The influence of plate thickness on the welding residual stresses from submerged arc welding in offshore steel structures

DEFF Research Database (Denmark)

Andreassen, Michael Joachim; Yu, Zhenzhen; Liu, Stephen

2017-01-01

Welding-induced residual tensile stresses and distortion have become a major concern in relation to the structural integrity of welded structures within the offshore wind industry. The stresses have a negative impact on the integrity of the welded joint, as they promote distortion, reduce fatigue...... leading to a better understanding of the distribution and development of the welding residual stresses. This can later be used to optimize the fatigue design, providing a more efficient and improved design. In this context, the current research is expected to benefit the offshore industry by leading...... to an improved design, which consequently may be included in future norms and standards. Submerged Arc Welding (SAW) was used to make a fully penetrated butt weld in 10 mm and 40 mm thick steel plates with the same welding parameters as used in the production procedures. The base material is thermomechanical hot...

Effects of alloying element on weld characterization of laser-arc hybrid welding of pure copper

Science.gov (United States)

Hao, Kangda; Gong, Mengcheng; Xie, Yong; Gao, Ming; Zeng, Xiaoyan

2018-06-01

Effects of alloying elements of Si and Sn on weld characterizations of laser-arc hybrid welded pure copper (Cu) with thickness of 2 mm was studied in detail by using different wires. The weld microstructure was analyzed, and the mechanical properties (micro-hardness and tensile property), conductivity and corrosion resistance were tested. The results showed that the alloying elements benefit the growth of column grains within weld fusion zone (FZ), increase the ultimate tensile strength (UTS) of the FZ and weld corrosion resistance, and decrease weld conductivity. The mechanisms were discussed according to the results.

Homogeneous weldings of copper

International Nuclear Information System (INIS)

Campurri, C.; Lopez, M.; Fernandez, R.; Osorio, V.

1995-01-01

This research explored the metallurgical and mechanical properties of arc welding of copper related with influence of Argon, Helium and mixtures of them. Copper plates of 6 mm thickness were welded with different mixtures of the mentioned gases. The radiography of welded specimens with 100% He and 100% Ar does not show show any porosity. On the other hand, the copper plates welded different gas mixtures presented uniform porosity in the welded zone. The metallographies show recrystallized grain in the heat affected zone, while the welding zone showed a dendritic structure. The results of the tensile strength vary between a maximum of 227 MPa for 100% He and a minimum of 174 MOa for the mixture of 60% He and 40% Ar. For the elongation after fracture the best values, about 36%, were obtained for pure gases. As a main conclusion, we can say that arc welding of copper is possible without loosing the mechanical and metallurgical properties of base metal. 6 refs

Mathematical model for optimization of multilayer submerged-arc welding of frame equipment of power units

International Nuclear Information System (INIS)

Pankov, V.V.; Chernyshev, G.G.; Kozlov, N.E.

1987-01-01

A mathematical model for optimization of multilayer submerged arc welding of frame equipment of power units is constructed. The variation-energy method permits to construct the universal mathematical model for strengthening formation of a single bead; the method is reasonable for simulation of a multilayer welded joint. Minimization of the distance between maximum and minimum layer height of a built-up metal is the necessary condition for qualitative formation of the multilayer joint. One can calculate in real time scale the optimal vector of maximally ten parameters under the multilayer welding condition immediately after change in the grooving width using the developed mathematical model of optimization

STUDY OF THE INFLUENCE OF THE HEAT INPUT ON MECHANICAL PROPERTIES OF C-Mn STEEL WELD METALS OBTAINED BY SUBMERGED ARC PROCESS

Directory of Open Access Journals (Sweden)

Erick de Sousa Marouço

2013-06-01

Full Text Available The present work is part of a research program that aims to evaluate the technical feasibility of increasing productivity in the manufacturing of tubular components for offshore oil industry, which are fully welded by automatic submerged arc welding process, with high heat input, but with no impairment on the impact toughness of the weld metal. Multipass welds were produced by the submerged arc welding process, with a combination of F7A4-EM12K (wire/flux, by using a 3.2 mm-diameter wire, preheating at 80°C, with direct current, in flat position, with heat input varying from 3.5 kJ/mm to 12 kJ/mm. After welding, tensile tests and Charpy-V impact tests at –60°C, –40°C, –20°C, 0°C and 20°C were carried out, as well as metallographic examination by both optical (OM and scanning electron microscopy (SEM, of specimens obtained entirely from the weld metal, allowing the discussion over the toughness X microstructure relationship. The weld metals have shown higher toughness levels in relation to the minimum required for use with low-alloy C-Mn steels welding with requirements of impact toughness of 27 J at 0°C for heat input up to 12 kJ/mm allowing an increase in productivity of 58% on the effective manufacturing time.

Optimization of submerged arc welding process parameters using quasi-oppositional based Jaya algorithm

International Nuclear Information System (INIS)

Rao, R. Venkata; Rai, Dhiraj P.

2017-01-01

Submerged arc welding (SAW) is characterized as a multi-input process. Selection of optimum combination of process parameters of SAW process is a vital task in order to achieve high quality of weld and productivity. The objective of this work is to optimize the SAW process parameters using a simple optimization algorithm, which is fast, robust and convenient. Therefore, in this work a very recently proposed optimization algorithm named Jaya algorithm is applied to solve the optimization problems in SAW process. In addition, a modified version of Jaya algorithm with oppositional based learning, named “Quasi-oppositional based Jaya algorithm” (QO-Jaya) is proposed in order to improve the performance of the Jaya algorithm. Three optimization case studies are considered and the results obtained by Jaya algorithm and QO-Jaya algorithm are compared with the results obtained by well-known optimization algorithms such as Genetic algorithm (GA), Particle swarm optimization (PSO), Imperialist competitive algorithm (ICA) and Teaching learning based optimization (TLBO).

Optimization of submerged arc welding process parameters using quasi-oppositional based Jaya algorithm

Energy Technology Data Exchange (ETDEWEB)

Rao, R. Venkata; Rai, Dhiraj P. [Sardar Vallabhbhai National Institute of Technology, Gujarat (India)

2017-05-15

Submerged arc welding (SAW) is characterized as a multi-input process. Selection of optimum combination of process parameters of SAW process is a vital task in order to achieve high quality of weld and productivity. The objective of this work is to optimize the SAW process parameters using a simple optimization algorithm, which is fast, robust and convenient. Therefore, in this work a very recently proposed optimization algorithm named Jaya algorithm is applied to solve the optimization problems in SAW process. In addition, a modified version of Jaya algorithm with oppositional based learning, named “Quasi-oppositional based Jaya algorithm” (QO-Jaya) is proposed in order to improve the performance of the Jaya algorithm. Three optimization case studies are considered and the results obtained by Jaya algorithm and QO-Jaya algorithm are compared with the results obtained by well-known optimization algorithms such as Genetic algorithm (GA), Particle swarm optimization (PSO), Imperialist competitive algorithm (ICA) and Teaching learning based optimization (TLBO).

Study of the transfer efficiency of alloyed elements in fluxes during submerged arc welding process

International Nuclear Information System (INIS)

Quintana, R.; Cruz, A.; Perdomo, L.; Castellanos, G.; Garcia, L. L.; Formoso, A.; Cores, A.

2003-01-01

It is assessed the transfer of chromium, manganese and carbon of different agglomerate fluxes constituted by 18.75% of alloyed load and 81.25% of matrix during the SAW process (submerge Arc Welding). A vitreous basic matrix corresponding to the system SiO 2 -Al 2 O 3 -(CaO+MgO) was obtained from minerals by fusion in the electric arc furnace. The current proportions of the alloyed load components (FeCr, FeMn and graphite) were carried out using a McLean Anderson experiment design. The corresponding fluxes to each experimental point were obtained by granulation with liquid glass;afterwards, their transfer coefficient for a given regimen of welding was determined. The transfer coefficients were calculated by means of a formula based on the laws of mass conservation and of distribution. (Author) 17 refs

The effect of heat treatment on phosphorus segregation in a submerged-arc weld metal

International Nuclear Information System (INIS)

Beere, W.B.; Buswell, J.T.

1999-01-01

Intergranular fracture (IGF) has been observed in carbon-manganese steels after irradiation or high temperature exposure for prolonged periods. The effect is associated with an increase in the ductile-brittle transition temperature and has been related to phosphorus diffusion to grain boundaries. Phosphorus also diffuses thermally at the temperatures used for post-weld heat treatments such that in principle, the slightly different heat treatments given to different parts of a large vessel could lead to differing grain boundary phosphorus coverage and hence susceptibility to IGF. The effect of typical heat treatments on phosphorus coverage has been investigated using a finite difference model based on a theory that has been fitted to a wide range of constant temperature data. Regardless of previous history, the grain boundary coverage of phosphorus was predicted to depend on the final anneal and cooling rate. These differed insufficiently in the typical heat treatments to produce significant differences in segregation. It was concluded that the ductile-brittle transition temperature in submerged-arc welds would be unaffected in vessels that had seen typical post-weld heat treatments

Results of crack-arrest tests on two irradiated high-copper welds

International Nuclear Information System (INIS)

Iskander, S.K.; Corwin, W.R.; Nanstead, R.K.

1990-12-01

The objective of this study was to determine the effect of neutron irradiation on the shift and shape of the lower-bound curve to crack-arrest data. Two submerged-arc welds with copper contents of 0.23 and 0.31 wt % were commercially fabricated in 220-mm-thick plate. Crack-arrest specimens fabricated from these welds were irradiated at a nominal temperature of 288 degree C to an average fluence of 1.9 x 10 19 neutrons/cm 2 (>1 MeV). Evaluation of the results shows that the neutron-irradiation-induced crack-arrest toughness temperature shift is about the same as the Charpy V-notch impact temperature shift at the 41-J energy level. The shape of the lower-bound curves (for the range of test temperatures covered) did not seem to have been altered by irradiation compared to those of the ASME K Ia curve. 9 refs., 21 figs., 10 tabs

Advanced characterization techniques in understanding the roles of nickel in enhancing strength and toughness of submerged arc welding high strength low alloy steel multiple pass welds in the as-welded condition

Science.gov (United States)

Sham, Kin-Ling

Striving for higher strength along with higher toughness is a constant goal in material properties. Even though nickel is known as an effective alloying element in improving the resistance of a steel to impact fracture, it is not fully understood how nickel enhances toughness. It was the goal of this work to assist and further the understanding of how nickel enhanced toughness and maintained strength in particular for high strength low alloy (HSLA) steel submerged arc welding multiple pass welds in the as-welded condition. Using advanced analytical techniques such as electron backscatter diffraction, x-ray diffraction, electron microprobe, differential scanning calorimetry, and thermodynamic modeling software, the effect of nickel was studied with nickel varying from one to five wt. pct. in increments of one wt. pct. in a specific HSLA steel submerged arc welding multiple pass weldment. The test matrix of five different nickel compositions in the as-welded and stress-relieved condition was to meet the targeted mechanical properties with a yield strength greater than or equal to 85 ksi, a ultimate tensile strength greater than or equal to 105 ksi, and a nil ductility temperature less than or equal to -140 degrees F. Mechanical testing demonstrated that nickel content of three wt. pct and greater in the as-welded condition fulfilled the targeted mechanical properties. Therefore, one, three, and five wt. pct. nickel in the as-welded condition was further studied to determine the effect of nickel on primary solidification mode, nickel solute segregation, dendrite thickness, phase transformation temperatures, effective ferrite grain size, dislocation density and strain, grain misorientation distribution, and precipitates. From one to five wt. pct nickel content in the as-welded condition, the primary solidification was shown to change from primary delta-ferrite to primary austenite. The nickel partitioning coefficient increased and dendrite/cellular thickness was

Welding by submerged arc of steel with addition of iron powder; Soldagem por arco submerso de aco microligado com adicao de po de ferro

Energy Technology Data Exchange (ETDEWEB)

Gomes, Samuel I.N.; Spinelli, Dirceu [Sao Paulo Univ., Sao Carlos, SP (Brazil). Escola de Engenharia; Souza, Paulo C.R. D. de [SICOM Compressores Ltda., Sao Carlos, SP (Brazil); Magalhaes Bento Goncalves, Gilberto de [Bauru Univ., SP (Brazil)

1993-12-31

Welding metals with and without iron powder addition were produced in steel plates ASTM A 242 by submerged arc process. as a conclusion, the mechanical properties of hardness and toughness of weld metal and heat affect zone were more affected when the welding were done with lower heat input. (author). 16 refs., 3 figs., 9 tabs.

Arc Shape Characteristics with Ultra-High-Frequency Pulsed Arc Welding

Directory of Open Access Journals (Sweden)

Mingxuan Yang

2017-01-01

Full Text Available Arc plasma possesses a constriction phenomenon with a pulsed current. The constriction is created by the Lorentz force, the radial electromagnetic force during arc welding, which determines the energy distribution of the arc plasma. Welding experiments were carried out with ultra-high-frequency pulsed arc welding (UHFP-AW. Ultra-high-speed camera observations were produced for arc surveillance. Hue-saturation-intensity (HSI image analysis was used to distinguish the regions of the arc plasma that represented the heat energy distribution. The measurement of arc regions indicated that, with an ultra-high-frequency pulsed arc, the constriction was not only within the decreased arc geometry, but also within the constricted arc core region. This can be checked by the ratio of the core region to the total area. The arc core region expanded significantly at 40 kHz at 60 A. A current level of 80 A caused a decrease in the total region of the arc. Meanwhile, the ratio of the core region to the total increased. It can be concluded that arc constriction depends on the increased area of the core region with the pulsed current (>20 kHz.

Effects of irradiation on crack-arrest toughness of two high-copper welds

International Nuclear Information System (INIS)

Iskander, S.K.; Corwin, W.R.; Nanstad, R.K.

1990-01-01

The objective of this study is to determine the effect of neutron irradiation on the shift and shape of the lower-bound curve to crack-arrest data. Two submerged-arc welds with copper contents of 0.23 and 0.31 wt % were commercially fabricated in 220-mm-thick plate. Crack-arrest specimens fabricated from these welds were irradiated at a nominal temperature of 288 degree C to an average fluence of 1.9 x 10 19 neutrons/cm 2 (>1 MeV). A preliminary evaluation of the results shows that the neutron-irradiation induced crack-arrest toughness temperature shift is about the same as the Charpy V-notch impact temperature shift at the 41-J energy level. The shape of the lower-bound curves, (for the range of test temperatures covered), compared to those of the ASME K Ia -curve did not seem to have been altered by irradiation. 10 refs., 9 figs., 7 tabs

Characterization of a manganese ore to define the use in the fluxes synthesis for submerged arc welding

International Nuclear Information System (INIS)

Cruz, A.; Quintana, R.; Perdomo, L.; Garcia, L. L.; Formoso, A.; Cores, A.

2003-01-01

Chemical analysis, thermal analysis (DTA and TG), phase determination by X-ray diffraction and granulometric analysis of the manganese ore from the location Margarita de Cambute in the eastern part of cuba were carried out. Based on these characterization results, a flux synthesis strategy was established, comprising the definition, as a basic condition, of the MnO/SiO 2 range of values. This strategy was confirmed experimentally by obtaining a flux prototype in an electric arc furnace connected to direct current source and the carrying out of the flux in submerged arc welding tests. (Author) 26 refs

Fatigue assessment of a double submerged arc welded gas pipeline

Energy Technology Data Exchange (ETDEWEB)

Fazzini, Pablo; Otegui, Jose Luis [Universidad Nacional Mar del Plata, Mar del Plata (Argentina). Instituto de Ciencia y Tecnologia de Materiales (INTEMA); Teutonico, Mauricio; Manfredi, Carlos [GIE S.A., Mar del Plata (Argentina)

2005-07-01

An uncommon blowout in a 24'' diameter, 7 mm thick API 5L X52 gas pipeline was due to fracture at the longitudinal double submerged arc weld. Oddly enough for gas pipelines, it was found that fatigue cracks had propagated from a large embedded weld defect of lack of fusion resulting from severe geometrical mismatch between inner and outer weld passes. What makes this failure particularly interesting is that: previous in line inspections failed to detect any defect, no evidence of third party damage was found, and very few large pressure cycles had been recorded during the last 5 years of service, which were believed to be representative of the entire service life of the pipeline. Fatigue tests were carried out to characterize propagation of fatigue cracks in weld metal, it was found that a large Paris exponent made the few large amplitude cycles most contributing to crack propagation. Crack growth path and striation patterns were studied. Fatigue growth was modelled by integrating experimental results and by extrapolating striation spacing in the fracture surface of the failed pipe. Crack growth path and striation patterns were studied. It was found that microstructure discontinuities govern propagation at low {delta}K, but one striation per cycle was produced at large {delta}K, due to a mostly ductile propagation mode. Fatigue growth was modelled by integrating experimental results and by extrapolating striation spacing in the fracture surface of the failed pipe. It was found that in the early life of the line many more large pressure cycles than expected had occurred. Good correspondence between predicted and actual fatigue lives was in this way obtained (author)

Fatigue assessment of a double submerged arc welded gas pipeline

Energy Technology Data Exchange (ETDEWEB)

Fazzini, Pablo; Otegui, Jose Luis [Universidad Nacional Mar del Plata, Mar del Plata (Argentina). Instituto de Ciencia y Tecnologia de Materiales (INTEMA); Teutonico, Mauricio; Manfredi, Carlos [GIE S.A., Mar del Plata (Argentina)

2005-07-01

An uncommon blowout in a 24'' diameter, 7 mm thick API 5L X52 gas pipeline was due to fracture at the longitudinal double submerged arc weld. Oddly enough for gas pipelines, it was found that fatigue cracks had propagated from a large embedded weld defect of lack of fusion resulting from severe geometrical mismatch between inner and outer weld passes. What makes this failure particularly interesting is that: previous in line inspections failed to detect any defect, no evidence of third party damage was found, and very few large pressure cycles had been recorded during the last 5 years of service, which were believed to be representative of the entire service life of the pipeline. Fatigue tests were carried out to characterize propagation of fatigue cracks in weld metal, it was found that a large Paris exponent made the few large amplitude cycles most contributing to crack propagation. Crack growth path and striation patterns were studied. Fatigue growth was modelled by integrating experimental results and by extrapolating striation spacing in the fracture surface of the failed pipe. Crack growth path and striation patterns were studied. It was found that microstructure discontinuities govern propagation at low {delta}K, but one striation per cycle was produced at large {delta}K, due to a mostly ductile propagation mode. Fatigue growth was modelled by integrating experimental results and by extrapolating striation spacing in the fracture surface of the failed pipe. It was found that in the early life of the line many more large pressure cycles than expected had occurred. Good correspondence between predicted and actual fatigue lives was in this way obtained (author)

Metallurgical and mechanical characterization of a submerged arc welded joint in a 316 type stainless steel

International Nuclear Information System (INIS)

Piatti, G.; Vedani, M.

1990-01-01

The tensile (deformation and fracture) behaviour of a multipass submerged arc welded joint Type 316 stainless steel is investigated by tests at room temperature and at 400 0 C on all-weld metal and transverse to weld (composite) specimens as well as by microstructural and compositional analyses (optical, scanning electron and transmission electron microscopy). The as-deposited metal is characterised by a systematic variation in the tensile properties across the thickness with the higher strength and the lower ductility in the weld centre. These variations are related to material variability (mainly in dislocation density) because of local dissimilarities in thermal and mechanical histories occurring during the welding process. However, the material variability in the fusion zone, although important is not so large in the present weld and it does not influence the tensile properties of the weld as a whole. Moreover, the tensile behaviour concerning the transverse to weld specimens is characterized by a supporting effect from the higher yield strength material zone (fusion zone) to the lower yield strength material zone (parent metal) justified by the different contribution of the parent metal and of the weld-deposit metal to the integral plastic strain of the specimens. (author)

Analytical model of stress field in submerged arc welding butt joint with thorough penetration

Directory of Open Access Journals (Sweden)

Winczek Jerzy

2018-01-01

Full Text Available Analytical model of temporary and residual stresses for butt welding with thorough penetration was described assuming planar section hypothesis and using integral equations of stress equilibrium of the bar and simple Hooke’s law. In solution the effect of phase transformations (structure changes and structural strains has been taken into account. Phase transformations during heating are limited by temperature values at the beginning and at the end of austenitic transformation, depending on chemical composition of steel while the progress of phase transformations during cooling is determined on the basis of TTT-welding diagram. Temperature values at the beginning and at the end of transformation are conditioned by the speed of heating. Kinetics of diffusional transformation is described basing on Johnson-Mehl-Avrami-Kolmogorov equation, while martensitic transformation, basing on Koistinen-Marburger equation. Stresses in elasto-plastic state are determined by iteration, using elastic solutions method with changeable longitudinal modulus of elasticity, conditioned by stress-strain curve. Computations of stress field have been conducted for one-side butt welded of two steel flats made from S235 steel. It has enabled a clear interpretation of influence of temperature field and phase transformation on stresses caused by welding using Submerged Arc Welding (SAW method.

The application of imperialist competitive algorithm for optimization of deposition rate in submerged arc welding process using TiO2 nano particle

International Nuclear Information System (INIS)

Ghaderi, Mohammad Reza; Eslampanah, Amirhossein; Ghaderi, Kianoosh; Aghakhani, Masood

2015-01-01

We used a novel optimization algorithm based on the imperialist competitive algorithm (ICA) to optimize the deposition rate in the submerged arc welding (SAW) process. This algorithm offers some advantages such as simplicity, accuracy and time saving. Experiments were conducted based on a five factor, five level rotatable central composite design (RCCD) to collect welding data for deposition rate as a function of welding current, arc voltage, contact tip to plate distance, welding speed and thickness of TiO 2 nanoparticles coated on the plates of mild steel. Furthermore, regression equation for deposition rate was obtained using least squares method. The regression equation as the cost function was optimized using ICA. Ultimately, the levels of input variables to achieve maximum deposition rate were obtained using ICA. Computational results indicate that the proposed algorithm is quite effective and powerful in optimizing the cost function.

Upper shelf toughness of six submerged-arc weldmetals manufactured using Linde 124 flux

International Nuclear Information System (INIS)

Druce, S.G.; Hippsley, C.A.

1984-06-01

This paper describes the testing technique, data analysis procedures and results from the first phase of an experimental programme investigating upper shelf toughness of six submerged-arc weldmetals. The welds were manufactured using uncoated, Nickel coated and Copper coated wire electrodes and Linde 124 flux. J integral crack growth resistance curves have been derived from tests on single specimens over a range in temperature from 150 to 290 deg C. The results indicate a general decline in toughness with increasing temperature. At 290 deg C, the levels of initiation toughness from all six welds were essentially constant varying between 152 to 159 MPa square root of m. The Jsub(I)-R curves derived from this work are compared with toughness data used in the Marshall Study Group report of an assessment of the integrity of PWR pressure vessels. (author)

Effects of annealing time on the recovery of Charpy V-notch properties of irradiated high-copper weld metal

International Nuclear Information System (INIS)

Iskander, S.K.; Sokolov, M.A.; Nanstad, R.K.

1994-01-01

One of the options to mitigate the effects of irradiation on reactor pressure vessels is to thermally anneal them to restore the toughness properties that have been degraded by neutron irradiation. An important issue to be resolved is the effect on the toughness properties of reirradiating a vessel that has been annealed. This paper describes the annealing response of irradiated high-copper submerged-arc weld HSSI 73W. For this study, the weld has been annealed at 454 C (850 F) for lengths of time varying between 1 and 14 days. The Charpy V-notch 41-J (30-ft-lb) transition temperature (TT 41J ) almost fully recovered for the longest period studied, but recovered to a lesser degree for the shorter periods. No significant recovery of the TT 41J was observed for a 7-day anneal at 343 C (650 F). At 454 C for the durations studied, the values of the upper-shelf impact energy of irradiated and annealed weld metal exceeded the values in the unirradiated condition. Similar behavior was observed after aging the unirradiated weld metal at 460 and 490 C for 1 week

The grain boundary segregation of phosphorus in thermally aged and irradiated C-Mn submerged-are weld metal

International Nuclear Information System (INIS)

Mendes, C.M.

1999-01-01

The segregation of free phosphorus atoms to grain boundaries in C-Mn steels has been identified as an embrittlement mechanism. A change in the brittle fracture mechanism from transgranular to intergranular has been observed for materials with higher phosphorus grain boundary coverage. The grain boundary segregation of phosphorus in various steels used in the nuclear power industry has been thermodynamically and kinetically modelled mostly with the Langmuir-McLean model. Recent publications have also suggested that neutron irradiation can affect segregation and various attempts at modelling this are currently under way. The present paper describes a data base assembled on phosphorus grain boundary coverage measured by Auger electron spectroscopy on thermally aged and irradiated C-Mn submerged-arc weld specimens. Software tools were developed to evaluate the changes in phosphorus grain boundary coverage associated with instantaneous temperature changes and temperature gradients. The phosphorus free energy change associated with grain boundary segregation was modelled from the thermally aged data and used with the software to determine the phosphorus segregation in submerged-arc weld metals following the post weld stress relief heat treatments received prior to plant operation. The phosphorus grain boundary coverage changes arising from the thermal history of submerged-arc weld materials during irradiation were also modelled and found to compare well with data obtained on irradiated materials. It was concluded that under the irradiation conditions sampled, phosphorus grain boundary segregation in submerged-arc weld materials can be modelled successfully using only the thermal term without appealing to an irradiation induced segregation process. (author)

The application of imperialist competitive algorithm for optimization of deposition rate in submerged arc welding process using TiO{sub 2} nano particle

Energy Technology Data Exchange (ETDEWEB)

Ghaderi, Mohammad Reza; Eslampanah, Amirhossein; Ghaderi, Kianoosh [Islamic Azad University, Sanandaj (Iran, Islamic Republic of); Aghakhani, Masood [Razi University, Kermanshah (Iran, Islamic Republic of)

2015-01-15

We used a novel optimization algorithm based on the imperialist competitive algorithm (ICA) to optimize the deposition rate in the submerged arc welding (SAW) process. This algorithm offers some advantages such as simplicity, accuracy and time saving. Experiments were conducted based on a five factor, five level rotatable central composite design (RCCD) to collect welding data for deposition rate as a function of welding current, arc voltage, contact tip to plate distance, welding speed and thickness of TiO{sub 2} nanoparticles coated on the plates of mild steel. Furthermore, regression equation for deposition rate was obtained using least squares method. The regression equation as the cost function was optimized using ICA. Ultimately, the levels of input variables to achieve maximum deposition rate were obtained using ICA. Computational results indicate that the proposed algorithm is quite effective and powerful in optimizing the cost function.

