addition to the two-member specimens, several joints were made by buttering. Longitudinal weld specimens of the three-member combination Al/Ni/Fe18Cr8Ni and the five member combination Fe18Cr8Ni/V/Cb/Ti/Zr2Sn showed good tensile strength and satisfactory elongation. 6 tables, 16 figures

  13. Grain topology in Ti-6Al-4V welds-Monte Carlo simulation and experiments

    International Nuclear Information System (INIS)

    Mishra, S; DebRoy, T

    2004-01-01

    The importance of topological features of grains in the evolution of grain structure is well recognized in isothermal systems. However, during fusion welding, strong spatial gradients of temperature exist in the heat-affected zone (HAZ), and this region undergoes rapid heating and cooling. The effects of spatial and temporal variations of temperature on the topological class distribution, relationship between size and topology of grains and the interdependence between grain topology and its neighbours are not known. Topological features of grains in the HAZ of Ti-6Al-4V alloy welds were measured for various heat inputs in the range 0.55-4.33 MJ m -1 . The topological class distributions were also calculated using a three-dimensional Monte Carlo model utilizing thermal cycles computed from a well tested numerical heat transfer and fluid flow model. The computed results showed that the topological class distributions were unaffected by the spatial and temporal variations of temperature. Experimental investigations of a few sections confirmed the simulation results. The average grain size for each edge class varied linearly with the edge class number. The local topological environment, i.e. the average number of sides of neighbours, n n , varied linearly with the inverse of the number of sides of grains, 1/n r , at a given location in the HAZ. Locations with the same topological environment showed the same grain size, indicating the significant influence of grain topology on grain growth in the HAZ

  14. Selective Laser Melting Produced Ti-6Al-4V: Post-Process Heat Treatments to Achieve Superior Tensile Properties.

    Science.gov (United States)

    Ter Haar, Gerrit M; Becker, Thorsten H

    2018-01-17

    Current post-process heat treatments applied to selective laser melting produced Ti-6Al-4V do not achieve the same microstructure and therefore superior tensile behaviour of thermomechanical processed wrought Ti-6Al-4V. Due to the growing demand for selective laser melting produced parts in industry, research and development towards improved mechanical properties is ongoing. This study is aimed at developing post-process annealing strategies to improve tensile behaviour of selective laser melting produced Ti-6Al-4V parts. Optical and electron microscopy was used to study α grain morphology as a function of annealing temperature, hold time and cooling rate. Quasi-static uniaxial tensile tests were used to measure tensile behaviour of different annealed parts. It was found that elongated α'/α grains can be fragmented into equiaxial grains through applying a high temperature annealing strategy. It is shown that bi-modal microstructures achieve a superior tensile ductility to current heat treated selective laser melting produced Ti-6Al-4V samples.

  15. Numerical analysis of weld pool oscillation in laser welding

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jung Ho [Chungbuk National University, Cheongju (Korea, Republic of); Farson, Dave F [The Ohio State University, Columbus (United States); Hollis, Kendall; Milewski, John O. [Los Alamos National Laboratory, Los Alamos (United States)

    2015-04-15

    Volume of fluid (VOF) numerical simulation was used to investigate melt flow and volumetric oscillation of conduction-mode pulsed laser weld pools. The result is compared to high speed video stream of titanium laser spot welding experiment. The total simulation time is 10ms with the first 5 ms being heating and melting under constant laser irradiation and the remaining 5 ms corresponding to resolidification of the weld pool. During the melting process, the liquid pool did not exhibit periodic oscillation but was continually depressed by the evaporation recoil pressure. After the laser pulse, the weld pool was excited into volumetric oscillation by the release of pressure on its surface and oscillation of the weld pool surface was analyzed. The simulation model suggested adjusting thermal diffusivity to match cooling rate and puddle diameter during solidification which is distinguishable from previous weld pool simulation. The frequency continuously increased from several thousand cycles per second to tens of thousands of cycles per second as the weld pool solidified and its diameter decreased. The result is the first trial of investigation of small weld pool oscillation in laser welding although there have been several reports about arc welding.

  16. The laser revolution in shipbuilding: laser welding and cutting at Blohm + Voss

    Energy Technology Data Exchange (ETDEWEB)

    Minsks, T. [Blohm und Voss GmbH, Hamburg (Germany). Laser Production Line

    2000-12-01

    Precision manufacturing in steel shipbuilding has gained significantly in importance in recent years as a means of raising productivity and thus enhancing competitiveness. Precision manufacturing means working to very narrow tolerances, minimizing assembly costs by eliminating the need for straightening and adjustment, reducing reworking requirements and shortening throughput times. Blohm+Voss GmbH is the world's first shipbuilding company to use laser technology as part of its precision manufacturing approach, combined with complex clamping techniques which render exact prepositioning and tack welding of components superfluous. Laser cutting makes it possible to cut large formats with virtually parallel cut edges and very narrow cutting gaps which - in conjunction with suitable clamping - allow laser welding without the use of fillers. With a smaller heat-affected zone, laser welding causes less part distortion than conventional methods. This makes it possible to use thinner sheets and sections and thus supports the very low-weight constructions required for the types of ship built by Blohm+Voss. By combining laser cutting and laser welding in a single production line, Blohm+Voss currently boasts the most advanced prefabrication facility in shipbuilding, capable of producing components up to 12 meters long and 4 meters wide. (orig.)

  17. Coupling between magnetic, dielectric properties and crystal structure in MnT2O4 (T = V, Cr, Mn)

    International Nuclear Information System (INIS)

    Suzuki, T; Adachi, K; Katsufuji, T

    2006-01-01

    We measured the temperature dependence of dielectric constant and striction for spinel MnT 2 O 4 (T = V, Cr, Mn) under magnetic field. We found critical changes of the dielectric constant and striction with ferrimagnetic ordering as well as applied magnetic field in MnV 2 O 4 and Mn 3 O 4 , which have orbital degree of freedom in the T 3+ ion. This result indicates the importance of the orbital degree of freedom for the coupling between dielectric, magnetic properties and crystal structure in these spinel compounds

  18. 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.

  19. Soft X-ray laser using pumping of 3P and 4P levels of He-like and H-like ions

    Science.gov (United States)

    Hagelstein, Peter L.

    1987-01-01

    X-ray laser method and apparatus for producing coherent radiation at, for example, energies of at least 40 eV, using Be-like Cr, N-like Ni, He-like Na, B-like Cr, Be-like Mn or similar multiply ionized species to pump appropriate high energy transitions in He-like or H-like N, O, F, C or rare gases, with associated laser transition gains of 4-50 cm.sup.-1.

  20. RESIDUAL STRESS MEASUREMENTS AND STRUCTURAL INTEGRITY IMPLICATIONS FOR SELECTIVE LASER MELTED TI-6AL-4V

    Directory of Open Access Journals (Sweden)

    Knowles, C. R.

    2012-11-01

    Full Text Available Selective laser melting (SLM of Ti-6Al-4V has significant potential in the aerospace and biotechnology industries. SLM employs a focused laser beam to melt successive layers of metallic powder into complex components. This process can result in the generation of high thermally-induced residual stresses. These residual stresses, together with micro-flaws/ pores from the inherent fabrication process, may lead to premature fatigue crack initiation and propagation at relatively low cyclic stresses. The hole-drilling strain gauge method was used to evaluate residual stresses within SLM Ti-6Al-4V specimens, with the intention of understanding the associated mechanisms for the successful application of SLM Ti-6Al-4V in industry.

  1. Experimental design approach to the process parameter optimization for laser welding of martensitic stainless steels in a constrained overlap configuration

    Science.gov (United States)

    Khan, M. M. A.; Romoli, L.; Fiaschi, M.; Dini, G.; Sarri, F.

    2011-02-01

    This paper presents an experimental design approach to process parameter optimization for the laser welding of martensitic AISI 416 and AISI 440FSe stainless steels in a constrained overlap configuration in which outer shell was 0.55 mm thick. To determine the optimal laser-welding parameters, a set of mathematical models were developed relating welding parameters to each of the weld characteristics. These were validated both statistically and experimentally. The quality criteria set for the weld to determine optimal parameters were the minimization of weld width and the maximization of weld penetration depth, resistance length and shearing force. Laser power and welding speed in the range 855-930 W and 4.50-4.65 m/min, respectively, with a fiber diameter of 300 μm were identified as the optimal set of process parameters. However, the laser power and welding speed can be reduced to 800-840 W and increased to 4.75-5.37 m/min, respectively, to obtain stronger and better welds.

  2. Microstructure evolution and grain refinement of Ti-6Al-4V alloy by laser shock processing

    Energy Technology Data Exchange (ETDEWEB)

    Ren, X.D., E-mail: renxd@mail.ujs.edu.cn [Department of Mechanical Engineering, Jiangsu University, Zhenjiang, 212013 (China); Research Center of Fluid Machinery Engineering and Technical, Jiangsu University, Zhenjiang, 212013 (China); Zhou, W.F.; Liu, F.F.; Ren, Y.P. [Department of Mechanical Engineering, Jiangsu University, Zhenjiang, 212013 (China); Yuan, S.Q. [Research Center of Fluid Machinery Engineering and Technical, Jiangsu University, Zhenjiang, 212013 (China); Ren, N.F.; Xu, S.D.; Yang, T. [Department of Mechanical Engineering, Jiangsu University, Zhenjiang, 212013 (China)

    2016-02-15

    Graphical abstract: The grain refinement process of Ti-6Al-4V alloy under LSP: (a) LDD in original grains; (b) Dislocations in β phase; (c) DTIs in α phase; (d) DTs transform into DCs; (e) DWs develop into sub-GBs; (f) GR accomplishes. - Highlights: • LSP could repair the surface defects and reduce the surface roughness. • Microstructure evolution of α phase in Ti-6Al-4V alloy processed by LSP is distinct from β phase. • Multidirectional twin intersections and subgrain boundaries are the main mechanism of grain refinement of Ti-6Al-4V alloy. • Grain refinement process of the Ti-6Al-4V alloy was illustrated. - Abstract: Microstructure evolution and grain refinement of Ti-6Al-4V alloy after laser shock processing (LSP) are systematically investigated in this paper. Laser shock waves were induced by a Q-switched Nd:YAG laser system operated with a wave-length of 1064 nm and 10 ns pulse width. The microstructures of LSP samples were characterized by scanning electron microscopy (SEM) and transmission electron microscope (TEM). Present results indicate that the surface hardness of samples subjected to LSP impacts has significantly improved. Multidirectional twin intersections and dislocation movements lead to grain subdivision in α phase with ultra-high plastic deformation. High-density dislocations are found in β phase. Multidirectional twin intersections and division of sub-grain boundaries play an important role in the grain refinement of Ti-6Al-4V alloy under LSP loading conditions.

  3. Tool material effect on the friction stir butt welding of AA2124-T4 Alloy Matrix MMC

    Directory of Open Access Journals (Sweden)

    Yahya Bozkurt

    2018-01-01

    Full Text Available The purpose of the present work is to study on the effect of material properties tool on friction stir butt welding of AA2124-T4 alloy matrix MMC. Uncoated tool, coated tool with a CrN, and coated tool with AlTiN were used to weld aluminum MMC plates. Macrostructure and microstructure observations, ultimate tensile strength, wear resistance, and chemical analysis were carried out to determine the appropriate tool for joining these composite plates. Results showed that the good welded joints could be obtained when a tool is coated with AlTiN.

  4. The influence of laser pulse waveform on laser-TIG hybrid welding of AZ31B magnesium alloy

    Science.gov (United States)

    Song, Gang; Luo, Zhimin

    2011-01-01

    By dividing laser pulse duration into two parts, three kinds of laser waveforms are designed, including a high power density pulse (HPDP) laser in a short duration set at the beginning of the laser waveform. This paper aims to find out the laser pulse waveform and idiographic critical values of HPDP, which can affect the magnesium penetration in laser-tungsten inert gas (TIG) hybrid welding. Results show that when the laser pulse duration of HPDP is not more than 0.4 ms, the welding penetration values of lasers with HPDP are larger than otherwise. Also, the welding penetration values of laser with HPDP have increased by up to 26.1%. It has been found that with HPDP, the laser can form the keyhole more easily because the interaction between laser and the plate is changed, when the TIG arc preheats the plate. Besides, the laser with high power density and short duration strikes on the plates so heavily that the corresponding background power can penetrate into the bottom of the keyhole and maintain the keyhole open, which facilitates the final welding penetration.

  5. Selective Laser Melting Produced Ti-6Al-4V: Post-Process Heat Treatments to Achieve Superior Tensile Properties

    Directory of Open Access Journals (Sweden)

    Gerrit M. Ter Haar

    2018-01-01

    Full Text Available Current post-process heat treatments applied to selective laser melting produced Ti-6Al-4V do not achieve the same microstructure and therefore superior tensile behaviour of thermomechanical processed wrought Ti-6Al-4V. Due to the growing demand for selective laser melting produced parts in industry, research and development towards improved mechanical properties is ongoing. This study is aimed at developing post-process annealing strategies to improve tensile behaviour of selective laser melting produced Ti-6Al-4V parts. Optical and electron microscopy was used to study α grain morphology as a function of annealing temperature, hold time and cooling rate. Quasi-static uniaxial tensile tests were used to measure tensile behaviour of different annealed parts. It was found that elongated α’/α grains can be fragmented into equiaxial grains through applying a high temperature annealing strategy. It is shown that bi-modal microstructures achieve a superior tensile ductility to current heat treated selective laser melting produced Ti-6Al-4V samples.

  6. Ab-initio study of electronic, magnetic and thermoelectric behaviors of LiV2O4 and LiCr2O4 using modified Becke-Johson (mBJ) potential

    Science.gov (United States)

    Ali, Saima; Rashid, Muhammad; Hassan, M.; Noor, N. A.; Mahmood, Q.; Laref, A.; Haq, Bakhtiar Ul

    2018-05-01

    Owing to the large energy storage capacity and higher working voltage, the spinel oxides LiV2O4 and LiCr2O4, have remained under intense research attention for utilization as electrode materials in lithium-ion batteries. In this study, we explore the half-metallic nature and thermoelectric response in both LiV2O4 and LiCr2O4 spinel oxides using ab-initio density functional theory (DFT) based computations. The ground-state energies of these compounds have been studied at the optimized structural parameters in the ferromagnetic phase. In order to obtain a correct picture of the electronic structure and magnetic properties, the modified Becke-Johnson (mBJ) potential is applied to compute the electronic structures. The half-metallic behavior is confirmed by the spin-polarized electronic band structures and density of state plots. The magnetic nature is elucidated by computing the John-Teller energy, direct and indirect exchange and crystal field splitting energies. Our computations indicate strong hybridization decreasing the V/Cr site magnetic moments and increasing magnetic momenta at the nonmagnetic atomic sites. We also present the computed parameters significant for expressing the thermoelectric response, which are electrical conductivity, thermal conductivity, See-beck coefficient and power factor. The computed properties are of immense interest owing to the potential spintronics and Li-ion battery applications of the studied spinel materials.

  7. Direct Laser Cladding of Cobalt on Ti-6Al-4V with a Compositionally Graded Interface

    Directory of Open Access Journals (Sweden)

    Jyotsna Dutta Majumdar

    2011-01-01

    Full Text Available Direct laser cladding of cobalt on Ti-6Al-4V with and without a graded interface has been attempted using a continuous wave CO2 laser. Graded interface is developed by depositing a thin copper layer on Ti-6Al-4V substrate prior to multiple laser cladding of cobalt on it. Presence of copper interlayer was found to suppress the formation of brittle intermetallics of Ti and Co. The effect of process parameters on the microstructures, compositions, and phases of the interface was studied in details. Finally, the mechanical and electrochemical properties of the interface processed under optimum process parameters are reported.

  8. Excimer laser processing of Ti-6Al-4V

    International Nuclear Information System (INIS)

    Folkes, J.A.; Shibata, K.

    1994-01-01

    The effect of the excimer laser on the surface of Ti-6Al-4V is reported. Particular concentration is given to surface modification for potential materials processing applications. Results showed that: (1) there is an optimum energy for smoothing titanium; (2) at this energy density increasing the number of pulses has some, but not a significant, effect on the smoothing process; and (3) relatively smooth surfaces could be achieved at higher energy densities if the sample was processed in a helium atmosphere. Other typical surface modifications and features are also reported, including the effect of different gases on the process

  9. Effects of laser shock peening with contacting foil on micro laser texturing surface of Ti6Al4V

    Science.gov (United States)

    Dai, Fengze; Zhang, Zidong; Ren, Xudong; Lu, Jinzhong; Huang, Shu

    2018-02-01

    Ti6Al4V samples with micro-dimple arrays were subjected to laser shock peening in contact with foil (HCLSP). The surface roughness, micro-hardness, the residual stress distribution and the surface morphology of the micro-dimple arrays were studied to evaluate the effects of HCLSP. Moreover, the surface topography of the foils in contact was also analyzed. The gap existence between the foil and the to-be treated surface led the mechanism of HCLSP to be different compared to regular laser shock peening. The surface roughness reduction, the work-hardening effects, the compressive residual stress and the micro crack enclosure were achieved. A simplified ball-hitting-surface model was utilized to analyze the HCLSP impact. The model could well explain the experimental results. When treated by the HCLSP with H62 foil at the laser power density of 4.24 GW/cm2, the Ti6Al4V samples with micro-dimple arrays exhibit well surface topography and mechanical performance.

  10. Technology of electron beam welding for Zr-4 alloy spacer grid

    International Nuclear Information System (INIS)

    Pei Qiusheng; Wu Xueyi; Yang Qishun

    1989-10-01

    The welding technology for Zr-4 alloy spacer grid by using vacuum electron beam was studied. Through a series of welding technological experiments, metallographic examinations of seam structure and detecting tests for welding defect by X-ray defectoscopy, a good welding technology was selected to meet the requirements. The experimental results indicated that the Zr-4 alloy spacer grid welded by vacuum electron beam welding is feasible

  11. 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.

  12. Study on Laser Welding Process Monitoring Method

    OpenAIRE

    Knag , Heeshin

    2017-01-01

    International audience; In this paper, a study of quality monitoring technology for the laser welding was conducted. The laser welding and the industrial robotic systems were used with robot-based laser welding systems. The laser system used in this study was 1.6 kW fiber laser, while the robot system was Industrial robot (pay-load : 130 kg). The robot-based laser welding system was equipped with a laser scanner system for remote laser welding. The welding joints of steel plate and steel plat...

  13. Study on Laser Welding Process Monitoring Method

    OpenAIRE

    Heeshin Knag

    2016-01-01

    In this paper, a study of quality monitoring technology for the laser welding was conducted. The laser welding and the industrial robotic systems were used with robot-based laser welding systems. The laser system used in this study was 1.6 kW fiber laser, while the robot system was Industrial robot (pay-load : 130 kg). The robot-based laser welding system was equipped with a laser scanner system for remote laser welding. The welding joints of steel plate and steel plate coated with zinc were ...

  14. Hybrid laser-TIG welding, laser beam welding and gas tungsten arc welding of AZ31B magnesium alloy

    International Nuclear Information System (INIS)

    Liu Liming; Wang Jifeng; Song Gang

    2004-01-01

    Welding of AZ31B magnesium alloy was carried out using hybrid laser-TIG (LATIG) welding, laser beam welding (LBW) and gas tungsten arc (TIG) welding. The weldability and microstructure of magnesium AZ31B alloy welded using LATIG, LBW and TIG were investigated by OM and EMPA. The experimental results showed that the welding speed of LATIG was higher than that of TIG, which was caught up with LBW. Besides, the penetration of LATIG doubles that of TIG, and was four times that of LBW. In addition, arc stability was improved in hybrid of laser-TIG welding compared with using the TIG welding alone, especially at high welding speed and under low TIG current. It was found that the heat affect zone of joint was only observed in TIG welding, and the size of grains in it was evidently coarse. In fusion zone, the equiaxed grains exist, whose size was the smallest welded by LBW, and was the largest by TIG welding. It was also found that Mg concentration of the fusion zone was lower than that of the base one by EPMA in three welding processes

  15. Numerical calculations of the absorption and oscillation processes in the nonlinear polarized crystal Cr4+:YAG pumped by Nd-glass laser

    International Nuclear Information System (INIS)

    Abdul Ghani, B.; Hammadi, M.

    2007-01-01

    A mathematical model describing the dynamic emission of intracavity isotropic Cr 4+ : YAG polarized solid-state saturable absorber as a tool of dual Q-switching and lasing processes 1.06 μm and 1.4 μm by double pumping pulse has been developed. This model describes the time evolution of interaction between the pumping laser pulse with a changed polarization state and the polarized absorber. (author)

  16. Laser welding of tailored blanks

    International Nuclear Information System (INIS)

    Pecas, P.; Gouveia, H.; Quintino, L.; Olsen, F.O.

    1998-01-01

    Laser welding has an increasing role in the automotive industry, namely on the sub-assemblies manufacturing. Several sheet-shape parts are laser welded, on a dissimilar combination of thicknesses and materials, and are afterwards formed (stamped) being transformed in a vehicle body component. In this paper low carbon CO 2 laser welding, on the thicknesses of 1,25 and 0.75 mm, formability investigation is described. There will be a description of how the laser welded blanks behave in different forming tests, and the influence of misalignment and undercut on the formability. The quality is evaluated by measuring the limit strain and limit effective strain for the laser welded sheets and the base material, which will be presented in a forming limit diagram. (Author) 14 refs

  17. Evidences for the Formation of Chromium in the Unusual Oxidation State Cr(IV). I. Chemical Reactivity, Microhomogeneity, and Crystal Structures of the Nonstoichiometric Channel Compounds Tl xCr 5Se 8(0 ≤ x≤ 1)

    Science.gov (United States)

    Bensch, W.; Helmer, O.; Näther, C.

    1996-11-01

    The topotactic redox reaction between TlCr 5Se 8and bromine in acetonitrile leads to the formation of metastable samples with 0 ≤ xtransition metal chalcogenide crystallizing in the TlV 5S 8type structure with a Tl content xtopotactic redox reaction does not follow simple kinetics but is rather explained on the basis of the superposition of at least three different fundamental steps. EDAX investigations conducted on selected single crystals reveal that dependent on the deintercalation temperature, Tl is laterally inhomogeneous distributed along the needle axis which coincides with the crystallographic baxis. A pronounced maximum is observed at the middle of the crystals. In stoichiometric TlCr 5Se 8the detailed analysis of the anisotropic displacement parameters of the Tl atoms reveal that the Tl atoms are displaced from the central position by about 0.26 Å. As a consequence the Tl atoms are coordinated by seven Se atoms in an irregular coordination polyhedron. Since the positions x0 zare related by a center of symmetry they cannot be occupied simultaneously. Hence it must be assumed that TlCr 5Se 8has a domain structure with local symmetry Cm. In the Tl poorer phases the refinement of the Tl atoms at the central position leads to unusual high U22components. The observed microinhomogenity as well as an enhanced mobility and/or static disorder of the Tl atom within the channel may be responsible for this. The value for U11decreases with decreasing Tl content whereas U33is not affected. This observation is indicative for a different displacement of the Tl atoms from the central position. With respect to the possible reaction mechanisms, according to our structural investigations, the oxidation of monovalent Tl to trivalent Tl can be excluded. With decreasing Tl content the lattice parameters exhibit very anisotropic behavior, which is a direct consequence of the large changes of the interatomic Cr-Cr distances. The average as well as the nonbonding Se-Se distances

  18. The enhancement in wear resistance of W18Cr4V steel by ion implantation

    International Nuclear Information System (INIS)

    Zhou Ping; Xu Peiguang

    1987-01-01

    Two new methods of ion implantation were adopted in comparison with nitrogen implantation: carbon monoxide was implanted directly into W18Cr4V steel, and nitrogen was implanted into a deposited titanium film about 1000 A thick. It is shown that higher surface hardness and wear resistance have been achieved. The composition and phase structure of the implanted layer was determined in detail. The wear mechanisms were discussed

  19. Cyclic deformation of dissimilar welded joints between Ti–6Al–4V and Ti17 alloys: Effect of strain ratio

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S.Q. [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, 127 Youyi Road, Xi' an 710072 (China); Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Liu, J.H., E-mail: jinhliu@nwpu.edu.cn [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, 127 Youyi Road, Xi' an 710072 (China); Lu, Z.X. [Department of Materials Science and Engineering, Xi' an University of Technology, 5 Jinhuanan Road, Xi' an 710048 (China); Chen, D.L., E-mail: dchen@ryerson.ca [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada)

    2014-03-01

    Cyclic deformation characteristics of electron beam welded (EBWed) joints between Ti–6Al–4V and Ti17 (Ti–5Al–4Mo–4Cr–2Sn–2Zr) titanium alloys were evaluated via strain-controlled low-cycle fatigue tests at varying strain ratios at a constant strain amplitude. The welding led to a significant microstructural change across the dissimilar joint, with hexagonal close-packed (HCP) martensite α' and orthorhombic martensite α″ in the fusion zone (FZ), α' in the heat-affected zone (HAZ) of Ti–6Al–4V side, and coarse β in the HAZ of Ti17 side. A distinctive asymmetrical hardness profile across the joint was observed with the highest hardness in the FZ and a lower hardness in the HAZ of Ti17 side than in the Ti17 base metal (BM), indicating the presence of soft zone. The strength and ductility of the dissimilar joint lay in-between those of two base metals (BMs). Unlike wrought magnesium alloys, the Ti–6Al–4V BM, Ti17 BM, and joint basically exhibited symmetrical hysteresis loops in tension and compression in the fully reversed strain-controlled tests at a strain ratio of R{sub ε}=−1. At a strain ratio of R{sub ε}=0 and 0.5, a large amount of plastic deformation occurred in the ascending phase of the first cycle of hysteresis loops of Ti–6Al–4V BM, Ti17 BM, and joint due to the high positive mean strain values. Fatigue life of the joint was observed to be the longest at R{sub ε}=−1, and it decreased as the strain ratio deviated from R{sub ε}=−1. A certain degree of mean stress relaxation was observed in the non-fully reversed strain controlled tests (i.e., R{sub ε}≠−1). Fatigue failure of the dissimilar joints occurred in the Ti–6Al–4V BM, with crack initiation from the specimen surface or near-surface defect and crack propagation characterized by fatigue striations.

  20. Effects of Laser Power Level on Microstructural Properties and Phase Composition of Laser-Clad Fluorapatite/Zirconia Composite Coatings on Ti6Al4V Substrates

    Directory of Open Access Journals (Sweden)

    Chi-Sheng Chien

    2016-05-01

    Full Text Available Hydroxyapatite (HA is one of the most commonly used materials for the coating of bioceramic titanium (Ti alloys. However, HA has poor mechanical properties and a low bonding strength. Accordingly, the present study replaces HA with a composite coating material consisting of fluorapatite (FA and 20 wt % yttria (3 mol % stabilized zirconia (ZrO2, 3Y-TZP. The FA/ZrO2 coatings are deposited on Ti6Al4V substrates using a Nd:YAG laser cladding system with laser powers and travel speeds of 400 W/200 mm/min, 800 W/400 mm/min, and 1200 W/600 mm/min, respectively. The experimental results show that a significant inter-diffusion of the alloying elements occurs between the coating layer (CL and the transition layer (TL. Consequently, a strong metallurgical bond is formed between them. During the cladding process, the ZrO2 is completely decomposed, while the FA is partially decomposed. As a result, the CLs of all the specimens consist mainly of FA, Ca4(PO42O (TTCP, CaF2, CaZrO3, CaTiO3 and monoclinic phase ZrO2 (m-ZrO2, together with a small amount of θ-Al2O3. As the laser power is increased, CaO, CaCO3 and trace amounts of tetragonal phase ZrO2 (t-ZrO2 also appear. As the laser power increases from 400 to 800 W, the CL hardness also increases as a result of microstructural refinement and densification. However, at the highest laser power of 1200 W, the CL hardness reduces significantly due to the formation of large amounts of relatively soft CaO and CaCO3 phase.

  1. Soft X-ray laser using pumping of 3P and 4P levels of He-like and H-like ions

    Science.gov (United States)

    Hagelstein, P.L.

    1987-04-21

    X-ray laser method and apparatus are disclosed for producing coherent radiation at, for example, energies of at least 40 eV, using Be-like Cr, N-like Ni, He-like Na, B-like Cr, Be-like Mn or similar multiply ionized species to pump appropriate high energy transitions in He-like or H-like N, O, F, C or rare gases, with associated laser transition gains of 4-50 cm[sup [minus]1]. 8 figs.

  2. Effect of phase transformations on laser forming of Ti-6Al-4V alloy

    International Nuclear Information System (INIS)

    Fan, Y.; Cheng, P.; Yao, Y.L.; Yang, Z.; Egland, K.

    2005-01-01

    In laser forming, phase transformations in the heat-affected zone take place under steep thermal cycles, and have a significant effect on the flow behavior of Ti-6Al-4V alloy and the laser-forming process. The flow-stress data of a material are generally provided as only dependent on strain, strain rate, and temperature, while phase transformations are determined by both temperature and temperature history. Therefore, effect of phase transformations on the flow behavior of materials in thermomechanical processing is not given necessary considerations. In the present work, both the α→β transformation during heating and the decomposition of β phase, producing martensite α ' or lamellae α dependent on cooling rate, are numerically investigated. The spatial distribution of volume fractions of phases is obtained by coupling thermal and phase transformation kinetic modeling. Consequently, the flow stress of Ti-6Al-4V alloy is calculated by the rule of mixtures based on the phase ratio and the flow stress of each single phase, which is also a function of temperature, strain, and strain rate. According to the obtained flow-stress data, the laser-forming process of Ti-6Al-4V alloy is modeled by finite element method, and the deformation is predicted. A series of carefully controlled experiments are conducted to validate the theoretically predicted results

  3. Life prediction of repaired welds in a pressurised CrMoV pipe with incorporation of initial damage

    International Nuclear Information System (INIS)

    Hyde, T.H.; Sun, W.; Becker, A.A.; Williams, J.A.

    2004-01-01

    Creep damage FE modelling was performed for fully and partially repaired, thick-walled, circumferential pipe weldments, in which initial damage was incorporated into the calculations to take account of the material degradation of the aged materials. The pipe welds were subjected to a realistic internal pressure and axial loading, the latter of which is allowed to vary within the range allowed by design codes. The material properties used are related to a CrMoV weldment at 640 deg. C. The initial damage distribution was numerically determined using an established procedure. A full post weld heat treatment is assumed to be carried out and the effects of welding induced residual stresses were neglected. The results obtained cover a number of initial damage levels, magnitudes of axial load, and repair excavation depth. On this basis, the sensitivities of the failure life of the repaired welds to these important factors can be evaluated. It was found that both the peak initial damage and the total life are very sensitive to the repair time, particularly when system load is high. The effect of the repair depth for depth: thickness ratios ≥0.5 is generally small for these loadings. There could be a significant benefit if the initial damage in the HAZ of the repair weld, which could be relatively high when the repair time is relatively large, could be reduced by repair welding or by post weld heat treatment

  4. Influence of annealing temperature on the electrochemical and surface properties of the 5-V spinel cathode material LiCr0.2Ni0.4Mn1.4O4 synthesized by a sol–gel technique

    DEFF Research Database (Denmark)

    Younesi, Reza; Malmgren, Sara; Edström, Kristina

    2014-01-01

    LiCr0.2Ni0.4Mn1.4O4 was synthesized by a sol–gel technique in which tartaric acid was used as oxide precursor. The synthesized powder was annealed at five different temperatures from 600 to 1,000 °C and tested as a 5-V cathode material in Li-ion batteries. The study shows that annealing at higher...

  5. METHOD AND SYSTEM FOR LASER WELDING

    DEFF Research Database (Denmark)

    2008-01-01

    The invention relates to laser welding of at least two adjacent, abutting or overlapping work pieces in a welding direction using multiple laser beams guided to a welding region, wherein at least two of the multiple laser beams are coupled into the welding region so as to form a melt and at least...