Crack-arrest tests on two irradiated high-copper welds

International Nuclear Information System (INIS)

Iskander, S.K.; Corwin, W.R.; Nanstad, R.K.

1994-03-01

The objective of the Heavy-Section Steel Irradiation Program Sixth Irradiation Series is to determine the effect of neutron irradiation on the shift and shape of the lower-bound curve to crack-arrest toughness data. Two submerged-arc welds with copper contents of 0.23 and 0.31 wt % were commercially fabricated in 220-mm-thick plate. Crack-arrest specimens fabricated from these welds were irradiated at a nominal temperature of 288 degrees C to an average fluence of 1.9 x 10 19 neutrons/cm 2 (>1 MeV). This is the second report giving the results of the tests on irradiated duplex-type crack-arrest specimens. A previous report gave results of tests on irradiated weld-embrittled-type specimens. Charpy V-notch (CVN) specimens irradiated in the same capsules as the crack-arrest specimens were also tested, and a 41-J transition temperature shift was determined from these specimens. open-quotes Mean close-quote curves of the same form as the American Society of Mechanical Engineers (ASME) K la curve were fit to the data with only the open-quotes reference temperatureclose quotes as a parameter. The shift between the mean curves agrees well with the 41-J transition temperature shift obtained from the CVN specimen tests. Moreover, the four data points resulting from tests on the duplex crack-arrest specimens of the present study did not make a significant change to mean curve fits to either the previously obtained data or all the data combined

Submerged Arc Stainless Steel Strip Cladding—Effect of Post-Weld Heat Treatment on Thermal Fatigue Resistance

Science.gov (United States)

Kuo, I. C.; Chou, C. P.; Tseng, C. F.; Lee, I. K.

2009-03-01

Two types of martensitic stainless steel strips, PFB-132 and PFB-131S, were deposited on SS41 carbon steel substrate by a three-pass submerged arc cladding process. The effects of post-weld heat treatment (PWHT) on thermal fatigue resistance and hardness were evaluated by thermal fatigue and hardness testing, respectively. The weld metal microstructure was investigated by utilizing optical microscopy, scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). Results showed that, by increasing the PWHT temperature, hardness decreased but there was a simultaneous improvement in weldment thermal fatigue resistance. During tempering, carbide, such as (Fe, Cr)23C6, precipitated in the weld metals and molybdenum appeared to promote (Fe, Cr, Mo)23C6 formation. The precipitates of (Fe, Cr, Mo)23C6 revealed a face-centered cubic (FCC) structure with fine grains distributed in the microstructure, thereby effectively increasing thermal fatigue resistance. However, by adding nickel, the AC1 temperature decreased, causing a negative effect on thermal fatigue resistance.

The modelling of irradiation-enhanced phosphorus segregation in neutron irradiated reactor pressure vessel submerged-arc welds

Energy Technology Data Exchange (ETDEWEB)

Druce, S.G.; English, C.A.; Foreman, A.J.E.; McElroy, R.J.; Vatter, I.A. [AEA Technology, Didcot (United Kingdom). Harwell Lab.; Bolton, C.J.; Buswell, J.T.; Jones, R.B. [Nuclear Electric, Berkeley (United Kingdom). Berkeley Technology Centre

1996-12-31

Recent results on neutron-irradiated RPV submerged-arc welds have revealed grain boundary segregation of phosphorus during irradiation, which may lead to intergranular fracture. However, the experimental database is insufficient to define the dependence of the process on variables such ad dose, dose-rate and temperature. This paper describes work in which two existing models of phosphorus segregation, under thermal or irradiation conditions, have been developed to obtain predictions of these dependencies. The critical parameters in the models have been adjusted to give consistency with the available reference data, and predictions have been made of the dependence of segregation on a number of variables.

High-power laser and arc welding of thorium-doped iridium alloys

International Nuclear Information System (INIS)

David, S.A.; Liu, C.T.

1980-05-01

The arc and laser weldabilities of two Ir-0.3% W alloys containing 60 and 200 wt ppM Th have been investigated. The Ir-.03% W alloy containing 200 wt ppM Th is severely prone to hot cracking during gas tungsten-arc welding. Weld metal cracking results from the combined effects of heat-affected zone liquation cracking and solidification cracking. Scanning electron microscopic analysis of the fractured surface revealed patches of low-melting eutectic. The cracking is influenced to a great extent by the fusion zone microstructure and thorium content. The alloy has been welded with a continuous-wave high-power CO 2 laser system with beam power ranging from 5 to 10 kW and welding speeds of 8 to 25 mm/s. Successful laser welds without hot cracking have been obtained in this particular alloy. This is attributable to the highly concentrated heat source available in the laser beam and the refinement in fusion zone microstructure obtained during laser welding. Efforts to refine the fusion zone structure during gas tungsten-arc welding of Ir-0.3 % W alloy containing 60 wt ppM Th were partially successful. Here transverse arc oscillation during gas tungsten-arc welding refines the fusion zone structure to a certain extent. However, microstructural analysis of this alloy's laser welds indicates further refinement in the fusion zone microstructure than in that from the gas tungsten-arc process using arc oscillations. The fusion zone structure of the laser weld is a strong function of welding speed

Narrow gap mechanised arc welding in nuclear components manufactured by AREVA NP

International Nuclear Information System (INIS)

Peigney, A.

2007-01-01

Nuclear components require welds of irreproachable and reproducible quality. Moreover, for a given welding process, productivity requirements lead to reduce the volume of deposited metal and thus to use narrow gap design. In the shop, narrow gap Submerged Arc Welding process (SAW) is currently used on rotating parts in flat position for thicknesses up to 300 mm. Welding is performed with one or two wires in two passes per layer. In Gas Tungsten Arc Welding process (GTAW), multiple applications can be found because this process presents the advantage of allowing welding in all positions. Welding is performed in one or two passes per layer. The process is used in factory and on the nuclear sites for assembling new components but also for replacing components and for repairs. Presently, an increase of productivity of the process is sought through the use of hot wire and/or two wires. Concerning Gas Metal Arc Welding process (GMAW), its use is growing for nuclear components, including narrow gap applications. This process, limited in its applications in the past on account of the defects it generated, draws benefit from the progress of the welding generators. Then it is possible to use this efficient process for high security components such as those of nuclear systems. It is to be noted that the process is applicable in the various welding positions as it is the case for GTAW, while being more efficient than the latter. This paper presents the state of the art in the use of narrow gap mechanised arc welding processes by AREVA NP units. (author) [fr

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

Directory of Open Access Journals (Sweden)

Yakup Kaya

2013-01-01

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

Use of refractory chromites for obtaining fluxes amassed employed in submerged arc welding (SAW); Empleo de cromitas refractarias par la obtencion de fundentes aglomerados utilizados en la soldadura automatica por arco sumegido (SAW)

Energy Technology Data Exchange (ETDEWEB)

Perdomo-Gonzalez, L.; Quintana-Puchol, R.; Cruz-Crespo, A.; Castellanos-Estupinan, J.; Garcia-Sanchez, L. L.; Formoso-Prego, A.; Cores-Sanchez, A.

2003-07-01

In the present work high carbon ferrochrome (load ferrochrome) and slags are obtained, starting from the metallurgic reductive processing of refractory chromites. The obtaining of alloys and slags is studied using an experiment design based in the relationships among components. The chemical compositions of alloys and slags guarantee their application for the conformation of alloys loads and matrix fluxes amassed for the superficial filling by means of submerged arc welding (SAW). The melting-reduction process is carried out in an electric arc furnace. (Author) 16 refs.

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...

Welding technologies for nuclear machinery and equipment

International Nuclear Information System (INIS)

Kobayashi, Masahiro; Yokono, Tomomi.

1991-01-01

The main welding methods applied to nuclear machinery and equipment are shielded metal arc welding, submerged arc welding, MAG welding and TIG welding. But in the last 10 years, in order to improve the reliability required for the welding of nuclear machinery and equipment, the welding technologies aiming at the reduction of heat input, the decrease of the number of welding pass and the automatic control of welding factors have been applied for the main purpose of bettering the quality and excluding human errors. The merits and the technology of narrow gap, pulsed MAG welding and melt-through welding are explained. As the automation of TIG welding, image processing type narrow gap, hot wire TIG welding and remote control type automatic TIG welding are described. For the longitudinal welding of active metal sheet products, plasma key-hole welding is applied. Since the concentration of its arc is good, high speed welding with low heat input can be done. For the stainless steel cladding by welding, electroslag welding has become to be employed in place of conventional submerged arc welding. Arc is not generated in the electroslag welding, and the penetration into base metal is small. (K.I.)

Effects of irradiation on initiation and crack-arrest toughness of two high-copper welds and on stainless steel cladding

International Nuclear Information System (INIS)

Nanstad, R.K.; Iskander, S.K.; Haggag, F.M.

1990-01-01

The objective of the study on the high-copper welds is to determine the effect of neutron irradiation on the shift and shape of the ASME K Ic and K Ia toughness curves. Two submerged-arc welds with copper contents of 0.23 and 0.31 wt % were commercially fabricated in 220-mm-thick plate. Compact specimens fabricated from these welds were irradiated at a nominal temperature of 288 degree C to fluences from 1.5 to 1.9 x 10 19 neutrons/cm 2 (>1 MeV). The fracture toughness test results show that the irradiation-induced shifts at 100 MPa/m were greater than the Charpy 41-J shifts by about 11 and 18 degree C. Mean curve fits indicate mixed results regarding curve shape changes, but curves constructed as lower boundaries to the data do indicate curves of lower slopes. A preliminary evaluation of the crack-arrest results shows that the neutron-irradiation induced crack-arrest toughness temperature shift is about the same as the Charpy V-notch impact temperature shift at the 41-J energy level. The shape of the lower bound curves (for the range of test temperatures covered), compared to those of the ASME K Ia curve did not appear to have been altered by the irradiation. Three-wire stainless steel weld overlay cladding was irradiated at 288 degree C to fluences of 2 and 5 x 10 19 neutrons/cm 2 (>1 MeV). Charpy 41-J temperature shifts of 13 and 28 degree C were observed, respectively. For the lower fluence only, 12.7-mm thick compact specimens showed decreases in both J Ic and the tearing modulus. Comparison of the fracture toughness results with typical plate and a low upper-shelf weld reveals that the irradiated stainless steel cladding possesses low ductile initiation fracture toughness comparable to the low upper-shelf weld. 8 refs., 12 figs., 2 tabs

Characterization of magnetically impelled arc butt welded T11 tubes for high pressure applications

Directory of Open Access Journals (Sweden)

R. Sivasankari

2015-09-01

Full Text Available Magnetically impelled arc butt (MIAB welding is a pressure welding process used for joining of pipes and tubes with an external magnetic field affecting arc rotation along the tube circumference. In this work, MIAB welding of low alloy steel (T11 tubes were carried out to study the microstructural changes occurring in thermo-mechanically affected zone (TMAZ. To qualify the process for the welding applications where pressure could be up to 300 bar, the MIAB welds are studied with variations of arc current and arc rotation time. It is found that TMAZ shows higher hardness than that in base metal and displays higher weld tensile strength and ductility due to bainitic transformation. The effect of arc current on the weld interface is also detailed and is found to be defect free at higher values of arc currents. The results reveal that MIAB welded samples exhibits good structural property correlation for high pressure applications with an added benefit of enhanced productivity at lower cost. The study will enable the use of MIAB welding for high pressure applications in power and defence sectors.

Arc-weld pool interactions

International Nuclear Information System (INIS)

Glickstein, S.S.

1978-08-01

The mechanisms involved in arc-weld pool interactions are extremely complex and no complete theory is presently available to describe much of the phenomena observed during welding. For the past several years, experimental and analytical studies have been undertaken at the Bettis Atomic Power Laboratory to increase basic understanding of the gas tungsten arc welding process. These studies have included experimental spectral analysis of the arc in order to determine arc temperature and analytical modeling of the arc and weld puddle. The investigations have been directed toward determining the cause and effects of variations in the energy distribution incident upon the weldment. In addition, the effect of weld puddle distortion on weld penetration was investigated, and experimental and analytical studies of weld process variables have been undertaken to determine the effects of the variables upon weld penetration and configuration. A review of the results and analysis of these studies are presented

Electron beam welding of high-purity copper accelerator cells

International Nuclear Information System (INIS)

Delis, K.; Haas, H.; Schlebusch, P.; Sigismund, E.

1986-01-01

The operating conditions of accelerator cells require high thermal conductivity, low gas release in the ultrahigh vacuum, low content of low-melting metals and an extremely good surface quality. In order to meet these requirements, high-purity copper (OFHC, Grade 1, according to ASTM B 170-82 and extra specifications) is used as structural material. The prefabricated components of the accelerator cells (noses, jackets, flanges) are joined by electron beam welding, the weld seam being assessed on the basis of the same criteria as the base material. The welding procedures required depend, first, on the material and, secondly, on the geometries involved. Therefore experimental welds were made first on standardized specimens in order to study the behaviour of the material during electron beam welding and the influence of parameter variations. The welded joints of the cell design were planned on the basis of these results. Seam configuration, welding procedures and the parameters were optimized on components of original geometry. The experiments have shown that high-quality joints of this grade of copper can be produced by the electron beam welding process, if careful planning and preparation of the seams and adequate containment of the welding pool are assured. (orig.)

Physical characteristics of welding arc ignition process

Science.gov (United States)

Shi, Linan; Song, Yonglun; Xiao, Tianjiao; Ran, Guowei

2012-07-01

The existing research of welding arc mainly focuses on the stable combustion state and the research on the mechanism of welding arc ignition process is quite lack. The tungsten inert gas(TIG) touch arc ignition process is observed via a high speed camera and the high time resolution spectral diagnosis system. The changing phenomenon of main ionized element provided the electrons in the arc ignition is found. The metallic element is the main contributor to provide the electrons at the beginning of the discharging, and then the excitated shielding gas element replaces the function of the metallic element. The electron density during the period of the arc ignition is calculated by the Stark-broadened lines of Hα. Through the discussion with the repeatability in relaxation phenomenon, the statistical regularity in the arc ignition process is analyzed. The similar rules as above are observed through the comparison with the laser-assisted arc ignition experiments and the metal inert gas(MIG) arc ignition experiments. This research is helpful to further understanding on the generation mechanism of welding arc ignition and also has a certain academic and practical significance on enriching the welding physical theoretical foundation and improving the precise monitoring on automatic arc welding process.

Metallurgical and mechanical examinations of steel–copper joints arc welded using bronze and nickel-base superalloy filler materials

International Nuclear Information System (INIS)

Velu, M.; Bhat, Sunil

2013-01-01

Highlights: ► Optical and scanning electron microscopy show defect free weld interfaces. ► Energy dispersive spectroscopy shows low dilution level of the weld by Fe. ► XRD studies show no brittle intermetallic phases in the weld interfaces. ► Weld interfaces did not fail during tensile, transverse bending and impact tests. ► The joint exhibits superior strength properties than that of bronze filler. - Abstract: The paper presents metallurgical and mechanical examinations of joints between dissimilar metals viz. copper (UNSC11000) and alloy steel (En31) obtained by Shielded Metal Arc Welding (SMAW) using two different filler materials, bronze and nickel-base super alloy. The weld bead of the joint with bronze-filler displayed porosity, while that with nickel-filler did not. In tension tests, the weldments with bronze-filler fractured in the centre of the weld, while those with nickel-filler fractured in the heat affected zone (HAZ) of copper. Since the latter exhibited higher strength than the former, all the major tests were undertaken over the joints with nickel-filler alone. Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS) indicated corrugated weld interfaces and favorable elemental diffusions across them. X-ray diffraction (XRD) studies around the weld interfaces did not reveal any detrimental intermetallic compounds. Transverse bending tests showed that flexural strengths of the weldments were higher than the tensile strengths. Transverse side bend tests confirmed good ductility of the joints. Shear strength of the weld-interface (Cu–Ni or Ni–steel) was higher than the yield strength of weaker metal. Microhardness and Charpy impact values were measured at all the important zones across the weldment

Study of electric arc welding of castings for nuclear power machine-building

International Nuclear Information System (INIS)

Rymkevich, A.I.; Korsunov, P.M.

1977-01-01

Mechanical and corrosion-resistance properties are studied of the welded joints of cast billets from steel 00Kh12N3DL by automatic submerged arc welding. It is shown by testing the joints made with preheating up to 100 deg C and subsequent tempering (620 deg C for 25 h + 640 deg C for 16 h) that in the temperature range of 20-350 deg C they possess fairly good strength, ductility, impact viscosity, and corrosion-resistance properties approximating the corresponding characteristics of the base metal. The welding technology developed can be used to make pump casings for atomic power equipment

Statistical analyses of fracture toughness results for two irradiated high-copper welds

International Nuclear Information System (INIS)

Nanstad, R.K.; McCabe, D.E.; Haggag, F.M.; Bowman, K.O.; Downing, D.J.

1990-01-01

The objectives of the Heavy-Section Steel Irradiation Program Fifth Irradiation Series were to determine the effects of neutron irradiation on the transition temperature shift and the shape of the K Ic curve described in Sect. 6 of the ASME Boiler and Pressure Vessel Code. Two submerged-arc welds with copper contents of 0.23 and 0.31% were commercially fabricated in 215-mm-thick plates. Charpy V-notch (CVN) impact, tensile, drop-weight, and compact specimens up to 203.2 mm thick [1T, 2T, 4T, 6T, and 8T C(T)] were tested to provide a large data base for unirradiated material. Similar specimens with compacts up to 4T were irradiated at about 288 degrees C to a mean fluence of about 1.5 x 10 19 neutrons/cm 2 (>1 MeV) in the Oak Ridge Research Reactor. Both linear-elastic and elastic-plastic fracture mechanics methods were used to analyze all cleavage fracture results and local cleavage instabilities (pop-ins). Evaluation of the results showed that the cleavage fracture toughness values determined at initial pop-ins fall within the same scatter band as the values from failed specimens; thus, they were included in the data base for analysis (all data are designated K Jc )

Further contribution to the study of buffer layer on austenitic stainless stell overlays obtained by means of automatic submerged arc welding with electrode-wire

International Nuclear Information System (INIS)

Colla, G.

1988-01-01

The influence of several buffer layer types on a 308 type austenitic stainless steel surface overlay having a 19-21% chromium and 10-12% nikel content have been analysed. Cladding passes have been deposited on carbon steel test samples by using automatic submerged arc welding process with electrode-wire. The experimental tests have involved buffer layers having seven different chemical compositions and the obtained results are reported and discussed in the paper. The achieved experimetal results allow selecting the most suitable buffer layer to be deposited in order to reach the required cladding performance in service

Narrow groove gas metal-arc welding of aluminum

International Nuclear Information System (INIS)

Armstrong, R.E.

1975-01-01

The Gas Metal-Arc (GMA) welding process is explained and the equipment used described with an analysis of power supply function and the action of the arc, followed by discussion of general applications and problems. GMA braze welding of beryllium is then described, as is the development of a special high purity filler wire and a narrow deep groove joint design for improved weld strength in beryllium. This joint design and the special wire are applied in making high strength welds in high strength aluminum for special applications. High speed motion pictures of the welding operation are shown to illustrate the talk. (auth)

Arc modeling for welding analysis

International Nuclear Information System (INIS)

Glickstein, S.S.

1978-04-01

A one-dimensional model of the welding arc that considers heat generation by the Joule effect and heat losses by radiation and conduction has been used to study the effects of various gases and gas mixtures currently employed for welding applications. Minor additions of low ionization potential impurities to these gases are shown to significantly perturb the electrical properties of the parent gas causing gross changes in the radial temperature distribution of the arc discharge. Such changes are reflected in the current density distribution and ultimately in the input energy distribution to the weldment. The result is observed as a variation in weld penetration. Recently published experiments and analyses of welding arcs are also evaluated and shown to contain erroneous data and results. Contrary to previous beliefs, the inclusion of a radiation loss term in the basic energy balance equation is important and cannot be considered as negligible in an argon arc at temperatures as low as 10,000 0 K. The one-dimensional analysis of the welding arc as well as the evaluation of these earlier published reports helps to explain the effects of various gases used for welding, improves our understanding of the physics of the welding arc, and provides a stepping stone for a more elaborate model which can be applied to help optimize welding parameters

Recent advances in the TIG welding process and the application of the welding of nuclear components

International Nuclear Information System (INIS)

Lucas, W.; Males, B.O.

1982-01-01

Recent advances in the field of precision arc welding techniques and infacilities for production of nuclear power plant components arc presented. Of the precision welding techniques, pulsed TIG welding, pulsed plasma arc welding, hot-wire TIG welding, and pulsed inert-gas metal-arc welding. In the field of weld cladding, GMA plasma welding is cited as an alternative to submerged-arc welding with a strip electrode. Transistors and computer-controlled welding systems get a special mention. Applications of TIG welding in the UK are cited, e.g. welding of components for the AGR nuclear power plant and construction of equipment for repair work in feedwater pipes of the MAGNOX reactor. (orig.) [de

Characterization of duplex stainless steel weld metals obtained by hybrid plasma-gas metal arc welding

OpenAIRE

Yurtisik,Koray; Tirkes,Suha; Dykhno,Igor; Gur,C. Hakan; Gurbuz,Riza

2013-01-01

Despite its high efficiency, autogenous keyhole welding is not well-accepted for duplex stainless steels because it causes excessive ferrite in as-welded duplex microstructure, which leads to a degradation in toughness and corrosion properties of the material. Combining the deep penetration characteristics of plasma arc welding in keyhole mode and metal deposition capability of gas metal arc welding, hybrid plasma - gas metal arc welding process has considered for providing a proper duplex mi...

Approximate entropy—a new statistic to quantify arc and welding process stability in short-circuiting gas metal arc welding

International Nuclear Information System (INIS)

Cao Biao; Xiang Yuanpeng; Lü Xiaoqing; Zeng Min; Huang Shisheng

2008-01-01

Based on the phase state reconstruction of welding current in short-circuiting gas metal arc welding using carbon dioxide as shielding gas, the approximate entropy of welding current as well as its standard deviation has been calculated and analysed to investigate their relation with the stability of electric arc and welding process. The extensive experimental and calculated results show that the approximate entropy of welding current is significantly and positively correlated with arc and welding process stability, whereas its standard deviation is correlated with them negatively. A larger approximate entropy and a smaller standard deviation imply a more stable arc and welding process, and vice versa. As a result, the approximate entropy of welding current promises well in assessing and quantifying the stability of electric arc and welding process in short-circuiting gas metal arc welding

Emissions of chromium (VI) from arc welding.

Science.gov (United States)

Heung, William; Yun, Myoung-Jin; Chang, Daniel P Y; Green, Peter G; Halm, Chris

2007-02-01

The presence of Cr in the +6 oxidation state (Cr[VI]) is still observed in ambient air samples in California despite steps taken to reduce emissions from plating operations. One known source of emission of Cr(VI) is welding, especially with high Cr-content materials, such as stainless steels. An experimental effort was undertaken to expand and update Cr(VI) emission factors by conducting tests on four types of arc-welding operations: gas-metal arc welding (GMAW), shielded metal arc welding (SMAW), fluxcore arc welding, and pulsed GMAW. Standard American Welding Society hood results were compared with a total enclosure method that permitted isokinetic sampling for particle size-cut measurement, as well as total collection of the aerosol. The fraction of Cr(VI) emitted per unit mass of Cr electrode consumed was determined. Consistent with AP-42 data, initial results indicate that a significant fraction of the total Cr in the aerosol is in the +6 oxidation state. The fraction of Cr(VI) and total aerosol mass produced by the different arc welding methods varies with the type of welding process used. Self-shielded electrodes that do not use a shield gas, for example, SMAW, produce greater amounts of Cr(VI) per unit mass of electrode consumed. The formation of Cr(VI) from standard electrode wires used for welding mild steel was below the method detection limit after eliminating an artifact in the analytical method used.

Single-purpose welding machines used in the manufacture of power equipment

International Nuclear Information System (INIS)

Bartak, J.

1988-01-01

A dedicated welding machine based on submerged arc welding with a wire electrode was developed for welding pipe sockets, spacers and other rotary parts to pressure vessel bodies. Two modifications of this apparatus were devised: one is designed for welding low-alloy carbon steels, where preheating is requisite, the other, for welding austenitic materials, requiring vigorous cooling. The single-purpose ADFS-1 device is designed for surfacing rings 200 to 1200 mm in diameter; it consists of a pillar with a drive, a rotary console, a collector, a horizontal support, a console with a vertical motor support, and a welding head with a feed equipment. Submerged arc welding using a 20x0.5 mm strip electrode is applied. Another dedicated welding machine employing submerged arc welding with a strip electrode was developed for the continuous welding of inner surfaces of pressure vessels in the sites of holes for flares. (Z.M.). 3 figs., 3 refs

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...

Welding processes handbook

CERN Document Server

Weman, Klas

2011-01-01

Offers an introduction to the range of available welding technologies. This title includes chapters on individual techniques that cover principles, equipment, consumables and key quality issues. It includes material on such topics as the basics of electricity in welding, arc physics, and distortion, and the weldability of particular metals.$bThe first edition of Welding processes handbook established itself as a standard introduction and guide to the main welding technologies and their applications. This new edition has been substantially revised and extended to reflect the latest developments. After an initial introduction, the book first reviews gas welding before discussing the fundamentals of arc welding, including arc physics and power sources. It then discusses the range of arc welding techniques including TIG, plasma, MIG/MAG, MMA and submerged arc welding. Further chapters cover a range of other important welding technologies such as resistance and laser welding, as well as the use of welding techniqu...

Effect of pulsed current and post weld aging treatment on tensile properties of argon arc welded high strength aluminium alloy

International Nuclear Information System (INIS)

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

2007-01-01

This paper reveals the effect of pulsed current and post weld aging treatment on tensile properties of argon arc welded AA7075 aluminium alloy. This alloy has gathered wide acceptance in the fabrication of light weight structures requiring high strength-to-weight ratio, such as transportable bridge girders, military vehicles, road tankers and railway transport systems. The preferred welding processes of high strength aluminium alloy are frequently gas tungsten arc welding (GTAW) process and gas metal arc welding (GMAW) process due to their comparatively easier applicability and better economy. Weld fusion zones typically exhibit coarse columnar grains because of the prevailing thermal conditions during weld metal solidification. This often results inferior weld mechanical properties and poor resistance to hot cracking. In this investigation, an attempt has been made to refine the fusion zone grains by applying pulsed current welding technique. Four different welding techniques have been used to fabricate the joints and they are: (i) continuous current GTAW (CCGTAW), (ii) pulsed current GTAW (PCGTAW), (iii) continuous current GMAW (CCGMAW) and (iv) pulsed current GMAW (PCGMAW) processes. As welded joint strength is much lower than the base metal strength and hence, a simple aging treatment has been given to improve the tensile strength of the joints. Current pulsing leads to relatively finer and more equi-axed grain structure in GTA and GMA welds. In contrast, conventional continuous current welding resulted in predominantly columnar grain structures. Post weld aging treatment is accompanied by an increase in tensile strength and tensile ductility

Boosting Active Contours for Weld Pool Visual Tracking in Automatic Arc Welding

DEFF Research Database (Denmark)

Liu, Jinchao; Fan, Zhun; Olsen, Søren Ingvor

2015-01-01

Detecting the shape of the non-rigid molten metal during welding, so-called weld pool visual sensing, is one of the central tasks for automating arc welding processes. It is challenging due to the strong interference of the high-intensity arc light and spatters as well as the lack of robust...... approaches to detect and represent the shape of the nonrigid weld pool. We propose a solution using active contours including an prior for the weld pool boundary composition. Also, we apply Adaboost to select a small set of features that captures the relevant information. The proposed method is applied...... to weld pool tracking and the presented results verified its feasibility....

Automatic Control Of Length Of Welding Arc

Science.gov (United States)

Iceland, William F.

1991-01-01

Nonlinear relationships among current, voltage, and length stored in electronic memory. Conceptual microprocessor-based control subsystem maintains constant length of welding arc in gas/tungsten arc-welding system, even when welding current varied. Uses feedback of current and voltage from welding arc. Directs motor to set position of torch according to previously measured relationships among current, voltage, and length of arc. Signal paths marked "calibration" or "welding" used during those processes only. Other signal paths used during both processes. Control subsystem added to existing manual or automatic welding system equipped with automatic voltage control.

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.

Electromagnetic characteristic of twin-wire indirect arc welding

Science.gov (United States)

Shi, Chuanwei; Zou, Yong; Zou, Zengda; Wu, Dongting

2015-01-01

Traditional welding methods are limited in low heat input to workpiece and high welding wire melting rate. Twin-wire indirect arc(TWIA) welding is a new welding method characterized by high melting rate and low heat input. This method uses two wires: one connected to the negative electrode and another to the positive electrode of a direct-current(DC) power source. The workpiece is an independent, non-connected unit. A three dimensional finite element model of TWIA is devised. Electric and magnetic fields are calculated and their influence upon TWIA behavior and the welding process is discussed. The results show that with a 100 A welding current, the maximum temperature reached is 17 758 K, arc voltage is 14.646 V while maximum current density was 61 A/mm2 with a maximum Lorene force of 84.5 μN. The above mentioned arc parameters near the cathode and anode regions are far higher than those in the arc column region. The Lorene force is the key reason for plasma velocity direction deviated and charged particles flowed in the channel formed by the cathode, anode and upper part of arc column regions. This led to most of the energy being supplied to the polar and upper part of arc column regions. The interaction between electric and magnetic fields is a major determinant in shaping TWIA as well as heat input on the workpiece. This is a first study of electromagnetic characteristics and their influences in the TWIA welding process, and it is significant in both a theoretical and practical sense.

Characterization of duplex stainless steel weld metals obtained by hybrid plasma-gas metal arc welding

Directory of Open Access Journals (Sweden)

Koray Yurtisik

2013-09-01

Full Text Available Despite its high efficiency, autogenous keyhole welding is not well-accepted for duplex stainless steels because it causes excessive ferrite in as-welded duplex microstructure, which leads to a degradation in toughness and corrosion properties of the material. Combining the deep penetration characteristics of plasma arc welding in keyhole mode and metal deposition capability of gas metal arc welding, hybrid plasma - gas metal arc welding process has considered for providing a proper duplex microstructure without compromising the welding efficiency. 11.1 mm-thick standard duplex stainless steel plates were joined in a single-pass using this novel technique. Same plates were also subjected to conventional gas metal arc and plasma arc welding processes, providing benchmarks for the investigation of the weldability of the material. In the first place, the hybrid welding process enabled us to achieve less heat input compared to gas metal arc welding. Consequently, the precipitation of secondary phases, which are known to be detrimental to the toughness and corrosion resistance of duplex stainless steels, was significantly suppressed in both fusion and heat affected zones. Secondly, contrary to other keyhole techniques, proper cooling time and weld metal chemistry were achieved during the process, facilitating sufficient reconstructive transformation of austenite in the ferrite phase.

Electric arc welding gun

Science.gov (United States)

Luttrell, Edward; Turner, Paul W.

1978-01-01

This invention relates to improved apparatus for arc welding an interior joint formed by intersecting tubular members. As an example, the invention is well suited for applications where many similar small-diameter vertical lines are to be welded to a long horizontal header. The improved apparatus includes an arc welding gun having a specially designed welding head which is not only very compact but also produces welds that are essentially free from rolled-over solidified metal. The welding head consists of the upper end of the barrel and a reversely extending electrode holder, or tip, which defines an acute angle with the barrel. As used in the above-mentioned example, the gun is positioned to extend upwardly through the vertical member and the joint to be welded, with its welding head disposed within the horizontal header. Depending on the design of the welding head, the barrel then is either rotated or revolved about the axis of the vertical member to cause the electrode to track the joint.

Transition welds in welding of two-ply steels

International Nuclear Information System (INIS)

Fartushnyj, V.G.; Evsyukov, Yu.G.

1977-01-01

Studied were physico-mechanical properties of welds made by various welding wires of chromium-nickel and nickel-chromium steels in submerged arc welding of double-layer steels with main layer of the VSt.3sp. carbon steel. It is shown that service-reliable structures welded of two-layer steels are obtained by providing the content from 11 to 20 % Ni in the automatically welded transition layer

Thermocapillary and arc phenomena in stainless steel welds

Energy Technology Data Exchange (ETDEWEB)

Pierce, Stanley W. [Colorado School of Mines, Golden, CO (United States)

1993-01-01

Goal was to study effect of power level and distribution on thermocapiilary-induced weld shape and of arc factors on weld shape. Thermocapillarity was apparent in both conduction mode EB welds and GTA welds, particularly in the former. A non-Gaussian arc distribution is suggested for accounting for the differences between the twoss processes. At higher current levels (200--300 A), plasma shear force also contributes to weld shape development. Evidence suggests that thermocapillary flow reversal is not a factor in normal GTA welds; EDB flow reversal occurs only at high power density levels where the keyhole mode is present.

Automatic welding processes for reactor coolant pipes used in PWR type nuclear power plant

International Nuclear Information System (INIS)

Hamada, T.; Nakamura, A.; Nagura, Y.; Sakamoto, N.

1979-01-01

The authors developed automatic welding processes (submerged arc welding process and TIG welding process) for application to the welding of reactor coolant pipes which constitute the most important part of the PWR type nuclear power plant. Submerged arc welding process is suitable for flat position welding in which pipes can be rotated, while TIG welding process is suitable for all position welding. This paper gives an outline of the two processes and the results of tests performed using these processes. (author)

Arc Interference Behavior during Twin Wire Gas Metal Arc Welding Process

Directory of Open Access Journals (Sweden)

Dingjian Ye

2013-01-01

Full Text Available In order to study arc interference behavior during twin wire gas metal arc welding process, the synchronous acquisition system has been established to acquire instantaneous information of arc profile including dynamic arc length variation as well as relative voltage and current signals. The results show that after trailing arc (T-arc is added to the middle arc (M-arc in a stable welding process, the current of M arc remains unchanged while the agitation increases; the voltage of M arc has an obvious increase; the shape of M arc changes, with increasing width, length, and area; the transfer frequency of M arc droplet increases and the droplet itself becomes smaller. The wire extension length of twin arc turns out to be shorter than that of single arc welding.

Simultaneous obtention of multicomponent ferroalloy and slag from black sands for the development of electrical arc welding consumables

International Nuclear Information System (INIS)

Cruz-Crespo, A.; Gomez-Rodriguez, L.; Garcia-Sanchez, L. L.; Quintana-Puchol, R.; Cerpa-Naranjo, A.; Cores-Sanchez, A.

2004-01-01

In this paper, chemical and mineralogical characterizations of the black sands of the Mejias placer of Sagua de Tanamo (the most important beach littoral placer of the northwest of oriental Cuba) are exposed. Starting from these characterizations a calculation strategy is developed for the making of the metallurgical load that allows to obtain simultaneously, when processed by carbothermic reduction in an electrical arc furnace, a multicomponent ferroalloy and a useful slag for the making of electric arch welding consumables. The powder of the obtained slag is agglomerated with liquid glass. The resulting pellets, due to their behavior on the submerged arc welding (SAW) present technological and metallurgical properties that correspond with the requirements of an agglomerated flux matrix. The chemical composition of the multicomponent ferroalloy is constituted by metallic elements of high metallurgical and alloyed values (V, Cr, Mo, Ti, Nb). It is appropriate for the formulation of consumables for manual welding (SMAW) and SAW, as well. (Author) 15 refs

Welding robot package; Arc yosetsu robot package

Energy Technology Data Exchange (ETDEWEB)

Nishikawa, S. [Yaskawa Electric Corp., Kitakyushu (Japan)

1998-09-01

For the conventional high-speed welding robot, the welding current was controlled mainly for reducing the spatters during short circuits and for stabilizing the beads by the periodic short circuits. However, an increase of deposition amount in response to the speed is required for the high-speed welding. Large-current low-spatter welding current region control was added. Units were integrated into a package by which the arc length is kept in short without dispersion of arc length for welding without defects such as undercut and unequal beads. In automobile industry, use of aluminum parts is extended for the light weight. The welding is very difficult, and automation is not so progressing in spite of the poor environment. Buckling of welding wire is easy to occur, and supply of wire is obstructed by the deposition of chipped powders on the torch cable, which stay within the contact chip resulting in the deposition. Dislocation of locus is easy to occur at the corner of rectangular pipe during the welding. By improving these troubles, an aluminum MIG welding robot package has been developed. 13 figs.

effect of post-weld heat treatment on the microstructure

African Journals Online (AJOL)

user

while the hardness, toughness and tensile properties of the samples were determined by using Indentec universal hardness testing ... submerge arc welding, gas metal arc welding, plasma ..... [4] Vijendra Singh, Physical Metallurgy, Standard.

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.

The influence of TIG-Arc physical characteristics on the penetration and weld width under different Ar and He supply conditions

Science.gov (United States)

Dai, Hongbin; Shen, Xiuqiang; Wang, Haoran

2018-06-01

In the paper, the 5A03 aluminium alloy was employed to study the influence of TIG arc on the penetration and the weld width. And the split anode method with water-cooled copper plate was used to measure and record the distribution of arc current, under different flow ratio of argon and helium conditions. And a gas supply device controlled by a solenoid valve was employed to obtain the stable TIG welding arc of gas supply alternately at the frequency of 1 Hz and 4 Hz, and then collected the phenomenon of arc alternate by the high-speed camera. The experimental results indicated that the current density at the arc anode center of argon and helium supply alternately with different mixing ratio is lower than that of the pure argon-arc center. Nonetheless, the former is more uniform in current density within 2 mm from the arc center. Furthermore, it presented as a component arc of argon-arc and helium-arc switched, with the condition of argon and helium supply alternately at a frequency of 1 Hz and the arc power density is greater and concentrated, leading to the wider and deeper weld.

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)

Liquid Metal Oscillation and Arc Behaviour during Welding

NARCIS (Netherlands)

Yudodibroto, B.Y.B.

2010-01-01

The purpose of this research is to obtain insight into the oscillation behaviour of the liquid metal and the arc behaviour during GMA welding. Observations of the weld pool and the arc were undertaken by visual means using a high-speed video and by analysis of the voltage. To deal with the complex

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

Directory of Open Access Journals (Sweden)

Sivaraman Arunkumar

2016-09-01

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

Comparison of Welding Residual Stresses of Hybrid Laser-Arc Welding and Submerged Arc Welding in Offshore Steel Structures

DEFF Research Database (Denmark)

Andreassen, Michael Joachim; Yu, Zhenzhen; Liu, Stephen

2016-01-01

In the offshore industry, welding-induced distortion and tensile residual stresses have become a major concern in relation to the structural integrity of a welded structure. Particularly, the continuous increase in size of welded plates and joints needs special attention concerning welding induced...... residual stresses. These stresses have a negative impact on the integrity of the welded joint as they promote distortion, reduce fatigue life, and contribute to corrosion cracking and premature failure in the weld components. This paper deals with the influence and impact of welding method on the welding...... induced residual stresses. It is also investigated whether the assumption of residual stresses up to yield strength magnitude are present in welded structures as stated in the design guidelines. The fatigue strength for welded joints is based on this assumption. The two welding methods investigated...

PC-based arc ignition and arc length control system for gas tungsten arc welding

International Nuclear Information System (INIS)

Liu, Y.; Cook, G.E.; Barnett, R.J.; Springfield, J.F.

1992-01-01

In this paper, a PC-based digital control system for gas tungsten arc welding (GTAW) is presented. This system controls the arc ignition process, the arc length, and the process of welding termination. A DT2818 made by Data Translation is used for interface and A/D and D/A conversions. The digital I/O ports of the DT2818 are used for control of wirefeed, shield gas, cooling water, welding power supply, etc. The DT2818 is housed in a PC. The welding signals and status are displayed on the screen for in-process monitoring. A user can control the welding process by the keyboard

29 CFR 1910.254 - Arc welding and cutting.

Science.gov (United States)

2010-07-01

... 29 Labor 5 2010-07-01 2010-07-01 false Arc welding and cutting. 1910.254 Section 1910.254 Labor... OCCUPATIONAL SAFETY AND HEALTH STANDARDS Welding, Cutting and Brazing § 1910.254 Arc welding and cutting. (a... following limits shall not be exceeded: (i) Alternating-current machines (A) Manual arc welding and cutting...

Process stability during fiber laser-arc hybrid welding of thick steel plates

Science.gov (United States)

Bunaziv, Ivan; Frostevarg, Jan; Akselsen, Odd M.; Kaplan, Alexander F. H.

2018-03-01

Thick steel plates are frequently used in shipbuilding, pipelines and other related heavy industries, and are usually joined by arc welding. Deep penetration laser-arc hybrid welding could increase productivity but has not been thoroughly investigated, and is therefore usually limited to applications with medium thickness (5-15 mm) sections. A major concern is process stability, especially when using modern welding consumables such as metal-cored wire and advanced welding equipment. High speed imaging allows direct observation of the process so that process behavior and phenomena can be studied. In this paper, 45 mm thick high strength steel was welded (butt joint double-sided) using the fiber laser-MAG hybrid process utilizing a metal-cored wire without pre-heating. Process stability was monitored under a wide range of welding parameters. It was found that the technique can be used successfully to weld thick sections with appropriate quality when the parameters are optimized. When comparing conventional pulsed and the more advanced cold metal transfer pulse (CMT+P) arc modes, it was found that both can provide high quality welds. CMT+P arc mode can provide more stable droplet transfer over a limited range of travel speeds. At higher travel speeds, an unstable metal transfer mechanism was observed. Comparing leading arc and trailing arc arrangements, the leading arc configuration can provide higher quality welds and more stable processing at longer inter-distances between the heat sources.

Forming Completely Penetrated Welded T-joints when Pulsed Arc Welding

Science.gov (United States)

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

2016-04-01

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

Automatic welding and cladding in heavy fabrication

International Nuclear Information System (INIS)

Altamer, A. de

1980-01-01

A description is given of the automatic welding processes used by an Italian fabricator of pressure vessels for petrochemical and nuclear plant. The automatic submerged arc welding, submerged arc strip cladding, pulsed TIG, hot wire TIG and MIG welding processes have proved satisfactory in terms of process reliability, metal deposition rate, and cost effectiveness for low alloy and carbon steels. An example shows sequences required during automatic butt welding, including heat treatments. Factors which govern satisfactory automatic welding include automatic anti-drift rotator device, electrode guidance and bead programming system, the capability of single and dual head operation, flux recovery and slag removal systems, operator environment and controls, maintaining continuity of welding and automatic reverse side grinding. Automatic welding is used for: joining vessel sections; joining tubes to tubeplate; cladding of vessel rings and tubes, dished ends and extruded nozzles; nozzle to shell and butt welds, including narrow gap welding. (author)

49 CFR 195.226 - Welding: Arc burns.

Science.gov (United States)

2010-10-01

... 49 Transportation 3 2010-10-01 2010-10-01 false Welding: Arc burns. 195.226 Section 195.226 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... PIPELINE Construction § 195.226 Welding: Arc burns. (a) Each arc burn must be repaired. (b) An arc burn may...

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.

Stud arc welding in a magnetic field – Investigation of the influences on the arc motion

International Nuclear Information System (INIS)

Hartz-Behrend, K; Forster, G; Schein, J; Marqués, J L; Jenicek, A; Müller, M; Cramer, H; Jilg, A; Soyer, H

2014-01-01

Stud arc welding is widely used in the construction industry. For welding of studs with a diameter larger than 14 mm a ceramic ferrule is usually necessary in order to protect the weld pool. Disadvantages of using such a ferrule are that more metal is molten than necessary for a high quality welded joint and that the ferrule is a consumable generally thrown away after the welding operation. Investigations show that the ferrule can be omitted when the welding is carried out in a radially symmetric magnetic field within a shielding gas atmosphere. Due to the Lorentz force the arc is laterally shifted so that a very uniform and controlled melting of the stud contact surface as well as of the work piece can be achieved. In this paper a simplified physical model is presented describing how the parameters welding current, flux density of the magnetic field, radius of the arc and mass density of the shielding gas influence the velocity of the arc motion. The resulting equation is subsequently verified by comparing it to optical measurements of the arc motion. The proposed model can be used to optimize the required field distribution for the magnetic field stud welding process

The Mechanism of Ultrasonic Vibration on Grain Refining and Degassing in GTA Spot Welding of Copper Joints.

Science.gov (United States)

Al-Ezzi, Salih; Quan, Gaofeng; Elrayah, Adil

2018-05-07

This paper examines the effect of ultrasonic vibration (USV) on grain size and interrupted porosity in Gas Tungsten Arc (GTA) spot-welded copper. Grain size was refined by perpendicularly attaching a transducer to the welded sheet and applying USV to the weld pool for a short time (0, 2, 4, and 6 s) in addition improvements to the degassing process. Results illustrate a significant reduction of grain size (57%). Notably, USV provided interaction between reformations (fragmentation) and provided nucleation points (detaching particles from the fusion line) for grains in the nugget zone and the elimination of porosity in the nugget zone. The GTA spot welding process, in conjunction with USV, demonstrated an improvement in the corrosion potential for a copper spot-welded joint in comparison to the joint welded without assistance of USV. Finally, welding of copper by GTA spot welding in conjunction with ultrasound for 2 s presented significant mechanical properties.

Interactions between laser and arc plasma during laser-arc hybrid welding of magnesium alloy

Science.gov (United States)

Liu, Liming; Chen, Minghua

2011-09-01

This paper presents the results of the investigation on the interactions between laser and arc plasma during laser-arc hybrid welding on magnesium alloy AZ31B using the spectral diagnose technique. By comparably analyzing the variation in plasma information (the shape, the electron temperature and density) of single tungsten inert gas (TIG) welding with the laser-arc hybrid welding, it is found that the laser affects the arc plasma through the keyhole forming on the workpiece. Depending on the welding parameters there are three kinds of interactions taking place between laser and arc plasma.

MAGNETIC ARC WELDING STABILIZATION USING NON-CONSUMABLE ELECTRODE

Directory of Open Access Journals (Sweden)

Павло Юрійович Сидоренко

2017-06-01

Full Text Available Results of development torch to magnetically operated   welding arc are defined. Changing the design of the electrode unit is provided the ability to create within the area of the arc magnetic field and induction given configuration without additional equipment. The features of the arc in an axial magnetic field which make it possible to avoid the welding process of unsteady abnormalities resulted in the inappropriate formation of defects in welds. Significant increase in the depth of  weld penetration is connected with the more concentrated magnetically operated   welding arc transmission energy to the product. It is concluded about the feasibility of using a designed torch for the implementation of modern technological processes non-consumable electrode welding.

[Study on the arc spectral information for welding quality diagnosis].

Science.gov (United States)

Li, Zhi-Yong; Gu, Xiao-Yan; Li, Huan; Yang, Li-Jun

2009-03-01

Through collecting the spectral signals of TIG and MIG welding arc with spectrometer, the arc light radiations were analyzed based on the basic theory of plasma physics. The radiation of welding arc distributes over a broad range of frequency, from infrared to ultraviolet. The arc spectrum is composed of line spectra and continuous spectra. Due to the variation of metal density in the welding arc, there is great difference between the welding arc spectra of TIG and MIG in both their intensity and distribution. The MIG welding arc provides more line spectra of metal and the intensity of radiation is greater than TIG. The arc spectrum of TIG welding is stable during the welding process, disturbance factors that cause the spectral variations can be reflected by the spectral line related to the corresponding element entering the welding arc. The arc spectrum of MIG welding will fluctuate severely due to droplet transfer, which produces "noise" in the line spectrum aggregation zone. So for MIG welding, the spectral zone lacking spectral line is suitable for welding quality diagnosis. According to the characteristic of TIG and MIG, special spectral zones were selected for welding quality diagnosis. For TIG welding, the selected zone is in ultraviolet zone (230-300 nm). For MIG welding, the selected zone is in visible zone (570-590 nm). With the basic theory provided for welding quality diagnosis, the integral intensity of spectral signal in the selected zone of welding process with disturbing factor was studied to prove the theory. The results show that the welding quality and disturbance factors can be diagnosed with good signal to noise ratio in the selected spectral zone compared with signal in other spectral zone. The spectral signal can be used for real-time diagnosis of the welding quality.

Influence of the arc plasma parameters on the weld pool profile in TIG welding

Science.gov (United States)

Toropchin, A.; Frolov, V.; Pipa, A. V.; Kozakov, R.; Uhrlandt, D.

2014-11-01

Magneto-hydrodynamic simulations of the arc and fluid simulations of the weld pool can be beneficial in the analysis and further development of arc welding processes and welding machines. However, the appropriate coupling of arc and weld pool simulations needs further improvement. The tungsten inert gas (TIG) welding process is investigated by simulations including the weld pool. Experiments with optical diagnostics are used for the validation. A coupled computational model of the arc and the weld pool is developed using the software ANSYS CFX. The weld pool model considers the forces acting on the motion of the melt inside and on the surface of the pool, such as Marangoni, drag, electromagnetic forces and buoyancy. The experimental work includes analysis of cross-sections of the workpieces, highspeed video images and spectroscopic measurements. Experiments and calculations have been performed for various currents, distances between electrode and workpiece and nozzle diameters. The studies show the significant impact of material properties like surface tension dependence on temperature as well as of the arc structure on the weld pool behaviour and finally the weld seam depth. The experimental weld pool profiles and plasma temperatures are in good agreement with computational results.

Influence of the arc plasma parameters on the weld pool profile in TIG welding

International Nuclear Information System (INIS)

Toropchin, A; Frolov, V; Pipa, A V; Kozakov, R; Uhrlandt, D

2014-01-01

Magneto-hydrodynamic simulations of the arc and fluid simulations of the weld pool can be beneficial in the analysis and further development of arc welding processes and welding machines. However, the appropriate coupling of arc and weld pool simulations needs further improvement. The tungsten inert gas (TIG) welding process is investigated by simulations including the weld pool. Experiments with optical diagnostics are used for the validation. A coupled computational model of the arc and the weld pool is developed using the software ANSYS CFX. The weld pool model considers the forces acting on the motion of the melt inside and on the surface of the pool, such as Marangoni, drag, electromagnetic forces and buoyancy. The experimental work includes analysis of cross-sections of the workpieces, highspeed video images and spectroscopic measurements. Experiments and calculations have been performed for various currents, distances between electrode and workpiece and nozzle diameters. The studies show the significant impact of material properties like surface tension dependence on temperature as well as of the arc structure on the weld pool behaviour and finally the weld seam depth. The experimental weld pool profiles and plasma temperatures are in good agreement with computational results

Mathematical Modeling of Metal Active Gas (MAG) Arc Welding

Institute of Scientific and Technical Information of China (English)

无

2001-01-01

In the present paper, a numerical model for MAG (metal active gas) arc welding of thin plate has been developed. In MAG arc welding, the electrode wire is melted and supplied into the molten pool intermittently. Accordingly, it is assumed on the modeling that the thermal energy enters the base-plates through two following mechanisms, i.e., direct heating from arc plasma and “indirect” heating from the deposited metal. In the second part of the paper, MAG arc welding process is numerically analyzed by using the model, and the calculated weld bead dimension and surface profile have been compared with the experimental MAG welds on steel plate. As the result, it is made clear that the model is capable of predicting the bead profile of thin-plate MAG arc welding , including weld bead with undercutting.

Predicting of bead undercut defects in high-speed gas metal arc welding (GMAW)

Institute of Scientific and Technical Information of China (English)

Wen-jing XU; Chuan-song WU; De-gang ZOU

2008-01-01

In the gas metal arc welding (GMAW) process, when the welding speed reaches a certain threshold, there will be an onset of weld bead undercut defects which limit the further increase of the welding speed. Establishing a mathematical model for high-speed GMAW to predict the tendency of bead undercuts is of great significance to pre-vent such defects. Under the action of various forces, the transferred metal from filler wire to the weld pool, and the geometry and dimension of the pool itself decide if the bead undercut occurs or not. The previous model simpli-fied the pool shape too much. In this paper, based on the actual weld pool geometry and dimension calculated from a numerical model, a hydrostatic model for liquid metal surface is used to study the onset of bead undercut defects in the high-speed welding process and the effects of dif-ferent welding parameters on the bead undercut tendency.