  6. Nanoindentation of Electropolished FeCrAl Alloy Welds

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, Jordan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Aydogan, Eda [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mara, Nathan Allan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Maloy, Stuart Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-13

    The present report summarizes Berkovich nanoindentation modulus and hardness measurements on two candidate FeCrAl alloys (C35M and C37M) on as-received (AR) and welded samples. In addition, spherical nanoindentation stress-strain measurements were performed on individual grains to provide further information and demonstrate the applicability of these protocols to mechanically characterizing welds in FeCrAl alloys. The indentation results are compared against the reported tensile properties for these alloys to provide relationships between nanoindentation and tensile tests and insight into weldsoftening for these FeCrAl alloys. Hardness measurements revealed weld-softening for both alloys in good agreement with tensile test results. C35M showed a larger reduction in hardness at the weld center from the AR material compared to C37M; this is also consistent with tensile tests. In general, nanohardness was shown to be a good predictor of tensile yield strength and ultimate tensile stress for FeCrAl alloys. Spherical nanoindentation measurements revealed that the fusion zone (FZ) + heat affected zone (HAZ) has a very low defect density typical of well-annealed metals as indicated by the frequent pop-in events. Spherical nanoindentation yield strength, Berkovich hardness, and tensile yield strength measurements on the welded material all show that the C37M welded material has a higher strength than C35M welded material. From the comparison of nanoindentation and tensile tests, EBSD microstructure analysis, and information on the processing history, it can be deduced that the primary driver for weld-softening is a change in the defect structure at the grain-scale between the AR and welded material. These measurements serve as baseline data for utilizing nanoindentation for studying the effects of radiation damage on these alloys.

  7. 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.

  8. Influence of small particles inclusion on selective laser melting of Ti-6Al-4V powder

    Science.gov (United States)

    Gong, Haijun; Dilip, J. J. S.; Yang, Li; Teng, Chong; Stucker, Brent

    2017-12-01

    The particle size distribution and powder morphology of metallic powders have an important effect on powder bed fusion based additive manufacturing processes, such as selective laser melting (SLM). The process development and parameter optimization require a fundamental understanding of the influence of powder on SLM. This study introduces a pre-alloyed titanium alloy Ti-6Al-4V powder, which has a certain amount of small particles, for SLM. The influence of small particle inclusion is investigated through microscopy of surface topography, elemental and microstructural analysis, and mechanical testing, compared to the Ti-6Al-4V powder provided by SLM machine vendor. It is found that the small particles inclusion in Ti-6Al-4V powder has a noticeable effect on extra laser energy absorption, which may develop imperfections and deteriorate the SLM fatigue performance.

  9. Soft zone formation in dissimilar welds between two Cr-Mo steels

    International Nuclear Information System (INIS)

    Albert, S.K.; Gill, T.P.S.; Tyagi, A.K.; Mannan, S.L.; Rodriguez, P.; Kulkarni, S.D.

    1997-01-01

    Two dissimilar weldments between 9Cr-1Mo and 2.25Cr-1Mo ferritic steels have been characterized for their microstructural stability during various postweld heat treatments (PWHTs). The samples for the investigation were extracted from bead-on-plate weldments made by depositing 2.25Cr-1Mo weld metal on 9Cr-1Mo base plate and vice versa. Subsequent application of PWHT resulted in the formation of a soft zone in the low Cr ferritic steel weld or base plate. A carbide-rich hard zone, adjoining the soft zone, was also detected in the high Cr side of the weldment. Unmixed zones in the weld metal provided additional soft and hard zones in the weld metals. The migration of carbon from low-Cr steel to high-Cr steel, driven by the carbon activity gradient, has been shown to be responsible for the formation of soft and hard zones. A carbon activity diagram for 2.25Cr-1Mo/9Cr-1Mo weldments has been proposed to aid in the selection of welding consumables for reducing or preventing the soft zone formation

  10. Fibre Laser Welding of HY-80 Steel: Procedure Development and Testing

    Science.gov (United States)

    2010-09-01

    2 Welding The material used in this study was quenched and tempered martensitic HY80 steel which conforms to MIL-S-1621 [2]. The testing...Journal, 1977. [4] AWS, D1.6 in Structural Welding Code Stainless Steel . 2007, American Welding Society: Miami Florida. [5] DefStan, 02-770 Part 2...Canada Fibre Laser Welding of HY-80 Steel Proceedure Development and Testing Christopher Bayley DLP Neil Aucoin DLP Xinjin Cao NRC IAR AMTC Technical

  11. A study on laser welding deformation of 304 stainless steel

    International Nuclear Information System (INIS)

    Kitagawa, Akikazu; Maehara, Kenji; Takeda, Shinnosuke; Matsunawa, Akira

    2002-01-01

    In heavy industries, 304 austenitic stainless steel is the most popular material which is used for nuclear equipment, chemical vessels, vacuum vessels and so on. On the fabrication, not only a joint quality but also severe dimensional accuracy is required. To keep dimensional accuracy, considerable cost and efforts are requested, because the welding deformation of austenitic stainless steel is deeply depended on the physical properties of material itself. To decrease welding deformation, big jigs or water cooling method are commonly used which lead to the high cost. In general, the fusion welding by high energy density heat source results in less distortion. Today, laser welding technology has grown up to the stage that enables to weld thick plate with small deformation. The researches of welding deformation have been conducted intensively, but they are mainly concerned for arc welding, and studies for laser welding are very few. In this report, the authors will show the test results of deformation behavior in laser welding of 304 stainless steel. Also, they will discuss the deformation behavior comparing to that in arc welding. The main results of this study are as follows. 1. The angular distortion of laser welding can be unified by heat input parameter (Hp) which is used for arc welding deformation. 2. The angular distortion are same under the condition of Hp 3 in spite of different welding method, however under the condition of Hp>6-9 J/mm 3 the angular distortion is quite different depending on the power density of welding method. 3. Pure angular distortion seemed to complete just after welding, but following longitudinal distortion took place for long period. 4. The critical value of longitudinal distortion can be estimated from heat input parameter. The transverse deformation can be also estimated by heat input parameter. (author)

  12. Integrated sensors for robotic laser welding

    NARCIS (Netherlands)

    Iakovou, D.; Aarts, Ronald G.K.M.; Meijer, J.; Beyer, E.; Dausinger, F; Ostendorf, A; Otto, A.

    2005-01-01

    A welding head is under development with integrated sensory systems for robotic laser welding applications. Robotic laser welding requires sensory systems that are capable to accurately guide the welding head over a seam in three-dimensional space and provide information about the welding process as

  13. Feasibility evaluations for the integration of laser butt welding of tubes in industrial pipe coil production lines

    Science.gov (United States)

    Penasa, Mauro; Colombo, Enrico; Giolfo, Mauro

    1994-09-01

    Due to the good performance shown by laser welded joints, to the quality and repeatability achievable by this welding technique and to its high process productivity, a feature inherent to the laser technology which, together with its high flexibility, allows different operations to be performed by a single source, consistent savings in a production line may be obtained. Therefore laser welding techniques may be of high relevance for industrial applications, provided that a sufficient attention is paid to avoiding a low utilization time to the operating laser source. The paper describes a feasibility study for the integration of a laser source as an automatic unit for circumferential butt welding of tubes in production lines of pipe coils, just before the cold bending station. Using a 6 kW CO2 source, thickness ranging from 3.5 to 11.2 mm in carbon, low alloyed Cr-Mo and austenitic stainless steels, have been successfully welded. Cr-Mo steels require on line preheating treatment, which however can be achieved by laser defocused passes just before welding. The results of the preliminary qualification performed on laser welded joints of the involved topologies of product (materials, diameters and thicknesses) are described together with technological tests required for approval: laser circumferential butt welding of tubes has proven to be effective, with satisfactory and repeatable results and good joint performances. An exhaustive comparison with current welding techniques (TIG, MIG) is then carried out, along with a detailed analysis of the potential advantages and benefits which may be expected by using the laser welding technique, as well as with a first estimation of the investments and running costs. Since laser productivity is saturated only at a rough 35% during the year, an accurate analysis of other possible applications and of a possible lay out of a laser working cell integrated in the factory production lines is performed. Usually little attention is

  14. Phase formation in Na2MoO4 - MgMoO4 - Cr2(MoO4)3 system

    International Nuclear Information System (INIS)

    Kotova, I.Yu.; Kozhevnikova, N.M.

    1998-01-01

    Interaction within Na 2 MoO 4 - MgMoO 4 - Cr 2 (MoO 4 ) 3 ternary system is studied by X ray phase and DTA methods. State diagram of NaCr(MoO 4 ) 2 - MgMoO 4 section is plotted. Production of ternary molybdates of Na 1-x Mg 1-x Cr 1+x (MoO 4 ) 3 , where 0 ≤ x ≤ 0.3, and NaMg 3 Cr(MoO 4 ) 5 composition is ascertained [ru

  15. Microstructure, microhardness and corrosion resistance of remelted TiG2 and Ti6Al4V by a high power diode laser

    International Nuclear Information System (INIS)

    Amaya-Vazquez, M.R.; Sánchez-Amaya, J.M.; Boukha, Z.; Botana, F.J.

    2012-01-01

    Highlights: ► Laser remelting of TiG2 and Ti6Al4V is performed with argon shielded diode laser. ► Microstructure, microhardness and corrosion of remelted samples are deeply analysed. ► Microstructural changes of laser remelted TiG2 lead to microhardness increase. ► Remelted Ti6Al4V presents microhardness increase and corrosion improvement. ► Martensite depth in remelted Ti6Al4V is linearly proportional to laser fluence. - Abstract: The high strength, low density and superior corrosion resistance allow titanium alloys to be widely employed in different industrial applications. The properties of these alloys can be modulated by different heat treatments, including laser processing. In the present paper, laser remelting treatments, performed with a high power diode laser, were applied to samples of two titanium alloys (TiG2 and Ti6Al4V). The influence of the applied laser fluence on microstructure, microhardness and corrosion resistance is investigated. Results show that laser remelting treatments with appropriate fluences provoke microstructural changes leading to microhardness increase and corrosion resistance improvement.

  16. Real-time monitoring of the laser hot-wire welding process

    Science.gov (United States)

    Liu, Wei; Liu, Shuang; Ma, Junjie; Kovacevic, Radovan

    2014-04-01

    The laser hot-wire welding process was investigated in this work. The dynamics of the molten pool during welding was visualized by using a high-speed charge-coupled device (CCD) camera assisted by a green laser as an illumination source. It was found that the molten pool is formed by the irradiation of the laser beam on the filler wire. The effect of the hot-wire voltage on the stability of the welding process was monitored by using a spectrometer that captured the emission spectrum of the laser-induced plasma plume. The spectroscopic study showed that when the hot-wire voltage is above 9 V a great deal of spatters occur, resulting in the instability of the plasma plume and the welding process. The effect of spatters on the plasma plume was shown by the identified spectral lines of the element Mn I. The correlation between the Fe I electron temperature and the weld-bead shape was studied. It was noted that the electron temperature of the plasma plume can be used to real-time monitor the variation of the weld-bead features and the formation of the weld defects.

  17. Characterization of deep level defects in Tl6I4S single crystals by photo-induced current transient spectroscopy

    International Nuclear Information System (INIS)

    Peters, J A; Liu, Z; Sebastian, M; Wessels, B W; Im, J; Freeman, A J; Nguyen, S; Kanatzidis, M G

    2015-01-01

    Defect levels in semi-insulating Tl 6 I 4 S single crystals grown by the horizontal Bridgman technique have been characterized using photo-induced current transient spectroscopy (PICTS). These measurements revealed six electron traps located at (0.059  ±  0.007), (0.13  ±  0.012), (0.31  ±  0.074), (0.39  ±  0.019), (0.62  ±  0.110), and (0.597  ±  0.105). These defect levels are attributed to vacancies (V I , V S ) and antisite defects (I S , Tl S , Tl I ) upon comparison to calculations of native defect energy levels using density functional theory and defects recently reported from photoluminescence and photoconductivity measurements. (paper)

  18. The Tl{sub 2}S–PbS–SiS{sub 2} system and the crystal and electronic structure of quaternary chalcogenide Tl{sub 2}PbSiS{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Mozolyuk, M.Y.; Piskach, L.V. [Department of Inorganic and Physical Chemistry, Lesya Ukrainka Eastern European National University, 13 Voli Avenue, 43025, Lutsk (Ukraine); Fedorchuk, A.O. [Department of Inorganic and Organic Chemistry, Lviv National University of Veterinary Medicine and Biotechnologies, 50 Pekarska Street, 79010, Lviv (Ukraine); Olekseyuk, I.D.; Parasyuk, O.V. [Department of Inorganic and Physical Chemistry, Lesya Ukrainka Eastern European National University, 13 Voli Avenue, 43025, Lutsk (Ukraine); Khyzhun, O.Y., E-mail: khyzhun@ipms.kiev.ua [Frantsevych Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 3 Krzhyzhanivsky Street, 03142, Kyiv (Ukraine)

    2017-07-01

    Chalcogenides of the quasi-ternary system Tl{sub 2}S–PbS–SiS{sub 2} were synthesized in the evacuated silica ampoules by the melting and annealing technique. Phase equilibria in the system was investigated by XRD method. Isothermal section of the system was studied, and two intermediate quaternary phases were discovered to exist (Tl{sub 2}PbSiS{sub 4}, ∼Tl{sub 2}PbSi{sub 3}S{sub 8}). The quasi-binary section Tl{sub 2}SiS{sub 3}–PbS was investigated by DTA. Its phase diagram was constructed, and it was established that the equimolar compound melts incongruently at 818 K. The crystal structure of the quaternary compound Tl{sub 2}PbSiS{sub 4} was determined by X-ray powder diffraction. It crystallizes in the monoclinic space group P2{sub 1}/a with the unit-cell parameters a = 8.8141(4), b = 9.0150(5), c = 10.4383(5) Å, and β = 94.490(4)° (Tl{sub 2}PbGeS{sub 4} structure type). Reliability factors calculated in the isotropic approximation were found to be R{sub I} = 0.0564 and R{sub P} = 0.1070. The Tl{sub 2}PbSiS{sub 4} single crystal was tested with X-ray photoelectron spectroscopy. In particular, the XPS core-level and valence-band spectra were recorded for pristine and Ar{sup +}-ion bombarded surfaces of Tl{sub 2}PbSiS{sub 4}. The Tl{sub 2}PbSiS{sub 4} single crystal was found to be rather stable with respect to Ar{sup +}-ion irradiation. We have also measured the X-ray emission band depicting the energy distribution of mainly the S 3p states and compared it on a common energy scale with the XPS valence-band spectrum of the Tl{sub 2}PbSiS{sub 4} crystal. The above comparison indicates that the S 3p states contribute substantively in the upper portion of the valence band of Tl{sub 2}PbSiS{sub 4}, with their significant contributions in other portions of the valence-band region. - Highlights: • Chalcogenides of the quasi-ternary system Tl{sub 2}S–PbS–SiS{sub 2} were synthesized. • Two intermediate quaternary phases were discovered to exist (Tl

  19. Microstructure and mechanical properties of direct metal laser sintered TI-6AL-4V

    Directory of Open Access Journals (Sweden)

    Becker, Thorsten Hermann

    2015-05-01

    Full Text Available Direct metal laser sintering (DMLS is a selective laser melting (SLM manufacturing process that can produce near net shape parts from metallic powders. A range of materials are suitable for SLM; they include various metals such as titanium, steel, aluminium, and cobalt-chrome alloys. This paper forms part of a research drive that aims to evaluate the material performance of the SLM-manufactured metals. It presents DMLS-produced Ti-6Al-4V, a titanium alloy often used in biomedical and aerospace applications. This paper also studies the effect of several heat treatments on the microstructure and mechanical properties of Ti-6Al-4V processed by SLM. It reports the achievable mechanical properties of the alloy, including quasi-static, crack growth behaviour, density and porosity distribution, and post-processing using various heat-treatment conditions.

  20. High-pressure X-ray diffraction and Raman spectroscopy of CaFe2O4-type β-CaCr2O4

    Science.gov (United States)

    Zhai, Shuangmeng; Yin, Yuan; Shieh, Sean R.; Shan, Shuangming; Xue, Weihong; Wang, Ching-Pao; Yang, Ke; Higo, Yuji

    2016-04-01

    In situ high-pressure synchrotron X-ray diffraction and Raman spectroscopic studies of orthorhombic CaFe2O4-type β-CaCr2O4 chromite were carried out up to 16.2 and 32.0 GPa at room temperature using multi-anvil apparatus and diamond anvil cell, respectively. No phase transition was observed in this study. Fitting a third-order Birch-Murnaghan equation of state to the P-V data yields a zero-pressure volume of V 0 = 286.8(1) Å3, an isothermal bulk modulus of K 0 = 183(5) GPa and the first pressure derivative of isothermal bulk modulus K 0' = 4.1(8). Analyses of axial compressibilities show anisotropic elasticity for β-CaCr2O4 since the a-axis is more compressible than the b- and c-axis. Based on the obtained and previous results, the compressibility of several CaFe2O4-type phases was compared. The high-pressure Raman spectra of β-CaCr2O4 were analyzed to determine the pressure dependences and mode Grüneisen parameters of Raman-active bands. The thermal Grüneisen parameter of β-CaCr2O4 is determined to be 0.93(2), which is smaller than those of CaFe2O4-type CaAl2O4 and MgAl2O4.

  1. Formed electroslag welded joint from austenitic steel 18/10 CrNi

    International Nuclear Information System (INIS)

    Jilek, L.; Kusak, L.; Martinak, A.

    1987-01-01

    The electroslag welded joint from titanium stabilized steel 18/10 CrNi of 150 mm in thickness showed positive results for both nondestructive and destructive testing. Czechoslovak flux VUZ-4F and the optimized welding mode were completely proven. The weldment was subject to deformation by forging with a removal of 20 to 50% and to bending deformation. A 40% to 50% deformation was necessary for breaking the coarse-grain casting structure. The bending deformation resulted in breaking the coarse-grain casting structure in the entire cross-section, it was, however, only acting in a narrow band corresponding to the largest curvature. At the same time, the heat affected zone decayed. Following heat treatment, especially forming, the delta ferrite content in the weld metal decreased, the mechanical properties of the weld metal and the welded joint following welding and heat treatment showed a relatively large scatter. Forming reduced the scatter and improved plastic properties. Machining within 40 and 50% resulted in good echogenicity of the welded joint in ultrasound testing. The welded joint showed equal properties as the base material of the weldment. (author). 15 figs., 2 tabs., 16 refs

  2. Computerized simulation of YAG pulse laser welding of titanium alloy (TA6V): experimental characterization and modelling of the thermomechanical aspects of this process

    International Nuclear Information System (INIS)

    Robert, Y.

    2007-09-01

    This work is a part of study which goal is to realize a computer modelling of the thermomechanical phenomena occurring during the YAG pulse laser welding of titanium alloy (TA6V). The filet welding has different heterogeneities (microstructural and mechanical). In fact, the temperature causes microstructural changes (phase transformations, precipitations) and modifies the mechanical properties. Thermomechanical modelling has thus to be established for the welding of TA6V. (author)

  3. Multispot fiber laser welding

    DEFF Research Database (Denmark)

    Schutt Hansen, Klaus

    This dissertation presents work and results achieved in the field of multi beam fiber laser welding. The project has had a practical approach, in which simulations and modelling have been kept at a minimum. Different methods to produce spot patterns with high power single mode fiber lasers have...... been examined and evaluated. It is found that both diamond turned DOE’s in zinc sulphide and multilevel etched DOE’s (Diffractive Optical Elements) in fused silica have a good performance. Welding with multiple beams in a butt joint configuration has been tested. Results are presented, showing it has...... been possible to control the welding width in incremental steps by adding more beams in a row. The laser power was used to independently control the keyhole and consequently the depth of fusion. An example of inline repair of a laser weld in butt joint configuration was examined. Zinc powder was placed...

  4. Laser Welding Test Results with Gas Atmospheres in Welding Chamber

    Energy Technology Data Exchange (ETDEWEB)

    Joung, Chang-Young; Hong, Jin-Tae; Ahn, Sung-Ho; Heo, Sung-Ho; Jang, Seo-Yun; Yang, Tae-Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    The weld beads of specimens welded under identical conditions in the helium and argon gas were cleaner, more regular, and steadier than those in a vacuum. The penetration depth of the FZ in the vacuum was much deeper than those in the helium and argon gas. To measure the irradiation properties of nuclear fuel in a test reactor, a nuclear fuel test rod instrumented with various sensors must be fabricated with assembly processes. A laser welding system to assemble the nuclear fuel test rod was designed and fabricated to develop various welding technologies of the fuel test rods to joint between a cladding tube and end-caps. It is an air-cooling optical fiber type and its emission modes are a continuous (CW) mode of which the laser generates continuous emission, and pulse (QCW) mode in which the laser internally generates sequences of pulses. We considered the system welding a sample in a chamber that can weld a specimen in a vacuum and inert gas atmosphere, and the chamber was installed on the working plate of the laser welding system. In the chamber, the laser welding process should be conducted to have no defects on the sealing area between a cladding tube and an end-cap.

  5. LASER WELDING WITH MICRO-JET COOLING FOR TRUCK FRAME WELDING

    OpenAIRE

    Jan PIWNIK; Bożena SZCZUCKA-LASOTA; Tomasz WĘGRZYN; Wojciech MAJEWSKI

    2017-01-01

    The aim of this paper is to analyse the mechanical properties of the weld steel structure of car body truck frames after laser welding. The best welding conditions involve the use of proper materials and alloy elements in steel and filer materials, in addition to welding technology, state of stress and temperature of exploitation. We present for the first time the properties of steel track structures after laser welding with micro-jet cooling. Therefore, good selection of both welding paramet...

  6. Microstructure and deformation behavior of Ti-6Al-4V alloy by high-power laser solid forming

    International Nuclear Information System (INIS)

    Ren, Y.M.; Lin, X.; Fu, X.; Tan, H.; Chen, J.; Huang, W.D.

    2017-01-01

    This work investigated the microstructure and tensile deformation behavior of Ti-6Al-4V alloy fabricated using a high-power laser solid forming (LSF) additive manufacturing. The results show that the post-fabricated heat-treated microstructure consists of coarse columnar prior-β grains (630–1000 μm wide) and α-laths (5–9 μm) under different scanning velocities (900 and 1500 mm/min), which caused large elongation (∼18%) superior to the conventional laser additive manufacturing Ti-6Al-4V alloy. The deformation behavior of the LSF Ti-6Al-4V alloy was investigated using in situ tensile test scanning electron microscopy. The results show that shear-bands appeared along the α/β interface and slip-bands occurred within the α-laths, which lead to cracks decaying in a zigzag-pattern in the LSF Ti-6Al-4V alloy with basket-weave microstructure. These results demonstrate that the small columnar prior-β grains and fine basket-weave microstructure exhibiting more α/β interfaces and α-laths can disperse the load and resist the deformation in the LSF Ti-6Al-4V components. In addition, a modified microstructure selection map of the LSF Ti-6Al-4V alloy was established, which can reasonably predict the microstructure evolution and relative grain size in the LSF process.

  7. Comparative study of low-temperature photoluminescence and thermally stimulated current in quinary Tl{sub 4}Ga{sub 3}InSe{sub 6}S{sub 2} layered crystals

    Energy Technology Data Exchange (ETDEWEB)

    Gasanly, N.M., E-mail: nizami@metu.edu.tr [Physics Department, Middle East Technical University, 06800 Ankara (Turkey); Virtual International Scientific Research Centre, Baku State University, 1148 Baku (Azerbaijan)

    2016-04-15

    Photoluminescence (PL) and thermally stimulated current (TSC) spectra of Tl{sub 4}Ga{sub 3}InSe{sub 6}S{sub 2} layered crystals grown by Bridgman method have been studied in the wavelength region of 560–690 nm and the temperature range of 15–45 K (PL) and in the temperature region of 10–90 K (TSC). A broad PL band centered at 620 nm (2.00 eV) was observed at T=15 K. Variations of emission band has been studied as a function of excitation laser intensity in the 0.7–36.5 mW cm{sup −2} range. Radiative transitions from donor level located at 150 meV below the bottom of conduction band to shallow acceptor level located at 10 meV above the top of the valence band were suggested to be responsible for the observed PL band. TSC curve of Tl{sub 4}Ga{sub 3}InSe{sub 6}S{sub 2} crystal exhibited one broad peak at about 41 K. The activation energy of trap level was found to be 11 meV. An energy level diagram showing transitions in the band gap of the crystal was plotted taking into account the results of PL and TSC measurements carried out below room temperature.

  8. Solid solutions of thallium in TlGaSe2, TlGaS2, and TlInS2

    International Nuclear Information System (INIS)

    Voroshilov, Yu. V.; Potorii, M.V.; Shevchenko, S.V.

    1986-01-01

    The authors study the nature of the dissolution of thallium in ternary phases. They have synthesized alloys of the stoichiometric compositions TlGaS 2 , TlGaSe 2 , and T1InS 2 , and their solid solutions, maximally enriched in thallium, the compositions of which were Tl /SUB 1.34/ GA /SUB 0.89/ S 2 , Tl /SUB 1.31/ Ga /SUB 0.90/ Se 2 , and Tl /SUB 1.15/ In /SUB 0.95/ S /SUB 2./ . Samples were synthesized from the elemental components of the following purities: gallium of V4 grade; indium of V4 grade; thallium of T1000 grade; selenium of special purity 22-4 grade, and sulfur of special purity garde. The compositions were checked by x-ray-phase-(DRON-0.5) and microstructural-analyses with simultaneous determination of the density and microhardness of the samples. It is found that the lattic parameter increases and the increase in the density and microhardness points to strengthening of the structure during the formation of the solid solutions

  9. Chemical diffusion of Cr, Ni and Si in welded joints. II

    International Nuclear Information System (INIS)

    Kucera, J.; Ciha, K.

    1987-01-01

    The results are given of a study in chemical diffusion in welded joints P2/A and P3/A. P2 stands for the steel (Fe-17.48 Cr-8.15 Ni-0.14 Si), P3 for (Fe-18.52 Cr-8.20 Ni-1.78 Si) and A for the Fe-Arema. Triadic sandwiche-like samples were diffusion heated at temperatures from 920 to 1170 degC. The concentration distributions N(x,t) of the given elements were measured with microprobe JXA-3A. The evaluation of the experimental data was carried out either by Grube's method, or in some cases by the spline-polynomial method. The evaluated diffusivities D-bar satisfy the Arrhenius relation and yield the standard diffusion characteristics D 0 and H. The diffusivities D-bar of Cr, Ni and Si in P1/A, in P2/A and P3/A welded joints vary with Si content in P1, P2 and P3 alloys, similar to the Cr-51 and Ni-63 self-diffusivities in Fe-18 Cr-12 Ni-X Si steels, and tend to increase with increasing Si content. The values D-bar measured in the vicinity of grain boundaries are higher than the bulk diffusion coefficients. The most rapid diffusant is Si and the slowest one Ni. Thus, the relations D-bar Si :D-bar Cr :D-bar Ni ≅ 6:3:1 (P3/A) and D-bar Si :D-bar Cr :D-bar Ni ≅ 1.7:1.4:1 (P3/A) are valid at 1050 degC. Comparing the results with those published if can be noted that the Cr-51 and Ni-63 self-diffusion in Fe-18 Cr-12 Ni-X Si steels is faster than chemical diffusion of these elements in the said steel welded joints P2/A and P3/A; X varies from 0.14 to 1.98. (author). 7 tabs., 7 figs., 20 refs

  10. Gingiva laser welding: preliminary study on an ex vivo porcine model.

    Science.gov (United States)

    Rasca, Emilia; Nyssen-Behets, Catherine; Tielemans, Marc; Peremans, André; Hendaoui, Nordine; Heysselaer, Daniel; Romeo, Umberto; Nammour, Samir

    2014-08-01

    The use of lasers to fuse different tissues has been studied for 50 years. As none of these experiments concerned the oral soft tissues, our objective was to assess the feasibility of laser gingiva welding. Porcine full-thickness gingival flaps served to prepare calibrated samples in the middle of which a 2 cm long incision was closed, either by conventional suture or by laser tissue welding (LTW). To determine the irradiation conditions yielding the best tensile strength, 13 output power values, from 0.5 to 5 W, delivered either at 10 Hz or in continuous wave mode, were tested on six indocyanine green (ICG) concentrations, from 8% to 13% (588 samples). Then, some samples served to compare the tensile strength between the laser welded and the sutured gingiva; the other samples were histologically processed in order to evaluate the thermal damage extent. The temperature rise during the LTW was measured by thermocouples. Another group of 12 samples was used to measure the temperature elevation by thermal camera. In the laser welding groups, the best tensile strength (pwelded gingiva at 4.5 W, 10 Hz, and 9% ICG solution. The mean temperature was 74±5.4°C at the upper surface and 42±8.9°C at the lower surface. The damaged zone averaged 333 μm at the upper surface. The 808 nm diode laser associated with ICG can achieve oral mucosa LTW, which is conceivable as a promising technique of gingival repair.

  11. Microstructure, microhardness and corrosion resistance of remelted TiG2 and Ti6Al4V by a high power diode laser

    Energy Technology Data Exchange (ETDEWEB)

    Amaya-Vazquez, M.R. [Laboratorio de Corrosion y Proteccion, Universidad de Cadiz, Departamento de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorganica, Avda. Republica Saharaui s/n, 11510 Puerto Real, Cadiz (Spain); Sanchez-Amaya, J.M., E-mail: josemaria.sanchez@uca.es [Titania, Ensayos y Proyectos Industriales S.L., Ctra Sanlucar A-2001 Km 7,5, Parque Tecnologico TecnoBahia-Edif. RETSE Nave 4, 11500 El Puerto de Santa Maria, Cadiz (Spain); Departamento de Fisica Aplicada, CASEM, Avda. Republica Saharaui s/n, 11510-Puerto Real, Cadiz (Spain); Boukha, Z.; Botana, F.J. [Laboratorio de Corrosion y Proteccion, Universidad de Cadiz, Departamento de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorganica, Avda. Republica Saharaui s/n, 11510 Puerto Real, Cadiz (Spain)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Laser remelting of TiG2 and Ti6Al4V is performed with argon shielded diode laser. Black-Right-Pointing-Pointer Microstructure, microhardness and corrosion of remelted samples are deeply analysed. Black-Right-Pointing-Pointer Microstructural changes of laser remelted TiG2 lead to microhardness increase. Black-Right-Pointing-Pointer Remelted Ti6Al4V presents microhardness increase and corrosion improvement. Black-Right-Pointing-Pointer Martensite depth in remelted Ti6Al4V is linearly proportional to laser fluence. - Abstract: The high strength, low density and superior corrosion resistance allow titanium alloys to be widely employed in different industrial applications. The properties of these alloys can be modulated by different heat treatments, including laser processing. In the present paper, laser remelting treatments, performed with a high power diode laser, were applied to samples of two titanium alloys (TiG2 and Ti6Al4V). The influence of the applied laser fluence on microstructure, microhardness and corrosion resistance is investigated. Results show that laser remelting treatments with appropriate fluences provoke microstructural changes leading to microhardness increase and corrosion resistance improvement.

  12. Effect of laser power and scanning speed on laser deposited Ti6Al4V/TiB2 matrix composites

    CSIR Research Space (South Africa)

    Mokgalaka, MN

    2012-10-01

    Full Text Available Additive Manufacturing in Industry Conference, Kwa Maritane, Pilanesberg National Park, 31 October-2 November 2012 EFFECT OF LASER POWER AND SCANNING SPEED ON LASER DEPOSITED Ti6Al4V/TiB2 MATRIX COMPOSITES M.N. Mokgalaka2,1, S.L. Pityana1,2, A.P.I...