Optical Arc-Length Sensor For TIG Welding

Science.gov (United States)

Smith, Matthew A.

1990-01-01

Proposed subsystem of tungsten/inert-gas (TIG) welding system measures length of welding arc optically. Viewed by video camera, in one of three alternative optical configurations. Length of arc measured instead of inferred from voltage.

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.

Grain refinement control in TIG arc welding

Science.gov (United States)

Iceland, W. F.; Whiffen, E. L. (Inventor)

1975-01-01

A method for controlling grain size and weld puddle agitation in a tungsten electrode inert gas welding system to produce fine, even grain size and distribution is disclosed. In the method the frequency of dc welding voltage pulses supplied to the welding electrode is varied over a preselected frequency range and the arc gas voltage is monitored. At some frequency in the preselected range the arc gas voltage will pass through a maximum. By maintaining the operating frequency of the system at this value, maximum weld puddle agitation and fine grain structure are produced.

Keyhole behavior and liquid flow in molten pool during laser-arc hybrid welding

Science.gov (United States)

Naito, Yasuaki; Katayama, Seiji; Matsunawa, Akira

2003-03-01

Hybrid welding was carried out on Type 304 stainless steel plate under various conditions using YAG laser combined with TIG arc. During arc and laser-arc hybrid welding, arc voltage variation was measured, and arc plasma, laser-induced plume and evaporation spots as well as keyhole behavior and liquid flow in the molten pool were observed through CCD camera and X-ray real-time transmission apparatus. It was consequently found that hybrid welding possessed many features in comparison with YAG laser welding. The deepest weld bead could be produced when the YAG laser beam of high power density was shot on the molten pool made beforehand stably with TIG arc. A keyhole was long and narrow, and its behavior was rather stable inside the molten pool. It was also confirmed that porosity was reduced by the suppression of bubble formation in hybrid welding utilizing a laser of a moderate power density.

Multi Objective Optimization of Weld Parameters of Boiler Steel Using Fuzzy Based Desirability Function

Directory of Open Access Journals (Sweden)

M. Satheesh

2014-01-01

Full Text Available The high pressure differential across the wall of pressure vessels is potentially dangerous and has caused many fatal accidents in the history of their development and operation. For this reason the structural integrity of weldments is critical to the performance of pressure vessels. In recent years much research has been conducted to the study of variations in welding parameters and consumables on the mechanical properties of pressure vessel steel weldments to optimize weld integrity and ensure pressure vessels are safe. The quality of weld is a very important working aspect for the manufacturing and construction industries. Because of high quality and reliability, Submerged Arc Welding (SAW is one of the chief metal joining processes employed in industry. This paper addresses the application of desirability function approach combined with fuzzy logic analysis to optimize the multiple quality characteristics (bead reinforcement, bead width, bead penetration and dilution of submerged arc welding process parameters of SA 516 Grade 70 steels(boiler steel. Experiments were conducted using Taguchi’s L27 orthogonal array with varying the weld parameters of welding current, arc voltage, welding speed and electrode stickout. By analyzing the response table and response graph of the fuzzy reasoning grade, optimal parameters were obtained. Solutions from this method can be useful for pressure vessel manufacturers and operators to search an optimal solution of welding condition.

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

Method to reduce arc blow during DC arc welding of pipelines

Energy Technology Data Exchange (ETDEWEB)

Espina-Hernandez, J. H.; Rueda-Morales, G.L.; Caleyo, F.; Hallen, J. M. [Instituto Politecnico Nacional, Mexico, (Mexico); Lopez-Montenegro, A.; Perz-Baruch, E. [Pemex Exploracion y Produccion, Tabasco, (Mexico)

2010-07-01

Steel pipelines are huge ferromagnetic structures and can be easily subjected to arc blow during the DC arc welding process. The development of methods to avoid arc blow during pipeline DC arc welding is a major objective in the pipeline industry. This study developed a simple procedure to compensate the residual magnetic field in the groove during DC arc welding. A Gaussmeter was used to perform magnetic flux density measurements in pipelines in southern Mexico. These data were used to perform magnetic finite element simulations using FEMM. Different variables were studied such as the residual magnetic field in the groove or the position of the coil with respect to the groove. An empirical predictive equation was developed from these trials to compensate for the residual magnetic field. A new method of compensating for the residual magnetic field in the groove by selecting the number of coil turns and the position of the coil with respect to the groove was established.

Optical emission spectroscopy of metal vapor dominated laser-arc hybrid welding plasma

International Nuclear Information System (INIS)

Ribic, B.; DebRoy, T.; Burgardt, P.

2011-01-01

During laser-arc hybrid welding, plasma properties affect the welding process and the weld quality. However, hybrid welding plasmas have not been systematically studied. Here we examine electron temperatures, species densities, and electrical conductivity for laser, arc, and laser-arc hybrid welding using optical emission spectroscopy. The effects of arc currents and heat source separation distances were examined because these parameters significantly affect weld quality. Time-average plasma electron temperatures, electron and ion densities, electrical conductivity, and arc stability decrease with increasing heat source separation distance during hybrid welding. Heat source separation distance affects these properties more significantly than the arc current within the range of currents considered. Improved arc stability and higher electrical conductivity of the hybrid welding plasma result from increased heat flux, electron temperatures, electron density, and metal vapor concentrations relative to arc or laser welding.

29 CFR 1915.56 - Arc welding and cutting.

Science.gov (United States)

2010-07-01

... 29 Labor 7 2010-07-01 2010-07-01 false Arc welding and cutting. 1915.56 Section 1915.56 Labor... (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR SHIPYARD EMPLOYMENT Welding, Cutting and Heating § 1915.56 Arc welding and cutting. The provisions of this section shall apply to ship repairing...

29 CFR 1926.351 - Arc welding and cutting.

Science.gov (United States)

2010-07-01

... 29 Labor 8 2010-07-01 2010-07-01 false Arc welding and cutting. 1926.351 Section 1926.351 Labor... (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Welding and Cutting § 1926.351 Arc welding and cutting. (a) Manual electrode holders. (1) Only manual electrode holders which are specifically designed...

Advanced Gas Tungsten Arc Weld Surfacing Current Status and Application

Directory of Open Access Journals (Sweden)

Stephan Egerland

2015-09-01

Full Text Available Abstract Gas Shielded Tungsten Arc Welding (GTAW – a process well-known providing highest quality weld results joined though by lower performance. Gas Metal Arc Welding (GMAW is frequently chosen to increase productivity along with broadly accepted quality. Those industry segments, especially required to produce high quality corrosion resistant weld surfacing e.g. applying nickel base filler materials, are regularly in consistent demand to comply with "zero defect" criteria. In this conjunction weld performance limitations are overcome employing advanced 'hot-wire' GTAW systems. This paper, from a Welding Automation perspective, describes the technology of such devices and deals with the current status is this field – namely the application of dual-cathode hot-wire electrode GTAW cladding; considerably broadening achievable limits.

Arc pressure control in GTA welding

International Nuclear Information System (INIS)

Cook, G.E.; Wells, F.M.; Levick, P.C.

1986-01-01

Relationships are established between the peak current of a pulsed, rectangular current waveform and the pulse current duty cycle under conditions of constant arc power. By appropriate choice of these interrelated parameters, it is shown that the arc pressure may be varied over a wide range even though the arc power is held constant. The methodology is suggested as a means of countering the effect of gravity in 5-G welding, while maintaining constant heat input to the weld. Combined with appropriate penetration sensors, the methodology is additionally suggested as a means of controlling penetration

More About Arc-Welding Process for Making Carbon Nanotubes

Science.gov (United States)

Benavides, Jeanette M.; Leidecker, Henning

2005-01-01

High-quality batches of carbon nanotubes are produced at relatively low cost in a modified atmospheric-pressure electric-arc welding process that does not include the use of metal catalysts. What would normally be a welding rod and a weldment are replaced by an amorphous carbon anode rod and a wider, hollow graphite cathode rod. Both electrodes are water-cooled. The cathode is immersed in ice water to about 0.5 cm from the surface. The system is shielded from air by flowing helium during arcing. As the anode is consumed during arcing at 20 to 25 A, it is lowered to maintain it at an approximately constant distance above the cathode. The process causes carbon nanotubes to form on the lowest 5 cm of the anode. The arcing process is continued until the anode has been lowered to a specified height. The nanotube-containing material is then harvested. The additional information contained in the instant report consists mostly of illustrations of carbon nanotubes and a schematic diagram of the arc-welding setup, as modified for the production of carbon nanotubes.

Welding for the CRBRP steam generators

International Nuclear Information System (INIS)

Spalaris, C.N.; Ring, P.J.; Durand, R.E.; Wright, E.A.

1979-01-01

The rationale for selecting weld design, welding procedures and inspection methods was based upon the desire to obtain the highest reliability welds for the CRBRP steam generators. To assure the highest weld reliability, heavy emphasis was placed on the control of material cleanliness and composition substantially exceeding the requirements of the ASME Code for 2-1/4Cr--1Mo. The high tube/tubesheet weld quality was achieved through close material control, an extensive weld development program and the selection of high reliability welding equipment. Shell and nozzle weld fabrication using TIG, MIG, and submerged arc procedures are also being controlled through precise specifications, including preheat and postheat programs, together with radiography and ultrasonic inspection to ascertain the weld quality desired. Details of the tube/tubesheet welding and shell welding are described and results from the weld testing program are discussed

Welding procedure specification for arc welding of St 52-3N steel plates with covered electrodes

International Nuclear Information System (INIS)

Cvetkovski, S.; Slavkov, D.; Magdeski, J.

2003-01-01

In this paper the results of approval welding technology for arc welding of plates made of St 52-3N steel are presented. Metal arc welding with covered electrode is used welding process. Test specimens are butt welded in different welding positions P A , P F , P C and P D . Before start welding preliminary welding procedure was prepared. After welding of test specimens non destructive and destructive testing was performed. Obtained results were compared with standard DIN 17100 which concerns to chemical composition and mechanical properties of base material. It was confirmed that in all cases mechanical properties of welded joint are higher than those of base material, so preliminary welding procedure (pWTS) can be accepted as welding procedure specification WPS for metal arc welding of St52-3N steel. (Original)

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.

A control system for uniform bead in fillet arc welding on tack welds

International Nuclear Information System (INIS)

Kim, Jae Woong; Lee, Jun Young

2008-01-01

Positioning a workpiece accurately and preventing weld distortion, tack welding is often adopted before main welding in the construction of welded structures. However, this tack weld deteriorates the final weld bead profile, so that the grinding process is usually performed for a uniform weld bead profile. In this study, a control system for uniform weld bead is proposed for the fillet arc welding on tack welds. The system consists of GMA welding machine, torch manipulator, laser vision sensor for measuring the tack weld size and the database for optimal welding conditions. Experiments have been performed for constructing the database and for evaluating the control capability of the system. It has been shown that the system has the capability to smooth the bead at the high level of quality

Specification for corrosion-resisting chromium and chromium-nickel steel welding rods and bare electrodes - approved 1969

International Nuclear Information System (INIS)

Anon.

1975-01-01

This specification covers corrosion-resisting chromium and chromium-nickel steel welding rods for use with the atomic hydrogen and gas-tungsten-arc welding processes and bare electrodes for use with the submerged arc and gas metal-arc welding processes. These welding rods and electrodes include those alloy steels designated as corrosion- or heat-resisting chromium and chromium-nickel steels, in which chromium exceeds 4% and nickel does not exceed 50%

Distribution of Argon Arc Contaminated with Nitrogen as Function of Frequency in Pulsed TIG Welding

Science.gov (United States)

Takahashi, Hiroki; Tanaka, Tatsuro; Yamamoto, Shinji; Iwao, Toru

2016-09-01

TIG arc welding is the high-quality and much applicable material joining technology. However, the current has to be small because the cathode melting should be prevented. In this case, the heat input to the welding pool becomes low, then, the welding defect sometimes occurs. The pulsed TIG arc welding is used to improve this disadvantage This welding can be controlled by some current parameters such as frequency However, few report has reported the distribution of argon arc contaminated with nitrogen It is important to prevent the contamination of nitrogen because the melting depth increases in order to prevent the welding defects. In this paper, the distribution of argon arc contaminated as function of frequency with nitrogen in pulsed TIG welding is elucidated. The nitrogen concentration, the radial flow velocity, the arc temperature were calculated using the EMTF simulation when the time reached at the base current. As a result, the nitrogen concentration into the arc became low with increasing the frequency The diffusion coefficient decreased because of the decrement of temperature over 4000 K. In this case, the nitrogen concentration became low near the anode. Therefore, the nitrogen concentration became low because the frequency is high.

Performance of high molybdenum superaustenitic stainless steel welds in harsh chloride environments

International Nuclear Information System (INIS)

Stenvall, P.; Liljas, M.; Wallen, B.

1996-01-01

Superaustenitic steels are normally welded with nickel-based alloys as filler materials. To clarify the understanding of weld behavior in superaustenitic stainless steels this paper presents the development history of 6Mo and 7Mo steels, and results of laboratory tests and field tests on welds of UNS S31254 (6Mo) and UNS S32654 (7 Mo) in different types of chloride containing environments. The laboratory tests consisted of the well known ferric chloride test (ASTM G 48 Method A). Shielded metal arc welds, gas tungsten arc welds and submerged arc welds in both grades were tested. The critical pitting temperatures were determined and the locations of the attack were noted. Some specimens were sectioned at the position of the attack followed by studies using light optical microscopy. The critical pitting temperatures of the welds in S31254 and S32654 were at normal levels for both grades, i.e., 40--50 C for S31254 and 60--75 C for S32654. The locations of the attack differed depending on the welding process. In shielded metal arc welds the attack was mostly located in the weld metal. In gas tungsten arc welds the attack was predominantly located next to the fusion line. The field tests showed that the behavior of welds and parent metal of superaustenitic stainless steels, as well as of nickel-based alloys, is much dependent on the corrosive environment. In oxidizing chloride solutions, similar results to those of the ferric chloride test, are observed. However, crevice corrosion in the parent material is at a greater risk than pitting corrosion in the welds. In very oxidizing solutions of low chloride concentrations, welds made of nickel-based fillers may corrode faster than the stainless steel base metal due to transpassive uniform corrosion. The opposite situation exists when active uniform corrosion prevails, i.e., welds made of nickel-based fillers corrode less than the stainless steel parent material

Process Stability of Ultrasonic-Wave-Assisted Gas Metal Arc Welding

Science.gov (United States)

Fan, Chenglei; Xie, Weifeng; Yang, Chunli; Lin, Sanbao; Fan, Yangyang

2017-10-01

As a newly developed arc welding method, ultrasonic-wave-assisted arc welding successfully introduced power ultrasound into the arc and weld pool, during which the ultrasonic acts on the top of the arc in the coaxial alignment direction. The advanced process for molten metals can be realized by using an additional ultrasonic field. Compared with the conventional gas metal arc welding (GMAW), the welding arc is compressed, the droplet size is decreased, and the droplet transfer frequency is increased significantly in ultrasonic-wave-assisted GMAW (U-GMAW). However, the stability of the metal transfer has deep influence on the welding quality equally, and the ultrasonic wave effect on the stability of the metal transfer is a phenomenon that is not completely understood. In this article, the stabilities of the short-circuiting transfer process and globular transfer process are studied systematically, and the effect of ultrasonic wave on the metal transfer is analyzed further. The transfer frequency and process stability of the U-GMAW process are much higher than those of the conventional GMAW. Analytical results show that the additional ultrasonic wave is helpful for improving welding stability.

An approach for optimizing arc welding applications

International Nuclear Information System (INIS)

Chapuis, Julien

2011-01-01

The dynamic and transport mechanisms involved in the arc plasma and the weld pool of arc welding operations are numerous and strongly coupled. They produce a medium the magnitudes of which exhibit rapid time variations and very marked gradients which make any experimental analysis complex in this disrupted environment. In this work, we study the TIG and MIG processes. An experimental platform was developed to allow synchronized measurement of various physical quantities associated with welding (process parameters, temperatures, clamping forces, metal transfer, etc.). Numerical libraries dedicated to applied studies in arc welding are developed. They enable the treatment of a large flow of data (signals, images) with a systematic and global method. The advantages of this approach for the enrichment of numerical simulation and arc process control are shown in different situations. Finally, this experimental approach is used in the context of the chosen application to obtain rich measurements to describe the dynamic behavior of the weld pool in P-GMAW. Dimensional analysis of these experimental measurements allows to identify the predominant mechanisms involved and to determine experimentally the characteristic times associated. This type of approach includes better description of the behavior of a macro-drop of molten metal or the phenomena occurring in the humping instabilities. (author)

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...

Thick-joint welding process. Chapter 5

International Nuclear Information System (INIS)

Wood, D.; Terry, P.; Dickinson, F.S.

1980-01-01

This chapter reviews the techniques currently employed in the welding of pressure vessels, ranging from traditional manual metal arc and submerged arc processes to the more recently introduced narrow-gap and high-energy processes, e.g. electron beam and laser. The effect on the properties of the base materials being joined and the relative economics of the various processes is examined, from which guidance on the balance between joint properties and economy can be gained. (author)

Fracture toughness of stainless steel welds

International Nuclear Information System (INIS)

Mills, W.J.

1985-11-01

The effects of temperature, composition and weld-process variations on the fracture toughness behavior for Types 308 and 16-8-2 stainless steel (SS) welds were examined using the multiple-specimen J/sub R/-curve procedure. Fracture characteristics were found to be dependent on temperature and weld process but not on filler material. Gas-tungsten-arc (GTA) welds exhibited the highest fracture toughness, a shielded metal-arc (SMA) weld exhibited an intermediate toughness and submerged-arc (SA) welds yielded the lowest toughness. Minimum-expected fracture properties were defined from lower-bound J/sub c/ and tearing modulus values generated here and in previous studies. Fractographic examination revealed that microvoid coalescence was the operative fracture mechanism for all welds. Second phase particles of manganese silicide were found to be detrimental to the ductile fracture behavior because they separated from the matrix during the initial stages of plastic straining. In SA welds, the high density of inclusions resulting from silicon pickup from the flux promoted premature dimple rupture. The weld produced by the SMA process contained substantially less manganese silicide, while GTA welds contained no silicide inclusions. Delta ferrite particles present in all welds were substantially more resistant to local failure than the silicide phase. In welds containing little or no manganese silicide, delta ferrite particles initiated microvoid coalescence but only after extensive plastic straining

Steels and welding nuclear

International Nuclear Information System (INIS)

Sessa, M.; Milella, P.P.

1987-01-01

This ENEA Data-Base regards mechanical properties, chemical composition and heat treatments of nuclear pressure vessel materials: type A533-B, A302-B, A508 steel plates and forgings, submerged arc welds and HAZ before and after nuclear irradiation. Irradiation experiments were generally performed in high flux material test reactors. Data were collected from international available literature about water nuclear reactors pressure vessel materials embrittlement

Mars Atmosphere Effects on Arc Welds: Phase 1

Science.gov (United States)

Courtright, Z. S.

2016-01-01

NASA has been unprecedented in achieving its goals related to space exploration and furthering the understanding of our solar system. In keeping with this trend, NASA's current mission is to land a team of astronauts on Mars and return them safely to Earth. In addition to comprising much of the structure and life support systems that will be brought to Mars for the habitat and vehicle, titanium and aluminum can be found and mined on Mars and may be used when building structures.Where metals are present, there will be a need for welding capabilities. For welds that need to be made quickly and are located far from heavy resistance or solid state welding machinery, there will be a need for basic arc welding. Arc welding has been a major cornerstone of manufacturing throughout the 20th century, and the portability and capability of gas tungsten arc welding (GTAW) will be necessary for repair, manufacturing, and survival on Mars. The two primary concerns for welding on Mars are that the Martian atmosphere contains high levels of carbon dioxide (CO2), and the atmospheric pressure is much lower than it is on Earth. The high levels of CO2 in the Martian atmosphere may dissociate and produce oxygen in the arc and therefore increase the risk of oxidation. For simplification, atmospheric pressure will not be taken into account for this experiment. For survival on Mars during this mission, the life support and water filtration systems must be kept operational at all times. In order to ensure that water filtration systems can be repaired in the event of an emergency, it is very important to have the capability to weld. The Orion capsule and Mars lander must also remain operational throughout the duration of the mission to ensure the safe return of the astronauts on the mission to Mars. A better understanding of welding in a Mars environment is important to ensure that repair welds are possible if the Orion capsule/Mars lander or water filtration system is damaged at any point

production of manual arc welding electrodes with local raw materials

African Journals Online (AJOL)

CHUKSSUCCESS 4 LOVE

Manual arc welding using flux coated electrodes is carried out by producing an electric arc between ... major objectives: to form fusible slags, to stabilize the arc and to produce an inert gas shielding ... Current fusion welding techniques rely.

Reflection of illumination laser from gas metal arc weld pool surface

International Nuclear Information System (INIS)

Ma, Xiaoji; Zhang, YuMing

2009-01-01

The weld pool is the core of the welding process where complex welding phenomena originate. Skilled welders acquire their process feedback primarily from the weld pool. Observation and measurement of the three-dimensional weld pool surface thus play a fundamental role in understanding and future control of complex welding processes. To this end, a laser line is projected onto the weld pool surface in pulsed gas metal arc welding (GMAW) and an imaging plane is used to intercept its reflection from the weld pool surface. Resultant images of the reflected laser are analyzed and it is found that the weld pool surface in GMAW does specularly reflect the projected laser as in gas tungsten arc welding (GTAW). Hence, the weld pool surface in GMAW is also specular and it is in principle possible that it may be observed and measured by projecting a laser pattern and then intercepting and imaging the reflection from it. Due to high frequencies of surface fluctuations, GMAW requires a relatively short time to image the reflected laser

Operator Bias in the Estimation of Arc Efficiency in Gas Tungsten Arc Welding

Directory of Open Access Journals (Sweden)

Fredrik Sikström

2015-03-01

Full Text Available In this paper the operator bias in the measurement process of arc efficiency in stationary direct current electrode negative gas tungsten arc welding is discussed. An experimental study involving 15 operators (enough to reach statistical significance has been carried out with the purpose to estimate the arc efficiency from a specific procedure for calorimetric experiments. The measurement procedure consists of three manual operations which introduces operator bias in the measurement process. An additional relevant experiment highlights the consequences of estimating the arc voltage by measuring the potential between the terminals of the welding power source instead of measuring the potential between the electrode contact tube and the workpiece. The result of the study is a statistical evaluation of the operator bias influence on the estimate, showing that operator bias is negligible in the estimate considered here. On the contrary the consequences of neglecting welding leads voltage drop results in a significant under estimation of the arc efficiency.

Gas Metal Arc Welding. Welding Module 5. Instructor's Guide.

Science.gov (United States)

Missouri Univ., Columbia. Instructional Materials Lab.

This guide is intended to assist vocational educators in teaching an eight-unit module in gas metal arc welding. The module is part of a welding curriculum that has been designed to be totally integrated with Missouri's Vocational Instruction Management System. The following topics are covered in the module: safety and testing, gas metal arc…

Solid state impact welding of BMG and copper by vaporizing foil actuator welding

Energy Technology Data Exchange (ETDEWEB)

Vivek, Anupam, E-mail: vivek.4@osu.edu [Department of Materials Science and Engineering, The Ohio State University, 2041 College Road, Columbus, OH 43210 (United States); Presley, Michael [Department of Materials Science and Engineering, The Ohio State University, 2041 College Road, Columbus, OH 43210 (United States); Flores, Katharine M. [Department of Materials Science and Engineering, The Ohio State University, 2041 College Road, Columbus, OH 43210 (United States); Department of Mechanical Engineering and Materials Science, Institute of Materials Science and Engineering, Washington University, One Brookings Drive, St. Louis, MO 63130 (United States); Hutchinson, Nicholas H.; Daehn, Glenn S. [Department of Materials Science and Engineering, The Ohio State University, 2041 College Road, Columbus, OH 43210 (United States)

2015-05-14

The objective of this study was to create impact welds between a Zr-based Bulk Metallic Glass (BMG) and copper at a laboratory scale and subsequently investigate the relationship between interfacial structure and mechanical properties. Vaporizing Foil Actuator (VFA) has recently been demonstrated as a versatile tool for metalworking applications: impact welding of dissimilar materials being one of them. Its implementation for welding is termed as VFA Welding or VFAW. With 8 kJ input energy into an aluminum foil actuator, a 0.5 mm thick Cu110 alloy sheet was launched toward a BMG target resulting in an impact at a velocity of nearly 600 m/s. For this experiment, the welded interface was straight with a few BMG fragments embedded in the copper sheet in some regions. Hardness tests across the interface showed increase in strength on the copper side. Instrumented peel test resulted in failure in the parent copper sheet. A slower impact velocity during a separate experiment resulted in a weld, which had wavy regions along the interface and in peel failure again happened in the parent copper sheet. Some through-thickness cracks were observed in the BMG plate and there was some spall damage in the copper flyers. TEM electron diffraction on a sample, cut out from the wavy weld interface region using a focused ion beam, showed that devitrification of the BMG was completely avoided in this welding process.

Passive Visual Sensing in Automatic Arc Welding

DEFF Research Database (Denmark)

Liu, Jinchao

For decades much work has been devoted to the research and development of automatic arc welding systems. However, it has remained a challenging problem. Besides the very complex arc welding process itself, the lack of ability to precisely sense the welding process, including the seam geometry...... and the weld pool, has also prevented the realization of a closed-loop control system for many years, even though a variety of sensors have been developed. Among all the sensor systems, visual sensors have the advantage of receiving visual information and have been drawn more and more attentions. Typical...... industrial solutions for seam detection such as using laser scanners suer from several limitations. For instance, it must be positioned some distance ahead to the molten pool and may cause problem when dealing with shiny surfaces. Existing techniques for weld pool sensing mostly rely on auxiliary light...

Artificial defects detection and location during welding

International Nuclear Information System (INIS)

Asty, M.