  13. 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.

  14. Low-temperature cyclic cracking resistance of Fe-Cr-Ni and Fe-Cr-Mn steels welded joints

    International Nuclear Information System (INIS)

    Ostash, O.P.; Zhmur-Klimenko, V.T.; Yarema, S.Ya.; Yushchenko, K.A.; Strok, L.P.; Belotserkovets, V.I.

    1983-01-01

    Results of further investigations into regularities of development of low-temperature fatigue fracture of welded oints in 07Kh13G20AN4 steel are presented, they are compared with analogous data traditional cryogenic 0Kh18N10T and 03Kh13AG19 steels. Welded joints have been prepared by means of automatic V-like level arc Welding of plates; 0Kh18N10T and 07Kh13G20AN4 steels have been welded by means of sv-04Kh19N9 wire, 03Kh13AG19 steel-by means of sv-07Kh13AG19 wire. Tests at almost zero (asymmetry coefficient R=0.05) cycle of extension at 15-20 Hz frequency have been conducted on 5 mm thick disk samples at 20 deg C and - 160 deg C according to the given methods. It is shown that by cyclic crack resistance of welded joint zones of 0Kh18N10T steel and chromium-manganese steels at normal temperature the 07Kh13G20AN4 steel exceeds 0Kh18N10T steel, at low temperature it yields to 0Kh18N10T only by fracture toughness of heat affected zones HAZ and weld metal (ne). 07Kh13G20AN4 steel and its welded joints as most hardened and cheap may be a good substituent for 0Kh18N10T steel. Optimization of WM alloying for increase of its cyclic fracture toughness at cryogenic temperatures is necessary

  15. Development of technique for laser welding of biological tissues using laser welding device and nanocomposite solder.

    Science.gov (United States)

    Gerasimenko, A; Ichcitidze, L; Podgaetsky, V; Ryabkin, D; Pyankov, E; Saveliev, M; Selishchev, S

    2015-08-01

    The laser device for welding of biological tissues has been developed involving quality control and temperature stabilization of weld seam. Laser nanocomposite solder applied onto a wound to be weld has been used. Physicochemical properties of the nanocomposite solder have been elucidated. The nature of the tissue-organizing nanoscaffold has been analyzed at the site of biotissue welding.

  16. Bringing Pulsed Laser Welding into Production

    DEFF Research Database (Denmark)

    Olsen, Flemmming Ove

    1996-01-01

    In this paper, some research and develop-ment activities within pulsed laser welding technology at the Tech-nical University of Denmark will be described. The laser group at the Insti-tute for Manufacturing Technology has nearly 20 years of experience in laser materials process-ing. Inter......-nationally the group is mostly known for its contri-butions to the development of the laser cutting process, but further it has been active within laser welding, both in assisting industry in bringing laser welding into production in several cases and in performing fundamental R & D. In this paper some research...... activities concerning the weldability of high alloyed austenitic stainless steels for mass production industry applying industrial lasers for fine welding will be described. Studies on hot cracking sensitivity of high alloyed austenitic stainless steel applying both ND-YAG-lasers and CO2-lasers has been...

  17. Influence of laser-welding and electroerosion on passive fit of implant-supported prosthesis.

    Science.gov (United States)

    Silva, Tatiana Bernardon; De Arruda Nobilo, Mauro Antonio; Pessanha Henriques, Guilherme Elias; Mesquita, Marcelo Ferraz; Guimaraes, Magali Beck

    2008-01-01

    This study investigated the influence of laser welding and electroerosion procedure on the passive fit of interim fixed implant-supported titanium frameworks. Twenty frameworks were made from a master model, with five parallel placed implants in the inter foramen region, and cast in commercially pure titanium. The frameworks were divided into 4 groups: 10 samples were tested before (G1) and after (G2) electroerosion application; and another 10 were sectioned into five pieces and laser welded before (G3) and after (G4) electroerosion application. The passive fit between the UCLA abutment of the framework and the implant was evaluated using an optical microscope Olympus STM (Olympus Optical Co., Tokyo, Japan) with 0.0005mm of accuracy. Statistical analyses showed significant differences between G1 and G2, G1 and G3, G1 and G4, G2 and G4. However, no statistical difference was observed when comparing G2 and G3. These results indicate that frameworks may show a more precise adaptation if they are sectioned and laser welded. In the same way, electroerosion improves the precision in the framework adaptation.

  18. TL sensitivity of CaSO4:Dy phosphor powder - effect of grinding

    International Nuclear Information System (INIS)

    Shastry, S.S.; Kher, R.K.

    1979-01-01

    Grinding of polycrystalline CaSO 4 :Dy phosphor to powder form induces lattice defects. Changes in thermoluminescence (TL) sensitivity due to variation in trap density in the bulk and on the surface of phosphor grains are studied using gamma and UV radiations. TL sensitivity to gamma increases with grinding time due to the contribution from the new bulk traps which are generated by grinding. The surface traps degrade with increase in grinding time resulting in a decrease in UV sensitivity. Results on regeneration of the TL sensitivity due to annealing at different temperatures are also included. (Auth.)

  19. Dosimetric characteristics of Li2B4O7:Cu,Ag,P solid TL detectors

    International Nuclear Information System (INIS)

    Proki, M.

    2002-01-01

    The main dosimetric characteristics are presented of newly prepared tissue-equivalent, highly sensitive thermoluminescent detector, Li 2 B 4 O 7 :Cu,Ag,P in the form of sintered pellets, developed at the Institute of Nuclear Sciences, Vin a . As a result of an advancement in the preparation procedure by the sensitising of basic copper activated lithium borate TL material, significant improvement in the TL sensitivity of Li 2 B 4 O 7 :Cu,Ag,P was gained. The glow curve of Li 2 B 4 O 7 :Cu,Ag,P consists of well defined main dosimetric peak situated at about 185-190 deg. C with the TL sensitivity which is about four to five times higher than that of LiF:Mg,Ti (TLD-100). From the experimental results a very wide linear dose response range, up to 10 3 Gy is evident. Dosimetric characteristics make sintered solid Li 2 B 4 O 7 :Cu,Ag,P TL detectors very promising for different dosimetry applications particularly in medical dosimetry and also for individual monitoring. (author)

  20. Magnetic phase diagram of Co(Cr1-xA lx) 2O4 (x = 0.0-1.0)

    Science.gov (United States)

    Padam, R.; Sarkar, T.; Mathieu, R.; Thota, S.; Pal, D.

    2017-08-01

    We report the role of Al substitution in the magnetic properties of spinel CoCr2O4 by means of temperature dependent dc and ac magnetization and heat capacity measurements. Various compositions (0.0 ≤ x ≤ 1.0) of polycrystalline Co(Cr1-xAlx)2O4 samples have been prepared by sol-gel processing and their crystal structure was investigated by X-ray diffraction which was found to crystallize in the normal cubic spinel structure. For x ≤ 0.1, the system exhibits multiple magnetic orderings (long range ferrimagnetic ordering TC, spin-spiral ordering TS, and lock-in transition TL), similar to that of the parent compound, CoCr2O4. However, all the compositions between x = 0.1 and 0.5 exhibit long range ferrimagnetic ordering below TC and also a short range order at low temperature. Spin-glass like ordering was noticed between x = 0.6 and 0.8 due to the diluted B-site occupancy, whereas the end compound CoAl2O4 (x = 1.0) shows antiferromagnetic behavior. On the basis of these results, we propose a magnetic phase diagram for the Co(Cr1-xAlx)2O4 series as a function of the Al content (x) and measuring temperature (T).

  1. Comparison study between GTWA and PAW welding techniques in zircaloy-4

    International Nuclear Information System (INIS)

    Martinez, R.L.; Boccanera, L.; Ortiz, L.; Fernandez, L.; Corso, H.

    2003-01-01

    The wide use of zirconium alloys in different structural parts of nuclear reactors mainly under severe environmental conditions has encouraged the study of Zircaloy-4 and specifically welded joints of this material.Many different factors affect mechanical properties, specifically hydrides, formed by absorbed hydrogen.Hydrogen solubility in Zircaloy-4 is low and because Zircaloy-4 picks up hydrogen during service the potential exist that zirconium hydrides phase precipitate causing loss of ductility, the most undesirable consequence. Therefore, the study and characterization of welded joint of nuclear materials assumes fundamental importance in the safety of nuclear reactors.This paper presents experimental results regarding of hardness and hydrogen concentration in Zircaloy-4 plates obtained by two different welding techniques GTWA (Gas Tungsten Arc Welding) and PAW (Plasma Arc Welding).In this work following these remarks the difference observed between these two techniques are presented and point out some aspects of PAW for further discussion

  2. 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.

  3. Microstructural characterization and formation of α′ martensite phase in Ti–6Al–4V alloy butt joints produced by friction stir and gas tungsten arc welding processes

    International Nuclear Information System (INIS)

    Esmaily, M.; Nooshin Mortazavi, S.; Todehfalah, P.; Rashidi, M.

    2013-01-01

    Highlights: ► A fusion (GTAW) and a solid state method (FSW) are used to weld Ti–6Al–4V alloy. ► Optimal parameters yielding defects-free weldments are identified. ► A very careful microstructural quantification of the FSW and GTAW weldments are performed. ► α′ Martensite formed only in FSWed samples and avoided in GTAWed samples. ► FSW process produced joints with considerably smaller HAZ and higher hardness values. - Abstract: The obtained microstructures of a Ti–6Al–4V alloy welded by Gas Tungsten Arc Welding (GTAW) and Friction Stir Welding (FSW) were investigated and evaluated quantitatively. In the GTAW method, the effect of current was examined so that the samples were subjected to various currents between 90 and 120 A. In the FSW process, samples were welded by different rotational speeds (450–850 rpm). Non-destructive tests including Visual and Radiography Tests (VT and RT) were used to identify defect-free samples. The microstructural studies by electron microscopes revealed formation of different phases in the weld area of the samples welded via mentioned methods. The recorded peak temperatures in the weld regions compared favorably with the expectations about the evolved microstructures. A bi-modal microstructure was just obtained in the FSWed sample with a peak temperature below β transus temperature (T < 995 °C). α′ martensite phase, which is an acicular and strengthening phase in this alloy, was only observed in FSWed specimens

  4. Preliminary study of mechanical behavior for Cr coated Zr-4 Fuel Cladding

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Do-Hyoung; Kim, Hak-Sung [Hanyang Univ., Seoul (Korea, Republic of); Kim, Hyo-Chan; Yang, Yong-Sik [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    To decrease the oxidation rate of Zr-based alloy components, many concepts of accident tolerant fuel (ATF) such as Mo-Zr cladding, SiC/SiCf cladding and iron-based alloy cladding are under development. One of the promised concept is the coated cladding which can remarkably increase the corrosion and wear resistance. Recently, KAERI is developing the Cr coated Zircaloy cladding as accident tolerance cladding. To coat the Cr powder on the Zircaloy, 3D laser coating technology has been employed because it is possible to make a coated layer on the tubular cladding surface by controlling the 3-diminational axis. Therefore, for this work, the mechanical integrity of Cr coated Zircaloy should be evaluated to predict the safety of fuel cladding during the operating or accident of nuclear reactor. In this work, the mechanical behavior of the Cr coated Zircaloy cladding has been studied by using finite element analysis (FEA). The ring compression test (RCT) of fuel cladding was simulated to evaluate the validity of mechanical properties of Zr-4 and Cr, which were referred from the literatures and experimental reports. In this work, the mechanical behavior of the Cr coated Zircaloy cladding has been studied by using finite element analysis (FEA). The ring compression test (RCT) of fuel cladding was simulated to evaluate the validity of mechanical properties of Zr-4 and Cr. The pellet-clad mechanical interaction (PCMI) properties of Cr coated Zr-4 cladding were investigated by thermo-mechanical finite element analysis (FEA) simulation. The mechanical properties of Zr-4 and Cr was validated by simulation of ring compression test (RCT) of fuel cladding.

  5. LASER WELDING WITH MICRO-JET COOLING FOR TRUCK FRAME WELDING

    Directory of Open Access Journals (Sweden)

    Jan PIWNIK

    2017-12-01

    Full Text Available The aim of this paper is to analyse the mechanical properties of the weld steel structure of car body truck frames after laser welding. The best welding conditions involve the use of proper materials and alloy elements in steel and filer materials, in addition to welding technology, state of stress and temperature of exploitation. We present for the first time the properties of steel track structures after laser welding with micro-jet cooling. Therefore, good selection of both welding parameters and micro-jet cooling parameters is very important to achieve a proper steel structure. In this study, the metallographic structure, tensile results and impact toughness of welded joints have been analysed in terms of welding parameters.

  6. Gamma-radiation-induced change in the activation energy of TL traps in LiRbSO[sub 4]:Tl

    Energy Technology Data Exchange (ETDEWEB)

    Kassem, M.E.; El-Kolaly, M.A.; Al-Houty, L.I. (Qatar Univ., Doha (Qatar). Dept. of Physics)

    1994-06-01

    Thermoluminescence (TL) measurements were carried out for pure and doped LiRbSO[sub 4], with different concentrations of thallium (Tl). The glow-curve range of measurement is between room temperature up to 300[sup o]C. The radiation absorbed dose is in the range 56-3.2 x 10[sup 5] Gy. The results show that both pure and doped samples have glow peak temperatures that are dose dependent, and vary between 70-80[sup o]C and 140-170[sup o]C for pure and doped samples respectively. Doped samples display double peaks that increase with dopant concentration up to about 0.7% wt. The second peak which occurs at high temperature increases linearly with dose up to 4500 Gy. From the results it is proposed that LiRbSO[sub 4] doped with 0.7% Tl can be used for dosimetric purposes in this range. The activation energies of structural transitions are estimated and the results are discussed on the basis of radiation-induced stable dipoles in the random field system. (Author).

  7. Studies on corrosion protection of laser hybrid welded AISI 316 by laser remelting

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove; Ambat, Rajan; Rasmussen, A.J.

    2005-01-01

    laser surface melting on microstructure and corrosion behaviour of AISI 316L welds. Welding and laser treatment parameters were varied. General corrosion behaviour of the weld and laser treated surface was characterised using a gel visualization test. The local electrochemistry of the weld and laser......Unlike in autogenous laser welding, hybrid laser welding of stainless steel could introduce grain boundary carbides due to low cooling rates. Formation of grain boundary carbides leads to reduced corrosion properties. Studies have initially been carried out on hybrid laser welding and subsequent...... treated surface was investigated using a novel micro electrochemical technique with a tip resolution of ~1 mm. Results show that hybrid laser welding of 316L has increased corrosion susceptibility probably as a result of grain boundary carbide formation. However a suitable post laser treatment could...

  8. Study on laser welding of austenitic stainless steel by varying incident angle of pulsed laser beam

    Science.gov (United States)

    Kumar, Nikhil; Mukherjee, Manidipto; Bandyopadhyay, Asish

    2017-09-01

    In the present work, AISI 304 stainless steel sheets are laser welded in butt joint configuration using a robotic control 600 W pulsed Nd:YAG laser system. The objective of the work is of twofold. Firstly, the study aims to find out the effect of incident angle on the weld pool geometry, microstructure and tensile property of the welded joints. Secondly, a set of experiments are conducted, according to response surface design, to investigate the effects of process parameters, namely, incident angle of laser beam, laser power and welding speed, on ultimate tensile strength by developing a second order polynomial equation. Study with three different incident angle of laser beam 89.7 deg, 85.5 deg and 83 deg has been presented in this work. It is observed that the weld pool geometry has been significantly altered with the deviation in incident angle. The weld pool shape at the top surface has been altered from semispherical or nearly spherical shape to tear drop shape with decrease in incident angle. Simultaneously, planer, fine columnar dendritic and coarse columnar dendritic structures have been observed at 89.7 deg, 85.5 deg and 83 deg incident angle respectively. Weld metals with 85.5 deg incident angle has higher fraction of carbide and δ-ferrite precipitation in the austenitic matrix compared to other weld conditions. Hence, weld metal of 85.5 deg incident angle achieved higher micro-hardness of ∼280 HV and tensile strength of 579.26 MPa followed by 89.7 deg and 83 deg incident angle welds. Furthermore, the predicted maximum value of ultimate tensile strength of 580.50 MPa has been achieved for 85.95 deg incident angle using the developed equation where other two optimum parameter settings have been obtained as laser power of 455.52 W and welding speed of 4.95 mm/s. This observation has been satisfactorily validated by three confirmatory tests.

  9. Experimental Development of Dual Phase Steel Laser-arc Hybrid Welding and its Comparison to Laser and Gas Metal Arc Welding

    Directory of Open Access Journals (Sweden)

    Wagner Duarte Antunes

    Full Text Available Abstract Dual phase DP600 steels have been used in many automobile structures and laser welding has been the standard method for the joining of different sections. This work proposed a comparison between laser welding with arc welding (GMAW and with hybrid laser-arc welding in order to access the microstructures and the mechanical behavior. The laser and hybrid welds are competitive in terms of microstructure and mechanical behavior, presenting both acceptable and tough welds. The maximum ductility of the laser and hybrid welds are very similar, around 14%, and near to the values observed in the base material. The GMAW presents low ductility due to the softening caused by tampering of the martensite, and thus is unacceptable as the welding procedure.

  10. Developing mathematical models to predict tensile properties of pulsed current gas tungsten arc welded Ti-6Al-4V alloy

    International Nuclear Information System (INIS)

    Balasubramanian, M.; Jayabalan, V.; Balasubramanian, V.

    2008-01-01

    Titanium (Ti-6Al-4V) alloy has gathered wide acceptance in the fabrication of light weight structures requiring a high strength-to-weight ratio, such as transportable bridge girders, military vehicles, road tankers and railway transport systems. The preferred welding process of titanium alloy is frequently gas tungsten arc (GTA) welding due to its comparatively easier applicability and better economy. In the case of single pass GTA welding of thinner section of this alloy, the pulsed current has been found beneficial due to its advantages over the conventional continuous current process. Many considerations come into the picture and one need to carefully balance various pulse current parameters to arrive at an optimum combination. Hence, in this investigation an attempt has been made to develop mathematical models to predict tensile properties of pulsed current GTA welded titanium alloy weldments. Four factors, five level, central composite, rotatable design matrix is used to optimise the required number of experiments. The mathematical models have been developed by response surface method (RSM). The adequacy of the models has been checked by ANOVA technique. By using the developed mathematical models, the tensile properties of the joints can be predicted with 99% confidence level

  11. Developing mathematical models to predict tensile properties of pulsed current gas tungsten arc welded Ti-6Al-4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Balasubramanian, M. [Department of Production Engineering, Sathyabama University, Old Mamallapuram Road, Chennai 600 119 (India)], E-mail: manianmb@rediffmail.com; Jayabalan, V. [Department of Manufacturing Engineering, Anna University, Guindy, Chennai 600 025 (India)], E-mail: jbalan@annauniv.edu; Balasubramanian, V. [Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar 608 002 (India)], E-mail: visvabalu@yahoo.com

    2008-07-01

    Titanium (Ti-6Al-4V) alloy has gathered wide acceptance in the fabrication of light weight structures requiring a high strength-to-weight ratio, such as transportable bridge girders, military vehicles, road tankers and railway transport systems. The preferred welding process of titanium alloy is frequently gas tungsten arc (GTA) welding due to its comparatively easier applicability and better economy. In the case of single pass GTA welding of thinner section of this alloy, the pulsed current has been found beneficial due to its advantages over the conventional continuous current process. Many considerations come into the picture and one need to carefully balance various pulse current parameters to arrive at an optimum combination. Hence, in this investigation an attempt has been made to develop mathematical models to predict tensile properties of pulsed current GTA welded titanium alloy weldments. Four factors, five level, central composite, rotatable design matrix is used to optimise the required number of experiments. The mathematical models have been developed by response surface method (RSM). The adequacy of the models has been checked by ANOVA technique. By using the developed mathematical models, the tensile properties of the joints can be predicted with 99% confidence level.

  12. Hybrid laser-gas metal arc welding (GMAW) of high strength steel gas transmission pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Harris, Ian D.; Norfolk, Mark I. [Edison Welding Institute (EWI), Columbus, Ohio (United States)

    2009-07-01

    Hybrid Laser/arc welding process (HLAW) can complete 5G welds, assure weld soundness, material properties, and an acceptable geometric profile. Combining new lasers and pulsed gas metal arc welding (GMAW-P) has led to important innovations in the HLAW process, increasing travel speed for successful root pass welding. High power Yb fiber lasers allow a 10 kW laser to be built the size of a refrigerator, allowing portability for use on the pipeline right-of-way. The objective was to develop and apply an innovative HLAW system for mechanized welding of high strength, high integrity, pipelines and develop 5G welding procedures for X80 and X100 pipe, including mechanical testing to API 1104. A cost-matched JIP developed a prototype HLAW head based on a commercially available bug and band system (CRC-Evans P450). Under the US Department of Transportation (DOT) project, the subject of this paper, the system was used to advance pipeline girth welding productivity. External hybrid root pass welding achieved full penetration welds with a 4-mm root at a travel speed of 2.3-m/min. Welds were made 'double down' using laser powers up to 10 kW and travel speeds up to 3-m/min. The final objective of the project was to demonstrate the hybrid LBW/GMAW system under simulated field conditions. (author)

  13. Performance of novel materials for radiation detection: Tl{sub 3}AsSe{sub 3}, TlGaSe{sub 2}, and Tl{sub 4}HgI{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Kahler, D., E-mail: david.kahler@ngc.com [Northrop Grumman Corporation, ES-ATL, 1212 Winterson Road, Linthicum, MD 21090 (United States); Singh, N.B.; Knuteson, D.J.; Wagner, B.; Berghmans, A.; McLaughlin, S.; King, M.; Schwartz, K. [Northrop Grumman Corporation, ES-ATL, 1212 Winterson Road, Linthicum, MD 21090 (United States); Suhre, D.; Gotlieb, M. [DRS Scientific, 300 Oak Lake Road, New Kensington, PA 15068 (United States)

    2011-10-01

    In this paper we report on the electrical characteristics of three novel ternary compounds, Tl{sub 3}AsSe{sub 3} (TAS), TlGaSe{sub 2} (TGS), and Tl{sub 4}HgI{sub 6} (THI), pertaining to their use as radiation detectors. The details for growth and material characterization are not presented. A semiconductor based gamma ray detector requires a material with high Z, high density, high resistivity, appropriate bandgap (1.5-2 eV), low energy/electron-hole pair, and a high {mu}{tau} product. CZT is currently the best semiconductor material for room temperature gamma ray spectroscopy; however, it is extremely difficult to produce large volumes of detector grade material, making it expensive and in limited supply. DNDO/DHS began searching for other materials that might perform as well as CZT but be easier to grow and in the end lower the cost. For this purpose, we investigated the above three materials as possible replacements for CZT as gamma ray detectors. The bulk resistivity, I-V curves, X-ray response, and gamma ray response measurements for doped and undoped crystals are presented and discussed. TAS shows good X-ray and gamma ray response, but has poor resistivity, which results in large dark current and poor spectral response. TGS has good resistivity, but shows poor X-ray and gamma ray response. THI has excellent resistivity, shows some X-ray and gamma ray response, and has great potential as a gamma ray detector.

  14. HOS cell adhesion on Ti6Al4V surfaces texturized by laser engraving

    Science.gov (United States)

    Sandoval Amador, A.; Carreño Garcia, H.; Escobar Rivero, P.; Peña Ballesteros, D. Y.; Estupiñán Duran, H. A.

    2016-02-01

    The cell adhesion of the implant is determinate by the chemical composition, topography, wettability, surface energy and biocompatibility of the biomaterial. In this work the interaction between human osteosarcoma HOS cells and textured Ti6Al4V surfaces were evaluated. Ti6Al4V surfaces were textured using a CO2 laser in order to obtain circular spots on the surfaces. Test surfaces were uncoated (C1) used as a control surface, and surfaces with points obtained by laser engraving, with 1mm spacing (C2) and 0.5mm (C3). The HOS cells were cultured in RPMI-1640 medium with 10% fetal bovine serum and 1% antibiotics. No cells toxicity after one month incubation time occurred. The increased cell adhesion and cell spreading was observed after 1, 3 and 5 days without significant differences between the sample surfaces (C2 and C3) and control (uncoated) at the end of the experiment.

  15. HOS cell adhesion on Ti6Al4V surfaces texturized by laser engraving

    International Nuclear Information System (INIS)

    Sandoval Amador, A; Carreño Garcia, H; Escobar Rivero, P; Peña Ballesteros, D Y; Estupiñán Duran, H A

    2016-01-01

    The cell adhesion of the implant is determinate by the chemical composition, topography, wettability, surface energy and biocompatibility of the biomaterial. In this work the interaction between human osteosarcoma HOS cells and textured Ti 6 Al 4 V surfaces were evaluated. Ti 6 Al 4 V surfaces were textured using a CO 2 laser in order to obtain circular spots on the surfaces. Test surfaces were uncoated (C1) used as a control surface, and surfaces with points obtained by laser engraving, with 1mm spacing (C2) and 0.5mm (C3). The HOS cells were cultured in RPMI-1640 medium with 10% fetal bovine serum and 1% antibiotics. No cells toxicity after one month incubation time occurred. The increased cell adhesion and cell spreading was observed after 1, 3 and 5 days without significant differences between the sample surfaces (C2 and C3) and control (uncoated) at the end of the experiment. (paper)

  16. Sensor integration for robotic laser welding processes

    NARCIS (Netherlands)

    Iakovou, D.; Aarts, Ronald G.K.M.; Meijer, J.; Ostendorf, A; Hoult, A.; Lu, Y.

    2005-01-01

    The use of robotic laser welding is increasing among industrial applications, because of its ability to weld objects in three dimensions. Robotic laser welding involves three sub-processes: seam detection and tracking, welding process control, and weld seam inspection. Usually, for each sub-process,

  17. Optical design and development of a fiber coupled high-power diode laser system for laser transmission welding of plastics

    Science.gov (United States)

    Rodríguez-Vidal, Eva; Quintana, Iban; Etxarri, Jon; Azkorbebeitia, Urko; Otaduy, Deitze; González, Francisco; Moreno, Fernando

    2012-12-01

    Laser transmission welding (LTW) of thermoplastics is a direct bonding technique already used in different industrial applications sectors such as automobiles, microfluidics, electronics, and biomedicine. LTW evolves localized heating at the interface of two pieces of plastic to be joined. One of the plastic pieces needs to be optically transparent to the laser radiation whereas the other part has to be absorbent, being that the radiation produced by high power diode lasers is a good alternative for this process. As consequence, a tailored laser system has been designed and developed to obtain high quality weld seams with weld widths between 0.7 and 1.4 mm. The developed laser system consists of two diode laser bars (50 W per bar) coupled into an optical fiber using a nonimaging solution: equalization of the beam parameter product (BPP) in the slow and fast axes by a pair of step-mirrors. The power scaling was carried out by means of a multiplexing polarization technique. The analysis of energy balance and beam quality was performed considering ray tracing simulation (ZEMAX) and experimental validation. The welding experiments were conducted on acrylonitrile/butadiene/styrene (ABS), a thermoplastic frequently used in automotive, electronics and aircraft applications, doped with two different concentrations of carbon nanotubes (0.01% and 0.05% CNTs). Quality of the weld seams on ABS was analyzed in terms of the process parameters (welding speed, laser power and clamping pressure) by visual and optical microscope inspections. Mechanical properties of weld seams were analyzed by mechanical shear tests. High quality weld seams were produced in ABS, revealing the potential of the laser developed in this work for a wide range of plastic welding applications.

  18. Mechanical properties and microstructure of laser welded Ti–6Al–2Sn–4Zr–2Mo (Ti6242) titanium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Chamanfar, A., E-mail: ahc215@lehigh.edu [Institute for Metal Forming, Department of Materials Science and Engineering, Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015 (United States); Pasang, T. [Department of Mechanical Engineering, Auckland University of Technology, Auckland (New Zealand); Ventura, A.; Misiolek, W.Z. [Institute for Metal Forming, Department of Materials Science and Engineering, Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015 (United States)

    2016-04-29

    Room temperature tensile properties and microhardness of a laser welded Ti–6Al–2Sn–4Zr–2Mo (Ti6242) titanium alloy sheet were examined and correlated to the microstructure evolution across the weld. Tensile testing integrated with the optical image correlation Instron® system indicated that the average yield strength (YS), ultimate tensile strength (UTS), and total elongation of the weldment were respectively 88%, 87%, and 69% of the corresponding base material (BM) values. Electron probe microanalysis (EPMA) demonstrated a uniform distribution of the main alloying elements across the weld. The hardness raised increasingly from the BM toward the heat affected zone (HAZ) and the fusion zone (FZ) due to mainly a higher α volume fraction in HAZ and acicular α′ martensite formation in the FZ. Because of the higher hardness of the HAZ and FZ, a higher YS for the weldment relative to the BM would be expected. However, the lower YS as well as the lower UTS of the weldment can be explained by presence of some porosity and underfill in the FZ. The lower total elongation of the weldment compared to the BM can be related to the higher hardness of the HAZ and FZ.

  19. Mechanical properties and microstructure of laser welded Ti–6Al–2Sn–4Zr–2Mo (Ti6242) titanium alloy

    International Nuclear Information System (INIS)

    Chamanfar, A.; Pasang, T.; Ventura, A.; Misiolek, W.Z.

    2016-01-01

    Room temperature tensile properties and microhardness of a laser welded Ti–6Al–2Sn–4Zr–2Mo (Ti6242) titanium alloy sheet were examined and correlated to the microstructure evolution across the weld. Tensile testing integrated with the optical image correlation Instron® system indicated that the average yield strength (YS), ultimate tensile strength (UTS), and total elongation of the weldment were respectively 88%, 87%, and 69% of the corresponding base material (BM) values. Electron probe microanalysis (EPMA) demonstrated a uniform distribution of the main alloying elements across the weld. The hardness raised increasingly from the BM toward the heat affected zone (HAZ) and the fusion zone (FZ) due to mainly a higher α volume fraction in HAZ and acicular α′ martensite formation in the FZ. Because of the higher hardness of the HAZ and FZ, a higher YS for the weldment relative to the BM would be expected. However, the lower YS as well as the lower UTS of the weldment can be explained by presence of some porosity and underfill in the FZ. The lower total elongation of the weldment compared to the BM can be related to the higher hardness of the HAZ and FZ.

  20. Laser surface textured titanium alloy (Ti–6Al–4V): Part 1 – Surface characterization

    Energy Technology Data Exchange (ETDEWEB)

    Pfleging, Wilhelm [Karlsruhe Institute of Technology, IAM-AWP, P.O. Box 3640, 76021 Karlsruhe (Germany); Karlsruhe Nano Micro Facility, H.-von-Helmholtz-Pl. 1, 76344 Egg.-Leopoldshafen (Germany); Kumari, Renu [Department of Metal. and Maters. Eng., I. I. T. Kharagpur, WB 721302 (India); Besser, Heino [Karlsruhe Institute of Technology, IAM-AWP, P.O. Box 3640, 76021 Karlsruhe (Germany); Scharnweber, Tim [Karlsruhe Institute of Technology, IBG-1, P.O. Box 3640, 76021 Karlsruhe (Germany); Majumdar, Jyotsna Dutta, E-mail: jyotsna@metal.iitkgp.ernet.in [Department of Metal. and Maters. Eng., I. I. T. Kharagpur, WB 721302 (India)

    2015-11-15

    Highlights: • Texturing of Ti–6Al–4V with linear and dimple patterns are developed with ArF laser. • Linear textures have width of 25 μm and are at an interval of 20 μm. • Dimple textures are equi-spaced and have a diameter of 60 μm. • Significant refinement of microstructure in textured zone as compared to substrate. • Increased wettability of the textured surface against simulated body fluid. - Abstract: In the present study, a detailed study of the characterization of laser-surface textured titanium alloy (Ti–6Al–4V) with line and dimple geometry developed by using an ArF excimer laser operating at a wavelength of 193 nm with a pulse length of 5 ns is undertaken. The characterization of the textured surface (both the top surface and cross section) is carried out by scanning electron microscopy, electron back scattered diffraction (EBSD) technique and X-ray diffraction techniques. There is refinement of microstructure along with presence of titanium oxides (rutile, anatase and few Ti{sub 2}O{sub 3} phase) in the textured surface as compared to as-received one. The area fractions of linear texture and dimple texture measured by image analysis software are 45% and 20%, respectively. The wettability is increased after laser texturing. The total surface energy is decreased due to linear (29.6 mN/m) texturing and increased due to dimple (67.6 mN/m) texturing as compared to as-received Ti–6Al–4V (37 mN/m). The effect of polar component is more in influencing the surface energy of textured surface.