1978-01-01

Welding control by acoustic emission allows defects detection as soon as they are created. Acoustic testing saves time and gives better quality assurance in the case of multiple pass welding of plates. A welded joint was performed on A533B steel plates 250 mm thick by submerged arc welding. Artificial defects were implanted to determine significative parameters of acoustic reception. In operating conditions a significant acoustic activity takes place only during welding as shown by preliminary tests. At the same time an important noise is created by the arc, scories cooling and metal solidification and cooling. These problems are solved by an original processing in time-space detecting and locating defects with a good approximation [fr

Atom Probe Tomography Characterization of the Solute Distributions in a Neutron-Irradiated and Annealed Pressure Vessel Steel Weld

Energy Technology Data Exchange (ETDEWEB)

Miller, M.K.

2001-01-30

A combined atom probe tomography and atom probe field ion microscopy study has been performed on a submerged arc weld irradiated to high fluence in the Heavy-Section Steel irradiation (HSSI) fifth irradiation series (Weld 73W). The composition of this weld is Fe - 0.27 at. % Cu, 1.58% Mn, 0.57% Ni, 0.34% MO, 0.27% Cr, 0.58% Si, 0.003% V, 0.45% C, 0.009% P, and 0.009% S. The material was examined after five conditions: after a typical stress relief treatment of 40 h at 607 C, after neutron irradiation to a fluence of 2 x 10{sup 23} n m{sup {minus}2} (E > 1 MeV), and after irradiation and isothermal anneals of 0.5, 1, and 168 h at 454 C. This report describes the matrix composition and the size, composition, and number density of the ultrafine copper-enriched precipitates that formed under neutron irradiation and the change in these parameters with post-irradiation annealing treatments.

Underwater cladding with laser beam and plasma arc welding

International Nuclear Information System (INIS)

White, R.A.; Fusaro, R.; Jones, M.G.; Solomon, H.D.; Milian-Rodriguez, R.R.

1997-01-01

Two welding processes, plasma arc (transferred arc) (PTA) and laser beam, were investigated to apply cladding to austenitic stainless steels and Inconel 600. These processes have long been used to apply cladding layers , but the novel feature being reported here is that these cladding layers were applied underwater, with a water pressure equivalent to 24 m (80 ft). Being able to apply the cladding underwater is very important for many applications, including the construction of off-shore oil platforms and the repair of nuclear reactors. In the latter case, being able to weld underwater eliminates the need for draining the reactor and removing the fuel. Welding underwater in reactors presents numerous challenges, but the ability to weld without having to drain the reactor and remove the fuel provides a huge cost savings. Welding underwater in reactors must be done remotely, but because of the radioactive corrosion products and neutron activation of the steels, remote welding would also be required even if the reactor is drained and the fuel removed. In fact, without the shielding of the water, the remote welding required if the reactor is drained might be even more difficult than that required with underwater welds. Furthermore, as shall be shown, the underwater welds that the authors have made were of high quality and exhibit compressive rather than tensile residual stresses

Microstructural characterisation of Inconel 718 gas tungsten arc welds

International Nuclear Information System (INIS)

Ram, G.D.J.; Reddy, A.V.; Rao, K.P.

2005-01-01

The presence of Nb-rich, brittle, intermetallic Laves phase in Inconel 718 weld fusion zones is detrimental to weld mechanical properties. In the current work, autogenous bead-on-plate gas tungsten-arc welds were deposited in 2 mm thick IN 718 sheets. The welds were subjected to the following heat treatments: i) direct aging, ii) solution treatment at 980 C followed by aging, and iii) solution treatment at 1080 C followed by aging. Detailed microstructural characterisation was carried out using optical, scanning electron and transmission electron microscopes and electron probe microanalysis. The microstructural features in as-welded and post-weld heat treated conditions are discussed. The results show that post-weld heat treatments alone cannot provide satisfactory solution to the Laves problem in Inconel 718 gas tungsten-arc welds

GMAW (Gas Metal Arc Welding) process development for girth welding of high strength pipelines

Energy Technology Data Exchange (ETDEWEB)

Rajan, Vaidyanath; Daniel, Joe; Quintana, Marie [The Lincoln Electric Company, Cleveland, OH (United States); Chen, Yaoshan [Center for Reliable Energy Systems (CRES), Dublin, OH (United States); Souza, Antonio [Lincoln Electric do Brasil, Guarulhos, SP (Brazil)

2009-07-01

This paper highlights some of the results and findings from the first phase of a consolidated program co-funded by US Department of Transportation Pipeline and Hazardous Materials Safety Administration (PHMSA) and Pipeline Research Council Inc (PRCI) to develop pipe weld assessment and qualification methods and optimize X 100 pipe welding technologies. One objective of the program is to establish the range of viable welding options for X 100 line pipe, and define the essential variables to provide welding process control for reliable and consistent mechanical performance of the weldments. In this first phase, a series of narrow gap girth welds were made with pulsed gas metal arc welding (GMAW), instrumented with thermocouples in the heat affected zone (HAZ) and weld metal to obtain the associated thermal profiles, and instrumented to measure true energy input as opposed to conventional heat input. Results reveal that true heat input is 16%-22% higher than conventional heat input. The thermal profile measurements correlate very well with thermal model predictions using true energy input data, which indicates the viability of treating the latter as an essential variable. Ongoing microstructural and mechanical testing work will enable validation of an integrated thermal-microstructural model being developed for these applications. Outputs from this model will be used to correlate essential welding process variables with weld microstructure and hardness. This will ultimately enable development of a list of essential variables and the ranges needed to ensure mechanical properties are achieved in practice, recommendations for controlling and monitoring these essential variables and test methods suitable for classification of welding consumables. (author)

High-power CW and long-pulse lasers in the green wavelength regime for copper welding

Science.gov (United States)

Pricking, Sebastian; Huber, Rudolf; Klausmann, Konrad; Kaiser, Elke; Stolzenburg, Christian; Killi, Alexander

2016-03-01

We report on industrial high-power lasers in the green wavelength regime. By means of a thin disk oscillator and a resonator-internal nonlinear crystal for second harmonic generation we are able to extract up to 8 kW pulse power in the few-millisecond range at a wavelength of 515 nm with a duty cycle of 10%. Careful shaping and stabilization of the polarization and spectral properties leads to a high optical-to-optical efficiency larger than 55%. The beam parameter product is designed and measured to be below 5 mm·mrad which allows the transport by a fiber with a 100 μm core diameter. The fiber and beam guidance optics are adapted to the green wavelength, enabling low transmission losses and stable operation. Application tests show that this laser is perfectly suited for copper welding due to the superior absorption of the green wavelength compared to IR, which allows us to produce weld spots with an unprecedented reproducibility in diameter and welding depth. With an optimized set of parameters we could achieve a splatter-free welding process of copper, which is crucial for welding electronic components. Furthermore, the surface condition does not influence the welding process when the green wavelength is used, which allows to skip any expensive preprocessing steps like tin-coating. With minor changes we could operate the laser in cw mode and achieved up to 1.7 kW of cw power at 515 nm with a beam parameter product of 2.5 mm·mrad. These parameters make the laser perfectly suitable for additional applications such as selective laser melting of copper.

High-speed cinematography of gas-tungsten arc welding: theory and application

Energy Technology Data Exchange (ETDEWEB)

Reynolds, L.D.; Key, J.F.

1981-06-01

High-speed photo-instrumentation theory and application are reviewed, with particular emphasis on high-speed cinematography, for the engineer who has not acquired an extensive background in scientific photography. Camera systems, optics, timing system, lighting, photometric equipment, filters, and camera mounts are covered. Manufacturers and other resource material are listed in the Appendices. The properties and processing of photosensitive materials suitable for high-speed photography are reviewed, and selected film data are presented. Methods are described for both qualitative and quantitative film analysis. This technology is applied to the problem of analyzing plasma dynamics in a gas-tungsten welding arc.

Metal Droplet Formation in Gas Metal Arc Welding

International Nuclear Information System (INIS)

Haidar, J.

2000-01-01

A two-dimensional dynamic treatment has been developed for description of arc and electrode properties in gas metal arc welding (GMAW). The theory is a unified treatment of the arc the welding wire anode and the cathode, and includes a detailed account of sheath effects near the anode. The wire anode is included as a dynamic entity and the volume of fluid method is used to handle the movement of the free surface of the molten metal at the tip of the wire, accounting for effects of surface tension, inertia, gravity, arc pressure, viscous drag force of the plasma, magnetic forces and Marangoni effect, and also for the effects of wire feed rate in GMAW. Results of calculations made for a mild steel wire of diameter 0.16 cm are in good agreement with experimental measurements of droplet diameter and droplet detachment frequency at currents between 150 and 330 A, which includes the transition between ''globular'' and ''spray'' transfer. Quantitative predictions are also made of the amount of metal vapour that is generated from the welding droplets at the tip of the welding wire. (author)

Weldability of AISI 304 to copper by friction welding

Energy Technology Data Exchange (ETDEWEB)

Kirik, Ihsan [Batman Univ. (Turkey); Balalan, Zulkuf [Firat Univ., Elazig (Turkey)

2013-06-01

Friction welding is a solid-state welding method, which can join different materials smoothly and is excessively used in manufacturing industry. Friction welding method is commonly used in welding applications of especially cylindrical components, pipes and materials with different properties, for which other welding methods remain incapable. AISI 304 stainless steel and a copper alloy of 99.6 % purity were used in this study. This couple was welded in the friction welding machine. After the welding process, samples were analyzed macroscopically and microscopically, and their microhardness was measured. Tensile test was used to determine the bond strength of materials that were joined using the friction welding method. At the end of the study, it was observed that AISI 304 stainless steel and copper could be welded smoothly using the friction welding method and the bond strength is close to the tensile strength of copper. (orig.)

Manufacturing and use of spiral welded pipes for high pressure service : state of the art

Energy Technology Data Exchange (ETDEWEB)

Knoop, F.M.; Sommer, B. [Salzgitter GroBrohre GmbH, Salzgitter (Germany)

2004-07-01

This paper provided details of an improved helical seam 2-step (HTS) manufacturing process used to produce spiral welded large diameter pipes for high pressure transmission pipelines. During the process, pipe forming is combined with continuous tack welding and internal and external submerged arc welding at separate welding stations. The pipe forming unit consists of a 3 roll bending system with an outside roller cage used to guarantee the roundness of the pipe. The converging strip edges of the pipe are joined using a continuous shielded arc tack weld. Tack welding is done automatically with a laser-guided weld head. Run-out angles are adjusted by an automatic gap control system. The formed and tack-welded pipes are then fed to computer-controlled welding stations for final welding, where each pipe is rotated with a precise screw-like motion. The same welding materials used for the helical seam are used for the skelp end welding. The process offers more precise root gap control, as well as improved pipe geometry. Use of the process has also increased production rates and improved weld stability. The dimensions of the spiral-weld pipes are adjustable so that any diameter can be produced from a base material of the same width. The pipes can also be coated externally with fusion-bonded epoxy or 3-layer polyethylene/polypropylene. It was concluded that the process is being further refined to support the use of HTS pipes in high-pressure pipelines. New nondestructive testing techniques used to assess the performance of the line pipes were presented, as well as the results from hot and cold bending tests, field weldability trials, and tests related to the safety of spiral pipes. 16 refs., 2 tabs., 12 figs.

Numerical modelling of steel arc welding

International Nuclear Information System (INIS)

Hamide, M.

2008-07-01

Welding is a highly used assembly technique. Welding simulation software would give access to residual stresses and information about the weld's microstructure, in order to evaluate the mechanical resistance of a weld. It would also permit to evaluate the process feasibility when complex geometrical components are to be made, and to optimize the welding sequences in order to minimize defects. This work deals with the numerical modelling of arc welding process of steels. After describing the industrial context and the state of art, the models implemented in TransWeld (software developed at CEMEF) are presented. The set of macroscopic equations is followed by a discussion on their numerical implementation. Then, the theory of re-meshing and our adaptive anisotropic re-meshing strategy are explained. Two welding metal addition techniques are investigated and are compared in terms of the joint size and transient temperature and stresses. The accuracy of the finite element model is evaluated based on experimental results and the results of the analytical solution. Comparative analysis between experimental and numerical results allows the assessment of the ability of the numerical code to predict the thermomechanical and metallurgical response of the welded structure. The models limitations and the phenomena identified during this study are finally discussed and permit to define interesting orientations for future developments. (author)

Fabrication of Copper-Rich Cu-Al Alloy Using the Wire-Arc Additive Manufacturing Process

Science.gov (United States)

Dong, Bosheng; Pan, Zengxi; Shen, Chen; Ma, Yan; Li, Huijun

2017-12-01

An innovative wire-arc additive manufacturing (WAAM) process is used to fabricate Cu-9 at. pct Al on pure copper plates in situ, through separate feeding of pure Cu and Al wires into a molten pool, which is generated by the gas tungsten arc welding (GTAW) process. After overcoming several processing problems, such as opening the deposition molten pool on the extremely high-thermal conductive copper plate and conducting the Al wire into the molten pool with low feed speed, the copper-rich Cu-Al alloy was successfully produced with constant predesigned Al content above the dilution-affected area. Also, in order to homogenize the as-fabricated material and improve the mechanical properties, two further homogenization heat treatments at 1073 K (800 °C) and 1173 K (900 °C) were applied. The material and mechanical properties of as-fabricated and heat-treated samples were compared and analyzed in detail. With increased annealing temperatures, the content of precipitate phases decreased and the samples showed gradual improvements in both strength and ductility with little variation in microstructures. The present research opened a gate for in-situ fabrication of Cu-Al alloy with target chemical composition and full density using the additive manufacturing process.

Comparative estimation of the properties of heat resisting nickel alloy welded joints made by electron-beam and arc welding

International Nuclear Information System (INIS)

Morochko, V.P.; Sorokin, L.I.; Yakushin, B.F.; Moryakov, V.F.

1977-01-01

As compared to argon arc welding of refractory nickel alloys at 15 m/hour rate, electron beam welding decreases energy consumption per unit length (from 4300 to 2070 cal/cm), the weld area (from 108 to 24 mm 2 ), and the length of the thermal effect zone (from 0.9-1.8 to 0.4-0.8 mm). Electron beam welding also provides for better resistance to hot cracking in the weld metal and in the near-weld zone, as compared to automatic argon arc welding and manual welding with addition of the basic metal. However, this advantage is observed only at welding rates less than 45 m/hour. Electron beam welded joints of refractory nickel alloys with intermetallide reinforcement have higher strength, plasticity and impact strength, and lower scattering of these properties than arc welded joints

Recent progress on gas tungsten arc welding of vanadium alloys

Energy Technology Data Exchange (ETDEWEB)

Grossbeck, M.L.; King, J.F.; Alexander, D.J. [Oak Ridge National Lab., TN (United States)] [and others

1997-08-01

Emphasis has been placed on welding 6.4 mm plate, primarily by gas tungsten arc (GTA) welding. The weld properties were tested using blunt notch Charpy testing to determine the ductile to brittle transition temperature (DBTT). Erratic results were attributed to hydrogen and oxygen contamination of the welds. An improved gas clean-up system was installed on the welding glove box and the resulting high purity welds had Charpy impact properties similar to those of electron beam welds with similar grain size. A post-weld heat treatment (PWHT) of 950{degrees}C for two hours did not improve the properties of the weld in cases where low concentrations of impurities were attained. Further improvements in the gas clean-up system are needed to control hydrogen contamination.

On arc efficiency in gas tungsten arc welding

Directory of Open Access Journals (Sweden)

Nils Stenbacka

2013-12-01

Full Text Available The aim of this study was to review the literature on published arc efficiency values for GTAW and, if possible, propose a narrower band. Articles between the years 1955 - 2011 have been found. Published arc efficiency values for GTAW DCEN show to lie on a wide range, between 0.36 to 0.90. Only a few studies covered DCEP - direct current electrode positive and AC current. Specific information about the reproducibility in calorimetric studies as well as in modeling and simulation studies (considering that both random and systematic errors are small was scarce. An estimate of the average arc efficiency value for GTAW DCEN indicates that it should be about 0.77. It indicates anyway that the GTAW process with DCEN is an efficient welding method. The arc efficiency is reduced when the arc length is increased. On the other hand, there are conflicting results in the literature as to the influence of arc current and travel speed.

Microstructure and mechanical properties of aluminum 5083 weldments by gas tungsten arc and gas metal arc welding

International Nuclear Information System (INIS)

Liu Yao; Wang Wenjing; Xie Jijia; Sun Shouguang; Wang Liang; Qian Ye; Meng Yuan; Wei Yujie

2012-01-01

Highlights: ► Welding zones by GTAW and GMAW are softer than the parent material Al5083. ► GTAW for Al5083 are mechanically more reliable than that welded by GMAW. ► GTAW welds fail by shear, but GMAW welds show mixed shear and normal failure. - Abstract: The mechanical properties and microstructural features of aluminum 5083 (Al5083) weldments processed by gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) are investigated. Weldments processed by both methods are mechanically softer than the parent material Al5083, and could be potential sites for plastic localization. It is revealed that Al5083 weldments processed by GTAW are mechanical more reliable than those by GMAW. The former bears higher strength, more ductility, and no apparent microstructure defects. Perceivable porosity in weldments by GMAW is found, which could account for the distinct mechanical properties between weldments processed by GTAW and GMAW. It is suggested that caution should be exercised when using GMAW for Al5083 in the high-speed-train industry where such light weight metal is broadly used.

Corrosion resistance of copper canister weld material

International Nuclear Information System (INIS)

Gubner, Rolf; Andersson, Urban

2007-03-01

The proposed design for a final repository for spent fuel and other long-lived residues is based on the multi-barrier principle. The waste will be encapsulated in sealed cylindrical canisters, which will be placed in granite bedrock and surrounded by compacted bentonite clay. The canister design is based on a thick cast iron insert fitted inside a copper canister. SKB has since several years developed manufacturing processes for the canister components using a network of manufacturers. For the encapsulation process SKB has built the Canister Laboratory to demonstrate and develop the encapsulation technique in full scale. The critical part of the encapsulation of spent fuel is the sealing of the canister which is done by welding the copper lid to the cylindrical part of the canister. Two welding techniques have been developed in parallel, Electron Beam Welding (EBW) and Friction Stir Welding (FSW). During the past two decades, SKB has developed the technology EBW at The Welding Institute (TWI) in Cambridge, UK. The development work at the Canister Laboratory began in 1999. In electron beam welding, a gun is used to generate the electron beam which is aimed at the joint. The beam heats up the material to the melting point allowing a fusion weld to be formed. The gun was developed by TWI and has a unique design for use at reduced pressure. The system has gone through a number of improvements under the last couple of years including implementation of a beam oscillation system. However, during fabrication of the outer copper canisters there will be some unavoidable grain growth in the welded areas. As grains grow they will tend to concentrate impurities at the new grain boundaries that might pose adverse effects on the corrosion resistance of welds. As a new method for joining, SKB has been developing friction stir welding (FSW) for sealing copper canisters for spent nuclear fuel in cooperation with TWI since 1997. FSW was invented in 1991 at TWI and is a thermo

Corrosion resistance of copper canister weld material

Energy Technology Data Exchange (ETDEWEB)

Gubner, Rolf; Andersson, Urban [Corrosion and Metals Research Institute, Sto ckholm (Sweden)

2007-03-15

The proposed design for a final repository for spent fuel and other long-lived residues is based on the multi-barrier principle. The waste will be encapsulated in sealed cylindrical canisters, which will be placed in granite bedrock and surrounded by compacted bentonite clay. The canister design is based on a thick cast iron insert fitted inside a copper canister. SKB has since several years developed manufacturing processes for the canister components using a network of manufacturers. For the encapsulation process SKB has built the Canister Laboratory to demonstrate and develop the encapsulation technique in full scale. The critical part of the encapsulation of spent fuel is the sealing of the canister which is done by welding the copper lid to the cylindrical part of the canister. Two welding techniques have been developed in parallel, Electron Beam Welding (EBW) and Friction Stir Welding (FSW). During the past two decades, SKB has developed the technology EBW at The Welding Institute (TWI) in Cambridge, UK. The development work at the Canister Laboratory began in 1999. In electron beam welding, a gun is used to generate the electron beam which is aimed at the joint. The beam heats up the material to the melting point allowing a fusion weld to be formed. The gun was developed by TWI and has a unique design for use at reduced pressure. The system has gone through a number of improvements under the last couple of years including implementation of a beam oscillation system. However, during fabrication of the outer copper canisters there will be some unavoidable grain growth in the welded areas. As grains grow they will tend to concentrate impurities at the new grain boundaries that might pose adverse effects on the corrosion resistance of welds. As a new method for joining, SKB has been developing friction stir welding (FSW) for sealing copper canisters for spent nuclear fuel in cooperation with TWI since 1997. FSW was invented in 1991 at TWI and is a thermo

Peening as a stress relieving method for welded joints

International Nuclear Information System (INIS)

Ferreira, M.L.R.

1984-01-01

The efficacy of the process of stress relieving by hammer-peening, in heavy plates of low carbon steel is analysed. The effects of peening in the mechanical properties of welded metal deposited by shield metal arc welding, using the electrodes E-6010, E-7018 and E-8018C-2, and the weld metal deposited by submerged arc welding, using the filler metals ENil and EA3, are also analysed. X-ray diffraction was used in order to verify the efficacy of peening as a stress-relieving process. The obtained results and the literature reviewed show that, peening is effective in stress relieving. (author) [pt

Welding Current Distribution in the Work-piece and Pool in Arc Welding

Directory of Open Access Journals (Sweden)

A. M. Rybachuk

2015-01-01

Full Text Available In order to select the optimal configuration of controlling magnetic fields and build rational construction of magnetic systems, we need to know the distribution of welding current in the molten metal of the weld pool. So the objective of the work is to establish the calculated methods for determining current density in the weld pool during arc welding. The distribution of welding current in the pool depends on the field of the electrical resistance, which is determined by the deformed temperature field while arc moves with the welding speed. The previous works have shown experimentally and by simulation on the conductive paper that deformation of temperature field defines deformation of electric field. On the basis thereof, under certain boundary conditions the problem has been solved to give a general solution of differential equation, which relates the potential distribution to the temperature in the product during arc welding. This solution is obtained under the following boundary conditions: 1 metal is homogeneous; 2 input and output surfaces of heat flux and electric current coincide; 3 input and output surfaces of heat flux and electric current are insulated and equipotential; 4 other (lateral surfaces are adiabatic boundaries. Therefore, this paper pays basic attention to obtaining the analytical solution of a general differential equation, which relates distribution of potential to the temperature in the product. It considers the temperature field of the heat source, which moves at a welding speed with normal-circular distribution of the heat flow at a certain concentration factor. The distribution of current density is calculated on the assumption that the welding current is introduced through the same surface as the heat flux and the distribution of current density corresponds to the normally circular at a certain concentration factor. As a result, we get an expression that allows us to calculate the current density from the known

Mechanism and Microstructure of Oxide Fluxes for Gas Tungsten Arc Welding of Magnesium Alloy

Science.gov (United States)

Liu, L. M.; Zhang, Z. D.; Song, G.; Wang, L.

2007-03-01

Five single oxide fluxes—MgO, CaO, TiO2, MnO2, and Cr2O3—were used to investigate the effect of active flux on the depth/width ratio in AZ31B magnesium alloy. The microstructure and mechanical property of the tungsten inert gas (TIG) welding seam were studied. The oxygen content in the weld seam and the arc images during the TIG welding process were analyzed. A series of emission spectroscopy of weld arc for TIG welding for magnesium with and without flux were developed. The results showed that for the five single oxide fluxes, all can increase the weld penetration effectively and grain size in the weld seam of alternating current tungsten inert gas (ACTIG) welding of the Mg alloy. The oxygen content of the welds made without flux is not very different from those produced with oxide fluxes not considering trapped oxide. However, welds that have the best penetration have a relatively higher oxygen content among those produced with flux. It was found that the arc images with the oxide fluxes were only the enlarged form of the arc images without flux; the arc constriction was not observed. The detection of arc spectroscopy showed that the metal elements in the oxides exist as the neutral atom or the first cation in the weld arc. This finding would influence the arc properties. When TIG simulation was carried out on a plate with flux applied only on one side, the arc image video showed an asymmetric arc, which deviated toward the flux free side. The thermal stability, the dissociation energy, and the electrical conductivity of oxide should be considered when studying the mechanism for increased TIG flux weld penetration.

Characterization of Gas Metal Arc Welding welds obtained with new high Cr–Mo ferritic stainless steel filler wires

International Nuclear Information System (INIS)

Villaret, V.; Deschaux-Beaume, F.; Bordreuil, C.; Fras, G.; Chovet, C.; Petit, B.; Faivre, L.

2013-01-01

Highlights: • New metal cored filler wires for welding 444 grade stainless steel are manufactured. • The effect of Nb and Ti minor elements on the fusion zone properties is investigated. • The relation between composition of fusion zone and grain structure is investigated. • Oxidation rates of fusion zones and base metal are compared. • High temperature behavior of the welded samples are studied. - Abstract: Several compositions of metal cored filler wire were manufactured to define the best welding conditions for homogeneous welding, by Gas Metal Arc Welding (GMAW) process, of a modified AISI 444 ferritic stainless steel dedicated to automotive exhaust manifold applications. The patented grade is know under APERAM trade name K44X and has been developed to present improved high temperature fatigue properties. All filler wires investigated contained 19% Cr and 1.8% Mo, equivalent to the base metal K44X chemistry, but various titanium and niobium contents. Chemical analyses and microstructural observations of fusion zones revealed the need of a minimum Ti content of 0.15% to obtain a completely equiaxed grain structure. This structure conferred on the fusion zone a good ductility even in the as-welded state at room temperature. Unfortunately, titanium additions decreased the oxidation resistance at 950 °C if no significant Nb complementary alloying was made. The combined high Ti and Nb additions made it possible to obtain for the welded structure, after optimized heat treatment, high temperature tensile strengths and ductility for the fusion zones and assemblies, rather close to those of the base metal. 950 °C aging heat treatment was necessary to restore significantly the ductility of the as welded structure. Both fusion zone and base metal presented rather homogenized properties. Finally, with the optimized composition of the cored filler wire – 0.3 Ti minimum (i.e. 0.15% in the fusion zone) and high Nb complementary additions, the properties

Fluid Flow Behaviour under Different Gases and Flow Rate during Gas Metal Arc Welding

OpenAIRE

Jaison Peter

2013-01-01

Gas metal arc welding (GMAW) is a highly efficient and fast process for fabricating high quality weld. High quality welds are fabricated by proper selection of consumable includes gas and filler metals. The optimum flow rate of gas will ensure the proper quality of weld. In this project, a fluid flow behavior of different flow rate is modeled and the change quality will be studied.

Assessment of weld heat-affected zones in a reactor vessel material

International Nuclear Information System (INIS)

Marston, T.U.; Server, W.

1978-01-01

The mechanical properties of weld heat-affected zones (HAZ's) associated with the heavy section, nuclear quality weldments are evaluated and found to be superior to those of the parent base material. The nil ductility transition temperature (NDTT), Charpy impact and static and dynamic fracture toughness properties of a HAZ associated with a submerged arc weld and one associated with a manual metal arc weld are directly compared with those of the parent base material. It is concluded that the stigma normally associated with HAZ is not justified for this grade and quality of material and weld procedure

Investigation on mechanical properties of welded material under different types of welding filler (shielded metal arc welding)

Science.gov (United States)

Tahir, Abdullah Mohd; Lair, Noor Ajian Mohd; Wei, Foo Jun

2018-05-01

The Shielded Metal Arc Welding (SMAW) is (or the Stick welding) defined as a welding process, which melts and joins metals with an arc between a welding filler (electrode rod) and the workpieces. The main objective was to study the mechanical properties of welded metal under different types of welding fillers and current for SMAW. This project utilized the Design of Experiment (DOE) by adopting the Full Factorial Design. The independent variables were the types of welding filler and welding current, whereas the other welding parameters were fixed at the optimum value. The levels for types of welding filler were by the models of welding filler (E6013, E7016 and E7018) used and the levels for welding current were 80A and 90A. The responses were the mechanical properties of welded material, which include tensile strength and hardness. The experiment was analyzed using the two way ANOVA. The results prove that there are significant effects of welding filler types and current levels on the tensile strength and hardness of the welded metal. At the same time, the ANOVA results and interaction plot indicate that there are significant interactions between the welding filler types and the welding current on both the hardness and tensile strength of the welded metals, which has never been reported before. This project found that when the amount of heat input with increase, the mechanical properties such as tensile strength and hardness decrease. The optimum tensile strength for welded metal is produced by the welding filler E7016 and the optimum of hardness of welded metal is produced by the welding filler E7018 at welding current of 80A.

30 CFR 77.1112 - Welding, cutting, or soldering with arc or flame; safeguards.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Welding, cutting, or soldering with arc or... WORK AREAS OF UNDERGROUND COAL MINES Fire Protection § 77.1112 Welding, cutting, or soldering with arc or flame; safeguards. (a) When welding, cutting, or soldering with arc or flame near combustible...

Effect of Microstructure on Stress Corrosion Cracking Behaviour of High Nitrogen Stainless Steel Gas Tungsten Arc Welds

Science.gov (United States)

Mohammed, Raffi; Srinivasa Rao, K.; Madhusudhan Reddy, G.

2018-03-01

Present work is aimed to improve stress corrosion cracking resistance of high nitrogen steel and its welds. An attempt to weld high nitrogen steel of 5 mm thick plate using gas tungsten arc welding (GTAW) with three high strength age hardenable fillers i.e., 11-10 PH filler, PH 13- 8Mo and maraging grade of MDN 250 filler is made. Welds were characterized by optical microscopy and scanning electron microscopy. Vickers hardness testing of the welds was carried out to study the mechanical behaviour of welds. Potentio-dynamic polarization studies were done to determine pitting corrosion resistance in aerated 3.5% NaCl solution. Stress corrosion cracking (SCC) testing was carried out using constant load type machine with applied stress of 50% yield strength and in 45% MgCl2 solution boiling at 155°C. The results of the present investigation established that improvement in resistance to stress corrosion cracking was observed for PH 13- 8Mo GTA welds when compared to 11-10 PH and MDN 250 GTA welds. However, All GTA welds failed in the weld interface region. This may be attributed to relatively lower pitting potential in weld interface which acts as active site and the initiation source of pitting.

Heat transfer modeling of double-side arc welding

International Nuclear Information System (INIS)

Sun Junsheng; Wu Chuansong

2002-01-01

If a plasma arc and a TIG arc are connected in serial and with the plasma arc placed on the obverse side and the TIG arc on the opposite side of the workpiece, a special double-side arc welding (DSAW) system will be formed, in which the PAW current is forced to flow through the keyhole along the thickness direction so as to compensate the energy consumed for melting the workpiece and improve the penetration capacity of the PAW arc. By considering the mechanics factors which influence the DSAW pool geometric shape, the control equations of the pool surface deformation are derived, and the mathematics mode for DSAW heat transfer is established by using boundary-fitted non-orthogonal coordinate systems. With this model, the difference between DSAW and PAW heat transfer is analyzed and the reason for the increase of DSAW penetration is explained from the point of heat transfer. The welding process experiments show that calculated results are in good agreement with measured ones

30 CFR 75.1106 - Welding, cutting, or soldering with arc or flame underground.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Welding, cutting, or soldering with arc or... Protection § 75.1106 Welding, cutting, or soldering with arc or flame underground. [Statutory Provisions] All welding, cutting, or soldering with arc or flame in all underground areas of a coal mine shall, whenever...

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

Directory of Open Access Journals (Sweden)

Mert T.

2017-06-01

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

Effects of irradiation on the fracture properties of stainless steel weld overlay cladding

International Nuclear Information System (INIS)

Haggag, F.M.; Corwin, W.R.; Nanstad, R.K.

1989-01-01

Stainless steel weld overlay cladding was fabricated using the submerged arc, single-wire, oscillating-electrode, and the three-wire, series-arc methods. Three layers of cladding were applied to a pressure vessel plate to provide adequate thickness for fabrication of test specimens, and irradiations were conducted at temperatures and to fluences relevant to power reactor operation. For the first single-wire method, the first layer was type 309, and the upper two layers were type 308 stainless steel. The type 309 was diluted considerably by excessive melting of the base plate. The three-wire method used various combinations of types 308, 309, and 304 stainless steel weld wires, and produced a highly controlled weld chemistry, microstructure, and fracture properties in all three layers of the weld. 14 refs., 15 figs., 4 tabs

High quality, high efficiency welding technology for nuclear power plants

International Nuclear Information System (INIS)

Aoki, Shigeyuki; Nagura, Yasumi

1996-01-01

For nuclear power plants, it is required to ensure the safety under the high reliability and to attain the high rate of operation. In the manufacture and installation of the machinery and equipment, the welding techniques which become the basis exert large influence to them. For the purpose of improving joint performance and excluding human errors, welding heat input and the number of passes have been reduced, the automation of welding has been advanced, and at present, narrow gap arc welding and high energy density welding such as electron beam welding and laser welding have been put to practical use. Also in the welding of pipings, automatic gas metal arc welding is employed. As for the welding of main machinery and equipment, there are the welding of the joints that constitute pressure boundaries, the build-up welding on the internal surfaces of pressure vessels for separating primary water from them, and the sealing welding of heating tubes and tube plates in steam generators. These weldings are explained. The welding of pipings and the state of development and application of new welding methods are reported. (K.I.)

Application of YAG Laser TIG Arc Hybrid Welding to Thin AZ31B Magnesium Alloy Sheet

Science.gov (United States)

Kim, Taewon; Kim, Jongcheol; Hasegawa, Yu; Suga, Yasuo

A magnesium alloy is said to be an ecological material with high ability of recycling and lightweight property. Especially, magnesium alloys are in great demand on account of outstanding material property as a structural material. Under these circumstances, research and development of welding process to join magnesium alloy plates are of great significance for wide industrial application of magnesium. In order to use it as a structure material, the welding technology is very important. TIG arc welding process is the most ordinary process to weld magnesium alloy plates. However, since the heat source by the arc welding process affects the magnesium alloy plates, HAZ of welded joint becomes wide and large distortion often occurs. On the other hand, a laser welding process that has small diameter of heat source seems to be one of the possible means to weld magnesium alloy in view of the qualitative improvement. However, the low boiling point of magnesium generates some weld defects, including porosity and solidification cracking. Furthermore, precise edge preparation is very important in butt-welding by the laser welding process, due to the small laser beam diameter. Laser/arc hybrid welding process that combines the laser beam and the arc is an effective welding process in which these two heat sources influence and assist each other. Using the hybrid welding, a synegistic effect is achievable and the disadvantages of the respective processes can be compensated. In this study, YAG laser/TIG arc hybrid welding of thin magnesium alloy (AZ31B) sheets was investigated. First of all, the effect of the irradiation point and the focal position of laser beam on the quality of a weld were discussed in hybrid welding. Then, it was confirmed that a sound weld bead with sufficient penetration is obtained using appropriate welding conditions. Furthermore, it was made clear that the heat absorption efficiency is improved with the hybrid welding process. Finally, the tensile tests

Occupational asthma due to manual metal-arc welding of special stainless steels.

Science.gov (United States)

Hannu, T; Piipari, R; Kasurinen, H; Keskinen, H; Tuppurainen, M; Tuomi, T

2005-10-01

Occupational asthma (OA) can be induced by fumes of manual metal-arc welding on stainless steel. In recent years, the use of special stainless steels (SSS) with high chromium content has increased. This study presents two cases of OA caused by manual metal-arc welding on SSS. In both cases, the diagnosis of OA was based on respiratory symptoms, occupational exposure and positive findings in the specific challenge tests. In the first case, a 46-yr-old welder had experienced severe dyspnoea while welding SSS (SMO steel), but not in other situations. Challenge tests with both mild steel and stainless steel using a common electrode were negative. Welding SSS with a special electrode caused a delayed 37% drop in forced expiratory volume in one second (FEV1). In the second case, a 34-yr-old male had started to experience dyspnoea during the past few years, while welding especially SSS (Duplex steel). The workplace peak expiratory flow monitoring was suggestive of OA. Challenge tests with both mild steel and stainless steel using a common electrode did not cause bronchial obstruction. Welding SSS with a special electrode caused a delayed 31% drop in FEV1. In conclusion, exposure to manual metal-arc welding fumes of special stainless steel should be considered as a new cause of occupational asthma.

Microstructure and pitting corrosion of shielded metal arc welded high nitrogen stainless steel

Directory of Open Access Journals (Sweden)

Raffi Mohammed

2015-09-01

Full Text Available The present work is aimed at studying the microstructure and pitting corrosion behaviour of shielded metal arc welded high nitrogen steel made of Cromang-N electrode. Basis for selecting this electrode is to increase the solubility of nitrogen in weld metal due to high chromium and manganese content. Microscopic studies were carried out using optical microscopy (OM and field emission scanning electron microscopy (FESEM. Energy back scattered diffraction (EBSD method was used to determine the phase analysis, grain size and orientation image mapping. Potentio-dynamic polarization testing was carried out to study the pitting corrosion resistance in aerated 3.5% NaCl environment using a GillAC electrochemical system. The investigation results showed that the selected Cr–Mn–N type electrode resulted in a maximum reduction in delta-ferrite and improvement in pitting corrosion resistance of the weld zone was attributed to the coarse austenite grains owing to the reduction in active sites of the austenite/delta ferrite interface and the decrease in galvanic interaction between austenite and delta-ferrite.

Low temperature friction stir welding of P91 steel

Directory of Open Access Journals (Sweden)

Prasad Rao Kalvala

2016-08-01

Full Text Available Bead-on-plate friction stir welds were made on P91 alloy with low and high rotational speeds (100 and 1000 RPM to study their effects on weld microstructural changes and impression creep behavior. Temperatures experienced by the stir zone were recorded at the weld tool tip. Different zones of welds were characterized for their microstructural changes, hardness and creep behavior (by impression creep tests. The results were compared with submerged arc fusion weld. Studies revealed that the stir zone temperature with 100 RPM was well below Ac1 temperature of P91 steel while it was above Ac3 with 1000 RPM. The results suggest that the microstructural degradation in P91 welds can be controlled by low temperature friction stir welding technique.

Microstructure and mechanical properties of aluminum 5083 weldments by gas tungsten arc and gas metal arc welding

Energy Technology Data Exchange (ETDEWEB)

Liu Yao [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Wang Wenjing [School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Xie Jijia [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Sun Shouguang [School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Wang Liang [College of Metallurgy and Material Engineering, Chongqing University of Science and Technology, Chongqing 401331 (China); Qian Ye; Meng Yuan [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Wei Yujie, E-mail: yujie_wei@lnm.imech.ac.cn [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China)

2012-07-15

Highlights: Black-Right-Pointing-Pointer Welding zones by GTAW and GMAW are softer than the parent material Al5083. Black-Right-Pointing-Pointer GTAW for Al5083 are mechanically more reliable than that welded by GMAW. Black-Right-Pointing-Pointer GTAW welds fail by shear, but GMAW welds show mixed shear and normal failure. - Abstract: The mechanical properties and microstructural features of aluminum 5083 (Al5083) weldments processed by gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) are investigated. Weldments processed by both methods are mechanically softer than the parent material Al5083, and could be potential sites for plastic localization. It is revealed that Al5083 weldments processed by GTAW are mechanical more reliable than those by GMAW. The former bears higher strength, more ductility, and no apparent microstructure defects. Perceivable porosity in weldments by GMAW is found, which could account for the distinct mechanical properties between weldments processed by GTAW and GMAW. It is suggested that caution should be exercised when using GMAW for Al5083 in the high-speed-train industry where such light weight metal is broadly used.

Production of Manual Metal Arc Welding Electrodes with Local Raw ...

African Journals Online (AJOL)

Manual arc welding using flux coated electrodes is carried out by producing an electric arc between the base metal and a flux covered metal electrode with electric current that depends on the type of electrode, material, welding position and the desired strength. The composition of flux coated electrodes is complex and a ...

Toughness of submerged arc weld metals of controlled rolled NB bearing steel

International Nuclear Information System (INIS)

Yamaguchi, T.; Shiga, A.; Kamada, A.; Tsuboi, J.

1982-01-01

The toughness and the hardness of reheated weld metals depend on the maximum reheating temperature. When the maximum reheating temperature is 500 to 700 0 C, the hardness of single pass weld metal increases and the toughness decreases because of fine Nb- and V-carbonitride precipitation. When the maximum reheating temperature is over 800 0 C, the hardness and the toughness remain almost unchanged. The stress relieving treatment of single pass weld metal at 600 0 C for 1 up to about 100 hours causes the increase in hardness and then decreases the hardness gradually. It needs over 500 hours to obtain the same hardness value as that of as-welded metal. The addition of Ti to weld metal is very effective to improve the toughness, however excess Ti increases the hardness of stress relieved weld metal by precipitating as fine Ti-carbonitride. Therefore Ti addition should be restricted within the lowest limit required to improve as-welded metal toughness. The optimum Ti content is about 0.020% in the case of weld metal of which oxygen content is 350 ppM or so. In multipass welding, the hardness of weld metal affected by subsequent weld heat cycle varies from pass to pass, because Nb and V content change with the passes as the result of the change in dilution from base metal. The most hardened zone is observed in the reheated first pass weld metal, in which Nb and V content are the highest. Good weld metal toughness would be obtained by lowering dilution from base metal and taking advantage of grain refinement by subsequent passes

Remote automatic plasma arc-closure welding of a dry-storage canister for spent nuclear fuel and high-level radioactive waste

International Nuclear Information System (INIS)

Sprecace, R.P.; Blankenship, W.P.

1982-01-01

A carbon steel storage canister has been designed for the dry encapsulation of spent nuclear fuel assemblies or of logs of vitrified high level radioactive waste. The canister design is in conformance with the requirements of the ASME Code, Section III, Division 1 for a Class 3 vessel. The canisters will be loaded and sealed as part of a completely remote process sequence to be performed in the hot bay of an experimental encapsulation facility at the Nevada Test Site. The final closure to be made is a full penetration butt weld between the canister body, a 12.75-in O.D. x 0.25-in wall pipe, and a mating semiellipsoidal closure lid. Due to a combination of design, application and facility constraints, the closure weld must be made in the 2G position (canister vertical). The plasma arc welding system is described, and the final welding procedure is described and discussed in detail. Several aspects and results of the procedure development activity, which are of both specific and general interest, are highlighted; these include: The critical welding torch features which must be exactly controlled to permit reproducible energy input to, and gas stream interaction with, the weld puddle. A comparison of results using automatic arc voltage control with those obtained using a mechanically fixed initial arc gap. The optimization of a keyhole initiation procedure. A comparison of results using an autogenous keyhole closure procedure with those obtained using a filler metal addition. The sensitivity of the welding process and procedure to variations in joint configuration and dimensions and to variations in base metal chemistry. Finally, the advantages and disadvantages of the plasma arc process for this application are summarized from the current viewpoint, and the applicability of this process to other similar applications is briefly indicated

Structural stability of super duplex stainless weld metals and its dependence on tungsten and copper

International Nuclear Information System (INIS)

Nilsson, J.O.; Wilson, A.; Huhtala, T.; Karlsson, L.; Jonsson, P.

1996-01-01

Three different superduplex stainless weld metals have been produced using manual metal arc welding under identical welding conditions. The concentration of the alloying elements tungsten and copper corresponded to the concentrations in commercial superduplex stainless steels (SDSS). Aging experiments in the temperature range 700 C to 1,110 C showed that the formation of intermetallic phase was enhanced in tungsten-rich weld metal and also dissolved at higher temperatures compared with tungsten-poor and tungsten-free weld metals. It could be inferred from time-temperature-transformation (TTT) and continuous-cooling-transformation (CCT) diagrams produced in the present investigation that the critical cooling rate to avoid 1 wt pct of intermetallic phase was 2 times faster for tungsten-rich weld metal. Microanalysis in combination with thermodynamic calculations showed that tungsten was accommodated in χ phase, thereby decreasing the free energy. Experimental evidence supports the view that the formation of intermetallic phase is enhanced in tungsten-rich weld metal, owing to easier nucleation of nonequilibrium χ phase compared with σ phase. The formation of secondary austenite (γ 2 ) during welding was modeled using the thermodynamic computer program Thermo-Calc. Satisfactory agreement between theory and practice was obtained. Thermo-Calc was capable of predicting observed lower concentrations of chromium and nitrogen in γ 2 compared with primary austenite. The volume fraction of γ 2 was found to be significantly higher in tungsten-rich and tungsten + copper containing weld metal. The results could be explained by a higher driving force for precipitation of γ 2 in these

Structural stability of super duplex stainless weld metals and its dependence on tungsten and copper

Science.gov (United States)

Nilsson, J.-O.; Huhtala, T.; Jonsson, P.; Karlsson, L.; Wilson, A.

1996-08-01

Three different superduplex stainless weld metals have been produced using manual metal arc welding under identical welding conditions. The concentration of the alloying elements tungsten and copper corresponded to the concentrations in commercial superduplex stainless steels (SDSS). Aging experiments in the temperature range 700 °C to 1110 °C showed that the formation of intermetallic phase was enhanced in tungsten-rich weld metal and also dissolved at higher temperatures compared with tungsten-poor and tungsten-free weld metals. It could be inferred from time-temperature-transformation (TTT) and continuous-cooling-transformation (CCT) diagrams produced in the present investigation that the critical cooling rate to avoid 1 wt pct of intermetallic phase was 2 times faster for tungsten-rich weld metal. Microanalysis in combination with thermodynamic calculations showed that tungsten was accommodated in χ phase, thereby decreasing the free energy. Experimental evidence supports the view that the formation of intermetallic phase is enhanced in tungsten-rich weld metal, owing to easier nucleation of nonequilibrium χ phase compared with σ phase. The formation of secondary austenite (γ2) during welding was modeled using the thermodynamic computer program Thermo-Calc. Satisfactory agreement between theory and practice was obtained. Thermo-Calc was capable of predicting observed lower concentrations of chromium and nitrogen in γ2 compared with primary austenite. The volume fraction of γ2 was found to be significantly higher in tungsten-rich and tungsten + copper containing weld metal. The results could be explained by a higher driving force for precipitation of γ2 in these.

Progress in welding studies for Canadian nuclear fuel waste disposal containers

International Nuclear Information System (INIS)

Maak, P.Y.Y.

1985-11-01

This report describes the progress in the development of closure-welding technology for Canadian nuclear fuel waste disposal containers. Titanium, copper and Inconel 625 are being investigated as candidate materials for fabrication of these containers. Gas-tungsten-arc welding, gas metal-arc-welding, resistance-heated diffusion bonding and electron beam welding have been evaluated as candidate closure welding processes. Characteristic weldment properties, relative merits of welding techniques, suitable weld joint configurations and fit-up tolerances, and welding parameter control ranges have been identified for various container designs. Furthermore, the automation requirements for candidate welding processes have been assessed. Progress in the development of a computer-controlled remote gas-shielded arc welding system is described

Effects of Surface Alloying and Laser Beam Treatment on the Microstructure and Wear Behaviour of Surfaces Modified Using Submerged Metal Arc Welding

Directory of Open Access Journals (Sweden)

Regita BENDIKIENE

2016-05-01

Full Text Available In this study, the effects of surface alloying of cheap plain carbon steel using submerged metal arc technique and subsequent laser beam treatment on the microstructure and wear behaviour of surfaced layers were studied. This method is the cheapest one to obtain high alloyed coatings, because there is no need to apply complex technologies of powder making (metal powder is spread on the surface of base metal or inserted into the flux, it is enough to grind, granulate and blend additional materials. On the other hand, strengthening of superficial layers of alloys by thermal laser radiation is one of the applications of laser. Surface is strengthened by concentrated laser beam focused into teeny area (from section of mm till some mm. Teeny area of metal heat up rapidly and when heat is drain to the inner metal layers giving strengthening effect. Steel surface during this treatment exceeds critical temperatures, if there is a need to strengthen deeper portions of the base metal it is possible even to fuse superficial layer. The results presented in this paper are based on micro-structural and micro-chemical analyses of the surfaced and laser beam treated surfaces and are supported by analyses of the hardness, the wear resistance and resultant microstructures. Due to the usage of waste raw materials a significant improvement (~ 30 % in wear resistance was achieved. The maximum achieved hardness of surfaced layer was 62 HRC, it can be compared with high alloyed conventional steel grade. Wear properties of overlays with additional laser beam treatment showed that weight loss of these layers was ~10 % lower compared with overlays after welding; consequently it is possible to replace high alloyed conventional steel grades forming new surfaces or restoring worn machine elements and tools.DOI: http://dx.doi.org/10.5755/j01.ms.22.1.7621

Prediction of the weld pool geometry of TIG arc welding by using ...

African Journals Online (AJOL)

Prediction of the weld pool geometry of TIG arc welding by using fuzzy logic controller. ... The experimental data were then used for building a fuzzy logic model to predict the effects of control factors on the responses. A graphical mapping scheme was employed for the graphical representation of the macrostructure zones' ...

Discontinuity Detection in the Shield Metal Arc Welding Process.

Science.gov (United States)

Cocota, José Alberto Naves; Garcia, Gabriel Carvalho; da Costa, Adilson Rodrigues; de Lima, Milton Sérgio Fernandes; Rocha, Filipe Augusto Santos; Freitas, Gustavo Medeiros

2017-05-10

This work proposes a new methodology for the detection of discontinuities in the weld bead applied in Shielded Metal Arc Welding (SMAW) processes. The detection system is based on two sensors-a microphone and piezoelectric-that acquire acoustic emissions generated during the welding. The feature vectors extracted from the sensor dataset are used to construct classifier models. The approaches based on Artificial Neural Network (ANN) and Support Vector Machine (SVM) classifiers are able to identify with a high accuracy the three proposed weld bead classes: desirable weld bead, shrinkage cavity and burn through discontinuities. Experimental results illustrate the system's high accuracy, greater than 90% for each class. A novel Hierarchical Support Vector Machine (HSVM) structure is proposed to make feasible the use of this system in industrial environments. This approach presented 96.6% overall accuracy. Given the simplicity of the equipment involved, this system can be applied in the metal transformation industries.

Corrosion Behavior of Arc Weld and Friction Stir Weld in Al 6061-T6 Alloys

International Nuclear Information System (INIS)

Yoon, Byoung Hyun; Kim, Heung Ju; Chang, Woong Seong; Kweon, Young Gak

2006-01-01

For the evaluation of corrosion resistance of Al 6061-T6 Alloy, Tafel method and immersion test was performed with Friction Stir Weld(FSW) and Gas Metal Arc Weld(GMAW). The Tafel and immersion test results indicated that GMA weld was severely attacked compared with those of friction stir weld. It may be mainly due to the galvanic corrosion mechanism act on the GMA weld

Development of New Materials and Technologies for Welding and Surfacing at Research and Production Center 'Welding Processes and Technologies'

International Nuclear Information System (INIS)

Kozyrev, N A; Kryukov, R E; Galevsky, G V; Titov, D A; Shurupov, V M

2015-01-01

The paper provides description of research into the influence of new materials and technologies on quality parameters of welds and added metal carried out at research and production center «Welding processes and technologies».New welding technologies of tanks for northern conditions are considered, as well as technologies of submerged arc welding involving fluxing agents AN - 348, AN - 60, AN - 67, OK. 10.71 and carbon-fluorine containing additives, new flux cored wires and surfacing technologies, teaching programs and a trainer for welders are designed. (paper)

Tensile Strength and Hardness Correlations with Microscopy in Friction welded Aluminium to Copper

Science.gov (United States)

Satish, Rengarajan; Seshagiri Rao, Vaddi; Ananthapadmanaban, Dattaguru; Ravi, Balappa

2016-01-01

Aluminium and copper are good conductors of heat and electricity, copper being the better conductor, is a costly metal indeed. On the other hand, aluminium is cheap, easily available and also has a lower density than copper. Hence, worldwide efforts are being made to partially replace copper wire. Solid state welding should be used to join aluminium to copper. This is because the use of fusion welding results in brittle phases formed in the weld interface. One of the solid state welding techniques used for joining aluminium to copper is friction welding. In this paper, an attempt has been made to join aluminium to copper by friction welding by varying the friction welding parameters, namely friction pressure, upset pressure, burn-off length and speed of rotation of the workpiece. Nine different friction welding parameter combinations were used during welding in accordance with ASTM standards and results have been reported. Tensile strength and hardness tests were carried out for each parameter combination. Optimum friction welding parameter combination was identified with respect to tensile strength. Scanning Electron Microscopy and Electron dispersive spectroanalysis were obtained to identify modes of fracture and presence of intermetallic phases for each friction welding combination with the aim to narrow down friction welding parameters that give good properties on the whole.