  1. Laser surface textured titanium alloy (Ti–6Al–4V): Part 1 – Surface characterization

    International Nuclear Information System (INIS)

    Pfleging, Wilhelm; Kumari, Renu; Besser, Heino; Scharnweber, Tim; Majumdar, Jyotsna Dutta

    2015-01-01

    Highlights: • Texturing of Ti–6Al–4V with linear and dimple patterns are developed with ArF laser. • Linear textures have width of 25 μm and are at an interval of 20 μm. • Dimple textures are equi-spaced and have a diameter of 60 μm. • Significant refinement of microstructure in textured zone as compared to substrate. • Increased wettability of the textured surface against simulated body fluid. - Abstract: In the present study, a detailed study of the characterization of laser-surface textured titanium alloy (Ti–6Al–4V) with line and dimple geometry developed by using an ArF excimer laser operating at a wavelength of 193 nm with a pulse length of 5 ns is undertaken. The characterization of the textured surface (both the top surface and cross section) is carried out by scanning electron microscopy, electron back scattered diffraction (EBSD) technique and X-ray diffraction techniques. There is refinement of microstructure along with presence of titanium oxides (rutile, anatase and few Ti_2O_3 phase) in the textured surface as compared to as-received one. The area fractions of linear texture and dimple texture measured by image analysis software are 45% and 20%, respectively. The wettability is increased after laser texturing. The total surface energy is decreased due to linear (29.6 mN/m) texturing and increased due to dimple (67.6 mN/m) texturing as compared to as-received Ti–6Al–4V (37 mN/m). The effect of polar component is more in influencing the surface energy of textured surface.

  2. Effect of time and temperature on grain size of V and V-Cr-Ti alloys

    International Nuclear Information System (INIS)

    Natesan, K.; Rink, D.L.

    1996-01-01

    Grain growth studies were conducted to evaluate the effect of time and temperature on the grain size of pure V, V-4 wt.%Cr-4 wt.%Ti, and V-5 wt.%Cr-5 wt.%Ti alloys. The temperatures used in the study were 500, 650, 800, and 1000 degrees C, and exposure times ranged between 100 and ∼5000 h. All three materials exhibited negligible grain growth at 500, 650, and 800 degrees C, even after ∼5000 h. At 1000 degrees C, pure V showed substantial grain growth after only 100 h, and V-4Cr-4Ti showed growth after 2000 h, while V-5Cr-5Ti showed no grain growth after exposure for up to 2000 h

  3. Metals welding by using laser

    International Nuclear Information System (INIS)

    Al-Qaisy, R.A.W.

    1991-01-01

    In the present work, same welding ''conduction limited type'' under atmospheric conditions was performed using pulsed Ng:YAG laser to weld; low carbon steel (LCS), stainless steel (304) (SUS304), stainless steel (303) (SUS303), and brass. Microstructure of welded zone, heat affected zone (HAZ), and the laser energy on penetration depth and effective diameter were studied. Tensile test, micro-hardness, and surface roughness of welded and parent metals were also dealt with. Melting efficiency was worked out and an under vacuum seam welding of low carbon steel has been accomplished. Finally spot welding of aluminium tungsten, and platinium wires were employed using different layer energies. 34 tabs.; 82 figs.; 51 refs.; 1 app

  4. Syntheses, structural variants and characterization of AInM′S4 (A=alkali metals, Tl; M′ = Ge, Sn) compounds; facile ion-exchange reactions of layered NaInSnS4 and KInSnS4 compounds

    International Nuclear Information System (INIS)

    Yohannan, Jinu P.; Vidyasagar, Kanamaluru

    2016-01-01

    Ten AInM′S 4 (A=alkali metals, Tl; M′= Ge, Sn) compounds with diverse structure types have been synthesized and characterized by single crystal and powder X-ray diffraction and a variety of spectroscopic methods. They are wide band gap semiconductors. KInGeS 4 (1-β), RbInGeS 4 (2), CsInGeS 4 (3-β), TlInGeS 4 (4-β), RbInSnS 4 (8-β) and CsInSnS 4 (9) compounds with three-dimensional BaGa 2 S 4 structure and CsInGeS 4 (3-α) and TlInGeS 4 (4-α) compounds with a layered TlInSiS 4 structure have tetrahedral [InM′S 4 ] − frameworks. On the other hand, LiInSnS 4 (5) with spinel structure and NaInSnS 4 (6), KInSnS 4 (7), RbInSnS 4 (8-α) and TlInSnS 4 (10) compounds with layered structure have octahedral [InM′S 4 ] − frameworks. NaInSnS 4 (6) and KInSnS 4 (7) compounds undergo facile topotactic ion-exchange, at room temperature, with various mono-, di- and tri-valent cations in aqueous medium to give rise to metastable layered phases. - Graphical abstract: NaInSnS 4 and KInSnS 4 compounds undergo, in aqueous medium at room temperature, facile topotactic ion-exchange with mono, di and trivalent cations. Display Omitted - Highlights: • Ten AInM′S 4 compounds with diverse structure types were synthesized. • They are wide band gap semiconductors. • NaInSnS 4 and KInSnS 4 compounds undergo facile topotactic ion-exchange at room temperature.

  5. Effects of picosecond laser repetition rate on ablation of Cr12MoV cold work mold steel

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Baoye; Deng, Leimin; Liu, Peng; Zhang, Fei; Duan, Jun, E-mail: duans@hust.edu.cn; Zeng, Xiaoyan

    2017-07-01

    In this paper, the effects of pulse repetition rate on ablation efficiency and quality of Cr12MoV cold work mold steel have been studied using a picosecond (ps) pulse Nd:YVO{sub 4} laser system at λ= 1064 nm. The experimental results of area ablation on target surface reveal that laser repetition rate plays a significant role in controlling ablation efficiency and quality. Increasing the laser repetition rate, while keeping a constant mean power improves the ablation efficiency and quality. For each laser mean power, there is an optimal repetition rate to achieve a higher laser ablation efficiency with low surface roughness. A high ablation efficiency of 42.29, 44.11 and 47.52 μm{sup 3}/mJ, with surface roughness of 0.476, 0.463 and 0.706 μm could be achieved at laser repetition rate of 10 MHz, for laser mean power of 15, 17 and 19 W, respectively. Scanning electron microcopy images revels that the surface morphology evolves from rough with numerous craters, to flat without pores when we increased the laser repetition rate. The effects of laser repetition rate on the heat accumulation, plasma shield and ablation threshold were analyzed by numerical simulation, spectral analysis and multi-laser shot, respectively. The synergetic effects of laser repetition rate on laser ablation rate and machining quality were analyzed and discussed systemically in this paper.

  6. TL characterization of Ag co-doped SrSO{sub 4}:Eu phosphor for gamma dosimetry applications

    Energy Technology Data Exchange (ETDEWEB)

    Jayasudha, S., E-mail: jsnair.india@gmail.com [Mahatma Gandhi College, Pattom Palace P.O., Thiruvananthapuram 695004 (India); Madhukumar, K.; Nair, C.M.K.; Nair, Resmi G.; Anandakumar, V.M. [Mahatma Gandhi College, Pattom Palace P.O., Thiruvananthapuram 695004 (India); Elias, T.S. [State Institute of Cancer Research, Medical College P.O., Thiruvananthapuram 695011 (India); Rajesh, S. [Campus Universitario de Santiago, Aveiro (Portugal)

    2017-04-15

    High temperature thermoluminescence (TL) emissions and improvement in fading due to the co-doping ofr Ag in the SrSO{sub 4}:Eu phosphor synthesized through chemical precipitation technique when subjected to γ-excitation is discussed. The dopant concentrations were tuned for optimum TL sensitivity. Preliminary crystallographic and structural studies of the phosphors were done using PXRD, SEM, and TEM. The phosphor has a single phase orthorhombic lattice structure and the crystallites are found to be nanostructured. The presence of dopants in the host matrix is established through EDS and ICP-AES studies. The TL glow curve shows a single intense emission at 314 ├ó┬ü┬░C under γ- exposure of dose 1 Gy, which is given from a {sup 60}Co build-up. The dosimetric properties such as sensitivity, dose dependence, fading and reusability of SrSO{sub 4}:Eu,Ag phosphor were also studied. It is observed that co-doping with Ag improves the fading rate of the SrSO{sub 4}:Eu phosphor by about 5%. Even though the luminescence intensity is found to be less than that of SrSO{sub 4}:Eu phosphor, the Ag co-doped phosphor becomes significant owing to its improved fading rate and high temperature afterglow. The gamma sensitivity of the SrSO{sub 4}:Eu,Ag(0.5,0.5 mol%) phosphor is compared to that of the standard CaSO{sub 4}:Dy TLD phosphor. The TL kinetic parameters were calculated using IR, Chen's peak shape method and verified by the theoretical fit using GCD functions. - Highlights: • A High temperature TL emission is observed for the SrSO{sub 4}:Eu,Ag phosphor. • TL intensity is 10 times higher than that of standard CaSO{sub 4}:Dy. • Fading rate of SrSO{sub 4}:Eu phosphor is improved by 5% with Ag co-doping. • Linear dose response in the range 10mGy-10Gy. • t .

  7. A study on martensitic structure in Fe-4Cr-0.4C steel

    International Nuclear Information System (INIS)

    Won, S.B.

    1980-01-01

    Morphology, dependence of prior austenite grain size and packet size upon austenitizing temperature, distribution of lath width, and habit plane of martensitic structure in Fe-4Cr-0.4C steel has been studied by optical microscopy and transmission electron microscopy. The results obtained are as follows. 1) Optical microstructures of martensitic Fe-4Cr-0.4C steel consist of lath martensite and lens martensite. Also the four types of morphology are observed by electron microscopy. The most common morphologies are a regular paralleled martensite and an irregular dovetailed lath martensite, while the remainder of microstructures consists mainly of groups of internally twinned martensite and autotempered laths. 2) Prior austenite grain size and packet size increased with austenizing temperature, and also the numbers of lath contained in a prior austenite grain or a packet are increased with austenizing temperature. 3) The mean width of lath in Fe-4Cr-0.4C steel is about 0.23μm and most of lath widths are below 0.5μm. 4) Martensite habit plane of Fe-4Cr-0.4C steel is nearly [110]α'. (author)

  8. Melt pool and keyhole behaviour analysis for deep penetration laser welding

    International Nuclear Information System (INIS)

    Fabbro, R

    2010-01-01

    One usually defines the main characteristic of the welding performances of a given laser system by its 'penetration curve' that corresponds to the welding depth as a function of the welding speed V w for a given set of operating parameters. Analysis of a penetration curve is interesting and gives very fruitful results. Coupled with high-speed video imaging of melt pool surface and ejected plume behaviour, the analysis of this penetration curve on a very large range of welding speeds, typically from 0 to 50 m min -1 , has allowed us to observe very different and characteristic regimes. These regimes are mainly characterized by the physical processes by which they impede the laser beam penetration inside the material. We show that it is only at rather high welding speeds that these limiting processes are reduced. Consequently, the scaling law of welding depth with welding speed is in agreement with adapted modelling of this process. On the other hand, as the welding speed is reduced, different effects depending on the weld pool dynamics and plume interaction strongly disturb the keyhole stability and are responsible for the deviation of the penetration curve from the previous modelling that agrees with a 1/V w scaling law. A corresponding criterion for the occurrence of this effect is defined.

  9. Microstructural analysis of laser weld fusion zone in Haynes 282 superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Osoba, L.O. [Department of Mechanical and Manufacturing Engineering, University of Manitoba, Winnipeg, Manitoba, R3T 5V6 (Canada); Ding, R.G. [Department of Metallurgy and Materials Engineering, University of Birmingham, Birmingham B15 2TT (United Kingdom); Ojo, O.A., E-mail: ojo@cc.umanitoba.ca [Department of Mechanical and Manufacturing Engineering, University of Manitoba, Winnipeg, Manitoba, R3T 5V6 (Canada)

    2012-03-15

    Analytical electron microscopy and spectroscopy analyses of the fusion zone (FZ) microstructure in autogenous laser beam welded Haynes 282 (HY 282) superalloy were performed. The micro-segregation patterns observed in the FZ indicate that Co, Cr and Al exhibited a nearly uniform distribution between the dendrite core and interdendritic regions while Ti and Mo were rejected into the interdendritic liquid during the weld solidification. Transmission electron diffraction analysis and energy dispersive X-ray microanalysis revealed the second phase particles formed along the FZ interdendritic region to be Ti-Mo rich MC-type carbide particles. Weld FZ solidification cracking, which is sometimes associated with the formation of {gamma}-{gamma}' eutectic in {gamma}' precipitation strengthened nickel-base superalloys, was not observed in the HY 282 superalloy. Modified primary solidification path due to carbon addition in the newly developed superalloy is used to explain preclusion of weld FZ solidification cracking in the material. - Highlights: Black-Right-Pointing-Pointer A newly developed superalloy was welded by CO{sub 2} laser beam joining technique. Black-Right-Pointing-Pointer Electron microscopy characterization of the weld microstructure was performed. Black-Right-Pointing-Pointer Identified interdendritic microconstituents consist of MC-type carbides. Black-Right-Pointing-Pointer Modification of primary solidification path is used to explain cracking resistance.

  10. Microstructural analysis of laser weld fusion zone in Haynes 282 superalloy

    International Nuclear Information System (INIS)

    Osoba, L.O.; Ding, R.G.; Ojo, O.A.

    2012-01-01

    Analytical electron microscopy and spectroscopy analyses of the fusion zone (FZ) microstructure in autogenous laser beam welded Haynes 282 (HY 282) superalloy were performed. The micro-segregation patterns observed in the FZ indicate that Co, Cr and Al exhibited a nearly uniform distribution between the dendrite core and interdendritic regions while Ti and Mo were rejected into the interdendritic liquid during the weld solidification. Transmission electron diffraction analysis and energy dispersive X-ray microanalysis revealed the second phase particles formed along the FZ interdendritic region to be Ti–Mo rich MC-type carbide particles. Weld FZ solidification cracking, which is sometimes associated with the formation of γ–γ' eutectic in γ' precipitation strengthened nickel-base superalloys, was not observed in the HY 282 superalloy. Modified primary solidification path due to carbon addition in the newly developed superalloy is used to explain preclusion of weld FZ solidification cracking in the material. - Highlights: ► A newly developed superalloy was welded by CO 2 laser beam joining technique. ► Electron microscopy characterization of the weld microstructure was performed. ► Identified interdendritic microconstituents consist of MC-type carbides. ► Modification of primary solidification path is used to explain cracking resistance.

  11. Effects of Laser Power Level on Microstructural Properties and Phase Composition of Laser-Clad Fluorapatite/Zirconia Composite Coatings on Ti6Al4V Substrates.

    Science.gov (United States)

    Chien, Chi-Sheng; Liu, Cheng-Wei; Kuo, Tsung-Yuan

    2016-05-17

    Hydroxyapatite (HA) is one of the most commonly used materials for the coating of bioceramic titanium (Ti) alloys. However, HA has poor mechanical properties and a low bonding strength. Accordingly, the present study replaces HA with a composite coating material consisting of fluorapatite (FA) and 20 wt % yttria (3 mol %) stabilized zirconia (ZrO₂, 3Y-TZP). The FA/ZrO₂ coatings are deposited on Ti6Al4V substrates using a Nd:YAG laser cladding system with laser powers and travel speeds of 400 W/200 mm/min, 800 W/400 mm/min, and 1200 W/600 mm/min, respectively. The experimental results show that a significant inter-diffusion of the alloying elements occurs between the coating layer (CL) and the transition layer (TL). Consequently, a strong metallurgical bond is formed between them. During the cladding process, the ZrO₂ is completely decomposed, while the FA is partially decomposed. As a result, the CLs of all the specimens consist mainly of FA, Ca₄(PO₄)₂O (TTCP), CaF₂, CaZrO₃, CaTiO₃ and monoclinic phase ZrO₂ (m-ZrO₂), together with a small amount of θ-Al₂O₃. As the laser power is increased, CaO, CaCO₃ and trace amounts of tetragonal phase ZrO₂ (t-ZrO₂) also appear. As the laser power increases from 400 to 800 W, the CL hardness also increases as a result of microstructural refinement and densification. However, at the highest laser power of 1200 W, the CL hardness reduces significantly due to the formation of large amounts of relatively soft CaO and CaCO₃ phase.

  12. Mechanical Properties of TC4 Matrix Composites Prepared by Laser Cladding

    Directory of Open Access Journals (Sweden)

    WANG Lin

    2017-06-01

    Full Text Available In order to improve the penetration performance of TC4, the direct laser deposition technology was used to prepare TC4 composite material. TA15+30% TiC powder, TA15+20%Cr3C2 powder and TA15+15%B4C powder were used as deposited materials for TC4 matrix. The micromorphology, change of hardness of the deposited coating and mechanical properties of the three composites were studied. The experimental results demonstrate that the TC4 matrix with the three kinds of materials can form a complete metallurgical bonding, and the strength of TC4-(TA15+TiC, TC4-(TA15+Cr3C2 and TC4-(TA15+B4C are higher than that of TC4 matrix materials, while the plasticity is slightly worse.

  13. Electrochemical behaviour of laser-clad Ti6Al4V with CP Ti in 0.1 M oxalic acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Obadele, Babatunde Abiodun, E-mail: obadele4@gmail.com [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Olubambi, Peter A. [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Andrews, Anthony [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Department of Materials Engineering, Kwame Nkrumah University of Science and Technology, Kumasi (Ghana); Pityana, Sisa [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); National Laser Center, Council for Scientific and Industrial Research, Pretoria (South Africa); Mathew, Mathew T. [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL 60612 (United States)

    2015-10-15

    The relationship between the microstructure and corrosion behaviour of Ti6Al4V alloy and laser-clad commercially pure (CP) Ti coating was investigated. The microstructure, phases and properties of the clad layers were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Electrochemical measurement techniques including open circuit potential (OCP) and potentiodynamic polarisation were used to evaluate the corrosion behaviour of Ti6Al4V alloy in 0.1 M oxalic acid solution and the results compared to the behaviour of laser-clad CP Ti at varying laser scan speed. Results showed that laser-clad CP Ti at scan speed of 0.4 m/min formed a good cladding layer without defects such as cracks and pores. The phase present in the cladding layer was mostly α′-Ti. The microstructures of the clad layer were needle like acicular/widmanstätten α. An improvement in the microhardness values was also recorded. Although the corrosion potentials of the laser-clad samples were less noble than Ti6Al4V alloy, the polarisation measurement showed that the anodic current density was lower and also increases with increasing laser scanning speed. - Highlights: • The microstructure and corrosion behaviour of laser-clad CP Ti was investigated. • Laser-clad CP Ti 0.4 m/min scan speed gave a good coating without cracks and pores. • The phase present in the clad layer was mostly α′-Ti. • An improvement in the microhardness values was also recorded. • Anodic current density for coatings increases with increasing laser scan speed.

  14. Electrochemical behaviour of laser-clad Ti6Al4V with CP Ti in 0.1 M oxalic acid solution

    International Nuclear Information System (INIS)

    Obadele, Babatunde Abiodun; Olubambi, Peter A.; Andrews, Anthony; Pityana, Sisa; Mathew, Mathew T.

    2015-01-01

    The relationship between the microstructure and corrosion behaviour of Ti6Al4V alloy and laser-clad commercially pure (CP) Ti coating was investigated. The microstructure, phases and properties of the clad layers were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Electrochemical measurement techniques including open circuit potential (OCP) and potentiodynamic polarisation were used to evaluate the corrosion behaviour of Ti6Al4V alloy in 0.1 M oxalic acid solution and the results compared to the behaviour of laser-clad CP Ti at varying laser scan speed. Results showed that laser-clad CP Ti at scan speed of 0.4 m/min formed a good cladding layer without defects such as cracks and pores. The phase present in the cladding layer was mostly α′-Ti. The microstructures of the clad layer were needle like acicular/widmanstätten α. An improvement in the microhardness values was also recorded. Although the corrosion potentials of the laser-clad samples were less noble than Ti6Al4V alloy, the polarisation measurement showed that the anodic current density was lower and also increases with increasing laser scanning speed. - Highlights: • The microstructure and corrosion behaviour of laser-clad CP Ti was investigated. • Laser-clad CP Ti 0.4 m/min scan speed gave a good coating without cracks and pores. • The phase present in the clad layer was mostly α′-Ti. • An improvement in the microhardness values was also recorded. • Anodic current density for coatings increases with increasing laser scan speed

  15. Welding technology transfer task/laser based weld joint tracking system for compressor girth welds

    Science.gov (United States)

    Looney, Alan

    1991-01-01

    Sensors to control and monitor welding operations are currently being developed at Marshall Space Flight Center. The laser based weld bead profiler/torch rotation sensor was modified to provide a weld joint tracking system for compressor girth welds. The tracking system features a precision laser based vision sensor, automated two-axis machine motion, and an industrial PC controller. The system benefits are elimination of weld repairs caused by joint tracking errors which reduces manufacturing costs and increases production output, simplification of tooling, and free costly manufacturing floor space.

  16. Feasibility demonstration of using wire electrical-discharge machining, abrasive flow honing, and laser spot welding to manufacture high-precision triangular-pitch Zircaloy-4 fuel-rod-support grids

    International Nuclear Information System (INIS)

    Horwood, W.A.

    1982-05-01

    Results are reported supporting the feasibility of manufacturing high precision machined triangular pitch Zircaloy-4 fuel rod support grids for application in water cooled nuclear power reactors. The manufacturing processes investigated included wire electrical discharge machining of the fuel rod and guide tube cells in Zircaloy plate stock to provide the grid body, multistep pickling of the machined grid to provide smooth and corrosion resistant surfaces, and laser welding of thin Zircaloy cover plates to both sides of the grid body to capture separate AM-350 stainless steel insert springs in the grid body. Results indicated that dimensional accuracy better than +- 0.001 and +- 0.002 inch could be obtained on cell shape and position respectively after wire EDM and surface pickling. Results on strength, corrosion resistance, and internal quality of laser spot welds are provided

  17. Nd:YAG laser welding of aerospace grade ZE41A magnesium alloy: Modeling and experimental investigations

    International Nuclear Information System (INIS)

    Al-Kazzaz, H.; Medraj, M.; Cao, X.; Jahazi, M.

    2008-01-01

    Keyhole formation as well as the geometry of weld profiles during Nd:YAG laser welding of ZE41A-T5 were studied through combining various models and concepts. The results indicated that weld width and fusion area decrease with increasing welding speed. In the case of partially penetrated welding, penetration depth decreases with increasing welding speed. Also, the model predicted that excessive decrease in laser power or increase in defocusing distance decreases surface power density, thereby changing the welding mode from fully penetrated keyhole, to partially penetrated keyhole, and then to the conduction mode. The predicted conditions for keyhole stability and welding modes as well as the weld profiles for various processing conditions were validated by some selected welding experiments. These experiments included studying the effects of welding speed, laser power, joint gap and laser defocusing on the weld geometry of 2- and 6-mm butt joints or bead-on-plates of ZE41A-T5 sand castings using a continuous wave 4 kW Nd:YAG laser system and 1.6-mm EZ33A-T5 filler wire. Good agreements were found between the model predictions and experimental results indicating the validity of the assumptions made for the development of the model

  18. Present and future of laser welding machine; Laser yosetsuki no genjo to tenbo

    Energy Technology Data Exchange (ETDEWEB)

    Taniu, Y. [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan)

    1998-04-01

    This paper describes recent trends of laser welding machine. For CO2 laser welding machine, seam weld of large diameter weld pipes using a 25 kW-class machine, and plate weld of steel plate using a 45 kW-class machine are reported. For YAG laser welding machine, high-output 5.5 kW-class machines are commercialized. Machines with slab structure of plate-like YAG chrystal have been developed which show high-oscillation efficiency and can be applied to cutting. Machines have been developed in which YAG laser output with slab structure is transmitted through GI fiber. High-speed welding of aluminum alloys can be realized by improving the converging performance. Efficiency of YAG laser can be enhanced through the time-divided utilization by switching the beam transmission path using fiber change-over switch. In the automobile industry, CO2 laser is mainly used, and a system combining CO laser with articulate robot is realized. TIG and MIG welding is often used for welding of aluminum for railway vehicles. It is required to reduce the welding strain. In the iron and steel industry, the productivity has been improved by the laser welding. YAG laser is put into practice for nuclear reactors. 5 refs., 8 figs., 1 tab.

  19. The influence of welding and post heat treatment parameters on the diffusion and precipitation processes in dissimilar metal joints of a 1% and a 12% Cr-steel

    International Nuclear Information System (INIS)

    Kullik, M.; Katerbau, K.H.

    1989-05-01

    The influences of different weld metals, welding processes and post weld heat treatments (PWHT) on mechanical properties, carbon diffusion and precipitation processes were investigated by studying dissimilar metal welds between the cast steel GS-17 CrMoV 5 11 (1% Cr) and the steel X 20 CrMoV 12 1 (12% Cr). By means of tensile and impact tests, metallographic investigation, hardness measurements, electron beam X-ray microanalysis and transmission electron microscope examination changes in the welded joints were shown after different PWHT's as well as after creep tests. It was found that the joint with a 5% CrMoV-weld metal shows higher yield and rupture strength than the joint with a 12% CrMoV-weld metal. With increasing heat input during PWHT the strength decreases for both welds, but always remains higher than the values of the base materials. During PWTH as well as during service at elevated temperatures carbon diffuses from the lower chromium material to the higher chromium material. Width and carbon concentration of the carburized and decarburized zones depend on the heat input. A simple diffusion model was developed to describe the carbon profile for any annealing time and temperature. The consequence of the decarburization is a microstructural change in the heat effected zone of the cast steel. During longer annealing the fine M 2 C-carbides dissolve and coarse M 6 C-crbides form, resulting in a lower creep ductility of this zone. (orig.) With 19 refs., 15 tabs., 104 figs [de

  20. Welding of Thin Steel Plates by Hybrid Welding Process Combined TIG Arc with YAG Laser

    Science.gov (United States)

    Kim, Taewon; Suga, Yasuo; Koike, Takashi

    TIG arc welding and laser welding are used widely in the world. However, these welding processes have some advantages and problems respectively. In order to improve problems and make use of advantages of the arc welding and the laser welding processes, hybrid welding process combined the TIG arc with the YAG laser was studied. Especially, the suitable welding conditions for thin steel plate welding were investigated to obtain sound weld with beautiful surface and back beads but without weld defects. As a result, it was confirmed that the shot position of the laser beam is very important to obtain sound welds in hybrid welding. Therefore, a new intelligent system to monitor the welding area using vision sensor is constructed. Furthermore, control system to shot the laser beam to a selected position in molten pool, which is formed by TIG arc, is constructed. As a result of welding experiments using these systems, it is confirmed that the hybrid welding process and the control system are effective on the stable welding of thin stainless steel plates.

  1. Induction heat treatment of laser welds

    DEFF Research Database (Denmark)

    Bagger, Claus; Olsen, Flemming Ove; Sørensen, Joakim Ilsing

    2003-01-01

    of an induction coil. A number of systematic laboratory tests were then performed in order to study the effects of the coil on bead-on-plate laser welded samples. In these tests, important parameters such as coil current and distance between coil and sample were varied. Temperature measurements were made...... the laser beam as close as possible. After welding, the samples were quality assessed according to ISO 13.919-1 and tested for hardness. The metallurgical phases are analysed and briefly described. A comparison between purely laser welded samples and induction heat-treated laser welded samples is made......In this paper, a new approach based on induction heat-treatment of flat laser welded sheets is presented. With this new concept, the ductility of high strength steels GA260 with a thickness of 1.8 mm and CMn with a thickness of 2.13 mm is believed to be improved by prolonging the cooling time from...

  2. Comparison of the TL intensity of the sintered composites of CaSO4+Tm

    International Nuclear Information System (INIS)

    Junot, O.D.; Sousa, F.L. de; Chagas, M.A.P.; Souza, D.N.

    2009-01-01

    The objective of this work is to compare the thermoluminescent intensity (TL) of CaSO 4 +Tm, CaSO 4 +Tm+glass and glass+Tm composites for use as thermoluminescent dosimeter (TLD). The route used to prepare the CaSO 4 +Tm and the CaSO 4 +Tm+glass was by mixing 1 g of CaSO 4 with 0.02 g of thulium oxide (99,9% purity) and 0.3 g of commercial and colorless glass. To mixing the composites were taken to a magnetic stirrer for 30 min with 10 mL of distilled water for better homogenization. The powder mixtures were dried in a stove at 100 deg C for 24 h. After drying, it was added polyvinyl alcohol (PVA) to improve the binding material. The pellets were compacted by application of an uniaxial pressing and sintered at 700 deg C/ 6 h. The route used in the preparation of glass+Tm pellets was similar to one previously mentioned, except by the use of 1 g of glass and 0.02 of Tm. After the sintering, the pellets dimensions were 1 mm thick and 6 mm in diameter. All samples were irradiated by a beta source ( 90 Sr + 90 Y) and received doses from 1.00 Gy to 20 Gy. Each composite presented a characteristic emission curve. The dosimeter of CaSO 4 +Tm+glass presented two peaks, the first at 115 deg C, and the second, very intense, ate 150 deg C. The CaSO 4 +Tm dosimeter showed a less intense peak at 140 deg C and another, more intense, at 235 deg C. In the composites of glass+Tm, the most intense peak has a thermoluminescent signal 94,04% lower than the most intense peak of CaSO 4 +Tm+glass and 81.57% lower than the most intense peak of CaSO 4 +Tm. After the analysis of TL emission curves, we observed that the CaSO 4 +Tm+glass have the highest TL intensity and a TL response proportional to the dose absorbed. (author)

  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. 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.

  5. Exploration of microstructure and wear behaviour of laser metal deposited Ti6Al4V/Cu composites

    CSIR Research Space (South Africa)

    Erinosho, MF

    2016-01-01

    Full Text Available This paper presents the explorations conducted on the evolving microstructures and the dry sliding wear of the laser deposited Ti6Al4V/Cu composites. The laser powers between 1300 W and 1600 W; scanning speeds between 0.30 and 0.72 m/min were...