Studies on microstructure, mechanical and corrosion properties of high nitrogen stainless steel shielded metal arc welds

Science.gov (United States)

Mohammed, Raffi; Madhusudhan Reddy, G.; Srinivasa Rao, K.

2018-03-01

The present work is aimed at studying the microstructure, mechanical and corrosion properties of high nitrogen stainless steel shielded metal arc (SMA) welds made with Cromang-N electrode. Basis for selecting this electrode is to increase the solubility of nitrogen in weld metal due to high chromium and manganese content. Microstructures of the welds were characterized using optical microscopy (OM), field emission scanning electron microscopy (FESEM) and electron back scattered diffraction (EBSD) mainly to determine the morphology, phase analysis, grain size and orientation image mapping. Hardness, tensile and ductility bend tests were carried out to determine mechanical properties. Potentio-dynamic polarization testing was carried out to study the pitting corrosion resistance using a GillAC basic electrochemical system. Constant load type testing was carried out to study stress corrosion cracking (SCC) behaviour of welds. The investigation results shown that the selected Cr–Mn–N type electrode resulted in favourable microstructure and completely solidified as single phase coarse austenite. Mechanical properties of SMA welds are found to be inferior when compared to that of base metal and is due to coarse and dendritic structure.

Advanced Control Methods for Optimization of Arc Welding

DEFF Research Database (Denmark)

Thomsen, J. S.

Gas Metal Arc Welding (GMAW) is a proces used for joining pieces of metal. Probably, the GMAW process is the most successful and widely used welding method in the industry today. A key issue in welding is the quality of the welds produced. The quality of a weld is influenced by several factors...... in the overall welding process; one of these factors are the ability of the welding machine to control the process. The internal control algorithms in GMAW machines are the topic of this PhD project. Basically, the internal control includes an algorithm which is able to keep the electrode at a given distance...

Sensing the gas metal arc welding process

Science.gov (United States)

Carlson, N. M.; Johnson, J. A.; Smartt, H. B.; Watkins, A. D.; Larsen, E. D.; Taylor, P. L.; Waddoups, M. A.

1994-01-01

Control of gas metal arc welding (GMAW) requires real-time sensing of the process. Three sensing techniques for GMAW are being developed at the Idaho National Engineering Laboratory (INEL). These are (1) noncontacting ultrasonic sensing using a laser/EMAT (electromagnetic acoustic transducer) to detect defects in the solidified weld on a pass-by-pass basis, (2) integrated optical sensing using a CCD camera and a laser stripe to obtain cooling rate and weld bead geometry information, and (3) monitoring fluctuations in digitized welding voltage data to detect the mode of metal droplet transfer and assure that the desired mass input is achieved.

Fatigue crack growth behavior of pressure vessel steels and submerged arc weldments in a high-temperature pressurized water environment

International Nuclear Information System (INIS)

Liaw, P.K.; Logsdon, W.A.; Begley, J.A.

1989-01-01

The fatigue crack growth rate (FCGR) properties of SA508 Cl 2a and SA533 Gr A Cl 2 pressure vessel steels and the corresponding automatic submerged arc weldments were developed in a high-temperature pressurized water (HPW) environment at 288 degrees C (550 degrees F) and 7.2 MPa (1044 psi) at load ratios of 0.20 and 0.50. The properties were generally conservative compared to American Society of Mechanical Engineers Section XI water environment reference curve. The growth rate of fatigue cracks in the base materials, however, was faster in the HPW environment than in a 288 degrees C (550 degrees F) base line air environment. The growth rate of fatigue cracks in the two submerged arc weldments was also accelerated in the HPW environment but to a lesser degree than that demonstrated by the base materials. In the air environment, fatigue striations were observed, independent of material and load ratio, while in the HPW environment, some intergranular facets were present. The greater environmental effect on crack growth rates displayed by the base materials compared the weldments attributed to a different sulfide composition and morphology

MAG narrow gap welding - an economic way to minimize welding expenses

International Nuclear Information System (INIS)

Kast, W.; Scholz, E.; Weyland, F.

1982-01-01

The thicker structural components are, the more important it is to take measures to reduce the volume of the weld. The welding process requiring the smallest possible weld section is the so-called narrow gap process. In submerged arc narrow gap welding as well as in MAG narrow gap welding different variants are imaginable, some of them already in practical use. With regard to efficiency and weld quality an optimum variant of the MAG narrow gap welding process is described. It constitutes a two wire system in which two wire electrodes of 1.2 mm diameter are arranged one behind the other. In order to avoid lack of fusion, the wire guides are slightly pointed towards each groove face. Thus, by inclining the two arcs burning one behind the other in the direction of weld progress, it is achieved that two separately solidifying weld pools and two beads per layer are simultaneously formed. Welding parameters are selected in such a way that a heat input of 16-20 kJ/cm and a deposition rate of 11-16 kgs/h are obtained. In spite of this comparatively high deposition rate, good impact values are found both in the weld and HAZ (largely reduced coarse-grain zone) which is due to an optimum weld build-up. With the available welding equipment the process can be applied to structural members having a thickness of 40-400 mm. The width of gap is 13 mm (root section) with a bevel angle of 1 0 . As filler metal, basic flux-cored wires are used which, depending on the base metal to be welded and the required tensile properties, can be of the Mn-, MnMo-, MnCrMo-, MnNi-, or MnNiMo-alloyed types. (orig.)

Manual gas tungsten arc (dc) and semiautomatic gas metal arc welding of 6XXX aluminum. Welding procedure specification

International Nuclear Information System (INIS)

Wodtke, C.H.; Frizzell, D.R.; Plunkett, W.A.

1985-08-01

Procedure WPS-1009 is qualified under Section IX of the ASME Boiler and Pressure Vessel Code for manual gas tungsten arc (DC) and semiautomatic gas metal arc (DC) welding of aluminum alloys 6061 and 6063 (P-23), in thickness range 0.187 to 2 in.; filler metal is ER4043 (F-23); shielding gases are helium (GTAW) and argon (GMAW)

EB-welding of the copper canister for the nuclear waste disposal. Final report of the development programme 1994-1997

International Nuclear Information System (INIS)

Aalto, H.

1998-10-01

During 1994-1997 Posiva Oy and Outokumpu Poricopper Oy had a joint project Development of EB-welding method for massive copper canister manufacturing. The project was part of the national technology program 'Weld 2000' and it was supported financially by Technology Development Centre (TEKES). The spent fuel from Finnish nuclear reactors is planned to be encapsulated in thick-walled copper canisters and placed deep into the bedrock. The thick copper layer of the canister provides a long time corrosion resistance and prevents deposited nuclear fuel from contact with water. The quality requirements of the copper components are high because of the designed long lifetime of the canister. The EB-welding technology has proved to be applicable method for the production of the copper canisters and the EB-welding technique is needed at least when the lids of the copper canister will be closed. There are a number of parameters in EB-welding which affect weldability. However, the effect of the welding parameters and their optimization has not been extensively studied in welding of thick copper sections using conventional high vacuum EB-welding. One aim of this development work was to extensively study effect of welding parameters on weld quality. The final objective was to minimise welding defects in the main weld and optimize slope out procedure in thick copper EB-welding. Welding of 50 mm thick copper sections was optimized using vertical and horizontal EB-welding techniques. As a result two full scale copper lids were welded to a short cylinder successfully. The resulting weld quality with optimised welding parameters was reasonable good. The optimised welding parameters for horizontal and vertical beam can be applied to the longitudinal body welds of the canister. The optimal slope out procedure for the lid closure needs some additional development work. In addition of extensive EB-welding program ultrasonic inspection and creep strength of the weld were studied. According

EB-welding of the copper canister for the nuclear waste disposal. Final report of the development programme 1994-1997

Energy Technology Data Exchange (ETDEWEB)

Aalto, H. [Outokumpu Oy Poricopper, Pori (Finland)

1998-10-01

During 1994-1997 Posiva Oy and Outokumpu Poricopper Oy had a joint project Development of EB-welding method for massive copper canister manufacturing. The project was part of the national technology program `Weld 2000` and it was supported financially by Technology Development Centre (TEKES). The spent fuel from Finnish nuclear reactors is planned to be encapsulated in thick-walled copper canisters and placed deep into the bedrock. The thick copper layer of the canister provides a long time corrosion resistance and prevents deposited nuclear fuel from contact with water. The quality requirements of the copper components are high because of the designed long lifetime of the canister. The EB-welding technology has proved to be applicable method for the production of the copper canisters and the EB-welding technique is needed at least when the lids of the copper canister will be closed. There are a number of parameters in EB-welding which affect weldability. However, the effect of the welding parameters and their optimization has not been extensively studied in welding of thick copper sections using conventional high vacuum EB-welding. One aim of this development work was to extensively study effect of welding parameters on weld quality. The final objective was to minimise welding defects in the main weld and optimize slope out procedure in thick copper EB-welding. Welding of 50 mm thick copper sections was optimized using vertical and horizontal EB-welding techniques. As a result two full scale copper lids were welded to a short cylinder successfully. The resulting weld quality with optimised welding parameters was reasonable good. The optimised welding parameters for horizontal and vertical beam can be applied to the longitudinal body welds of the canister. The optimal slope out procedure for the lid closure needs some additional development work. In addition of extensive EB-welding program ultrasonic inspection and creep strength of the weld were studied. According

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.

Dry hyperbaric gas metal arc welding of subsea pipelines: experiments and modeling

Energy Technology Data Exchange (ETDEWEB)

Azar, Amin S.

2012-07-01

Ambitions in exploration of oil and gas fields at deeper water depth require continuous investigation and maintenance. The transportation pipelines laid in deep waters are both subjected to corrosion and buckling due to environmental phenomena. They may also often undergo branching (namely hot tapping) to redirect (or add to) the transportation paths. Mechanical joints and welding are both considered as available alternatives when sectioning and replacement of the pipes at shallow waters is necessary, yet, welding is more promising for deep waters where remote operation is central. Fusion welding on the other hand comprises several technological detractions for sound operations under high ambient pressures disregarding its low cost and flexibility. The foremost detracting phenomenon in the arc welding is called 'arc root constriction', which is defined as arc geometry shrinkage under the increased pressure. Consequently, the power delivery to the weld pool at different pressure levels is a major worry. Effects of ionization and dissociation energies of different gases and mixtures, partial pressure of environmental gases including hydrogen and oxygen, gasification and degasification of the weld metal, inclusions that affect the phase transformation, absorption and desorption kinetics, oxidation and deoxidation reactions and many more are the phenomena that can possibly be altered by the gas type and ambient pressure level. Spattering and fume generation is a problematic issue since the arc is rather unstable under high pressure. Thus, seeking the effect of different chamber gas mixtures on welding parameters, final microstructure and mechanical properties is the main objective of this work.Statistical analysis of the collected voltage and current waveforms is carried out to identify the source of arc misbehavior and instability (discussed in Paper I). The stochastic parameters is related to the electrical stability and resolved into a number of varying

Experience and Applications Up-date: Automation of Arc-Welding Operations Using Robot-Technology

International Nuclear Information System (INIS)

Teubel, G.

1996-01-01

In a short introduction, the important criteria for the correct choice of a robot cell, taking into account the given application, are highlighted. Furthermore, important hints are listed in terms of management decisions. The second chapter shows the main features of a welding robot cell in line with the present state of the art and describes some new developments with the aim of extending the arc-welding system to new applications such as flame cutting and beveling. The third chapter as centre piece gives an overall view of a brand new network control with many outstanding features for the users of arc-welding robots. the fourth and last chapter shows a recent realisation of a highly sophisticated F.M.S. system for welding, in random sequence, different large and heavy components. (Author) 1 ref

Welding wires for high-tensile steels

International Nuclear Information System (INIS)

Laz'ko, V.E.; Starova, L.L.; Koval'chuk, V.G.; Maksimovich, T.L.; Labzina, I.E.; Yadrov, V.M.

1993-01-01

Strength of welded joints in arc welding of high-tensile steels of mean and high thickness by welding wires is equal to approximately 1300 MPa in thermohardened state and approximately 600 MPa without heat treatment. Sv-15Kh2NMTsRA-VI (EhK44-VI) -Sv-30Kh2NMTsRA-VI (EkK47-VI) welding wires are suggested for welding of medium-carbon alloyed steels. These wires provide monotonous growth of ultimate strength of weld metal in 1250-1900 MPa range with increase of C content in heat-treated state

Fabrication of electroslag welded Magnox fuel transport flasks

International Nuclear Information System (INIS)

Tuliani, S.S.

1979-01-01

The high weld metal deposition rate of the electroslag welding process offers an attractive method of fabricating nuclear fuel transport flasks from 370 mm (14.5in) thick steel plates. The paper describes pre-production trials carried out on full scale corner-section joints to establish that the weld metal meets the exacting mechanical property requirements for the Nuclear Industry. The paper presents results obtained on welds produced using two base metal compositions and two wires, one recommended for submerged-arc and the other for electroslag welding processes. Details of mechanical tests and metallographic examinations are given which led to the selection of the latter type of wire. It was found that while the weld metal deposited by this process may be sensitive to cracking, this can be avoided by careful selection of welding consumables and sound joints can be obtained under production conditions. (author)

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.

Numerical and experimental study of heat transfers in an arc plasma. Application to TIG arc welding

International Nuclear Information System (INIS)

Borel, Damien

2013-01-01

The arc welding is used for many industrial applications, especially GTA welding. Given the excellent quality of the produced welds, GTA welding is used for the majority of the interventions (repairs, joined sealing) on the French nuclear park. This work is part of a project carried out by EDF R and D which aims to simulate the whole process and builds a tool able to predict the welds quality. In this study, we focus on the development of a predictive model of the exchanged heat flux at the arc - work piece interface, responsible of the work piece fusion. The modeling of the arc plasma using the electric module of the hydrodynamics software Code Saturne R developed by EDF R and D is required. Two types of experimental tests are jointly carried out to validate this numerical model: i) on density and temperature measurements of plasma by atomic emission spectroscopy and ii) on the evaluation of the heat transfers on the work piece surface. This work also aims at demonstrate that the usual method of using an equivalent thermal source to model the welding process, can be replaced by our plasma model, without the numerous trials inherent to the usual method. (author)

Development of a process model for intelligent control of gas metal arc welding

International Nuclear Information System (INIS)

Smartt, H.B.; Johnson, J.A.; Einerson, C.J.; Watkins, A.D.; Carlson, N.M.

1991-01-01

This paper discusses work in progress on the development of an intelligent control scheme for arc welding. A set of four sensors is used to detect weld bead cooling rate, droplet transfer mode, weld pool and joint location and configuration, and weld defects during welding. A neural network is being developed as the bridge between the multiple sensor set a conventional proportional-integral controller that provides independent control of process variables. This approach is being developed for the gas metal arc welding process. 20 refs., 8 figs

Grain boundary corrosion of copper canister weld material

International Nuclear Information System (INIS)

Gubner, Rolf; Andersson, Urban; Linder, Mats; Nazarov, Andrej; Taxen, Claes

2006-01-01

The proposed design for a final repository for spent fuel and other long-lived residues in Sweden is based on the multi-barrier principle. The waste will be encapsulated in sealed cylindrical canisters, which will then be placed in granite bedrock and surrounded by compacted bentonite clay. The canister design is based on a thick cast inner container fitted inside a corrosion-resistant copper canister. During fabrication of the outer copper canisters there will be some unavoidable grain growth in the welded areas. As grains grow, they will tend to concentrate impurities within the copper at the new grain boundaries. The work described in this report was undertaken to determine whether there is any possibility of enhanced corrosion at grain boundaries within the copper canister, based on the recommendations of the report SKB-TR--01-09 (INIS ref. 32025363). Grain boundary corrosion of copper is not expected to be a problem for the copper canisters in a repository. However, as one step in the experimental verification it is necessary to study grain boundary corrosion of copper in an environment where it may occur. A literature study aimed to find one or several solutions that are aggressive with respect to grain boundary corrosion of copper. Copper specimens cut from welds of real copper canisters where exposed to aerated ammonium hydroxide solution for a period of 14 days at 80 degrees C and 10 bar pressure. The samples were investigated prior to exposure using the scanning Kelvin probe technique to characterize anodic and cathodic areas on the samples. The degree of corrosion was determined by optical microscopy. No grain boundary corrosion could be observed in the autoclave experiments, however, a higher rate of corrosion was observed for the weld material compared to the base material. The work suggests that grain boundary corrosion of copper weld material is most unlikely to adversely affect SKB's copper canisters under the conditions in the repository

Grain boundary corrosion of copper canister weld material

Energy Technology Data Exchange (ETDEWEB)

Gubner, Rolf; Andersson, Urban; Linder, Mats; Nazarov, Andrej; Taxen, Claes [Corrosion and Metals Research Inst. (KIMAB), Stockholm (Sweden)

2006-01-15

The proposed design for a final repository for spent fuel and other long-lived residues in Sweden is based on the multi-barrier principle. The waste will be encapsulated in sealed cylindrical canisters, which will then be placed in granite bedrock and surrounded by compacted bentonite clay. The canister design is based on a thick cast inner container fitted inside a corrosion-resistant copper canister. During fabrication of the outer copper canisters there will be some unavoidable grain growth in the welded areas. As grains grow, they will tend to concentrate impurities within the copper at the new grain boundaries. The work described in this report was undertaken to determine whether there is any possibility of enhanced corrosion at grain boundaries within the copper canister, based on the recommendations of the report SKB-TR--01-09 (INIS ref. 32025363). Grain boundary corrosion of copper is not expected to be a problem for the copper canisters in a repository. However, as one step in the experimental verification it is necessary to study grain boundary corrosion of copper in an environment where it may occur. A literature study aimed to find one or several solutions that are aggressive with respect to grain boundary corrosion of copper. Copper specimens cut from welds of real copper canisters where exposed to aerated ammonium hydroxide solution for a period of 14 days at 80 degrees C and 10 bar pressure. The samples were investigated prior to exposure using the scanning Kelvin probe technique to characterize anodic and cathodic areas on the samples. The degree of corrosion was determined by optical microscopy. No grain boundary corrosion could be observed in the autoclave experiments, however, a higher rate of corrosion was observed for the weld material compared to the base material. The work suggests that grain boundary corrosion of copper weld material is most unlikely to adversely affect SKB's copper canisters under the conditions in the repository.

Progress in Effect of Nano-modified Coatings and Welding Process Parameters on Wear of Contact Tube for Non-copper Coated Solid Wires

Directory of Open Access Journals (Sweden)

LI Zhuo-xin

2017-12-01

Full Text Available Environment-friendly non-copper coated solid wire is the main developing trend for gas shielded solid wires, whereas wear of contact tube limits their wide application. The effect of nano-modified coatings and welding process parameters on wear of contact tube for non-copper coated solid wires was reviewed. It was found that the wear of contact tube can be reduced due to the formation of tribo-films on the rubbing surfaces of welding wires against contact tube; it is feasible to decrease contact tube wear when non-copper coated solid wires are coated with nano-modified lubricants, thereby displaying excellent lubricating and thermal or electrical conduction characteristics. The wear of contact tube increases with the increase of welding current. The wear of contact tube is worse in direct-current electrode positive (DCEP than in direct-current electrode negative (DCEN. Arc ablation and electrical erosion are the dominant wear mechanisms of contact tube.

INFLUENCE OF CHEMICAL COMPOUNDS ON THE FORMING OF WELDING ARC

Directory of Open Access Journals (Sweden)

I. О. Vakulenko

2014-10-01

Full Text Available Purpose. The purpose of work is a comparative analysis of chemical compounds influence on the process of forming arc welding and condition of its burning. Methodology. A wire with diameter 3 mm of low carbon steel with contain of carbon 0.15% was material for electrode. As chemical compounds, which determine the terms of arc welding forming the following compounds were used: kaolin; CaCO3 with admixtures of gypsum up to 60%; SiO2 and Fe − Si with the iron concentration up to 50%. Researches were conducted using the direct electric current and arc of reverse polarity. As a source of electric current a welding transformer of type PSO-500n was used. On the special stand initial gap between the electrode and metal plate was 1-1.5 mm. The inter electrode space was filled with the probed chemical compound and the electric arc was formed. At the moment of arc forming the values of electric current and arc voltage were determined. After the natural break of electric arc, the final gap value between electrodes was accepted as a maximal value of arc length. Findings. Experimentally the transfer of metal in interelectrode space corresponded to the tiny drop mechanism. According to external signs the relation between maximal arc length and the power of electric current has the form of exponential dependence. Specific power of electric arc at the moment of arc forming per unit of its length characterizes the environment in the interelectrode space. Originality. 1 Based on the analysis of influence of the studied chemical compounds on the formation processes of electric arc the inversely proportional relationship between the power of the electric current and the maximum arc length until the moment of its natural break is defined. 2 Ratio between the maximal arc length and the power of electric current, with the sufficiently high coefficient of correlation is submitted to the exponential dependence. Influence of the compounds under study on the process of

Carbothermic reduction of pyrolusite for obtaining carbon bearing ferromanganese and slags, adequated to the development of welding materials

International Nuclear Information System (INIS)

Cruz-Crespo, A.; Garcia-Sanchez, L. L.; Quintana-Puchol, R.; Perdomo Gonzalez, L.; Gomez-Perez, C. R.; Jimenez-Vielsa, G. E.; Cores-Sanchez, A.

2004-01-01

The high carbon ferromanganese obtained by means of carbothermic reduction in an electric arc furnace of direct current is proposed. the ideal composition of slag oxides to achieve a flux to be used in the submerged arc welding (SAW) is established. Calculation for charge components (pyrolusite, coke, steel wool, lime, rutile and fluorite) for no fluxes technology for FeMn is carried out taking into account the welding fluxes characteristics of the SiO 2 -MnO-CaO system. Change materials reduction experiments to obtain FeMn and slag are used to develop a SAW flux. (Author) 21 refs

Numerical simulation of gas metal arc welding parametrical study

International Nuclear Information System (INIS)

Szanto, M.; Gilad, I.; Shai, I.; Quinn, T.P.

2002-01-01

The Gas Metal Arc Welding (GMAW) is a widely used welding process in the industry. The process variables are usually determined through extensive experiments. Numerical simulation, reduce the cost and extends the understanding of the process. In the present work, a versatile model for numerical simulation of GMAW is presented. The model provides the basis for fundamental understanding of the process. The model solves the magneto-hydrodynamic equations for the flow and temperature fields of the molten electrode and the plasma simultaneously, to form a fully coupled model. A commercial CFD code was extended to include the effects of radiation, Lorentz forces, Joule heating and thermoelectric effects. The geometry of the numerical model assembled to fit an experimental apparatus. To demonstrate the method, an aluminum electrode was modeled in a pure argon arc. Material properties and welding parameters are the input variables in the numerical model. In a typical process, the temperature distribution of the plasma is over 15000 K, resulting high non-linearity of the material properties. Moreover, there is high uncertainty in the available property data, at that range of temperatures. Therefore, correction factors were derived for the material properties to adjust between the numerical and the experimental results. Using the compensated properties, parametric study was performed. The effects of the welding parameters on the process, such the working voltage, electrode feed rate and shielding gas flow, were derived. The principal result of the present work is the ability to predict, by numerical simulation, the mode, size and frequency of the metal transferred from the electrode, which is the main material and energy source for the welding pool in GMAW

3D Numerical Analysis of the Arc Plasma Behavior in a Submerged DC Electric Arc Furnace for the Production of Fused MgO

International Nuclear Information System (INIS)

Wang Zhen; Wang Ninghui; Li Tie; Cao Yong

2012-01-01

A three dimensional steady-state magnetohydrodynamic model is developed for the arc plasma in a DC submerged electric arc furnace for the production of fused MgO. The arc is generated in a small semi-enclosed space formed by the graphite electrode, the molten bath and unmelted raw materials. The model is first used to solve a similar problem in a steel making furnace, and the calculated results are found to be in good agreement with the published measurements. The behavior of arcs with different arc lengths is also studied in the furnace for MgO production. From the distribution of the arc pressure on the bath surface it is shown that the arc plasma impingement is large enough to cause a crater-like depression on the surface of the MgO bath. The circulation of the high temperature air under the electrode may enhance the arc efficiency, especially for a shorter arc.

Human biomonitoring of chromium and nickel from an experimental exposure to manual metal arc welding fumes of low and high alloyed steel.

Science.gov (United States)

Bertram, Jens; Brand, Peter; Schettgen, Thomas; Lenz, Klaus; Purrio, Ellwyn; Reisgen, Uwe; Kraus, Thomas

2015-05-01

The uptake and elimination of metals from welding fumes is currently not fully understood. In the Aachen Workplace Simulation Laboratory (AWSL) it is possible to investigate the impact of welding fumes on human subjects under controlled exposure conditions. In this study, the uptake and elimination of chromium or chromium (VI) respectively as well as nickel was studied in subjects after exposure to the emissions of a manual metal arc welding process using low or high alloyed steel. In this present study 12 healthy male non-smokers, who never worked as welders before, were exposed for 6h to welding fumes of a manual metal arc welding process. In a three-fold crossover study design, subjects were exposed in randomized order to either clean air, emissions from welding low alloyed steel, and emissions from welding high alloyed steel. Particle mass concentration of the exposure aerosol was 2.5mg m(-3). The content of chromium and nickel in the air was determined by analysing air filter samples on a high emission scenario. Urine analysis for chromium and nickel was performed before and after exposure using methods of human biomonitoring. There were significantly elevated chromium levels after exposure to welding fumes from high alloyed steel compared to urinary chromium levels before exposure to high alloyed welding fumes, as well as compared to the other exposure scenarios. The mean values increased from 0.27 µg l(-1) to 18.62 µg l(-1). The results were in good agreement with already existing correlations between external and internal exposure (German exposure equivalent for carcinogenic working materials EKA). The variability of urinary chromium levels was high. For urinary nickel no significant changes could be detected at all. Six-hour exposure to 2.5mg m(-3) high alloyed manual metal arc welding fumes lead to elevated urinary chromium levels far higher (7.11-34.16 µg l(-1)) than the German biological exposure reference value (BAR) of 0.6 µg l(-1) directly after

Multiphysics Simulation of Welding-Arc and Nozzle-Arc System: Mathematical-Model, Solution-Methodology and Validation

Science.gov (United States)

Pawar, Sumedh; Sharma, Atul

2018-01-01

This work presents mathematical model and solution methodology for a multiphysics engineering problem on arc formation during welding and inside a nozzle. A general-purpose commercial CFD solver ANSYS FLUENT 13.0.0 is used in this work. Arc formation involves strongly coupled gas dynamics and electro-dynamics, simulated by solution of coupled Navier-Stoke equations, Maxwell's equations and radiation heat-transfer equation. Validation of the present numerical methodology is demonstrated with an excellent agreement with the published results. The developed mathematical model and the user defined functions (UDFs) are independent of the geometry and are applicable to any system that involves arc-formation, in 2D axisymmetric coordinates system. The high-pressure flow of SF6 gas in the nozzle-arc system resembles arc chamber of SF6 gas circuit breaker; thus, this methodology can be extended to simulate arcing phenomenon during current interruption.