  6. Surface chemistry of Ti6Al4V components fabricated using selective laser melting for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Vaithilingam, Jayasheelan, E-mail: Jayasheelan.Vaithilingam@nottingham.ac.uk [Additive Manufacturing and 3D Printing Research Group, EPSRC Centre for Innovative Manufacturing in Additive Manufacturing, School of Engineering, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Prina, Elisabetta [School of Pharmacy, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Goodridge, Ruth D.; Hague, Richard J.M. [Additive Manufacturing and 3D Printing Research Group, EPSRC Centre for Innovative Manufacturing in Additive Manufacturing, School of Engineering, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Edmondson, Steve [School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Rose, Felicity R.A.J. [School of Pharmacy, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Christie, Steven D.R. [Department of Chemistry, Loughborough University, Loughborough LE11 3TU (United Kingdom)

    2016-10-01

    Selective laser melting (SLM) has previously been shown to be a viable method for fabricating biomedical implants; however, the surface chemistry of SLM fabricated parts is poorly understood. In this study, X-ray photoelectron spectroscopy (XPS) was used to determine the surface chemistries of (a) SLM as-fabricated (SLM-AF) Ti6Al4V and (b) SLM fabricated and mechanically polished (SLM-MP) Ti6Al4V samples and compared with (c) traditionally manufactured (forged) and mechanically polished Ti6Al4V samples. The SLM–AF surface was observed to be porous with an average surface roughness (Ra) of 17.6 ± 3.7 μm. The surface chemistry of the SLM-AF was significantly different to the FGD-MP surface with respect to elemental distribution and their existence on the outermost surface. Sintered particles on the SLM-AF surface were observed to affect depth profiling of the sample due to a shadowing effect during argon ion sputtering. Surface heterogeneity was observed for all three surfaces; however, vanadium was witnessed only on the mechanically polished (SLM-MP and FGD-MP) surfaces. The direct and indirect 3T3 cell cytotoxicity studies revealed that the cells were viable on the SLM fabricated Ti6Al4V parts. The varied surface chemistry of the SLM-AF and SLM-MP did not influence the cell behaviour. - Highlights: • Surface chemistry of selective laser melted (SLM) Ti6Al4V parts was compared with conventionally forged Ti6Al4V parts. • The surface elemental compositions of the SLM as-fabricated surfaces were significantly different to the forged surface. • Surface oxide-layer of the SLM as-fabricated was thicker than the polished SLM surfaces and the forged Ti6Al4V surfaces.

  7. Improvement of laser keyhole formation with the assistance of arc plasma in the hybrid welding process of magnesium alloy

    Science.gov (United States)

    Liu, Liming; Hao, Xinfeng

    2009-11-01

    In the previous work, low-power laser/arc hybrid welding technique is used to weld magnesium alloy and high-quality weld joints are obtained. In order to make clear the interactions between low-power laser pulse and arc plasma, the effect of arc plasma on laser pulse is studied in this article. The result shows that the penetration of low-power laser welding with the assistance of TIG arc is more than two times deeper than that of laser welding alone and laser welding transforms from thermal-conduction mode to keyhole mode. The plasma behaviors and spectra during the welding process are studied, and the transition mechanism of laser-welding mode is analyzed in detail. It is also found that with the assistance of arc plasma, the threshold value of average power density to form keyhole welding for YAG laser is only 3.3×10 4 W/cm 2, and the average peak power density is 2.6×10 5 W/cm 2 in the present experiment. Moreover, the distribution of energy density during laser pulse is modulated to improve the formation and stability of laser keyholes.

  8. Investigation of laser cladding high temperature anti-wear composite coatings on Ti6Al4V alloy with the addition of self-lubricant CaF2

    International Nuclear Information System (INIS)

    Xiang, Zhan-Feng; Liu, Xiu-Bo; Ren, Jia; Luo, Jian; Shi, Shi-Hong; Chen, Yao; Shi, Gao-Lian; Wu, Shao-Hua

    2014-01-01

    Highlights: • A novel high temperature self-lubricating wear-resistant coating was fabricated. • TiC carbides and self-lubricant CaF 2 were “in situ” synthesized in the coating. • The coating with the addition of CaF 2 possessed superior properties than without. - Abstract: To improve the high-temperature tribological properties of Ti–6Al–4V alloy, γ-NiCrAlTi/TiC and γ-NiCrAlTi/TiC/CaF 2 coatings were fabricated on Ti–6Al–4V alloy by laser cladding. The phase compositions and microstructure of the coatings were investigated using X-ray diffraction (XRD) and scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS). The tribological behaviors were evaluated using a ball-on-disk tribometer from ambient temperature to 600 °C under dry sliding wear conditions and the corresponding wear mechanisms were discussed. The results indicated that the γ-NiCrAlTi/TiC/CaF 2 coating consisted of α-Ti, the “in situ” synthesized TiC block particles and dendrite, γ-NiCrAlTi solid solution and spherical CaF 2 particles. The wear rates of γ-NiCrAlTi/TiC/CaF 2 coating were decreased greatly owing to the combined effects of the reinforced carbides and continuous lubricating films. Furthermore, the friction coefficients of γ-NiCrAlTi/TiC/CaF 2 coating presented minimum value of 0.21 at 600 °C, which was reduced by 43% and 50% compared to the substrate and γ-NiCrAlTi/TiC coating respectively. It was considered that the γ-NiCrAlTi/TiC/CaF 2 coating exhibited excellent friction-reducing and anti-wear properties at high temperature

  9. Effect of fiber laser parameters on laser welded AZ31B Magnesium alloys

    Directory of Open Access Journals (Sweden)

    Mat Salleh Naqiuddin

    2017-01-01

    Full Text Available Recently, the usage of Magnesium (Mg alloys has been hugely applied in the industrial application such as in automotive, marine, and electronic due to its advantages of recyclability and lightweight. This alloys required low heat input to be weld since it is easily evaporated due to the Magnesium Oxide (MgO at the surface and it also possesses lower melting point compared to steel. Laser welding is more convenient to weld Mg alloys due to its high power and lower heat input. AZ31B was selected since it has strong mechanical properties among others Mg alloys due to the major alloying elements; Aluminium (Al and Zinc (Zn. Low power fiber laser machine with wavelength of 900 nm was used in this experiment. The intention of this work was to investigate the effect of low power fiber laser parameters and effect of shielding gas on weld penetration and microstructure. Another aim in this work was to produce the joint for this thin sheets metal. Penetration depth and microstructure evaluation were emphasized in the analysis section. Bead-on-Plate (BOP and laser lap welding was conducted on AZ31B with thicknesses of 1.0 mm and 0.6 mm for feasibility study using pulsed wave (PW mode. Defocusing features was used in order to find better focal position, which has less occurrence of evaporation (underfill. The effect of different angle of irradiation was also investigated. Two types of shielding gases, Argon (Ar and Nitrogen (N2 were used in order to study the effect of shielding gas. Lastly, the effect of pulsed energy on penetration types and depth of BOP welded samples was investigated. Focus point was found at focal length of 156 mm with 393.75 μm. For BOP experiment, higher pulsed energy used contributes to melt through defect. Meanwhile, Ns shielding gas proved to be better shielding gas in laser welding the AZ31B. Higher angle of irradiation could reduce the underfill defect. Fillet Lap joint of similar metal was successfully done where 2.0 J of

  10. Fiber Laser Welding Properties of Copper Materials for Secondary Batteries

    Directory of Open Access Journals (Sweden)

    Young-Tae YOU

    2017-11-01

    Full Text Available Secondary battery is composed of four main elements: cathodes, anodes, membranes and electrolyte. The cathodes and the anodes are connected to the poles that allow input and output of the current generated while the battery is being charged or discharged. In this study laser welding is conducted for 40 sheets of pure copper material with thickness of 38μm, which are used in currently manufactured lithium-ion batteries, using pulse-wave fiber laser to compare welded joint to standard bolt joint and to determine optimum process parameters. The parameters, which has significant impact on penetration of the pulse waveform laser to the overlapped thin sheets, is the peak power while the size of the weld zone is mainly affected by the pulse irradiation time and the focal position. It is confirmed that overlapping rate is affected by the pulse repetition rate rather than by the pulse irradiation time. At the cross-section of the weld zone, even with the increased peak power, the width of the front bead weld size does not change significantly, but the cross-sectional area becomes larger. This is because the energy density per pulse increases as the peak power increases.DOI: http://dx.doi.org/10.5755/j01.ms.23.4.16316

  11. Keyhole shapes during laser welding of thin metal sheets

    International Nuclear Information System (INIS)

    Aalderink, B J; Lange, D F de; Aarts, R G K M; Meijer, J

    2007-01-01

    Camera observations of the full penetration keyhole laser welding process show that the keyhole shape is elongated under certain welding conditions. Under these unfavourable circumstances, the welding process is susceptible to holes in the weld bead. Existing models of the pressure balance at the keyhole wall cannot explain this keyhole elongation. In this paper a new model is presented, accounting for the doubly curved shape of the keyhole wall. In this model, the surface tension pressure has one term that tends to close the keyhole and another term that tries to open it. Model calculations show that when the keyhole diameter is of the same order as the sheet thickness, the latter part can become dominant, causing the keyhole to elongate. Experiments on thin aluminium (AA5182) and mild steel (DC04) sheets verify these model calculations. As the keyhole radius depends on the radius of the focused laser spot, it was found for both materials that the ratio of the spot radius and the sheet thickness must be above a critical value to prevent keyhole elongation. These critical radii are 0.25 for AA5182 and 0.4 for DC04, respectively. Furthermore, differences in appearance of the weld bead between the circular and the elongated keyhole welds could be explained by this model

  12. Environmental monitoring by CaSO4:Dy TL dosimeters

    International Nuclear Information System (INIS)

    Deme, S.; Szabo, P.P.

    1975-12-01

    The thermoluminescent dosimeters of high sensitivity are useful for monitoring the area near nuclear installations. CaSO 4 :Dy TL dosimeters have high sensitivity and low fading so that by means of them the dose from the background can be measured with an accuracy of 10-20%. An increase of 2 mR in the background can be observed and doses as high as 1000R can be registered with an accuracy of 5%. The measuring method and results are reported here. For two years these CaSO 4 :Dy dosimeters have been successfully used at the site of the Central Research Institute for Physics. (K.A.)

  13. Laser welding closed-loop power control

    DEFF Research Database (Denmark)

    Bagger, Claus; Olsen, Flemming Ove

    2003-01-01

    A closed-loop control system is developed to maintain an even seam width on the root side of a laser weld by continually controlling the output laser power of a 1500 W CO2 laser.......A closed-loop control system is developed to maintain an even seam width on the root side of a laser weld by continually controlling the output laser power of a 1500 W CO2 laser....

  14. Ti-6Al-4V Additively Manufactured by Selective Laser Melting with Superior Mechanical Properties

    Science.gov (United States)

    Xu, W.; Sun, S.; Elambasseril, J.; Liu, Q.; Brandt, M.; Qian, M.

    2015-03-01

    The Achilles' heel of additively manufactured Ti-6Al-4V by selective laser melting (SLM) is its inferior mechanical properties compared with its wrought (forged) counterparts. Acicular α' martensite resulted from rapid cooling by SLM is primarily responsible for high strength but inadequate tensile ductility achieved in the as-fabricated state. This study presents a solution to eliminating the adverse effect of the nonequilibrium α' martensite. This is achieved by enabling in situ martensite decomposition into a novel ultrafine (200-300 nm) lamellar ( α + β) microstructure via the selection of an array of processing variables including the layer thickness, energy density, and focal offset distance. The resulting tensile elongation reached 11.4% while the yield strength was kept above 1100 MPa. These properties compare favorably with those of mill-annealed Ti-6Al-4V consisting of globular α and β. The fatigue life of SLM-fabricated Ti-6Al-4V with an ultrafine lamellar ( α + β) structure has approached that of the mill-annealed counterparts and is much superior to that of SLM-fabricated Ti-6Al-4V with α' martensite.

  15. Plasma Arc Augmented CO2 laser welding

    DEFF Research Database (Denmark)

    Bagger, Claus; Andersen, Mikkel; Frederiksen, Niels

    2001-01-01

    In order to reduce the hardness of laser beam welded 2.13 mm medium strength steel CMn 250, a plasma arc has been used simultaneously with a 2.6 kW CO2 laser source. In a number of systematic laboratory tests, the plasma arc current, plasma gas flow and distance to the laser source were varied...... with all laser parameters fixed. The welds were quality assessed and hardness measured transversely to the welding direction in the top, middle and root of the seam. In the seams welded by laser alone, hardness values between 275 and 304 HV1 were measured, about the double of the base material, 150 HV1...

  16. Development of an auto-welding system for CRD nozzle repair welds using a 3D laser vision sensor

    International Nuclear Information System (INIS)

    Park, K.; Kim, Y.; Byeon, J.; Sung, K.; Yeom, C.; Rhee, S.

    2007-01-01

    A control rod device (CRD) nozzle attaches to the hemispherical surface of a reactor head with J-groove welding. Primary water stress corrosion cracking (PWSCC) causes degradation in these welds, which requires that these defect areas be repaired. To perform this repair welding automatically on a complicated weld groove shape, an auto-welding system was developed incorporating a laser vision sensor that measures the 3-dimensional (3D) shape of the groove and a weld-path creation program that calculates the weld-path parameters. Welding trials with a J-groove workpiece were performed to establish a basis for developing this auto-welding system. Because the reactor head is placed on a lay down support, the outer-most region of the CRD nozzle has restricted access. Due to this tight space, several parameters of the design, such as size, weight and movement of the auto-welding system, had to be carefully considered. The cross section of the J-groove weld is basically an oval shape where the included angle of the J-groove ranges from 0 to 57 degrees. To measure the complex shape, we used double lasers coupled to a single charge coupled device (CCD) camera. We then developed a program to generate the weld-path parameters using the measured 3D shape as a basis. The program has the ability to determine the first and final welding positions and to calculate all weld-path parameters. An optimized image-processing algorithm was applied to resolve noise interference and diffused reflection of the joint surfaces. The auto-welding system is composed of a 4-axis manipulator, gas tungsten arc welding (GTAW) power supply, an optimized designed and manufactured GTAW torch and a 3D laser vision sensor. Through welding trials with 0 and 38-degree included-angle workpieces with both J-groove and U-groove weld, the performance of this auto-welding system was qualified for field application

  17. Microstructure and Corrosion Behavior of Laser Synthesized Cobalt Based Powder on Ti-6Al-4V

    Science.gov (United States)

    Adesina, O. S.; Popoola, A. P. I.; Pityana, S. L.; Oloruntoba, D. T.

    2018-05-01

    The corrosion behavior of titanium alloys when used for various dynamic offshore components has been a major concern of titanium drilling risers in deepwater energy extraction. A way of achieving specified requirement is the development of coatings suitable to protect the base material against corrosion. In this work, laser cladding technique which is known as a leading edge due to its distinctive properties and outcomes was used in synthesizing Co-based powder on titanium alloy. The processing parameters used were laser power of 900W; scan speed of 0.6 to 1.2 m/min; powderfeedrate1.0g/min;beamspotsize3mm;gasflowrate1.2L/min.The effects of cobalt addition and laser parameters on corrosion behavior of laser clad Ti6AL4V coating in 0.5M sulfuric medium were investigated using linear potentiodynamic polarization. The changes in microstructure and corrosion behavior were analyzed using scanning electron microscopy (SEM) while the X –ray diffraction (XRD) indicates the intermetallics in the coatings. Results showed that the coatings displayed good metallurgical bonding with dendritic formations between the coatings and the substrate. The anodic current density increased with lower scan speed. However, the corrosion current densities of laser-clad samples were lower than Ti6Al4V alloy.

  18. 2C-R4WM Spectroscopy of Jet Cooled NO_3

    Science.gov (United States)

    Fukushima, Masaru; Ishiwata, Takashi; Hirota, Eizi

    2016-06-01

    We have generated NO_3 from pyrolysis of N_2O_5 following supersonic free jet expansion, and carried out two color resonant four wave mixing ( 2C-R4WM ) spectroscopy of the tilde{B} ^2E' - tilde{X} ^2A_2' electronic transition. One laser was fixed to pump NO_3 to a ro-vibronic level of the tilde{B} state, and the other laser ( probe ) was scanned across two levels of the tilde{X} ^2A_2' state lying at 1051 and 1492 cm-1, the ν_1 (a_1') and ν_3 (e') fundamentals, respectively. The 2C-R4WM spectra have unexpected back-ground signal of NO_3 ( stray signal due to experimental set-up is also detected ) similar to laser induced fluorescence ( LIF ) excitation spectrum of the 0-0 band, although the back-ground signal was not expected in considering the 2C-R4WM scheme. Despite the back-ground interference, we have observed two peaks at 1051.61 and 1055.29 cm-1 in the ν_1 region of the spectrum, and the frequencies agree with the two bands, 1051.2 and 1055.3 cm-1, of our relatively higher resolution dispersed fluorescence spectrum, the former of which has been assigned to the ν_1 fundamental. Band width of both peaks, ˜ 0.2 cm-1, is broader than twice the experimental spectral-resolution, 0.04 cm-1 ( because this experiment is double resonance spectroscopy ), and the 1051.61 cm-1 peak is attributed to a Q branch band head ( a line-like Q branch ) of the ν_1 fundamental. The other branches are suspected to be hidden in noise of the back-ground signal. The 1055.29 cm-1 peak is also attributed to a Q band head. The tilde{B} ^2E'1/2 ( J' = 3/2, K' = 1 ) - tilde{X} ^2A_2' ( N'' = 1, K'' = 0 ) ro-vibronic transition was used as the pump transition. The dump ( probe ) transition to both a_1' and e' vibronic levels are then allowed as perpendicular transition. Accordingly, it cannot be determined from present results whether the 1055.29 cm-1 band is attributed to a_1' or e' (ν_3), unfortunately. The 2C-R4WM spectrum of the 1492 cm-1 band region shows one Q head at 1499.79 cm

  19. Microstructure in welding zone of a zircaloy 4 tube welded by TIG process

    International Nuclear Information System (INIS)

    Bolfarini, C.; Domingues Filho, H.

    1982-01-01

    The details concerned with the welding of seamless zircaloy 4 tubes for nuclear application and the earlier welding tests made in the tubes that will be used for the construction of the Argonautas' Reactor fuel element, are described. Based on the references the microestructure changes in the heat affected zone were analyzed in respect to the material's performance in operation. (Author) [pt

  20. Influence of heat treatments for laser welded semi solid metal cast A356 alloy on the fracture mode of tensile specimens

    CSIR Research Space (South Africa)

    Kunene, G

    2008-09-01

    Full Text Available were then butt laser welded. It was found that the pre-weld as cast, T4 and post-weld T4 heat treated specimens fractured in the base metal. However, the pre-weld T6 heat treated specimens were found to have fractured in the heat affected zone (HAZ)...

  1. Crystal structure, Raman scattering and magnetic properties of CuCr2-xZrxSe4 and CuCr2-xSnxSe4 selenospinels

    Science.gov (United States)

    Pinto, C.; Galdámez, A.; Barahona, P.; Moris, S.; Peña, O.

    2018-06-01

    Selenospinels, CuCr2-xMxSe4 (M = Zr and Sn), were synthesized via conventional solid-state reactions. The crystal structure of CuCr1.5Sn0.5Se4, CuCr1.7Sn0.3Se4, CuCr1.5Zr0.5Se4, and CuCr1.8Zr0.2Se4 were determined using single-crystal X-ray diffraction. All the phases crystallized in a cubic spinel-type structure. The chemical compositions of the single-crystals were examined using energy-dispersive X-ray analysis (EDS). Powder X-ray diffraction patterns of CuCr1.3Sn0.7Se4 and CuCr1.7Sn0.3Se4 were consistent with phases belonging to the Fd 3 bar m Space group. An analysis of the vibrational properties on the single-crystals was performed using Raman scattering measurements. The magnetic properties showed a spin glass behavior with increasing Sn content and ferromagnetic order for CuCr1.7Sn0.3Se4.

  2. Microstructural Characterization of Clad Interface in Welds of Ni-Cr-Mo High Strength Low Alloy Steel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hong-Eun; Kim, Min-Chul; Lee, Ho-Jin; Kim, Keong-Ho [KAERI, Daejeon (Korea, Republic of); Lee, Ki-Hyoung [KAIST, Daejeon (Korea, Republic of); Lee, Chang-Hee [Hanyang Univ., Seoul (Korea, Republic of)

    2011-08-15

    SA508 Gr.4N Ni-Cr-Mo low alloy steel, in which Ni and Cr contents are higher than in commercial SA508 Gr.3 Mn-Mo-Ni low alloy steels, may be a candidate reactor pressure vessel (RPV) material with higher strength and toughness from its tempered martensitic microstructure. The inner surface of the RPV is weld-cladded with stainless steels to prevent corrosion. The goal of this study is to evaluate the microstructural properties of the clad interface between Ni-Cr-Mo low alloy steel and stainless weldment, and the effects of post weld heat treatment (PWHT) on the properties. The properties of the clad interface were compared with those of commercial Mn-Mo-Ni low alloy steel. Multi-layer welding of model alloys with ER308L and ER309L stainless steel by the SAW method was performed, and then PWHT was conducted at 610°C for 30 h. The microstructural changes of the clad interface were analyzed using OM, SEM and TEM, and micro-Vickers hardness tests were performed. Before PWHT, the heat affected zone (HAZ) showed higher hardness than base and weld metals due to formation of martensite after welding in both steels. In addition, the hardness of the HAZ in Ni-Cr-Mo low alloy steel was higher than that in Mn-Mo-Ni low alloy steel due to a comparatively high martensite fraction. The hardness of the HAZ decreased after PWHT in both steels, but the dark region was formed near the fusion line in which the hardness was locally high. In the case of Mn-Mo-Ni low alloy steel, formation of fine Cr-carbides in the weld region near the fusion line by diffusion of C from the base metal resulted in locally high hardness in the dark region. However, the precipitates of the region in the Ni-Cr-Mo low alloy steel were similar to that in the base metal, and the hardness in the region was not greatly different from that in the base metal.

  3. Microstructural Characterization of Clad Interface in Welds of Ni-Cr-Mo High Strength Low Alloy Steel

    International Nuclear Information System (INIS)

    Kim, Hong-Eun; Kim, Min-Chul; Lee, Ho-Jin; Kim, Keong-Ho; Lee, Ki-Hyoung; Lee, Chang-Hee

    2011-01-01

    SA508 Gr.4N Ni-Cr-Mo low alloy steel, in which Ni and Cr contents are higher than in commercial SA508 Gr.3 Mn-Mo-Ni low alloy steels, may be a candidate reactor pressure vessel (RPV) material with higher strength and toughness from its tempered martensitic microstructure. The inner surface of the RPV is weld-cladded with stainless steels to prevent corrosion. The goal of this study is to evaluate the microstructural properties of the clad interface between Ni-Cr-Mo low alloy steel and stainless weldment, and the effects of post weld heat treatment (PWHT) on the properties. The properties of the clad interface were compared with those of commercial Mn-Mo-Ni low alloy steel. Multi-layer welding of model alloys with ER308L and ER309L stainless steel by the SAW method was performed, and then PWHT was conducted at 610°C for 30 h. The microstructural changes of the clad interface were analyzed using OM, SEM and TEM, and micro-Vickers hardness tests were performed. Before PWHT, the heat affected zone (HAZ) showed higher hardness than base and weld metals due to formation of martensite after welding in both steels. In addition, the hardness of the HAZ in Ni-Cr-Mo low alloy steel was higher than that in Mn-Mo-Ni low alloy steel due to a comparatively high martensite fraction. The hardness of the HAZ decreased after PWHT in both steels, but the dark region was formed near the fusion line in which the hardness was locally high. In the case of Mn-Mo-Ni low alloy steel, formation of fine Cr-carbides in the weld region near the fusion line by diffusion of C from the base metal resulted in locally high hardness in the dark region. However, the precipitates of the region in the Ni-Cr-Mo low alloy steel were similar to that in the base metal, and the hardness in the region was not greatly different from that in the base metal.

  4. Corrosion of Ti6Al4V pins produced by direct metal laser sintering

    Energy Technology Data Exchange (ETDEWEB)

    Damborenea, J.J. de, E-mail: jdambo@cenim.csic.es [Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Avenida Gregorio del Amo, 8, E-28040 Madrid (Spain); Arenas, M.A. [Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Avenida Gregorio del Amo, 8, E-28040 Madrid (Spain); Larosa, Maria Aparecida; Jardini, André Luiz [National Institute of Biofabrication (INCT-BIOFABRIS), State of University of Campinas (UNICAMP), Campinas (Brazil); School of Chemical Engineering, State of University of Campinas (UNICAMP), Campinas (Brazil); Carvalho Zavaglia, Cecília Amélia de [National Institute of Biofabrication (INCT-BIOFABRIS), State of University of Campinas (UNICAMP), Campinas (Brazil); Faculty of Mechanical Engineering, State of University of Campinas (UNICAMP), Campinas (Brazil); Conde, A. [Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Avenida Gregorio del Amo, 8, E-28040 Madrid (Spain)

    2017-01-30

    Highlights: • Pins of Ti6Al4V have been produced by DMLS technique. • Corrosion behavior of pins is similar to Ti6Al4V commercial Kirschner wires. • Formation of voluminous white oxide can appear at potentials higher than 2.4 V. • Defects originated during processing may cause this unusual behavior. - Abstract: Direct Metal Laser Sintering (DMLS) technique allows the manufacturing a wide variety of medical devices for any type of prosthetic surgery (HIP, dental, cranial, maxillofacial) as well as for internal fixation devices (K-Wires or Steinmann Pins). There are a large number of research studies on DMLS, including microstructural characterization, mechanical properties and those based on production quality assurance but the influence of porosity in the corrosion behavior of these materials not been sufficiently considered. In the present paper, surgical pins of Ti6Al4V have been produced by DMLS. After testing in a phosphate buffered saline solution, the surface of the titanium alloy appeared locally covered by a voluminous white oxide. This unexpected behavior was presumably due to the existence of internal defects in the pins as result of the manufacturing process. The importance of these defects—that might act as crevice nucleation sites- has been revealed by electrochemical techniques and confirmed by computed tomography.

  5. Corrosion of Ti6Al4V pins produced by direct metal laser sintering

    International Nuclear Information System (INIS)

    Damborenea, J.J. de; Arenas, M.A.; Larosa, Maria Aparecida; Jardini, André Luiz; Carvalho Zavaglia, Cecília Amélia de; Conde, A.

    2017-01-01

    Highlights: • Pins of Ti6Al4V have been produced by DMLS technique. • Corrosion behavior of pins is similar to Ti6Al4V commercial Kirschner wires. • Formation of voluminous white oxide can appear at potentials higher than 2.4 V. • Defects originated during processing may cause this unusual behavior. - Abstract: Direct Metal Laser Sintering (DMLS) technique allows the manufacturing a wide variety of medical devices for any type of prosthetic surgery (HIP, dental, cranial, maxillofacial) as well as for internal fixation devices (K-Wires or Steinmann Pins). There are a large number of research studies on DMLS, including microstructural characterization, mechanical properties and those based on production quality assurance but the influence of porosity in the corrosion behavior of these materials not been sufficiently considered. In the present paper, surgical pins of Ti6Al4V have been produced by DMLS. After testing in a phosphate buffered saline solution, the surface of the titanium alloy appeared locally covered by a voluminous white oxide. This unexpected behavior was presumably due to the existence of internal defects in the pins as result of the manufacturing process. The importance of these defects—that might act as crevice nucleation sites- has been revealed by electrochemical techniques and confirmed by computed tomography.

  6. Uniaxial creep behavior of V-4Cr-4Ti alloy

    International Nuclear Information System (INIS)

    Natesan, K.; Soppet, W.K.; Purohit, A.

    2002-01-01

    We are undertaking a systematic study at Argonne National Laboratory to evaluate the uniaxial creep behavior of V-Cr-Ti alloys in a vacuum environment as a function of temperature in the range of 650-800 deg. C and at applied stress levels of 75-380 MPa. Creep strain in the specimens is measured by a linear-variable-differential transducer, which is attached between the fixed and movable pull rods of the creep assembly. Strain is measured at sufficiently frequent intervals during testing to define the creep strain/time curve. A linear least-squares analysis function is used to ensure consistent extraction of minimum creep rate, onset of tertiary creep and creep strain at the onset of tertiary creep. Creep test data, obtained at 650, 700, 725 and 800 deg. C, showed power-law creep behavior. Extensive analysis of the tested specimens is conducted to establish hardness profiles, oxygen content and microstructural characteristics. The data are also quantified by the Larson-Miller approach, and correlations are developed to relate time to rupture, onset of tertiary creep, times for 1% and 2% strain, exposure temperature and applied stress

  7. Relationships among the Microstructure, Mechanical Properties, and Fatigue Behavior in Thin Ti6Al4V

    Directory of Open Access Journals (Sweden)

    Y. Fan

    2016-01-01

    Full Text Available The microstructures of Ti6Al4V are complex and strongly affect its mechanical properties and fatigue behavior. This paper investigates the role of microstructure on mechanical and fatigue properties of thin-section Ti6Al4V sheets, with the aim of reviewing the effects of microstructure on fatigue properties where suboptimal microstructures might result following heat treatment of assemblies that may not be suited to further annealing, for example, following laser welding. Samples of Ti6Al4V sheet were subjected to a range of heat treatments, including annealing and water quenching from temperatures ranging from 650°C to 1050°C. Micrographs of these samples were inspected for microstructure, and hardness, 0.2% proof stress, elongation, and fracture strength were measured and attributed back to microstructure. Fractography was used to support the findings from microstructure and mechanical analyses. The strength ranking from high to low for the microstructures of thin Ti6Al4V sheets observed in this study is as follows: acicular α′ martensite, Widmanstätten, bimodal, and equiaxed microstructure. The fatigue strength ranking from high to low is as follows: equiaxed, bimodal, Widmanstätten, and acicular α′ martensite microstructure.

  8. Welding induced residual stress evaluation using laser-generated Rayleigh waves

    Science.gov (United States)

    Ye, Chong; Zhou, Yuanlai; Reddy, Vishnu V. B.; Mebane, Aaron; Ume, I. Charles

    2018-04-01

    Welding induced residual stress could affect the dimensional stability, fatigue life, and chemical resistance of the weld joints. Ultrasonic method serves as an important non-destructive tool for the residual stress evaluation due to its easy implementation, low cost and wide application to different materials. Residual stress would result in the ultrasonic wave velocity variation, which is the so called acoustoelastic effect. In this paper, Laser/EMAT ultrasonic technique was proposed to experimentally study the relative velocity variation ΔV/V of Rayleigh wave, which has the potential to evaluate surface/subsurface longitudinal residual stress developed during the Gas Metal Arc Welding process. Broad band ultrasonic waves were excited by pulsed Q-Switched Nd: YAG laser. An electromagnetic acoustic transducer (EMAT) attached to the welded plates was used to capture the Rayleigh wave signals propagating along the weld seam direction. Different time of flight measurements were conducted by varying the distance between the weld seam and Rayleigh wave propagating path in the range of 0 to 45 mm. The maximum relative velocity difference was found on the weld seam. With the increasing distance away from the weld seam, the relative velocity difference sharply decreased to negative value. With further increase in distance, the relative velocity difference slowly increased and approached zero. The distribution of relative velocity variations indicates that tensile stress appears in the melted zone as it becomes compressive near the heat-affected zone.

  9. X-ray attenuation coefficient measurements for photon energies 4.508-13.375 keV in Cu, Cr and their compounds and the validity of the mixture rule

    International Nuclear Information System (INIS)

    Turgut, Ue.; Simsek, Oe.; Bueyuekkasap, E.; Ertugrul, M.

    2004-01-01

    To investigate the validity of the mixture rule which is used to compute the mass attenuation coefficients in compounds, the total mass attenuation coefficients for Cu, Cr elements and Cu 2 O, CuC 2 O 4 , CuCl 2 ·2H 2 O, Cu(C 2 H 3 O 2 ) 2 ·H 2 O, Cr 2 O 3 , Cr(NO 3 ) 3 , Cr 2 (SO 4 ) 3 ·H 2 O, Cr 3 (CH 3 CO 7 )(OH) 2 compounds were measured at photon energies between 4.508 and 13.375 keV by using the secondary excitation method. Ti, Mn, Fe, Ni, Zn, Ge, As, Rb elements were used as secondary exciters. 59.5 keV gamma rays emitted from an 241 Am annular source were used to excite the secondary exciters and Kα (K-L 3 , L 2 ) rays emitted from the secondary exciter were counted by a Si(Li) detector with a resolution of 160 eV at 5.9 keV. Our measurements indicate that the mixture rule is not a suitable method for the computation of mass attenuation coefficients of compounds especially at an energy that is near the absorption edge. Obtained values were compared with theoretical values

  10. Hybrid laser arc welding: State-of-art review

    Science.gov (United States)

    Acherjee, Bappa

    2018-02-01

    Hybrid laser arc welding simultaneously utilizes the arc welding and the laser welding, in a common interaction zone. The synergic effects of laser beam and eclectic arc in the same weld pool results in an increase of welding speed and penetration depth along with the enhancement of gap bridging capability and process stability. This paper presents the current status of this hybrid technique in terms of research, developments and applications. Effort is made to present a comprehensive technical know-how about this process through a systematic review of research articles, industrial catalogues, technical notes, etc. In the introductory part of the review, an overview of the hybrid laser arc welding is presented, including operation principle, process requirements, historical developments, benefits and drawbacks of the process. This is followed by a detailed discussion on control parameters those govern the performance of hybrid laser arc welding process. Thereafter, a report of improvements of performance and weld qualities achieved by using hybrid welding process is presented based on review of several research papers. The succeeding sections furnish the examples of industrial applications and the concluding remarks.

  11. Supersonic Plasma Spray Deposition of CoNiCrAlY Coatings on Ti-6Al-4V Alloy

    Science.gov (United States)

    Caliari, F. R.; Miranda, F. S.; Reis, D. A. P.; Essiptchouk, A. M.; Filho, G. P.

    2017-06-01

    Plasma spray is a versatile technology used for production of environmental and thermal barrier coatings, mainly in the aerospace, gas turbine, and automotive industries, with potential application in the renewable energy industry. New plasma spray technologies have been developed recently to produce high-quality coatings as an alternative to the costly low-pressure plasma-spray process. In this work, we studied the properties of as-sprayed CoNiCrAlY coatings deposited on Ti-6Al-4V substrate with smooth surface ( R a = 0.8 μm) by means of a plasma torch operating in supersonic regime at atmospheric pressure. The CoNiCrAlY coatings were evaluated in terms of their surface roughness, microstructure, instrumented indentation, and phase content. Static and dynamic depositions were investigated to examine their effect on coating characteristics. Results show that the substrate surface velocity has a major influence on the coating properties. The sprayed CoNiCrAlY coatings exhibit low roughness ( R a of 5.7 μm), low porosity (0.8%), excellent mechanical properties ( H it = 6.1 GPa, E it = 155 GPa), and elevated interface toughness (2.4 MPa m1/2).

  12. Formation of ω-phase in Zr-4 at.% Cr alloy

    International Nuclear Information System (INIS)

    Dobromyslov, A.V.; Kazantseva, N.V.

    1996-01-01

    The ω-phase has been discovered in zirconium-base alloys with the transition metals of Period 4 of the Periodic Table only in Zr-V, Zr-Cr, and Zr-Cu alloys. The first mention about the ω-phase formation in Zr-Cr alloys was given for Zr-4.5 at.%. However, there were no experimental data that confirmed this fact. W.M. Rumball and F.G. Elder presented the X-ray results on the ω-phase formation in Zr-3.9 at.%Cr, but at the present time there are no electron microscope studies of the structure of the ω-phase in this system. Investigations of the features of the ω-phase formation, morphology of the ω-phase and the mechanism of its formation in the different zirconium-base alloys are necessary to establish the common features of the formation of structures with the metastable phases. The task of the present work is to study the conditions and features of the ω-phase formation in the Zr-Cr alloys and the effect of the eutectoid decomposition on the formation of ω-phase. This article is part of the detailed investigations of the feature and condition of the ω-phase formation in zirconium-base alloys with the transition metals of the groups I and V to VIII of the Periodic Table

  13. Thin-Sheet zinc-coated and carbon steels laser welding

    International Nuclear Information System (INIS)

    Pecas, P.; Gouveia, H.; Quintino, L.

    1998-01-01

    This paper describes the results of a research on CO 2 laser welding of thin-sheet carbon steels (Zinc-coated and uncoated), at several thicknesses combinations. Laser welding has an high potential to be applied on sub-assemblies welding before forming to the automotive industry-tailored blanks. The welding process is studied through the analysis of parameters optimization, metallurgical quality and induced distortions by the welding process. The clamping system and the gas protection system developed are fully described. These systems allow the minimization of common thin-sheet laser welding defects like misalignment, and zinc-coated laser welding defects like porous and zinc ventilation. The laser welding quality is accessed by DIN 8563 standard, and by tensile, microhardness and corrosion test. (Author) 8 refs

  14. Toughness of 2,25Cr-1Mo steel and weld metal

    Science.gov (United States)

    Acarer, Mustafa; Arici, Gökhan; Acar, Filiz Kumdali; Keskinkilic, Selcuk; Kabakci, Fikret

    2017-09-01

    2,25Cr-1Mo steel is extensively used at elevated temperature structural applications in fossil fire power plants for steam pipes, nozzle chambers and petrochemical industry for hydrocracking unit due to its excellent creep resistance and good redundant to oxidation. Also they should have acceptable weldability and toughness. The steels are supplied in quenched and tempered condition and their welded components are subjected to post-weld heat treatment (PWHT). Tempering process is carried out at 690-710°C to improve toughness properties. However they are sensitive to reheat cracking and temper embrittlement. To measure temper embrittlement of the steels and their weld metal, temper embrittlement factor and formula (J factor - Watanabe and X formula- Bruscato) are used. Step cooling heat treatment is also applied to determine temper embrittlement. In this study, toughness properties of Cr Mo (W) steels were reviewed. Also transition temperature curves of 2,25Cr-1Mo steel and its weld metal were constructed before and after step cool heat treatment as experimental study. While 2,25Cr-1Mo steel as base metal was supplied, all weld metal samples were produced in Gedik Welding Company. Hardness measurements and microstructure evaluation were also carried out.

  15. Hybrid Laser Welding of Large Steel Structures

    DEFF Research Database (Denmark)

    Farrokhi, Farhang

    Manufacturing of large steel structures requires the processing of thick-section steels. Welding is one of the main processes during the manufacturing of such structures and includes a significant part of the production costs. One of the ways to reduce the production costs is to use the hybrid...... laser welding technology instead of the conventional arc welding methods. However, hybrid laser welding is a complicated process that involves several complex physical phenomena that are highly coupled. Understanding of the process is very important for obtaining quality welds in an efficient way....... This thesis investigates two different challenges related to the hybrid laser welding of thick-section steel plates. Employing empirical and analytical approaches, this thesis attempts to provide further knowledge towards obtaining quality welds in the manufacturing of large steel structures....

  16. Investigation of laser cladding high temperature anti-wear composite coatings on Ti6Al4V alloy with the addition of self-lubricant CaF{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, Zhan-Feng [School of Mechanical and Electric Engineering, Soochow University, 178 East Ganjiang Road, Suzhou 215006 (China); Liu, Xiu-Bo, E-mail: liuxiubo@suda.edu.cn [School of Mechanical and Electric Engineering, Soochow University, 178 East Ganjiang Road, Suzhou 215006 (China); Ren, Jia; Luo, Jian; Shi, Shi-Hong; Chen, Yao [School of Mechanical and Electric Engineering, Soochow University, 178 East Ganjiang Road, Suzhou 215006 (China); Shi, Gao-Lian; Wu, Shao-Hua [Suzhou Institute of Industrial Technology, Suzhou 215104 (China)

    2014-09-15

    Highlights: • A novel high temperature self-lubricating wear-resistant coating was fabricated. • TiC carbides and self-lubricant CaF{sub 2} were “in situ” synthesized in the coating. • The coating with the addition of CaF{sub 2} possessed superior properties than without. - Abstract: To improve the high-temperature tribological properties of Ti–6Al–4V alloy, γ-NiCrAlTi/TiC and γ-NiCrAlTi/TiC/CaF{sub 2} coatings were fabricated on Ti–6Al–4V alloy by laser cladding. The phase compositions and microstructure of the coatings were investigated using X-ray diffraction (XRD) and scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS). The tribological behaviors were evaluated using a ball-on-disk tribometer from ambient temperature to 600 °C under dry sliding wear conditions and the corresponding wear mechanisms were discussed. The results indicated that the γ-NiCrAlTi/TiC/CaF{sub 2} coating consisted of α-Ti, the “in situ” synthesized TiC block particles and dendrite, γ-NiCrAlTi solid solution and spherical CaF{sub 2} particles. The wear rates of γ-NiCrAlTi/TiC/CaF{sub 2} coating were decreased greatly owing to the combined effects of the reinforced carbides and continuous lubricating films. Furthermore, the friction coefficients of γ-NiCrAlTi/TiC/CaF{sub 2} coating presented minimum value of 0.21 at 600 °C, which was reduced by 43% and 50% compared to the substrate and γ-NiCrAlTi/TiC coating respectively. It was considered that the γ-NiCrAlTi/TiC/CaF{sub 2} coating exhibited excellent friction-reducing and anti-wear properties at high temperature.

  17. Laser penetration spike welding: a welding tool enabling novel process and design opportunities

    Science.gov (United States)

    Dijken, Durandus K.; Hoving, Willem; De Hosson, J. Th. M.

    2002-06-01

    A novel method for laser welding for sheet metal. is presented. This laser spike welding method is capable of bridging large gaps between sheet metal plates. Novel constructions can be designed and manufactured. Examples are light weight metal epoxy multi-layers and constructions having additional strength with respect to rigidity and impact resistance. Its capability to bridge large gaps allows higher dimensional tolerances in production. The required laser systems are commercially available and are easily implemented in existing production lines. The lasers are highly reliable, the resulting spike welds are quickly realized and the cost price per weld is very low.

  18. Keyhole formation and thermal fluid flow-induced porosity during laser fusion welding in titanium alloys: Experimental and modelling

    International Nuclear Information System (INIS)

    Panwisawas, Chinnapat; Perumal, Bama; Ward, R. Mark; Turner, Nathanael; Turner, Richard P.; Brooks, Jeffery W.; Basoalto, Hector C.

    2017-01-01

    High energy-density beam welding, such as electron beam or laser welding, has found a number of industrial applications for clean, high-integrity welds. The deeply penetrating nature of the joints is enabled by the formation of metal vapour which creates a narrow fusion zone known as a “keyhole”. However the formation of the keyhole and the associated keyhole dynamics, when using a moving laser heat source, requires further research as they are not fully understood. Porosity, which is one of a number of process induced phenomena related to the thermal fluid dynamics, can form during beam welding processes. The presence of porosity within a welded structure, inherited from the fusion welding operation, degrades the mechanical properties of components during service such as fatigue life. In this study, a physics-based model for keyhole welding including heat transfer, fluid flow and interfacial interactions has been used to simulate keyhole and porosity formation during laser welding of Ti-6Al-4V titanium alloy. The modelling suggests that keyhole formation and the time taken to achieve keyhole penetration can be predicted, and it is important to consider the thermal fluid flow at the melting front as this dictates the evolution of the fusion zone. Processing induced porosity is significant when the fusion zone is only partially penetrating through the thickness of the material. The modelling results are compared with high speed camera imaging and measurements of porosity from welded samples using X-ray computed tomography, radiography and optical micrographs. These are used to provide a better understanding of the relationship between process parameters, component microstructure and weld integrity.

  19. Studies on CO2-laser Hybrid-Welding of Copper

    DEFF Research Database (Denmark)

    Nielsen, Jakob Skov; Olsen, Flemming Ove; Bagger, Claus

    2005-01-01

    CO2-laser welding of copper is known to be difficult due to the high heat conductivity of the material and the high reflectivity of copper at the wavelength of the CO2-laser light. THis paper presents a study of laser welding of copper, applying laser hybrid welding. Welding was performed as a hy...

  20. Peculiarities of single track formation from TI6AL4V alloy at different laser power densities by selective laser melting

    Directory of Open Access Journals (Sweden)

    Yadroitsava, I.

    2015-11-01

    Full Text Available This paper describes the geometrical characteristics of single tracks manufactured by selective laser melting (SLM at different laser powers (20-170 W and scanning speeds (0.1-2.0 m/s. Simulation of temperature distribution during processing is carried out. A conclusion about the optimal process parameters and peculiarities of selective laser melting of Ti6Al4V alloy at low and high laser powers and scanning speeds is reached. The analysis of temperature fields creates opportunities to build parts with the desired properties by using SLM.

  1. Syntheses, crystal structure, and electronic properties of the five ABaMQ{sub 4} compounds RbBaPS{sub 4}, CsBaPS{sub 4}, CsBaVS{sub 4}, RbBaVSe{sub 4}, and CsBaVSe{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Mesbah, Adel [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113 (United States); ICSM, UMR 5257 CEA / CNRS / UM / ENSCM, Site de Marcoule-Bâtiment 426, BP 17171, 30207 Bagnols-sur-Cèze Cedex (France); Prakash, Jai [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113 (United States); Rocca, Dario; Lebègue, Sébastien [Laboratoire de Cristallographie, Résonance Magnétique, et Modélisations CRM2 (UMR UHP-CNRS 7036), Faculté des Sciences et Techniques, Université de Lorraine, BP 70239, Boulevard des Aiguillettes, 54506 Vandoeuvre-lès-Nancy Cedex (France); Beard, Jessica C.; Lewis, Benjamin A. [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113 (United States); Ibers, James A., E-mail: ibers@chem.northwestern.edu [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113 (United States)

    2016-01-15

    Five new compounds belonging to the ABaMQ{sub 4} family were synthesized by solid-state chemistry at 1123 K. The compounds RbBaPS{sub 4}, CsBaPS{sub 4}, CsBaVS{sub 4}, RbBaVSe{sub 4}, and CsBaVSe{sub 4} are isostructural and have the TlEuPS{sub 4} structure type. They crystallize in space group D{sup 16}{sub 2h} – Pnma of the orthorhombic system. Their structure consists isolated MQ{sub 4} tetrahedra separated by A and Ba atoms to form a salt-like structure. Density Functional Theory (DFT) calculations of the electronic structures with the use of the HSE functional suggest that the compounds are semiconductors with calculated band gaps of 3.3 eV (RbBaPS{sub 4}), 3.4 eV (CsBaPS{sub 4}), 2.3 eV (CsBaVS{sub 4}), and 1.6 eV (RbBaVSe{sub 4}). - Graphical abstract: General view of the ABaMQ{sub 4} structure down the a axis. - Highlights: • Five new ABaMQ{sub 4} compounds were synthesized by solid-state chemistry at 1123 K. • RbBaPS{sub 4}, CsBaPS{sub 4}, CsBaVS{sub 4}, RbBaVSe{sub 4}, and CsBaVSe{sub 4} have the TlEuPS{sub 4} structure type. • The compounds are semiconductors with calculated band gaps ranging from 1.6 to 3.4 eV.

  2. Corrosion Properties of Laser Welded Stainless Steel

    DEFF Research Database (Denmark)

    Weldingh, Jakob; Olsen, Flemmming Ove

    1997-01-01

    In this paper the corrosion properties of laser welded AISI 316L stainless steel are examined. A number of different welds has been performed to test the influence of the weld parameters of the resulting corrosion properties. It has been chosen to use the potential independent critical pitting...... temperature (CPT) test as corrosion test. The following welding parameters are varied: Welding speed, lsser power, focus point position and laser operation mode (CW or pulsed)....

  3. Laser welding of tailored blanks

    Directory of Open Access Journals (Sweden)

    Peças, P.

    1998-04-01

    Full Text Available Laser welding has an incrising role in the automotive industry, namely on the sub-assemblies manufacturing. Several sheet-shape parts are laser welded, on a dissimilar combination of thicknesses and materials, and are afterwards formed (stamped being transformed in a vehicle body component. In this paper low carbon CO2 laser welding, on the thicknesses of 1,25 and 0,75 mm, formability investigation is described. There will be a description of how the laser welded blanks behave in different forming tests, and the influence of misalignment and undercut on the formibility. The quality is evaluated by measuring the limit strain and limit effective strain for the laser welded sheets and the base material, which will be presented in a forming limit diagram.

    A soldadura laser assume um papel cada vez mais importante na indústria automóvel, principalmente para a fabricação de sub-conjuntos constituídos por varias partes de chapa de diferentes espessuras (e diferentes materiais, que depois de estampados constituem um componente para integrar num veículo. Descreve-se neste artigo o trabalho de investigação de enformabilidade de chapa de ac.o de baixo carbono soldada por laser de CO2, nas espessuras de 1,25 e 0,75 mm. Apresenta-se uma descrição do comportamento das chapas soldadas por laser em diferentes testes de enformação, e a influência dos defeitos das soldaduras (desalinhamento e queda do banho-undercut no comportamento à enformação. A qualidade é avaliada pela medição da extensão limite e da extensão limite efectiva no material base e no material soldado, que serão representadas num diagrama de limite de enformabilidade.

  4. Method for laser spot welding monitoring

    Science.gov (United States)

    Manassero, Giorgio

    1994-09-01

    As more powerful solid state laser sources appear on the market, new applications become technically possible and important from the economical point of view. For every process a preliminary optimization phase is necessary. The main parameters, used for a welding application by a high power Nd-YAG laser, are: pulse energy, pulse width, repetition rate and process duration or speed. In this paper an experimental methodology, for the development of an electrooptical laser spot welding monitoring system, is presented. The electromagnetic emission from the molten pool was observed and measured with appropriate sensors. The statistical method `Parameter Design' was used to obtain an accurate analysis of the process parameter that influence process results. A laser station with a solid state laser coupled to an optical fiber (1 mm in diameter) was utilized for the welding tests. The main material used for the experimental plan was zinc coated steel sheet 0.8 mm thick. This material and the related spot welding technique are extensively used in the automotive industry, therefore, the introduction of laser technology in production line will improve the quality of the final product. A correlation, between sensor signals and `through or not through' welds, was assessed. The investigation has furthermore shown the necessity, for the modern laser production systems, to use multisensor heads for process monitoring or control with more advanced signal elaboration procedures.

  5. Computerized simulation of YAG pulse laser welding of titanium alloy (TA6V): experimental characterization and modelling of the thermomechanical aspects of this process; Simulation numerique du soudage du TA6V par laser YAG impulsionnel: caracterisation experimentale et modelisation des aspects thermomecanique associees a ce procede

    Energy Technology Data Exchange (ETDEWEB)

    Robert, Y

    2007-09-15

    This work is a part of study which goal is to realize a computer modelling of the thermomechanical phenomena occurring during the YAG pulse laser welding of titanium alloy (TA6V). The filet welding has different heterogeneities (microstructural and mechanical). In fact, the temperature causes microstructural changes (phase transformations, precipitations) and modifies the mechanical properties. Thermomechanical modelling has thus to be established for the welding of TA6V. (author)

  6. Thermal and molecular investigation of laser tissue welding

    Energy Technology Data Exchange (ETDEWEB)

    Small, W., IV

    1998-06-01

    Despite the growing number of successful animal and human trials, the exact mechanisms of laser tissue welding remain unknown. Furthermore, the effects of laser heating on tissue on the molecular scale are not fully understood. To address these issues, a multi-front attack oil both extrinsic (solder/patch mediated) and intrinsic (laser only) tissue welding was launched using two-color infrared thermometry, computer modeling, weld strength assessment, biochemical assays, and vibrational spectroscopy. The coupling of experimentally measured surface temperatures with the predictive numerical simulations provided insight into the sub-surface dynamics of the laser tissue welding process. Quantification of the acute strength of the welds following the welding procedure enabled comparison among trials during an experiment, with previous experiments, and with other studies in the literature. The acute weld integrity also provided an indication of tile probability of long-term success. Molecular effects induced In the tissue by laser irradiation were investigated by measuring tile concentrations of specific collagen covalent crosslinks and characterizing the Fourier-Transform infrared (FTIR) spectra before and after the laser exposure.

  7. Diffractive beam shaping for enhanced laser polymer welding

    Science.gov (United States)

    Rauschenberger, J.; Vogler, D.; Raab, C.; Gubler, U.

    2015-03-01

    Laser welding of polymers increasingly finds application in a large number of industries such as medical technology, automotive, consumer electronics, textiles or packaging. More and more, it replaces other welding technologies for polymers, e. g. hot-plate, vibration or ultrasonic welding. At the same rate, demands on the quality of the weld, the flexibility of the production system and on processing speed have increased. Traditionally, diode lasers were employed for plastic welding with flat-top beam profiles. With the advent of fiber lasers with excellent beam quality, the possibility to modify and optimize the beam profile by beam-shaping elements has opened. Diffractive optical elements (DOE) can play a crucial role in optimizing the laser intensity profile towards the optimal M-shape beam for enhanced weld seam quality. We present results on significantly improved weld seam width constancy and enlarged process windows compared to Gaussian or flat-top beam profiles. Configurations in which the laser beam diameter and shape can be adapted and optimized without changing or aligning the laser, fiber-optic cable or optical head are shown.

  8. Hydrogen isotopes mobility and trapping in V-Cr-Ti alloys

    International Nuclear Information System (INIS)

    Budylkin, N.; Voloschin, L.; Mironova, E.; Riazantseva, N.; Tebus, V.

    1996-01-01

    In the last years the V-Ti-Cr alloys were considered as candidate materials for different structures of fusion reactors (blanket, first wall, divertor and so on) due to their advantages over other structure materials. Mobility and trapping parameters of hydrogen are essential characteristics for an assessment of using the V-Ti-Cr alloys in FR. In this paper: hydrogen problems for V-Ti-Cr alloys are formulated; V-H system data base is analyzed; study results of the hydrogen mobility and trapping in V-4Ti-4Cr and V-10Ti-5Cr alloys are given; the classification of V-alloys as radioactive waste according to the Russian Federation waste management rules is developed taking into account the residual amount of tritium ('inventory'). (orig.)

  9. Heat treatment of Ti6Al4V produced by Selective Laser Melting: Microstructure and mechanical properties

    International Nuclear Information System (INIS)

    Vrancken, Bey; Thijs, Lore; Kruth, Jean-Pierre; Van Humbeeck, Jan

    2012-01-01

    Highlights: ► Responses of SLM-produced and wrought Ti6Al4V to heat treatment are compared. ► Temperature is found to be the controlling parameter for treatments in the α + β range. ► Ductility could be improved by a factor of 85%, from 7.27% to 13.59%. ► An optimal heat treatment for SLM produced Ti6Al4V is proposed. - Abstract: The present work shows that optimization of mechanical properties via heat treatment of parts produced by Selective Laser Melting (SLM) is profoundly different compared to conventionally processed Ti6Al4V. In order to obtain optimal mechanical properties, specific treatments are necessary due to the specific microstructure resulting from the SLM process. SLM is an additive manufacturing technique through which components are built by selectively melting powder layers with a focused laser beam. The process is characterized by short laser-powder interaction times and localized high heat input, which leads to steep thermal gradients, rapid solidification and fast cooling. In this research, the effect of several heat treatments on the microstructure and mechanical properties of Ti6Al4V processed by SLM is studied. A comparison is made with the effect of these treatments on hot forged and subsequently mill annealed Ti6Al4V with an original equiaxed microstructure. For SLM produced parts, the original martensite α′ phase is converted to a lamellar mixture of α and β for heat treating temperatures below the β-transus (995 °C), but features of the original microstructure are maintained. Treated above the β-transus, extensive grain growth occurs and large β grains are formed which transform to lamellar α + β upon cooling. Post treating at 850 °C for 2 h, followed by furnace cooling increased the ductility of SLM parts to 12.84 ± 1.36%, compared to 7.36 ± 1.32% for as-built parts.

  10. Manipulation of the osteoblast response to a Ti 6Al 4V titanium alloy using a high power diode laser

    Science.gov (United States)

    Hao, L.; Lawrence, J.; Li, L.

    2005-07-01

    To improve the bone integration of titanium-based implants a high power diode laser (HPDL) was used to modify the material for improved osteoblast cell response. The surface properties of un-treated and HPDL treated samples were characterized. Contact angles for the un-treated and the HPDL modified titanium alloy (Ti-6Al-4V) were determined with selected biological liquids by the sessile drop technique. The analysis revealed that the wettability of the Ti-6Al-4V improved after HPDL laser treatment, indicating that better interaction with the biological liquids occurred. Moreover, an in vitro human fetal osteoblast cells (hFOB 1.19) evaluation revealed a more favourable cell response on the HPDL laser treated Ti-6Al-4V alloy than on either un-treated sample or a mechanically roughened sample. It was consequently determined that the HPDL provides more a controllable and effective technique to improve the biocompatibility of bio-metals.

  11. Fundamental Laser Welding Process Investigations

    DEFF Research Database (Denmark)

    Bagger, Claus; Olsen, Flemming Ove

    1998-01-01

    In a number of systematic laboratory investigations the fundamental behavior of the laser welding process was analyzed by the use of normal video (30 Hz), high speed video (100 and 400 Hz) and photo diodes. Sensors were positioned to monitor the welding process from both the top side and the rear...... side of the specimen.Special attention has been given to the dynamic nature of the laser welding process, especially during unstable welding conditions. In one series of experiments, the stability of the process has been varied by changing the gap distance in lap welding. In another series...... video pictures (400 Hz), a clear impact on the seam characteristics has been identified when a hump occurs.Finally, a clear correlation between the position of the focus point, the resultant process type and the corresponding signal intensity and signal variation has been found for sheets welded...

  12. Influence of shielding gas pressure on welding characteristics in CO2 laser-MIG hybrid welding process

    Science.gov (United States)

    Chen, Yanbin; Lei, Zhenglong; Li, Liqun; Wu, Lin

    2006-01-01

    The droplet transfer behavior and weld characteristics have been investigated under different pressures of shielding gas in CO2 laser and metal inert/active gas (laser-MIG) hybrid welding process. The experimental results indicate that the inherent droplet transfer frequency and stable welding range of conventional MIG arc are changed due to the interaction between CO2 laser beam and MIG arc in laser-MIG hybrid welding process, and the shielding gas pressure has a crucial effect on welding characteristics. When the pressure of shielding gas is low in comparison with MIG welding, the frequency of droplet transfer decreases, and the droplet transfer becomes unstable in laser-MIG hybrid welding. So the penetration depth decreases, which shows the characteristic of unstable hybrid welding. However, when the pressure of shielding gas increases to a critical value, the hybrid welding characteristic is changed from unstable hybrid welding to stable hybrid welding, and the frequency of droplet transfer and the penetration depth increase significantly.

  13. French investigation of a new V-4Cr-4Ti grade: CEA-J57 - Fabrication and microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Duquesnes, Vincent; Guilbert, Thomas [CEA Saclay, DEN/DMN/SRMA/LA2M, 91191 Gif Sur Yvette (France); Le Flem, Marion, E-mail: marion.leflem@cea.fr [CEA Saclay, DEN/DMN/SRMA/LA2M, 91191 Gif Sur Yvette (France)

    2012-07-15

    In the scope of the development of structural materials for application in future fast neutron fission reactors, a V-4Cr-4Ti alloy, which is the reference alloy for the first wall/blanket in lithium fusion reactor, was fabricated. After vacuum arc melting of the starting ingot of 30 kg, 7 mm-thick plates were processed by forging and cold rolling down to 54% thickness reduction with intermediate heat treatment at 1050 Degree-Sign C. The pollution by interstitial impurities such as O, N and C was well controlled and was quite comparable to previous grades by US and Japan - O: 290 mass ppm, C: 70 mass ppm, N: 110 mass ppm. An additional cold-rolling was achieved on a small specimen to get a reduction in thickness of 87%. The recrystallization was investigated through heat treatments between 600 Degree-Sign C and 1200 Degree-Sign C. Hardness measurement on annealed samples suggested the recrystallization to occur around 800 Degree-Sign C for 54% thickness reduction and at a lower temperature for 87% thickness reduction. The minimum hardness was obtained after annealing at 950-1000 Degree-Sign C, the microstructure being fully recrystallized and the hardness isotropic. Above this temperature, hardness increase was significant. Large Ti-rich precipitates (500 nm) formed during forging and oriented along the rolling direction were easily observed but, on the contrary to previous studies, no small Ti-(O,C) precipitates could be detected.

  14. Effect of laser welding on the titanium ceramic tensile bond strength

    Directory of Open Access Journals (Sweden)

    Rodrigo Galo

    2011-08-01

    Full Text Available Titanium reacts strongly with elements, mainly oxygen at high temperature. The high temperature of titanium laser welding modifies the surface, and may interfere on the metal-ceramic tensile bond strength. OBJECTIVE: The influence of laser welding on the titanium-ceramic bonding has not yet been established. The purpose of this in vitro study was to analyze the influence of laser welding applied to commercially pure titanium (CpTi substructure on the bond strength of commercial ceramic. The influence of airborne particle abrasion (Al2O3 conditions was also studied. MATERIAL AND METHODS: Forty CpTi cylindrical rods (3 mm x 60 mm were cast and divided into 2 groups: with laser welding (L and without laser welding (WL. Each group was divided in 4 subgroups, according to the size of the particles used in airborne particle abrasion: A - Al2O3 (250 µm; B - Al2O3 (180 µm; C - Al2O3 (110 µm; D - Al2O3 (50 µm. Ceramic rings were fused around the CpTi rods. Specimens were invested and their tensile strength was measured at fracture with a universal testing machine at a crosshead speed of 2.0 mm/min and 200 kgf load cell. Statistical analysis was carried out with analysis of variance and compared using the independent t test (p<0.05. RESULTS: Significant differences were found among all subgroups (p<0.05. The highest and the lowest bond strength means were recorded in subgroups WLC (52.62 MPa and LD (24.02 MPa, respectively. CONCLUSION: Airborne particle abrasion yielded significantly lower bond strength as the Al2O3 particle size decreased. Mechanical retention decreased in the laser-welded specimens, i.e. the metal-ceramic tensile bond strength was lower.

  15. Assisting Gas Optimization in CO2 Laser Welding

    DEFF Research Database (Denmark)

    Gong, Hui; Olsen, Flemming Ove

    1996-01-01

    High quality laser welding is achieved under the condition of optimizing all process parameters. Assisting gas plays an important role for sound welds. In the conventional welding process assisting gas is used as a shielding gas to prevent that the weld seam oxidates. In the laser welding process...... assisting gas is also needed to control the laser induced plasma.Assisting gas is one of the most important parameters in the laser welding process. It is responsible for obtaining a quality weld which is characterized by deep penetration, no interior imperfections, i.e. porosity, no crack, homogeneous seam...... surface, etc. In this work a specially designed flexible off-axis nozzle capable of adjusting the angle of the nozzle, the diameter of the nozzle, and the distance between the nozzle end and the welding zone is tested. In addition to the nozzle parameters three gases, Nitrogen, Argon, and Helium...

  16. 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.

  17. Neutron diffraction studies of the Na-ion battery electrode materials NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Yahia, H. Ben [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 5825 Doha (Qatar); Essehli, R., E-mail: ressehli@qf.org.qa [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 5825 Doha (Qatar); Avdeev, M. [Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights NSW 2234 (Australia); Park, J-B.; Sun, Y-K. [Department of Energy Engineering Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Al-Maadeed, M.A. [Center for Advanced Materials (CAM), Qatar University, 2713 Doha (Qatar); Belharouak, I., E-mail: ibelharouak@qf.org.qa [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 5825 Doha (Qatar)

    2016-06-15

    The new compounds NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} were synthesized by sol-gel method and their crystal structures were determined by using neutron powder diffraction data. These compounds were characterized by galvanometric cycling and cyclic voltammetry. NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} crystallize with a stuffed α-CrPO{sub 4}-type structure. The structure consists of a 3D-framework made of octahedra and tetrahedra that are sharing corners and/or edges generating channels along [100] and [010], in which the sodium atoms are located. Of significance, in the structures of NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} a statistical disorder Ni{sup 2+}/Cr{sup 3+} was observed on both the 8g and 4a atomic positions, whereas in NaCoCr{sub 2}(PO{sub 4}){sub 3} the statistical disorder Co{sup 2+}/Cr{sup 3+} was only observed on the 8g atomic position. When tested as negative electrode materials, NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} delivered specific capacities of 352, 385, and 368 mA h g{sup −1}, respectively, which attests to the electrochemical activity of sodium in these compounds. - Highlights: • NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} were synthesized by sol-gel method. • The crystal structures were determined by using neutron powder diffraction data. • The three compounds crystallize with a stuffed α-CrPO{sub 4}-type structure. • The three compounds were tested as anodes in sodium-ion batteries. • Relatively high specific capacities were obtained for these compounds.

  18. Laser based spot weld characterization

    Science.gov (United States)

    Jonietz, Florian; Myrach, Philipp; Rethmeier, Michael; Suwala, Hubert; Ziegler, Mathias

    2016-02-01

    Spot welding is one of the most important joining technologies, especially in the automotive industry. Hitherto, the quality of spot welded joints is tested mainly by random destructive tests. A nondestructive testing technique offers the benefit of cost reduction of the testing procedure and optimization of the fabrication process, because every joint could be examined. This would lead to a reduced number of spot welded joints, as redundancies could be avoided. In the procedure described here, the spot welded joint between two zinc-coated steel sheets (HX340LAD+Z100MB or HC340LA+ZE 50/50) is heated optically on one side. Laser radiation and flash light are used as heat sources. The melted zone, the so called "weld nugget" provides the mechanical stability of the connection, but also constitutes a thermal bridge between the sheets. Due to the better thermal contact, the spot welded joint reveals a thermal behavior different from the surrounding material, where the heat transfer between the two sheets is much lower. The difference in the transient thermal behavior is measured with time resolved thermography. Hence, the size of the thermal contact between the two sheets is determined, which is directly correlated to the size of the weld nugget, indicating the quality of the spot weld. The method performs well in transmission with laser radiation and flash light. With laser radiation, it works even in reflection geometry, thus offering the possibility of testing with just one-sided accessibility. By using heating with collimated laser radiation, not only contact-free, but also remote testing is feasible. A further convenience compared to similar thermographic approaches is the applicability on bare steel sheets without any optical coating for emissivity correction. For this purpose, a proper way of emissivity correction was established.

  19. Functionally graded Ti6Al4V and Inconel 625 by Laser Metal Deposition

    Science.gov (United States)

    Pulugurtha, Syamala R.

    The objective of the current work was to fabricate a crack-free functionally graded Ti6Al4V and Inconel 625 thin wall structure by Laser Metal Deposition (LMD). One potential application for the current material system is the ability to fabricate a functionally graded alloy that can be used in a space heat exchanger. The two alloys, Inconel 625 and Ti6Al4V are currently used for aerospace applications. They were chosen as candidates for grading because functionally grading those combines the properties of high strength/weight ratio of Ti6Al4V and high temperature oxidation resistance of Inconel 625 into one multifunctional material for the end application. However, there were challenges associated with the presence of Ni-Ti intermetallic phases (IMPs). The study focused on several critical areas such as (1) understanding microstructural evolution, (2) reducing macroscopic cracking, and (3) reducing mixing between graded layers. Finite element analysis (FEA) was performed to understand the effect of process conditions on multilayer claddings for simplified material systems such as SS316L and Inconel 625 where complex microstructures did not form. The thermo-mechanical models were developed using Abaqus(TM) (and some of them experimentally verified) to predict temperature-gradients; remelt layer depths and residual stresses. Microstructure evolution along the functionally graded Ti6Al4V and Inconel 625 was studied under different processing and grading conditions. Thermodynamic modeling using Factsage (v 6.1) was used to construct phase diagrams and predict the possible equilibrium major/minor phases (verified experimentally by XRD) that may be present along the functionally graded Ti6Al4V and Inconel 625 thin wall structures.

  20. Laser-GMA Hybrid Pipe Welding System

    Science.gov (United States)

    2007-11-01

    Investigation of varying laser power. The welded pipe is shown, with close -ups of the rootside reinforcement and macro sections...68 Figure 44. Investigation of varying laser stand-off. The welded pipe is shown, along with close -ups of backside...conventional beveled joints. With appropriate joint configuration and preparation, deep keyhole penetration provided by the laser and additional filler

  1. Using Taguchi method to optimize welding pool of dissimilar laser welded components

    OpenAIRE

    Anawa, E.; Olabi, Abdul-Ghani

    2008-01-01

    In the present work CO2 continuous laser welding process was successfully applied and optimized for joining a dissimilar AISI 316 stainless steel and AISI 1009 low carbon steel plates. Laser power, welding speed, and defocusing distance combinations were carefully selected with the objective of producing welded joint with complete penetration, minimum fusion zone size and acceptable welding profile. Fusion zone area and shape of dissimilar austenitic stainless steel with ferritic low carbon s...

  2. LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Spectroscopy of V4+ and V3+ ions in a forsterite crystal

    Science.gov (United States)

    Veremeichik, T. F.; Gaister, A. V.; Zharikov, Evgeny V.; Protopopov, V. N.; Smirnov, Valerii A.; Subbotin, Kirill A.

    2000-05-01

    The absorption spectra of impurity vanadium ions in forsterite crystals are studied in the wavelength range from 600 to 2000 nm. It is found that the V4+ ion in the tetrahedral coordination in crystals grown by the Czochralski technique exhibits strong absorption in the range from 600 to 1200 nm. The intense electron-vibrational progressions in the absorption spectra of impurity d-ions in crystals were observed for the first time at temperatures 300 and 77 K. In the authors' opinion, these progressions appear due to the formation of the oxovanadate complex and distortions of the structural tetrahedron. The forsterite crystal doped with V4+ ions has a very high absorption cross section (up to 2.1×10-18 cm2) and a continuous broad absorption band, which makes this crystal promising as a passive laser switch in the range between 600 and 1200 nm. At the same time, the V4+ ions in the forsterite crystal do not emit luminescence because of a high probability of the nonradiative relaxation of their excited state. It is shown that luminescence of a V:Mg2SiO4 crystal is related to the tetrahedral V3+ ion.

  3. Research on electron beam welding technology of steel HR-4

    International Nuclear Information System (INIS)

    Guo Peng; Guan Kai

    2001-01-01

    The electron beam weldability of HR- 4 steels (J75 and J90) is studied and the welding parameters needed for design and usage are presented. The assessment on the effect of mechanical properties by different processing order of welding and heat-treatment is made

  4. The effect of CO2 laser beam welded AISI 316L austenitic stainless steel on the viability of fibroblast cells, in vitro.

    Science.gov (United States)

    Köse, Ceyhun; Kaçar, Ramazan; Zorba, Aslı Pınar; Bağırova, Melahat; Allahverdiyev, Adil M

    2016-03-01

    samples which were kept in the cell culture medium for 18 months, it was determined that the Fe, Ni and Cr ion concentration released to the cell culture medium from the laser welded test sample was less than that of the main material. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. TL dosimetric characterization of gamma irradiated SrSO{sub 4}:Eu phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Jayasudha, S., E-mail: jsnair.india@gmail.com [Mahatma Gandhi College, Kesavadasapuram, Pattom Palace P.O., Thiruvananthapuram 695004 (India); Madhukumar, K.; Nair, C.M.K.; Nair, Resmi G. [Mahatma Gandhi College, Kesavadasapuram, Pattom Palace P.O., Thiruvananthapuram 695004 (India); Rajesh, S. [Department of Materials & Ceramic Engineering, University of Aveiro, Aveiro 3810-193 (Portugal); Elias, T.S. [State Institute of Cancer Research, Medical College P.O., Thiruvananthapuram 695011 (India); Anandakumar, V.M. [Mahatma Gandhi College, Kesavadasapuram, Pattom Palace P.O., Thiruvananthapuram 695004 (India); State Institute of Cancer Research, Medical College P.O., Thiruvananthapuram 695011 (India); Department of Materials & Ceramic Engineering, University of Aveiro, Aveiro 3810-193 (Portugal); Gopakumar, N. [Mahatma Gandhi College, Kesavadasapuram, Pattom Palace P.O., Thiruvananthapuram 695004 (India)

    2017-03-15

    Thermoluminescence (TL) characteristics of SrSO{sub 4}:Eu nanostructured phosphor under gamma excitation has been studied and their suitability for environmental radiation dosimetry applications is discussed. The dopant level is tuned for optimum TL response. The effect of radiation dose and heating rate were investigated. The phosphor preserves linearity in the low dose region, 0.1 Gy to 20 Gy. PL studies of irradiated and un-irradiated phosphors reveal that the dopant Eu exists in divalent state and are the luminescence emission centres in the material. The fading properties of SrSO{sub 4}:Eu phosphor are observed to be better than that of the commercial dosimeters TLD-200 and TLD-400. The kinetic parameters are calculated using Chen's method and initial rise method and verified by Computerized Glow curve Deconvolution (CGCD). The sensitivity of the synthesized phosphor is found to be very high when compared with that of the commercial standard dosimeter CaSO{sub 4}:Dy. The phosphor is found to be stable for short term radiation monitoring.

  6. Neutron irradiation effect on the strength of jointed Ti-6Al-4V alloy

    International Nuclear Information System (INIS)

    Ishiyama, Shintaro; Miya, Naoyuki

    2002-01-01

    In order to investigate applicability of Ti alloy to large scaled structural material for fusion reactors, irradiation effect on the mechanical properties of Ti-6Al-4V alloy and its TIG welded material was investigated after neutron irradiation (temperature: 746-788K, fluence: 2.8 x 10 23 n/m 2 (>0.18 MeV). The following results were obtained. (1) Irradiated Ti alloy shows about 20-30% increase of its tensile strength and large degradation of fracture elongation, comparing with those of unirradiated Ti alloy. (2) TIG welded material behaves as Ti alloy in its tensile test, however, shows 30% increase of area reduction in 373-473K, whereas 1/2 degradation of area reduction over 600K. (3) Irradiated TIG welded material behaves heavier embrittlement than that of irradiated Ti alloy. (4) Charpy impact properties of un- and irradiated Ti alloys shift to ductile from brittle fracture and transition temperature shift, ΔT was estimated as about 100K. (5) Remarkable increase of hardness was found, especially in HAZ of TIG welded material after irradiation. (author)

  7. 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.

  8. Design Optimization and Fatigue Analysis of Laser Stake Welded Connections

    Science.gov (United States)

    2008-06-01

    is ultimately envisioned that laser welding will be as common in the shipyard as other processes such -- as MIG, TIG and SMAW. Laser stake- welding of...input from conventional welding techniques can be detrimental to the polymer matrix composite material. In comparison, the laser welding process allows...more discrete frequencies. In the laser welding process , the photons are targeted on the work piece surface which needs to be welded . Highly

  9. Thermal and molecular investigation of laser tissue welding

    Science.gov (United States)

    Small, Ward, IV

    Despite the growing number of successful animal and human trials, the exact mechanisms of laser tissue welding remain unknown. Furthermore, the effects of laser heating on tissue on the molecular scale are not fully understood. To address these issues, a multi-front attack on both extrinsic (solder/patch mediated) and intrinsic (laser only) tissue welding was launched using two-color infrared thermometry, computer modeling, weld strength assessment, biochemical assays, and vibrational spectroscopy. The coupling of experimentally measured surface temperatures with the predictive numerical simulations provided insight into the sub surface dynamics of the laser tissue welding process. Quantification of the acute strength of the welds following the welding procedure enabled comparison among trials during an experiment, with previous experiments, and with other studies in the literature. The acute weld integrity also provided an indication of the probability of long-term success. Molecular effects induced in the tissue by laser irradiation were investigated by measuring the concentrations of specific collagen covalent crosslinks and measuring the infrared absorption spectra before and after the laser exposure. This investigation yielded results pertaining to both the methods and mechanisms of laser tissue welding. The combination of two-color infrared thermometry to obtain accurate surface temperatures free from emissivity bias and computer modeling illustrated the importance of including evaporation in the simulations, which effectively serves as an inherent cooling mechanism during laser irradiation. Moreover, the hydration state predicted by the model was useful in assessing the role of electrostatic versus covalent bonding in the fusion. These tools also helped elicit differences between dye- enhanced liquid solders and solid-matrix patches in laser-assisted tissue welding, demonstrating the significance of repeatable energy delivery. Surprisingly, covalent bonds

  10. Microstructural characterization of weld joints of 9Cr reduced activation ferritic martensitic steel fabricated by different joining methods

    Energy Technology Data Exchange (ETDEWEB)

    Thomas Paul, V.; Saroja, S.; Albert, S.K.; Jayakumar, T.; Rajendra Kumar, E., E-mail: vtp@igcar.gov.in

    2014-10-15

    This paper presents a detailed electron microscopy study on the microstructure of various regions of weldment fabricated by three welding methods namely tungsten inert gas welding, electron beam welding and laser beam welding in an indigenously developed 9Cr reduced activation ferritic/martensitic steel. Electron back scatter diffraction studies showed a random micro-texture in all the three welds. Microstructural changes during thermal exposures were studied and corroborated with hardness and optimized conditions for the post weld heat treatment have been identified for this steel. Hollomon–Jaffe parameter has been used to estimate the extent of tempering. The activation energy for the tempering process has been evaluated and found to be corresponding to interstitial diffusion of carbon in ferrite matrix. The type and microchemistry of secondary phases in different regions of the weldment have been identified by analytical transmission electron microscopy. - Highlights: • Comparison of microstructural parameters in TIG, electron beam and laser welds of RAFM steel • EBSD studies to illustrate the absence of preferred orientation and identification of prior austenite grain size using phase identification map • Optimization of PWHT conditions for indigenous RAFM steel • Study of kinetics of tempering and estimation of apparent activation energy of the process.

  11. Susceptibility of 2 1/4 Cr-1Mo steel to liquid metal induced embrittlement by lithium-lead solutions

    International Nuclear Information System (INIS)

    Eberhard, B.A.; Edwards, G.R.

    1984-08-01

    An investigation has been conducted on the liquid metal induced embrittlement susceptibility of 2 1/4Cr-1Mo steel exposed to lithium and 1a/o lead-lithium at temperatures between 190 0 C and 525 0 C. This research was part of an ongoing effort to evaluate the compatibility of liquid lithium solutions with potential fusion reactor containment materials. Of particular interest was the microstructure present in a weld heat-affected zone, a microstructure known to be highly susceptible to corrosive attack by liquid lead-lithium solutions. Embrittlement susceptibility was determined by conducting tension tests on 2 1/4Cr-1Mo steel exposed to an inert environment as well as to a lead-lithium liquid and observing the change in tensile behavior. The 2 1/4Cr-1Mo steel was also given a base plate heat treatment to observe its embrittlement susceptibility to 1a/o lead-lithium. The base plate microstructure was severely embrittled at temperatures less than 500 0 C. Tempering the base plate was effective in restoring adequate ductility to the steel

  12. Repair by weld of steam and gas turbine rotors made of Cr-Mo-V steel; Reparacion por soldadura de rotores de turbinas de vapor y de gas fabricados con aceros al Cr-Mo-V

    Energy Technology Data Exchange (ETDEWEB)

    Mazur C, Zdzislaw; Hernandez R, Alejando [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico); Orozco S, Julian; Banuelos P, Jose E. [Comision Federal de Electricidad (Mexico)

    2003-07-01

    In this article an analysis is presented of the typical damages in steam and gas turbine rotors made of Cr-Mo-V low alloy steels. An analysis of the weldability of the Cr-Mo-V steel is carried out and a classification of the possible types of repairs of the turbine rotors is presented, starting off from the causes and ways of presentation of the faults/deterioration of the rotor materials during the operation of the turbine. With base on the damages detected in the rotor of a gas turbine of 20.65 MW, the development of the repairing technology carried out by weld in site is presented. After the repair process, the rotor was put again in operation. [Spanish] En este articulo se presenta un analisis de los danos tipicos en rotores de turbinas de vapor y de gas fabricados con aceros de baja aleacion al Cr-Mo-V. Se lleva a cabo un analisis de la soldabilidad de los aceros al Cr-Mo-V y se presenta una clasificacion de los posibles tipos de reparaciones de los rotores de turbinas, partiendo de las causas y modos de presentacion de las fallas/deterioro del material de los rotores durante la operacion de la turbina. Con base en los danos detectados en el rotor de una turbina de gas de 20.65 MW, se presenta el desarrollo de la tecnologia de reparacion por soldadura llevada a cabo en sitio. Despues del proceso de reparacion, el rotor fue puesto nuevamente en servicio.

  13. Thermodynamic Study of Tl6SBr4 Compound and Some Regularities in Thermodynamic Properties of Thallium Chalcohalides

    Directory of Open Access Journals (Sweden)

    Dunya Mahammad Babanly

    2017-01-01

    Full Text Available The solid-phase diagram of the Tl-TlBr-S system was clarified and the fundamental thermodynamic properties of Tl6SBr4 compound were studied on the basis of electromotive force (EMF measurements of concentration cells relative to a thallium electrode. The EMF results were used to calculate the relative partial thermodynamic functions of thallium in alloys and the standard integral thermodynamic functions (-ΔfG0, -ΔfH0, and S0298 of Tl6SBr4 compound. All data regarding thermodynamic properties of thallium chalcogen-halides are generalized and comparatively analyzed. Consequently, certain regularities between thermodynamic functions of thallium chalcogen-halides and their binary constituents as well as degree of ionization (DI of chemical bonding were revealed.

  14. TL and OSL properties of Mn2+-doped MgGa2O4 phosphor

    Science.gov (United States)

    Luchechko, A.; Zhydachevskyy, Ya; Maraba, D.; Bulur, E.; Ubizskii, S.; Kravets, O.

    2018-04-01

    The oxide MgGa2O4 spinel ceramics doped with Mn2+ ions was synthesized by a solid-state reaction at 1200 °C in air. The activator concentration was equal 0.05 mol% of MnO. Phase purity of the synthesized samples was analyzed by X-ray diffraction technique. This spinel ceramics show efficient green emission in the range from 470 to 550 nm with a maximum at about 505 nm under UV or X-ray excitations, which is due to Mn2+ ions. MgGa2O4: Mn2+ exhibits intense thermoluminescence (TL) and optically stimulated luminescence (OSL) after influence of ionizing radiation. Are complex nature of the TL glow curves is associated with a significant number of structural defects that are responsible for the formation of shallow and deep electron traps. In this work, time-resolved OSL characteristics of the samples exposed to beta particles are reported for the first time. A light from green LED was used for optical stimulation. Obtained TL and OSL results suggest MgGa2O4:Mn2+ as perspective material for further research and possible application in radiation dosimetry.

  15. Pre-Industry-Optimisation of the Laser Welding Process

    DEFF Research Database (Denmark)

    Gong, Hui

    This dissertation documents the investigations into on-line monitoring the CO2 laser welding process and optimising the process parameters for achieving high quality welds. The requirements for realisation of an on-line control system are, first of all, a clear understanding of the dynamic...... phenomena of the laser welding process including the behaviour of the keyhole and plume, and the correlation between the adjustable process parameters: laser power, welding speed, focal point position, gas parameters etc. and the characteristics describing the quality of the weld: seam depth and width......, porosity etc. Secondly, a reliable monitoring system for sensing the laser-induced plasma and plume emission and detecting weld defects and process parameter deviations from the optimum conditions. Finally, an efficient control system with a fast signal processor and a precise feed-back controller...

  16. Effects of Ar and He on Microstructures and Properties of Laser Welded 800MPa TRIP Steel

    Directory of Open Access Journals (Sweden)

    Wang Wen-Quan

    2018-01-01

    Full Text Available Fiber laser welding of cold rolled TRIP steel (transformation Induced Plasticity steel sheet with tensile strength of 820MPa and thickness of 1.4mm was carried out using shielding gases Ar and He, respectively. For the same laser power and welding speed, the effects of different shielding gases on penetration and bead section morphologies were investigated. The microstructures and properties of the TRIP steel joints were also studied. The investigation showed that higher penetration and lower porosity could be obtained under shielding gas He using the same laser power and welding speed. The microstructures of the TRIP joint mainly included martensite and retained austenite. But the joint microhardness and tensile strength were higher under the shielding gas He. The tensile strength of the welded joint perpendicular to the weld line was equal to that of the base metal. But the tensile strength of the joint parallel with the weld line was higher than that of the base metal. The plasticity and formability of the welded joint were impaired due to the formation of martensite in the weld metal.

  17. CO2 and diode laser welding of AZ31 magnesium alloy

    International Nuclear Information System (INIS)

    Zhu Jinhong; Li Lin; Liu Zhu

    2005-01-01

    Magnesium alloys are being increasingly used in automotive and aerospace structures. Laser welding is an important joining method in such applications. There are several kinds of industrial lasers available at present, including the conventional CO 2 and Nd:YAG lasers as well as recently available high power diode lasers. A 1.5 kW diode laser and a 2 kW CO 2 laser are used in the present study for the welding of AZ31 alloys. It is found that different welding modes exist, i.e., keyhole welding with the CO 2 laser and conduction welding with both the CO 2 and the diode lasers. This paper characterizes welds in both welding modes. The effect of beam spot size on the weld quality is analyzed. The laser processing parameters are optimized to obtain welds with minimum defects

  18. Assessment of Hot Crack Properties of Laser Welded Stainless Steel

    DEFF Research Database (Denmark)

    Juhl, Thomas Winther; Olsen, Flemming Ove

    2003-01-01

    Crack testing concerning small and fast solidifying laser welds in austenitic stainless steel has been studied. A set of methods has been applied to investigate alloy properties, including (1) Application of known information to predict solidification phases, (2) Weld metal solidification rate...... crack tests, the Weeter spot weld test has been chosen to form a basis for the development of a practicable method to select specific alloys for welding applications. A new test, the Groove weld test was developed, which has reduced the time consumption and lightened the analysis effort considerably...... measurements for prediction of phases, (3) Various crack tests to assess the crack susceptibility of alloys and (4) A combination of the above for selection of suitable, weldable alloys. The possibility of using such specific methods for alloys and applications has been investigated and recommendations...

  19. Laser desensitization of austenitic stainless steel weld AHZ. Desensibilizacion con Laser de la zona afectada por el calor (ZAC) en aceros inoxidables austeniticos

    Energy Technology Data Exchange (ETDEWEB)

    Lee, C.H.; Kim, K.C.; Chang, R.W. (Welding Research Center Research Institute of Industrial Science and Technology, Pohang (Korea, Republic of))

    1994-01-01

    This paper addressed the fundamental understanding of sensitization phenomena in the weld HAZ of austenitic stainless steel and a method of desensitization utilizing LASER, without degradation of other corrosion resistance (pitting resistance). Sensitization in the weld HAZ was due to a formation of CR depleted zone along grain boundaries and twin boundaries by precipitation of Cr[sub 2]3C[sub 6] which contains 70-80% Cr and a small amount of Fe having a cubic-cubic relationship with the austenite matrix. Common morphologies of carbides were found to be of bar and globular shapes. As the holding time increased, carbides with coarsened globular (iodomorph) and dendrite shapes were also found. However, there was no significant variation in the composition of carbides and width of the Cr depleted zone with morphology. Laser desensitization could be obtained with a proper choice of the beam power and travel speed under a constant beam size. As long as the beam density reached a critical amount, carbides and Cr depleted zone completed zone completely disappeared. The critical travel speed increased with higher beam power, but was constant regardless of the original degree of sensitization. Pitting resistance of the LASER desensitized base metal and HAZ appeared to be far superior to that found in the sensitized condition. The protection potential in the hysteresis loop test was very sensitive to the degree of sensitization, revealing that the protection potential was dependent upon the propagation of the pits through the Cr depleted grain boundaries. (Author) 10 refs.

  20. Laser welding of Ti-Ni type shape memory alloy

    International Nuclear Information System (INIS)

    Hirose, Akio; Araki, Takao; Uchihara, Masato; Honda, Keizoh; Kondoh, Mitsuaki.

    1990-01-01

    The present study was undertaken to apply the laser welding to the joining of a shape memory alloy. Butt welding of a Ti-Ni type shape memory alloy was performed using 10 kW CO 2 laser. The laser welded specimens showed successfully the shape memory effect and super elasticity. These properties were approximately identical with those of the base metal. The change in super elasticity of the welded specimen during tension cycling was investigated. Significant changes in stress-strain curves and residual strain were not observed in the laser welded specimen after the 50-time cyclic test. The weld metal exhibited the celler dendrite. It was revealed by electron diffraction analysis that the phase of the weld metal was the TiNi phase of B2 structure which is the same as the parent phase of base metal and oxide inclusions crystallized at the dendrite boundary. However, oxygen contamination in the weld metal by laser welding did not occur because there was almost no difference in oxygen content between the base metal and the weld metal. The transformation temperatures of the weld metal were almost the same as those of the base metal. From these results, laser welding is applicable to the joining of the Ti-Ni type shape memory alloy. As the application of laser welding to new shape memory devices, the multiplex shape memory device of welded Ti-50.5 at % Ni and Ti-51.0 at % Ni was produced. The device showed two-stage shape memory effects due to the difference in transformation temperature between the two shape memory alloys. (author)

  1. Spectroscopy of V4+ and V3+ ions in a forsterite crystal

    International Nuclear Information System (INIS)

    Veremeichik, T F; Gaister, A V; Subbotin, Kirill A; Zharikov, Evgeny V; Protopopov, V N; Smirnov, Valerii A

    2000-01-01

    The absorption spectra of impurity vanadium ions in forsterite crystals are studied in the wavelength range from 600 to 2000 nm. It is found that the V 4+ ion in the tetrahedral coordination in crystals grown by the Czochralski technique exhibits strong absorption in the range from 600 to 1200 nm. The intense electron-vibrational progressions in the absorption spectra of impurity d-ions in crystals were observed for the first time at temperatures 300 and 77 K. In the authors' opinion, these progressions appear due to the formation of the oxovanadate complex and distortions of the structural tetrahedron. The forsterite crystal doped with V 4+ ions has a very high absorption cross section (up to 2.1x10 -18 cm 2 ) and a continuous broad absorption band, which makes this crystal promising as a passive laser switch in the range between 600 and 1200 nm. At the same time, the V 4+ ions in the forsterite crystal do not emit luminescence because of a high probability of the nonradiative relaxation of their excited state. It is shown that luminescence of a V:Mg 2 SiO 4 crystal is related to the tetrahedral V 3+ ion. (laser applications and other topics in quantum electronics)

  2. Development and application of high-precision laser welding technology for manufacturing Ti alloy frames of glasses

    International Nuclear Information System (INIS)

    Kim, S. S.; Yang, M. S.; Kim, W. K.; Lee, D. Y.; Kim, J. M.; Leem, B. C.; Shin, J. S.; Lee, D. H.

    1999-12-01

    The research and development efforts of the high precision laser welding technology for manufacturing titanium alloy frames of glasses. For this purpose, laser welding device with the high beam quality is designed and fabricated, which consists of a optical fiber transmission part, a welding monitoring part and a welding controller. The welding nozzle and holding fixtures for manufacturing titanium and shape memory alloy frames of glasses. Titanium and shape memory alloy frames of glasses to be developed were experimentally manufactured by utilizing the laser welding using the optical fiber of GI 400 μm. As a result, the seam welding with the bead width of 0.3 mm or less and the weld penetration of 0.3-0.4mm could be accomplished. The fundamental technology was established through design of welding jigs with a variety of configurations and adequate welding conditions. Also, for the purpose to enable the companies participating in this project to commercialize the developed technology acceleratedly, a training program for the engineers belonging to such companies was conducted along with the technology transfer through joint experiments with the engineers. (author)

  3. Pulsed laser deposition of Tl-Ca-Ba-Cu-O films

    International Nuclear Information System (INIS)

    Ianno, N.J.; Liou, S.H.; Woollam, J.A.; Thompson, D.; Johs, B.

    1990-01-01

    Pulsed laser deposition is a technique commonly used to deposit high quality thin films of high temperature superconductors. This paper discusses the results obtained when this technique is applied to the deposition of Tl-Ca-Ba-Cu-O thin films using a frequency doubled Nd:YAG laser operating at 532 nm and an excimer laser operating at 248 nm. Films with onset temperatures of 125 K and zero resistance temperatures of 110 K deposited on (100) oriented MgO from a composite Tl2Ca2Ba2Cu3Ox target were obtained at both wavelengths upon appropriate post deposition annealing. Films deposited at 532 nm exhibit a rough surface, while those deposited at 248 nm are smooth and homogeneous. Upon annealing, films deposited at both wavelengths are single phase Tl2Ca2Ba2Cu3Ox. 12 refs

  4. Deformation behavior of laser welds in high temperature oxidation resistant Fe–Cr–Al alloys for fuel cladding applications

    Energy Technology Data Exchange (ETDEWEB)

    Field, Kevin G., E-mail: fieldkg@ornl.gov; Gussev, Maxim N., E-mail: gussevmn@ornl.gov; Yamamoto, Yukinori, E-mail: yamamotoy@ornl.gov; Snead, Lance L., E-mail: sneadll@ornl.gov

    2014-11-15

    Ferritic-structured Fe–Cr–Al alloys are being developed and show promise as oxidation resistant accident tolerant light water reactor fuel cladding. This study focuses on investigating the weldability and post-weld mechanical behavior of three model alloys in a range of Fe–(13–17.5)Cr–(3–4.4)Al (wt.%) with a minor addition of yttrium using modern laser-welding techniques. A detailed study on the mechanical performance of bead-on-plate welds using sub-sized, flat dog-bone tensile specimens and digital image correlation (DIC) has been carried out to determine the performance of welds as a function of alloy composition. Results indicated a reduction in the yield strength within the fusion zone compared to the base metal. Yield strength reduction was found to be primarily constrained to the fusion zone due to grain coarsening with a less severe reduction in the heat affected zone. For all proposed alloys, laser welding resulted in a defect free weld devoid of cracking or inclusions.

  5. Structure-property investigations on a laser beam welded dissimilar joint of aluminium AA6056 and titanium Ti6Al4V for aeronautical applications Part I: Local gradients in microstructure, hardness and strength

    Energy Technology Data Exchange (ETDEWEB)

    Horstmann, M.; Ventzke, V.; Petrovski, B.; Kocak, M. [GKSS Research Centre Geesthacht (Germany). Institute of Materials Research, Materials Mechanics; Kocik, R.; Tempus, G. [AIRBUS Deutschland GmbH, Metal Technology, Bremen (Germany); Vaidya, W.V.

    2009-08-15

    Sheets of AA6056 and Ti6Al4V were butt-joined by inserting the Ti-sheet into the profiled Al-sheet and by melting the Al-alloy alone using a split beam Nd:YAG laser. To study microstructural effects on properties, the Al-alloy was used in two tempers; T4 followed by post weld heat treatment T6, and in T6 followed by a defined duration of natural ageing at room temperature. As a basic step for fatigue and fracture investigations, local gradients in properties of this dissimilar joint are investigated using microscopy, hardness and tensile tests. Possible sites, from which fracture may initiate, have been then identified. All property changes are found to confine to the aluminium side. An intermetallic layer, although very thin, is found to form on the interface. The changeovers, firstly between the fusion zone and the heat affected zone and secondly between the heat affected zone and the base material, are found to be associated with changes in microstructure, hardness and strength. These are identified as the possible critical sites in addition to the interface. (Abstract Copyright [2009], Wiley Periodicals, Inc.) [German] Durch eine spezielle Stossvorbereitung wurden laserstrahlgeschweisster Mischverbindungen aus den Blechwerkstoffen AA6056 und Ti6Al4V hergestellt und zwar ohne die Verwendung von Zusatzwerkstoffen. Die grosse Differenz der Schmelztemperaturen erlaubt das selektive Erschmelzen des Aluminiumwerkstoffs, der wieder um den Titanwerkstoff benetzt, sodass es zur Ausbildung einer mechanisch-stabilen und tragfaehigen Verbindung kommt. Die Al-Legierung wurde in den Waermebehandlungszustaenden T4 und T6 verschweisst, um den mikrostrukturellen Einfluss auf die Eigenschaften der Verbindungen untersuchen zu koennen. Die Prozessfolgen sahen vor, dass beim Schweissen im Zustand T4 eine Warmauslagerung, beim Schweissen im Zustand T6 eine Kaltauslagerung definierter Dauer folgte. Die Charakterisierung lokaler Eigenschaftsgradienten hinsichtlich Gefuege, Mikrohaerte

  6. Laser beam welding and friction stir welding of 6013-T6 aluminium alloy sheet

    International Nuclear Information System (INIS)

    Braun, R.; Dalle Donne, C.; Staniek, G.

    2000-01-01

    Butt welds of 1.6 mm thick 6013-T6 sheet were produced using laser beam welding and friction stir welding processes. Employing the former joining technique, filler powders of the alloys Al-5%Mg and Al-12%Si were used. Microstructure, hardness profiles, tensile properties and the corrosion behaviour of the welds in the as-welded condition were investigated. The hardness in the weld zone was lower compared to that of the base material in the peak-aged temper. Hardness minima were measured in the fusion zone and in the thermomechanically affected zone for laser beam welded and friction stir welded joints, respectively. Metallographic and fractographic examinations revealed pores in the fusion zone of the laser beam welds. Porosity was higher in welds made using the filler alloy Al-5%Mg than using the filler metal Al-12%Si. Transmission electron microscopy indicated that the β '' (Mg 2 Si) hardening precipitates were dissolved in the weld zone due to the heat input of the joining processes. Joint efficiencies achieved for laser beam welds depended upon the filler powders, being about 60 and 80% using the alloys Al-5%Mg and Al-12%Si, respectively. Strength of the friction stir weld approached over 80% of the ultimate tensile strength of the 6013-T6 base material. Fracture occurred in the region of hardness minima unless defects in the weld zone led to premature failure. The heat input during welding did not cause a degradation of the corrosion behaviour of the welds, as found in continuous immersion tests in an aqueous chloride-peroxide solution. In contrast to the 6013-T6 parent material, the weld zone was not sensitive to intergranular corrosion. Alternate immersion tests in 3.5% NaCl solution indicated high stress corrosion cracking resistance of the joints. For laser beam welded sheet, the weld zone of alternately immersed specimens suffered severe degradation by pitting and intergranular corrosion, which may be associated with galvanic coupling of filler metal and

  7. Spin dynamics, electronic, and thermal transport properties of two-dimensional CrPS4 single crystal

    Science.gov (United States)

    Pei, Q. L.; Luo, X.; Lin, G. T.; Song, J. Y.; Hu, L.; Zou, Y. M.; Yu, L.; Tong, W.; Song, W. H.; Lu, W. J.; Sun, Y. P.

    2016-01-01

    2-Dimensional (2D) CrPS4 single crystals have been grown by the chemical vapor transport method. The crystallographic, magnetic, electronic, and thermal transport properties of the single crystals were investigated by the room-temperature X-ray diffraction, electrical resistivity ρ(T), specific heat CP(T), and the electronic spin response (ESR) measurements. CrPS4 crystals crystallize into a monoclinic structure. The electrical resistivity ρ(T) shows a semiconducting behavior with an energy gap Ea = 0.166 eV. The antiferromagnetic transition temperature is about TN = 36 K. The spin flipping induced by the applied magnetic field is observed along the c axis. The magnetic phase diagram of CrPS4 single crystal has been discussed. The extracted magnetic entropy at TN is about 10.8 J/mol K, which is consistent with the theoretical value R ln(2S + 1) for S = 3/2 of the Cr3+ ion. Based on the mean-field theory, the magnetic exchange constants J1 and Jc corresponding to the interactions of the intralayer and between layers are about 0.143 meV and -0.955 meV are obtained based on the fitting of the susceptibility above TN, which agree with the results obtained from the ESR measurements. With the help of the strain for tuning the magnetic properties, monolayer CrPS4 may be a promising candidate to explore 2D magnetic semiconductors.

  8. Crack repair welding by CMT brazing using low melting point filler wire for long-term used steam turbine cases of Cr-Mo-V cast steels

    Energy Technology Data Exchange (ETDEWEB)

    Kadoi, Kota, E-mail: kadoi@hiroshima-u.ac.jp [Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527 (Japan); Murakami, Aoi; Shinozaki, Kenji; Yamamoto, Motomichi [Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527 (Japan); Matsumura, Hideo [Chugoku Electric Power Co., 3-9-1 Kagamiyama, Higashi-Hiroshima 739-0046 (Japan)

    2016-06-01

    Surface melting by gas tungsten arc (GTA) welding and overlaying by cold metal transfer (CMT) brazing using low melting point filler wire were investigated to develop a repair process for cracks in worn cast steel of steam turbine cases. Cr-Mo-V cast steel, operated for 188,500 h at 566 °C, was used as the base material. Silver and gold brazing filler wires were used as overlaying materials to decrease the heat input into the base metal and the peak temperature during the welding thermal cycle. Microstructural analysis revealed that the worn cast steel test samples contained ferrite phases with intragranular precipitates of Cr{sub 7}C{sub 3}, Mo{sub 2}C, and CrSi{sub 2} and grain boundary precipitates of Cr{sub 23}C{sub 6} and Mo{sub 2}C. CMT brazing using low melting point filler wire was found to decrease the heat input and peak temperature during the thermal cycle of the process compared with those during GTA surface melting. Thus, the process helped to inhibit the formation of hardened phases such as intermetallics and martensite in the heat affected zone (HAZ). Additionally, in the case of CMT brazing using BAg-8, the change in the hardness of the HAZ was negligible even though other processes such as GTA surface melting cause significant changes. The creep-fatigue properties of weldments produced by CMT brazing with BAg-8 were the highest, and nearly the same as those of the base metal owing to the prevention of hardened phase formation. The number of fracture cycles using GTA surface melting and CMT brazing with BAu-4 was also quite small. Therefore, CMT brazing using low melting point filler wire such as BAg-8 is a promising candidate method for repairing steam turbine cases. However, it is necessary to take alloy segregation during turbine operation into account to design a suitable filler wire for practical use.

  9. Dry sliding wear behavior of laser clad TiVCrAlSi high entropy alloy coatings on Ti–6Al–4V substrate

    International Nuclear Information System (INIS)

    Huang, Can; Zhang, Yongzhong; Vilar, Rui; Shen, Jianyun

    2012-01-01

    Highlights: ► TiVCrAlSi high entropy alloy coatings were obtained on Ti–6Al–4V by laser cladding. ► (Ti,V) 5 Si 3 forms because the formation is accompanied of large variation on enthalpy. ► Wear resistance of Ti–6Al–4V is improved by laser cladding with TiVCrAlSi. ► The wear mechanism is investigated. -- Abstract: Approximately equimolar ratio TiVCrAlSi high entropy alloy coatings has been deposited by laser cladding on Ti–6Al–4V alloy. The analysis of the microstructure by scanning electron microscopy (SEM) shows that the coating is metallurgically bonded to the substrate. X-ray diffraction (XRD) and energy dispersive spectrometer (EDS) analyses show that TiVCrAlSi coating is composed of precipitates of (Ti,V) 5 Si 3 dispersed in a body-centered cubic (BCC) matrix. Intermetallic compound (Ti,V) 5 Si 3 forms because the formation is accompanied by larger variation on enthalpy, which may offset the entropy term. The dry sliding wear tests show that the wear resistance of Ti–6Al–4V is improved by laser cladding with TiVCrAlSi. The enhancement of the wear resistance is explained by the presence of the hard silicide phase dispersed in a relatively ductile BCC matrix, which allows sliding wear to occur in the mild oxidative regime for a wide range of testing conditions.

  10. Tailoring weld geometry during keyhole mode laser welding using a genetic algorithm and a heat transfer model

    International Nuclear Information System (INIS)

    Rai, R; DebRoy, T

    2006-01-01

    Tailoring of weld attributes based on scientific principles remains an important goal in welding research. The current generation of unidirectional laser keyhole models cannot determine sets of welding variables that can lead to a particular weld attribute such as specific weld geometry. Here we show how a computational heat transfer model of keyhole mode laser welding can be restructured for systematic tailoring of weld attributes based on scientific principles. Furthermore, the model presented here can calculate multiple sets of laser welding variables, i.e. laser power, welding speed and beam defocus, with each set leading to the same weld pool geometry. Many sets of welding variables were obtained via a global search using a real number-based genetic algorithm, which was combined with a numerical heat transfer model of keyhole laser welding. The reliability of the numerical heat transfer calculations was significantly improved by optimizing values of the uncertain input parameters from a limited volume of experimental data. The computational procedure was applied to the keyhole mode laser welding of the 5182 Al-Mg alloy to calculate various sets of welding variables to achieve a specified weld geometry. The calculated welding parameter sets showed wide variations of the values of welding parameters, but each set resulted in a similar fusion zone geometry. The effectiveness of the computational procedure was examined by comparing the computed weld geometry for each set of welding parameters with the corresponding experimental geometry. The results provide hope that systematic tailoring of weld attributes via multiple pathways, each representing alternative welding parameter sets, is attainable based on scientific principles

  11. Syntheses, structural variants and characterization of AInM′S{sub 4} (A=alkali metals, Tl; M′ = Ge, Sn) compounds; facile ion-exchange reactions of layered NaInSnS{sub 4} and KInSnS{sub 4} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Yohannan, Jinu P.; Vidyasagar, Kanamaluru, E-mail: kvsagar@iitm.ac.in

    2016-06-15

    Ten AInM′S{sub 4} (A=alkali metals, Tl; M′= Ge, Sn) compounds with diverse structure types have been synthesized and characterized by single crystal and powder X-ray diffraction and a variety of spectroscopic methods. They are wide band gap semiconductors. KInGeS{sub 4}(1-β), RbInGeS{sub 4}(2), CsInGeS{sub 4}(3-β), TlInGeS{sub 4}(4-β), RbInSnS{sub 4}(8-β) and CsInSnS{sub 4}(9) compounds with three-dimensional BaGa{sub 2}S{sub 4} structure and CsInGeS{sub 4}(3-α) and TlInGeS{sub 4}(4-α) compounds with a layered TlInSiS{sub 4} structure have tetrahedral [InM′S{sub 4}]{sup −} frameworks. On the other hand, LiInSnS{sub 4}(5) with spinel structure and NaInSnS{sub 4}(6), KInSnS{sub 4}(7), RbInSnS{sub 4}(8-α) and TlInSnS{sub 4}(10) compounds with layered structure have octahedral [InM′S{sub 4}]{sup −} frameworks. NaInSnS{sub 4}(6) and KInSnS{sub 4}(7) compounds undergo facile topotactic ion-exchange, at room temperature, with various mono-, di- and tri-valent cations in aqueous medium to give rise to metastable layered phases. - Graphical abstract: NaInSnS{sub 4} and KInSnS{sub 4} compounds undergo, in aqueous medium at room temperature, facile topotactic ion-exchange with mono, di and trivalent cations. Display Omitted - Highlights: • Ten AInM′S{sub 4} compounds with diverse structure types were synthesized. • They are wide band gap semiconductors. • NaInSnS{sub 4} and KInSnS{sub 4} compounds undergo facile topotactic ion-exchange at room temperature.

  12. Laser-TIG Welding of Titanium Alloys

    Science.gov (United States)

    Turichin, G.; Tsibulsky, I.; Somonov, V.; Kuznetsov, M.; Akhmetov, A.

    2016-08-01

    The article presents the results of investigation the technological opportunity of laser-TIG welding of titanium alloys. The experimental stand for implementation of process with the capability to feed a filler wire was made. The research of the nature of transfer the filler wire into the welding pool has been demonstrated. The influence of distance between the electrode and the surface of the welded plates on the stability of the arc was shown. The relationship between welding velocity, the position of focal plane of the laser beam and the stability of penetration of plates was determined.

  13. Recent progress on gas tungsten arc welding of vanadium alloys

    Energy Technology Data Exchange (ETDEWEB)

    King, J.F.; Grossbeck, M.L.; Goodwin, G.M.; Alexander, D.J. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    This is a progress report on a continuing research project to acquire a fundamental understanding of the metallurgical processes in the welding of vanadium alloys. It also has the goal of developing techniques for welding structural vanadium alloys. The alloy V-4Cr-4Ti is used as a representative alloy of the group; it is also the prime candidate vanadium alloy for the U.S. Fusion Program at the present time. However, other alloys of this class were used in the research as necessary. The present work focuses on recent findings of hydrogen embrittlement found in vanadium alloy welds. It was concluded that the atmosphere in the inert gas glove box was insufficient for welding 6mm thick vanadium alloy plates.

  14. Humidity-sensitive characteristics of PbCrO4-PbO thick film elements. PbCrO4-PbO kei atsumaku soshi no kanshitsu tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, F [Shonan Institute of Technology, Kanagawa (Japan); Nanba, N [Kantogakuin University, Tokyo (Japan)

    1992-12-20

    This paper describes humidity-sensitive characteristics, which depend on the host composition being PbCrO4 or Pb2CrO5, in the system PbCrO4 combined with various oxides, such as Al2O3, Fe2O3, ZrO2, SnO2, TiO2, ThO2, and Ta2O5. In order to confirm the predominant phase over elements in the system PbCrO4-PbO, the effect of composition and microstructure on the humidity-sensitive characteristics of thick film elements were examined. Consequently, it was found that the humidity-sensitivity in low humidity region increased as the host composition of elements changed from hydrophobic PbCrO4 to hydrophilic Pb2CrO5. It was also shown that these results can be interpreted by a humidity-sensitive mechanism proposed for hydrophilic Pb2CrO5. Furthermore, an absorption model of H2O molecules on to the surface of Pb2CrO5 in the PbCrO4-PbO system humidity sensor was provided. 4 refs., 12 figs.

  15. In vivo comparison of near infrared lasers for skin welding.

    Science.gov (United States)

    Tabakoğlu, Haşim Ozgür; Gülsoy, Murat

    2010-05-01

    The skin closure abilities of near infrared lasers and suturing were compared by histological examination and mechanical tensile tests during a 21-day healing period. One-centimeter incisions on the dorsal skin of Wistar rats were treated by one of the closing techniques: (a) soldering, using an 809 nm diode laser (0.5 W, 5 s) with 25% bovine serum albumin (BSA) and 2.5 mg/ml indocyanine green (ICG); (b) direct welding with a 980 nm diode laser (0.5 W, 5 s); (c) direct welding with a 1,070 nm fiber laser (0.5 W, 5 s); (d) suturing. Six spots (79.61 J/cm(2) for each spot) were applied through the incisions. Healing was inspected on the 1st, 4th, 7th, 14th, and 21st post-operative days. The closure index (CI), thermally altered area (TAA), granulation area (GA) and epidermal thickness (ET) were determined by histological examination. Tensile tests were performed at a 5 mm/min crosshead speed up to the first opening along the incision. Immediate superficial closure with high CI values was found for the laser-irradiated incisions at the early phase of recovery. Clear welds without thermal damage were observed for the group irradiated at 1,070 nm. For the sutured group, the incisions remained unclosed for the first day, and openings through the incision were observed. At the end of the 21-day recovery period, no differences between experimental groups were observed in terms of the CI, GA and ET values. However, the tensile strength of the groups irradiated at 980 nm and 1,070 nm was found to be higher than that of the sutured incisions. The laser welding techniques were found to be reliable in terms of immediate and mechanically strong closure compared with suturing. Of them, 1,070 nm laser welding yielded noticeably stronger bonds, with minimal scarring at the end of the 21-days of recovery.

  16. Microstructural characterisation of metallic shot peened and laser shock peened Ti–6Al–4V

    International Nuclear Information System (INIS)

    Lainé, Steven J.; Knowles, Kevin M.; Doorbar, Phillip J.; Cutts, Richard D.; Rugg, David

    2017-01-01

    A detailed analysis has been conducted of Ti–6Al–4V processed by metallic shot peening and laser shock peening. Analysis by incremental hole drilling, electron backscattered diffraction microscopy, transmission electron microscopy and transmission Kikuchi diffraction microscopy is evaluated and discussed. The results of this analysis highlight the very different dislocation structures in surfaces processed by these two techniques. Transmission Kikuchi diffraction also has been used to evaluate sub-grains generated by laser shock peening. A notable feature of material processed by laser shock peening is the almost complete absence of deformation twinning, contrasting with the frequent observation of extensive deformation twinning observed in the material processed by metallic shot peening.

  17. Laser fabrication of Ag-HA nanocomposites on Ti6Al4V implant for enhancing bioactivity and antibacterial capability

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiangmei; Man, H.C., E-mail: mfhcman@polyu.edu.hk

    2017-01-01

    For titanium alloy implants, both surface bioactivity and antibacterial infection are the two critical factors in determining the success of clinical implantation of these metallic implants. In the present work, a novel nanocomposite layer of nano-silver-containing hydroxyapatite (Ag-HA) was prepared on the surface of biomedical Ti6Al4V by laser processing. Analysis using SEM, EDS and XRD shows the formation of an Ag-HA layer of about 200 μm fusion bonded to the substrate. Mineralization tests in simulated body fluid (SBF) showed that laser fabricated Ag-HA nanocomposite layer favors the deposition of apatite on the surface of the implants. Antibacterial tests confirmed that all Ag-HA nanocomposite layers can kill bacteria while a higher Ag content would lower the cytocompatibility of these coatings. Cell viability decreases when the Ag content reaches 5% in these coatings, due to the larger amount of Ag leached out, as confirmed by ion release evaluation. Our results reveal that laser fabricated Ag-HA nanocomposite coatings containing 2% Ag show both excellent cytocompatibility and antibacterial capability. - Highlights: • Silver-containing hydroxyapatite (Ag-HA) nanocomposite layer was fabricated on Ti6Al4V by laser technique. • Both bioactivity and antibacterial capability were significantly enhanced compared with bare Ti6Al4V. • Ag-HA nanocomposite coatings containing 2% Ag show both excellent cytocompatibility and antibacterial capability.

  18. Material Properties of Laser-Welded Thin Silicon Foils

    Directory of Open Access Journals (Sweden)

    M. T. Hessmann

    2013-01-01

    Full Text Available An extended monocrystalline silicon base foil offers a great opportunity to combine low-cost production with high efficiency silicon solar cells on a large scale. By overcoming the area restriction of ingot-based monocrystalline silicon wafer production, costs could be decreased to thin film solar cell range. The extended monocrystalline silicon base foil consists of several individual thin silicon wafers which are welded together. A comparison of three different approaches to weld 50 μm thin silicon foils is investigated here: (1 laser spot welding with low constant feed speed, (2 laser line welding, and (3 keyhole welding. Cross-sections are prepared and analyzed by electron backscatter diffraction (EBSD to reveal changes in the crystal structure at the welding side after laser irradiation. The treatment leads to the appearance of new grains and boundaries. The induced internal stress, using the three different laser welding processes, was investigated by micro-Raman analysis. We conclude that the keyhole welding process is the most favorable to produce thin silicon foils.

  19. Qualification of Ti6Al4V ELI Alloy Produced by Laser Powder Bed Fusion for Biomedical Applications

    Science.gov (United States)

    Yadroitsev, I.; Krakhmalev, P.; Yadroitsava, I.; Du Plessis, A.

    2018-03-01

    Rectangular Ti6Al4V extralow interstitials (ELI) samples were manufactured by laser powder bed fusion (LPBF) in vertical and horizontal orientations relative to the build platform and subjected to various heat treatments. Detailed analyses of porosity, microstructure, residual stress, tensile properties, fatigue, and fracture surfaces were performed based on x-ray micro-computed tomography, scanning electron microscopy, and x-ray diffraction methods. The types of fracture and the tensile fracture mechanisms of the LPBF Ti6Al4V ELI alloy were also studied. Detailed analysis of the microstructure and the corresponding mechanical properties were compared against standard specifications for conventional Ti6Al4V alloy for use in surgical implant applications. Conclusions regarding the mechanical properties and heat treatment of LPBF Ti6Al4V ELI for biomedical applications are made.

  20. Negative and anomalous T-dependent magnetization trend in CoCr2O4 nanoparticles

    Science.gov (United States)

    Kamran, M.; Nadeem, K.; Mumtaz, M.

    2017-10-01

    We studied the temperature dependent magnetic properties of cobalt chromite (CoCr2O4) nanoparticles. X-ray diffraction revealed the cubic spinel structure of the nanoparticles and average crystallite size was about 42 nm. Raman and Fourier transform infrared spectroscopy confirmed the formation of single phase spinel structure. ZFC/FC curves revealed a paramagnetic (PM) to ferromagnetic (FiM) transition at TC = 100 K with conical spiral state at TS = 27 K and lock-in state at TL = 13 K. Negative magnetization is observed in the ZFC curve under 50 Oe applied field, which gets suppressed upon the application of higher field. The TC was shifted towards higher temperature with the application of higher field, while TS and TL remain unaffected. M-H loops showed FiM behavior below 100 K and nearly PM at TC = 100 K. Below 75 K, an abnormal decrease in MS is observed down to 5 K, which may be due to presence of stiffed/strong conical spin spiral and lock in states at low temperatures. Modified Kneller's law showed a good fit for temperature dependent Hc at higher temperature and deviated at low temperature (disordered surface spins. Nanoparticles showed slow spin relaxation in both ZFC and FC protocols at 5 K, which signifies the presence of spin-glass like behavior at low temperatures. Both curves were fitted with stretched exponential law and the value of β lies in the spin-glass regime. In summary, CoCr2O4 nanoparticles showed anomalous decrease of MS with decreasing temperature, negative magnetization at low field and rather stiffed/strong conical spin spiral and lock-in states in combination with spin-glass behavior at the low temperatures.

  1. Laser Welding of Sub-assemblies before Forming

    DEFF Research Database (Denmark)

    Rasmussen, Mads; Olsen, Flemmming Ove; Pecas, Paulo

    1996-01-01

    This paper describes some experimental investigations of the formability of CO2-laser-welded 0.75 mm and 1.25 mm low carbon steel. There will be a description of how the laser welded blanks behave in different forming tests, and the influene of misalignment and undercut on the formability....... The quality is evalutated by measuring the imit strain and the limit effective strain for the laser welded sheets and the base material. These strains will be presented in a forming limit diagram (FLD). Finally the formability of the laser sheets is compared to that of the base materials....

  2. Hydrogen absorption/desorption properties in the TiCrV based alloys

    Directory of Open Access Journals (Sweden)

    A. Martínez

    2012-10-01

    Full Text Available Three different Ti-based alloys with bcc structure and Laves phase were studied. The TiCr1.1V0.9, TiCr1.1V0.45Nb0.45 and TiCr1.1V0.9 + 4%Zr7Ni10 alloys were melted in arc furnace under argon atmosphere. The hydrogen absorption capacity was measured by using aparatus type Sievert's. Crystal structures, and the lattice parameters were determined by using X-ray diffraction, XRD. Microestructural analysis was performed by scanning electron microscope, SEM and electron dispersive X-ray, EDS. The hydrogen storage capacity attained a value of 3.6 wt. (% for TiCr1.1V0.9 alloy in a time of 9 minutes, 3.3 wt. (% for TiCr1.1V0.45Nb0.45 alloy in a time of 7 minutes and 3.6 wt. (% TiCr1.1V0.9 + 4%Zr7Ni10 with an increase of the hydrogen absorption kinetics attained in 2 minutes. This indicates that the addition of Nb and 4%Zr7Ni10 to the TiCrV alloy acts as catalysts to accelerate the hydrogen absorption kinetics.

  3. Laser welding in penetrating keratoplasty and cataract surgery of pediatric patients: early results

    Science.gov (United States)

    Rossi, Francesca; Pini, Roberto; Menabuoni, Luca; Malandrini, Alex; Canovetti, Annalisa; Lenzetti, Ivo; Capozzi, Paolo; Valente, Paola; Buzzonetti, Luca

    2013-03-01

    Diode laser welding of ocular tissues is a procedure that enables minimally invasive closure of a corneal wound. This procedure is based on a photothermal effect: a water solution of Indocyanine Green (ICG) is inserted in the surgical wound, in order to stain the corneal tissue walls. The stained tissue is then irradiated with a low power infrared diode laser, delivering laser light through a 300-μm core diameter optical fiber. This procedure enables an immediate closure of the wounds: it is thus possible to reduce or to substitute the use of surgical threads. This is of particular interest in children, because the immediate closure improves refractive outcome and anti-amblyopic effect; moreover this procedure avoids several general anaesthesia for suture management. In this work, we present the first use of diode laser welding procedure in paediatric patients. 5 selected patients underwent cataract surgery (Group 1), while 4 underwent fs-laserassisted penetrating keratoplasty (Group 2). In Group 1 the conventional surgery procedure was performed, while no stitches were used for the closure of the surgical wounds: these were laser welded and immediately closed. In Group 2 the donor button was sutured upon the recipient by 8 single stitches, instead of 16 single stitches or a running suture. The laser welding procedure was performed in order to join the donor tissue to the recipient bed. Objective observations in the follow up study evidenced a perfect adhesion of the laser welded tissues, no collateral effects and an optimal restoration of the treated tissues.

  4. The laser beam welding test of ODS fuel claddings

    International Nuclear Information System (INIS)

    Uwaba, Tomoyuki; Ukai, Shigeharu

    2004-06-01

    As a alternative method of pressurized resistance welding being currently developed, integrity evaluations for a laser beam welding joint between a ODS cladding tube and a FMS end plug were conducted for the purpose of studying the applicability of the laser beam welding technique to the welding with the lower end plug. The laser beam welding causes blowholes in the welding zone, whose effect on the high cycle fatigue strength of the joint is essential because of the flow-induced vibration during irradiation. The rotary bending tests using specimens with laser beam welding between ODS cladding tubes and FMS end plugs were carried out to evaluate the fatigue strength of the welding joint containing blowholes. The fatigue limit of stress amplitude about 200 MPa from 10 6 -10 7 cycles suggested that the laser beam welding joint had enough strength against the flow-induced vibration. Sizing of blowholes in the welding zone by using a micro X ray CT technique estimated the rate of defect areas due to blowholes at 1-2%. It is likely that the fatigue strength remained nearly unaffected by blowholes because of the no correlation between the breach of the rotary bending test specimen and the rate of defect area. Based on results of tensile test, internal burst test, Charpy impact test and fatigue test of welded zone, including study of allowable criteria of blowholes in the inspection, it is concluded that the laser beam welding can be probably applied to the welding between the ODS cladding tube and the FMS lower end plug. (author)

  5. Design of welding parameters for laser welding of thin-walled stainless steel tubes using numerical simulation

    Science.gov (United States)

    Nagy, M.; Behúlová, M.

    2017-11-01

    Nowadays, the laser technology is used in a wide spectrum of applications, especially in engineering, electronics, medicine, automotive, aeronautic or military industries. In the field of mechanical engineering, the laser technology reaches the biggest increase in the automotive industry, mainly due to the introduction of automation utilizing 5-axial movements. Modelling and numerical simulation of laser welding processes has been exploited with many advantages for the investigation of physical principles and complex phenomena connected with this joining technology. The paper is focused on the application of numerical simulation to the design of welding parameters for the circumferential laser welding of thin-walled exhaust pipes from theAISI 304 steel for automotive industry. Using the developed and experimentally verified simulation model for laser welding of tubes, the influence of welding parameters including the laser velocity from 30 mm.s-1 to 60 mm.s-1 and the laser power from 500 W to 1200 W on the temperature fields and dimensions of fusion zone was investigated using the program code ANSYS. Based on obtained results, the welding schedule for the laser beam welding of thin-walled tubes from the AISI 304 steel was suggested.

  6. Study on laser beam welding technology for nuclear power plants

    International Nuclear Information System (INIS)

    Chida, Itaru; Shiihara, Katsunori; Fukuda, Takeshi; Kono, Wataru; Obata, Minoru; Morishima, Yasuo

    2012-01-01

    Laser beam welding is one of the jointing processes by irradiating laser beam on the material surface locally and widely used at various industrial fields. Toshiba has developed various laser-based maintenance and repair technologies and already applied them to several existing nuclear power plants. Laser cladding is a technique to weld the corrosion resistant metal onto a substrate surface by feeding filler wire to improve the corrosion resistance. Temper-bead welding is the heat input process to provide the desired microstructure properties of welded low alloy steels without post weld heat treatment, by inducing proper heat cycle during laser welding. Both laser welding technologies would be performed underwater by blowing the shielding gas for creating the local dry area. In this report, some evaluation results of material characteristics by temper-bead welding to target at Reactor Coolant System nozzle of PWR are presented. (author)

  7. Preliminary results of laser tissue welding in extravesical reimplantation of the ureters.

    Science.gov (United States)

    Kirsch, A J; Dean, G E; Oz, M C; Libutti, S K; Treat, M R; Nowygrod, R; Hensle, T W

    1994-02-01

    One exciting potential use of laparoscopic technology is the extravesical reimplantation of the ureters. We have assessed the efficacy of laser-activated fibrinogen solder to close vesical muscle flaps over submucosal ureters (Lich-Gregoir technique) in a canine model. Four dogs were subjected to unilateral flap closures via a protein solder (indocyanine green and fibrinogen) applied to the bladder serosa and exposed to 808 nm. continuous wave diode laser energy. Contralateral reimplantation was performed using 4-zero vicryl muscle flap closures (controls). At 7, 14 and 28 days postoperatively, intravenous pyelograms confirmed bilateral ureteral patency. At intravesical pressures above 100 cm. H2O, there was no evidence of wound disruption in either group. Nondisrupted wound closures were sectioned and strained until ultimate breakage to determine tensile strength. At each study interval the laser-welded closures withstood greater stress than the controls. Although these data represent single tissue samples and are not amenable to statistical analysis, laser-welded closures appeared to be stronger at each study interval. In conclusion, laser-welded vesical wound closures appear at least as strong as suture closures in the canine model.

  8. A master curve-mechanism based approach to modeling the effects of constraint, loading rate and irradiation on the toughness-temperature behavior of a V-4Cr-4Ti alloy

    International Nuclear Information System (INIS)

    Odette, G.R.; Donahue, E.; Lucas, G.E.; Sheckherd, J.W.

    1996-01-01

    The influence of loading rate and constraint on the effective fracture toughness as a function of temperature [K e (T)] of the fusion program heat of V-4Cr-4Ti was measured using subsized, three point bend specimens. The constitutive behavior was characterized as a function of temperature and strain rate using small tensile specimens. Data in the literature on this alloy was also analysed to determine the effect of irradiation on K e (T) and the energy temperature (E-T) curves measured in subsized Charpy V-notch tests. It was found that V-4Cr-4Ti undergoes open-quotes normalclose quotes stress-controlled cleavage fracture below a temperature marking a sharp ductile-to-brittle transition. The transition temperature is increased by higher loading rates, irradiation hardening and triaxial constraint. Shifts in a reference transition temperature due to higher loading rates and irradiation can be reasonably predicted by a simple equivalent yield stress model. These results also suggest that size and geometry effects, which mediate constraint, can be modeled by combining local critical stressed area σ*/A* fracture criteria with finite element method simulations of crack tip stress fields. The fundamental understanding reflected in these models will be needed to develop K e (T) curves for a range of loading rates, irradiation conditions, structural size scales and geometries relying (in large part) on small specimen tests. Indeed, it may be possible to develop a master K e (T) curve-shift method to account for these variables. Such reliable and flexible failure assessment methods are critical to the design and safe operation of defect tolerant vanadium structures

  9. Fracture behavior of unirradiated HT-9 and modified 9Cr-1Mo welds

    International Nuclear Information System (INIS)

    Huang, F.H.; Gelles, D.S.

    1983-05-01

    Fracture toughness tests on HT-9 weld and HAZ samples and modified 9Cr-1Mo weld samples were performed at 93, 205, 427 and 538 0 C. Specimens were of circular compact tension type fabricated from welded material with the notch orientation parallel to the fusi