Copper welding in solid phase; Svarka medi v tverdoj faze

Energy Technology Data Exchange (ETDEWEB)

Avagyan, V Sh

1993-12-31

An analysis of the publications on the technology of diffusion welding of copper in solid phase is carried out. The aspects of diffusion welding of copper with silver, aluminium, nickels, chromium, titanium, stainless steel and refractory metals are considered 35 refs.

Monitoring and Control of the Hybrid Laser-Gas Metal-Arc Welding Process

Energy Technology Data Exchange (ETDEWEB)

Kunerth, D. C.; McJunkin, T. R.; Nichol, C. I.; Clark, D.; Todorov, E.; Couch, R. D.; Yu, F.

2013-07-01

Methods are currently being developed towards a more robust system real time feedback in the high throughput process combining laser welding with gas metal arc welding. A combination of ultrasonic, eddy current, electronic monitoring, and visual techniques are being applied to the welding process. Initial simulation and bench top evaluation of proposed real time techniques on weld samples are presented along with the concepts to apply the techniques concurrently to the weld process. Consideration for the eventual code acceptance of the methods and system are also being researched as a component of this project. The goal is to detect defects or precursors to defects and correct when possible during the weld process.

Electrochemical Testing of Gas Tungsten Arc Welded and Reduced Pressure Electron Beam Welded Alloy 22

International Nuclear Information System (INIS)

Day, S D; Wong, F G; Gordon, S R; Wong, L L; Rebak, R B

2006-01-01

Alloy 22 (N06022) is the material selected for the fabrication of the outer shell of the nuclear waste containers for the Yucca Mountain high-level nuclear waste repository site. A key technical issue in the waste package program has been the integrity of the container weld joints. The currently selected welding process for fabricating and sealing the containers is the traditional gas tungsten arc welding (GTAW) or TIG method. An appealing faster alternative technique is reduced pressure electron beam (RPEB) welding. It was of interest to compare the corrosion properties of specimens prepared using both types of welding techniques. Standard electrochemical tests were carried on GTAW and RPEB welds as well as on base metal (non-welded) to determine their relative corrosion behavior in simulated concentrated water (SCW) at 90 C (alkaline), 1 M HCl at 60 C (acidic) and 1 M NaCl at 90 C (neutral) solutions. Results show that for all practical purposes, the three tested materials had the same electrochemical behavior in the three tested electrolytes

Electrochemical Testing of Gas Tungsten ARC Welded and Reduced Pressure Electron Beam Welded Alloy 22

International Nuclear Information System (INIS)

S. Daniel Day; Frank M.G. Wong; Steven R. Gordon; Lana L. Wong; Raul B. Rebak

2006-01-01

Alloy 22 (N06022) is the material selected for the fabrication of the outer shell of the nuclear waste containers for the Yucca Mountain high-level nuclear waste repository site. A key technical issue in the waste package program has been the integrity of the container weld joints. The currently selected welding process for fabricating and sealing the containers is the traditional gas tungsten arc welding (GTAW) or TIC method. An appealing faster alternative technique is reduced pressure electron beam (RPEB) welding. It was of interest to compare the corrosion properties of specimens prepared using both types of welding techniques. Standard electrochemical tests were carried on GTAW and RPEB welds as well as on base metal (non-welded) to determine their relative corrosion behavior in simulated concentrated water (SCW) at 90 C (alkaline), 1 M HCI at 60 C (acidic) and 1 M NaCl at 90 C (neutral) solutions. Results show that for all practical purposes, the three tested materials had the same electrochemical behavior in the three tested electrolytes

Investigation of the Weld Properties of Dissimilar S32205 Duplex Stainless Steel with AISI 304 Steel Joints Produced by Arc Stud Welding

Directory of Open Access Journals (Sweden)

Aziz Barış Başyiğit

2017-03-01

Full Text Available UNS S32205 duplex stainless steel plates with a thickness of 3 mm are arc stud welded by M8 × 40 mm AISI 304 austenitic stainless steel studs with constant stud lifts in order to investigate the effects of welding arc voltages on mechanical and microstructural behaviors of the joints. As the welding arc voltage increases starting from 140 V, the tensile strength of the weldment also increases but the higher arc values results in more spatters around the weld seam up to 180 V. Conversely, the lower arc voltages causes poor tensile strength values to weldments. Tensile tests proved that all of the samples are split from each other in the welding zone but deformation occurs in duplex plates during the tensile testing of weldments so that the elongation values are not practically notable. The satisfactory tensile strength and bending values are determined by applying 180 volts of welding arc voltage according to ISO 14555 standard. Peak values of micro hardness occurred in weld metal most probably as a consequence of increasing heat input decreasing the delta ferrite ratios. As the arc voltage increases, the width of the heat affected zone increases. Coarsening of delta-ferrite and austenite grains was observed in the weld metal peak temperature zone but it especially becomes visible closer to the duplex side in all samples. The large voids and unwelded zones up to approximately 1 mm by length are observed by macro-structure inspections. Besides visual tests and micro-structural surveys; bending and microhardness tests with radiographic inspection were applied to samples for maintaining the correct welding parameters in obtaining well-qualified weldments of these two distinct groups of stainless steel materials.

Evaluation of plasma arc welding capabilities and applications

International Nuclear Information System (INIS)

Mills, G.S.

1978-01-01

Unique capabilities of plasma arc welding in the keyhole mode are described, and the potential applicability of these capabilities to Rocky Flats production needs are evaluated. For the areas of potential benefits studied, the benefits of this welding technique either did not materialize or the complication of implementing the process in production was not warranted by the demonstrated benefits

Hybrid Welding of 45 mm High Strength Steel Sections

Science.gov (United States)

Bunaziv, Ivan; Frostevarg, Jan; Akselsen, Odd M.; Kaplan, Alexander F.

Thick section welding has significant importance for oil and gas industry in low temperature regions. Arc welding is usually employed providing suitable quality joints with acceptable toughness at low temperatures with very limited productivity compared to modern high power laser systems. Laser-arc hybrid welding (LAHW) can enhance the productivity by several times due to higher penetration depth from laser beam and combined advantages of both heat sources. LAHW was applied to join 45 mm high strength steel with double-sided technique and application of metal cored wire. The process was captured by high speed camera, allowing process observation in order to identify the relation of the process stability on weld imperfections and efficiency. Among the results, it was found that both arc power and presence of a gap increased penetration depth, and that higher welding speeds cause unstable processing and limits penetration depth. Over a wide range of heat inputs, the welds where found to consist of large amounts of fine-grained acicular ferrite in the upper 60-75% part of welds. At the root filler wire mixing was less and cooling faster, and thus found to have bainitic transformation. Toughness of deposited welds provided acceptable toughness at -50 °C with some scattering.

Research Progress in Plasma arc welding of Magnesium Alloys and Magnesium Matrix Composites

Science.gov (United States)

Hui, Li; Yang, Zou; Yongbo, Li; Lei, Jiao; Ruijun, Hou

2017-11-01

Magnesium alloys and magnesium matrix composites by means of its excellent performance have wide application prospect in electronics, automotive, biotechnology, aerospace field, and welding technology has become a key of restricting its application. This paper describes the welding characteristics of magnesium, the obvious advantages in the application and the domestic and foreign research advance technology of plasma arc welding of magnesium, and summarizes the existing problems and development trends of plasma arc welding technology of magnesium.

[Calculation and analysis of arc temperature field of pulsed TIG welding based on Fowler-Milne method].

Science.gov (United States)

Xiao, Xiao; Hua, Xue-Ming; Wu, Yi-Xiong; Li, Fang

2012-09-01

Pulsed TIG welding is widely used in industry due to its superior properties, and the measurement of arc temperature is important to analysis of welding process. The relationship between particle densities of Ar and temperature was calculated based on the theory of spectrum, the relationship between emission coefficient of spectra line at 794.8 nm and temperature was calculated, arc image of spectra line at 794.8 nm was captured by high speed camera, and both the Abel inversion and Fowler-Milne method were used to calculate the temperature distribution of pulsed TIG welding.

Process Studies on Laser Welding of Copper with Brilliant Green and Infrared Lasers

Science.gov (United States)

Engler, Sebastian; Ramsayer, Reiner; Poprawe, Reinhart

Copper materials are classified as difficult to weld with state-of-the-art lasers. High thermal conductivity in combination with low absorption at room temperature require high intensities for reaching a deep penetration welding process. The low absorption also causes high sensitivity to variations in surface conditions. Green laser radiation shows a considerable higher absorption at room temperature. This reduces the threshold intensity for deep penetration welding significantly. The influence of the green wavelength on energy coupling during heat conduction welding and deep penetration welding as well as the influence on the weld shape has been investigated.

Three-dimensional modelling of arc behaviour and gas shield quality in tandem gas-metal arc welding using anti-phase pulse synchronization

International Nuclear Information System (INIS)

Schnick, M; Lohse, M; Fuessel, U; Wilhelm, G; Murphy, A B

2011-01-01

The paper presents a transient three-dimensional model of an anti-phase-synchronized pulsed tandem gas-metal arc welding process, which is used to analyse arc interactions and their influence on the gas shield flow. The shielding gases considered are pure argon and a mixture of argon with 18% CO 2 . Comparison of the temperature fields predicted by the model with high-speed images indicates that the essential features of the interactions between the arcs are captured. The paper demonstrates strong arc deflection and kinking, especially during the low-current phase of the pulse, in agreement with experimental observations. These effects are more distinct for the argon mixture with 18% CO 2 . The second part of the paper demonstrates the effects of arc deflection and instabilities on the shielding gas flow and the occurrence of air contamination in the process region. The results allow an improved understanding of the causes of periodic instabilities and weld seam imperfections such as porosity, spatter, heat-tint oxidation and fume deposits.

Finite element modelling of electric currents in AC submerged arc furnaces

CSIR Research Space (South Africa)

Mc Dougall, I

2007-01-01

Full Text Available and the power ratings is not a hindrance. 2. MATHEMATICAL FORMULATION As the frequency of the current is low, the quasi-static form of Maxwell’s equations is solved. (1) (2) (3) (4) where E denotes the electric field intensity, H the magnetic field... of Electric Currents in AC Submerged Arc Furnaces 637 REFERENCES [1] Bermudez, A., Muniz, M.C., Pena, F. , Bullon, J., “ Numerical Computation of the Electromagnetic Field in the Electrodes of a Three-Phase Arc Furnace”, Int. Jnl for Numerical Methods...

Process Studies on Laser Welding of Copper with Brilliant Green and Infrared Lasers

OpenAIRE

Engler, Sebastian; Ramsayer, Reiner; Poprawe, Reinhart

2011-01-01

Copper materials are classified as difficult to weld with state-of-the-art lasers. High thermal conductivity in combination with low absorption at room temperature require high intensities for reaching a deep penetration welding process. The low absorption also causes high sensitivity to variations in surface conditions. Green laser radiation shows a considerable higher absorption at room temperature. This reduces the threshold intensity for deep penetration welding significantly. The influen...

Abrasion Wear Resistance, Hardness and Microstructure of Hard Linings Deposited by Means of a Submerged Arc. Dureza, microestructura y resistencia al desgaste por abrasion de recargues duros depositados con arco sumergido

Energy Technology Data Exchange (ETDEWEB)

Paranhos, R; Alcoforado, J M; Castillo, J A; Sauer, A

1989-01-01

Consumable materials for submerged arc welding of the types alloyed flux-neutral electrode and neutral flux-alloyed electrode were used to form, through multipass welding, a light alloy hard lining of the C-Mn type on ASTM A36 Type structural steel. Emphasis was put on microstructural characterization of the linings surveyed under electron scanning microscopy, and tests were performed to study their hardness and abrasion wear resistance at low pressures. As a result of these tests, a great influence of welding parameters on hardness and abrasion resistance properties of the combination active flux-neutral electrode was noticed. As the results showed no relationship between the hardness and the abrasion wear resistance of the linings surveyed, an attempt was made to relate the resulting microstructure with their abrasion wear resistance. (Author)

Significance of the Resonance Condition for Controlling the Seam Position in Laser-assisted TIG Welding

Science.gov (United States)

Emde, B.; Huse, M.; Hermsdorf, J.; Kaierle, S.; Wesling, V.; Overmeyer, L.; Kozakov, R.; Uhrlandt, D.

As an energy-preserving variant of laser hybrid welding, laser-assisted arc welding uses laser powers of less than 1 kW. Recent studies have shown that the electrical conductivity of a TIG welding arc changes within the arc in case of a resonant interaction between laser radiation and argon atoms. This paper presents investigations on how to control the position of the arc root on the workpiece by means of the resonant interaction. Furthermore, the influence on the welding result is demonstrated. The welding tests were carried out on a cooled copper plate and steel samples with resonant and non-resonant laser radiation. Moreover, an analysis of the weld seam is presented.

On the choice of electromagnetic model for short high-intensity arcs, applied to welding

International Nuclear Information System (INIS)

Choquet, Isabelle; Shirvan, Alireza Javidi; Nilsson, Håkan

2012-01-01

We have considered four different approaches for modelling the electromagnetic fields of high-intensity electric arcs: (i) three-dimensional, (ii) two-dimensional axi-symmetric, (iii) the electric potential formulation and (iv) the magnetic field formulation. The underlying assumptions and the differences between these models are described in detail. Models (i) to (iii) reduce to the same limit for an axi-symmetric configuration with negligible radial current density, contrary to model (iv). Models (i) to (iii) were retained and implemented in the open source CFD software OpenFOAM. The simulation results were first validated against the analytic solution of an infinite electric rod. Perfect agreement was obtained for all the models tested. The electromagnetic models (i) to (iii) were then coupled with thermal fluid mechanics, and applied to axi-symmetric gas tungsten arc welding test cases with short arc (2, 3 and 5 mm) and truncated conical electrode tip. Models (i) and (ii) lead to the same simulation results, but not model (iii). Model (iii) is suited in the specific limit of long axi-symmetric arc with negligible electrode tip effect, i.e. negligible radial current density. For short axi-symmetric arc with significant electrode tip effect, the more general axi-symmetric formulation of model (ii) should instead be used. (paper)

Butt Weldability for SS400 Using Laser-Arc Hybrid Welding

International Nuclear Information System (INIS)

Kim, Jong Do; Myoung, Gi Hoon; Park, Duck; Myoung, Gi Hoon; Park, In Duck

2016-01-01

This study presents results of an experimental investigation of the laser-arc, hybrid, butt welding process of SS400 structural steel. Welding parameters including laser power, welding current and speed were varied in order to obtain one-pass, full-penetration welds without defects. The conditions that resulted in optimal beads were identified. After welding, hardness measurements and microstructure observations were carried out in order to study weld properties. The mechanical properties of both the base material and welded specimen were compared based on the results of tensile strength measurements. The yield and tensile strengths were found to be similar

Butt Weldability for SS400 Using Laser-Arc Hybrid Welding

Energy Technology Data Exchange (ETDEWEB)

Kim, Jong Do; Myoung, Gi Hoon; Park, Duck [Korea Maritime and Ocean Univ., Busan (Korea, Republic of); Myoung, Gi Hoon; Park, In Duck [Korea Institute of Machinery and Materials, Busan (Korea, Republic of)

2016-07-15

This study presents results of an experimental investigation of the laser-arc, hybrid, butt welding process of SS400 structural steel. Welding parameters including laser power, welding current and speed were varied in order to obtain one-pass, full-penetration welds without defects. The conditions that resulted in optimal beads were identified. After welding, hardness measurements and microstructure observations were carried out in order to study weld properties. The mechanical properties of both the base material and welded specimen were compared based on the results of tensile strength measurements. The yield and tensile strengths were found to be similar.

Investigation of the Microstructure of Laser-Arc Hybrid Welded Boron Steel

Science.gov (United States)

Son, Seungwoo; Lee, Young Ho; Choi, Dong-Won; Cho, Kuk-Rae; Shin, Seung Man; Lee, Youngseog; Kang, Seong-Hoon; Lee, Zonghoon

2018-05-01

The microstructure of boron steel for automotive driving shaft manufacturing after laser-arc hybrid welding was investigated. Laser-arc hybrid welding technology was applied to 3-mm-thick plates of boron steel, ST35MnB. The temperature distribution of the welding pool was analyzed using the finite element method, and the microstructure of the welded boron steel was characterized using optical microscopy and scanning and transmission electron microscopies. The microstructure of the weld joint was classified into the fusion zone, the heat-affected zone (HAZ), and the base material. At the fusion zone, the bainite grains exist in the martensite matrix and show directionality because of heat input from the welding. The HAZ is composed of smaller grains, and the hardness of the HAZ is greater than that of the fusion zone. We discuss that the measured grain size and the hardness of the HAZ originate from undissolved precipitates that retard the grain growth of austenite.

Micro-Welding of Copper Plate by Frequency Doubled Diode Pumped Pulsed Nd:YAG Laser

Science.gov (United States)

Nakashiba, Shin-Ichi; Okamoto, Yasuhiro; Sakagawa, Tomokazu; Takai, Sunao; Okada, Akira

A pulsed laser of 532 nm wavelength with ms range pulse duration was newly developed by second harmonic generation of diode pumped pulsed Nd:YAG laser. High electro-optical conversion efficiency more than 13% could be achieved, and 1.5 kW peak power green laser pulse was put in optical fiber of 100 μm in diameter. In micro- welding of 1.0 mm thickness copper plate, a keyhole welding was successfully performed by 1.0 kW peak power at spot diameter less than 200 μm. The frequency doubled pulsed laser improved the processing efficiency of copper welding, and narrow and deep weld bead was stably obtained.

Studies on the Parametric Effects of Plasma Arc Welding of 2205 Duplex Stainless Steel

Science.gov (United States)

Selva Bharathi, R.; Siva Shanmugam, N.; Murali Kannan, R.; Arungalai Vendan, S.

2018-03-01

This research study attempts to create an optimized parametric window by employing Taguchi algorithm for Plasma Arc Welding (PAW) of 2 mm thick 2205 duplex stainless steel. The parameters considered for experimentation and optimization are the welding current, welding speed and pilot arc length respectively. The experimentation involves the parameters variation and subsequently recording the depth of penetration and bead width. Welding current of 60-70 A, welding speed of 250-300 mm/min and pilot arc length of 1-2 mm are the range between which the parameters are varied. Design of experiments is used for the experimental trials. Back propagation neural network, Genetic algorithm and Taguchi techniques are used for predicting the bead width, depth of penetration and validated with experimentally achieved results which were in good agreement. Additionally, micro-structural characterizations are carried out to examine the weld quality. The extrapolation of these optimized parametric values yield enhanced weld strength with cost and time reduction.

Twin-Wire Pulsed Tandem Gas Metal Arc Welding of API X80 Steel Linepipe

Directory of Open Access Journals (Sweden)

Wenhao Wu

2018-01-01

Full Text Available Twin-Wire Pulsed Tandem Gas Metal Arc Welding process with high welding production efficiency was used to join the girth weld seam of API X80 steel linepipe of 18.4 mm wall thickness and 1422 mm diameter. The macrostructure, microstructure, hardness, and electrochemical corrosion behavior of welded joints were studied. Effects of temperature and Cl− concentration on the corrosion behavior of base metal and weld metal were investigated. Results show that the welded joint has good morphology, mechanical properties, and corrosion resistance. The corrosion resistance of both the base metal and the weld metal decreases with increasing temperature or Cl− concentration. In the solution with high Cl− concentration, the base metal and weld metal are more susceptible to pitting. The corrosion resistance of the weld metal is slightly lower than that of the base metal.

Tensile properties of four types of austenitic stainless steel welded joints

International Nuclear Information System (INIS)

Balladon, P.

1990-01-01

In the field of an LMFBR research programme on austenitic stainless steel welds in a Shared Cost Action Safety, Research Area 8, coordinated by JRC-Ispra, four cooperating laboratories (ECN, IKE/MPA, the Welding Institute and UNIREC) have been involved in the fabrication and extensive characterization of welded joints made from one plate of ICL 167 stainless steel. The materials included parent metal, four vacuum electron beam welds, one non vacuum electron beam weld, one submerged arc weld, one gas metal arc weld and one manual metal arc weld. This report summarizes the 106 tensile tests performed at room temperature and 550 0 C, including the influence of strain rate, specimen orientation and welding procedure. Main results are that electron beam welds have tensile properties close to those of parent metal with higher values of yield strength in longitudinal orientation and lower values of total elongation in transverse orientation but with a similar reduction of area, that filler metal welds own the highest values of yield strength and lowest values of ductility. Most of the welds properties are higher than the minimum specified for parent metal, except for some values of total elongation, mainly in transverse orientation. In view of using electron beam welding for production of components used in LMFBR, results obtained show that tensile properties of electron beam welds compare well to those of classical welds. (author)

MODEL PEMBELAJARAN PRAKTIK PENGELASAN SHIELED METAL ARC WELDING(SMAW POSISI 1G JURUSAN TEKNIK PENGELASAN

Directory of Open Access Journals (Sweden)

Masri Bin Ardin

2016-08-01

Full Text Available Penelitian ini bertujuan untuk: (1 mendeskripsikan model pembelajaran praktik yang berlangsung atau disebut model pembelajaran regular praktek pengelasan SMAW posisi 1G di SMK Negeri 2 Pengasih; (2 mengetahui efektifitas dan mendeskripsikan bahan yang digunakan dalam praktek pengelasan SMAW posisi 1G, misalnya: besi plat, mata gerinda, elektroda, dan waktu yang digunakan selama praktek pengelasan SMAW posisi 1G. Penelitian ini merupakan penelitian deskriptif dengan teknik pengumpulan data menggunakan wawancara, dokumentasi, angket dan penilaian skill pengelasan. Asessment skill pengelasan mengacu pada Acean Skill Welding Competition. Hasil penelitian yaitu: (1 model pembelajaran praktek pengelasan SMAW posisi 1G terdiri dari 4 pertemuan teori dan 13 pertemuan praktik; (2 model pembelajaran praktik pengelasan di SMKN 2 Pengasih sudah efektif tetapi untuk rutinitas pengelasan belum efektif untuk membentuk skill pengelasan SMAW posisi 1G dengan sistem assesment Asean Skill Welding Competition. Fasilitas utama dalam praktek pengelasan SMAW posisi 1G adalah mesin las. Sementara itu SMKN 2 pengasih memiliki 6 buah mesin las dengan rasio 1 mesin las untuk 5 orang siswa. Bahan habis pakai untuk 30 orang siswa per semester yang menggunakan model pembelajaran praktek pengelasan adalah besi plat ± 100-150 kg, mata gerinda total ± 5-6 keping, elektroda ± 9-10 box dan total waktunya aktif 77 jam selama satu semester. Kata kunci: pembelajaran Praktik Pengelasan SMAW, Skill Siswa untuk Posisi 1G LEARNING MODEL OF SHIELD METAL ARC WELDING (SMAW PRACTICE OF 1G POSITION AT THE WELDING ENGINEERING DEPARTMENT Abstract This research aimed to: (1 describe the learning model of shield metal arc welding (SMAW practice of 1G position at the Welding Engineering Department of State Vocational High School (SMKN 2 Pengasih; (2 find the effectiveness and describe materials needed in the learning model of shield metal arc welding (SMAW practice of 1G position, for examples

Feedback Linearization Based Arc Length Control for Gas Metal Arc Welding

DEFF Research Database (Denmark)

Thomsen, Jesper Sandberg

2005-01-01

a linear system to be controlled by linear state feedback control. The advantage of using a nonlinear approach as feedback linearization is the ability of this method to cope with nonlinearities and different operating points. However, the model describing the GMAW process is not exact, and therefore......In this paper a feedback linearization based arc length controller for gas metal arc welding (GMAW) is described. A nonlinear model describing the dynamic arc length is transformed into a system where nonlinearities can be cancelled by a nonlinear state feedback control part, and thus, leaving only......, the cancellation of nonlinear terms might give rise to problems with respect to robustness. Robustness of the closed loop system is therefore nvestigated by simulation....

Strain ageing in welds of nuclear pressure vessels

International Nuclear Information System (INIS)

Otterberg, R.; Karlsson, C.

1979-01-01

Static and dynamic strain ageing have been investigated on submerged-arc welds and repair welds from plates of the pressure vessel steel A 533B. The results permit the determination of the worst strain ageing conditions existing in a nuclear pressure vessel. Static strain ageing was investigated by means of data from tension tests, hardness measurements and Charpy-V impact properties for prestrained and aged material for ageing temperatures from room temperature to 350 deg C and ageing times up to 1000h. Dynamic strain ageing was investigated by tensile tests up to 350 deg C at different strain rates. At the most static strain ageing was found to increase the impact transition temperature from -75 deg C in the as-received condition to -55 deg C after prestraining and ageing for the plate material, from -35 to -10 deg C for the submerged arc weld and from -90 to -40 deg C for the repair weld. Approximately 10 deg C of the deleterious effect is due to the effect of ageing for the two former materials whereas the corresponding figure for the repair weld amounts to 35 deg C. The dynamic strain ageing is strongest at very low strain rates at temperatures just below 300 deg C. The effect of strain ageing can be reduced by stress relief heat treatment or by other means decreasing the content of nitrogen in solution. (author)

Retinal injury from a welding arc

International Nuclear Information System (INIS)

Naidoff, M.A.; Sliney, D.H.

1974-01-01

An 18-year-old man stared at a welding arc for approximately ten minutes, sustaining moderate facial erythema, keratoconjunctivitis, marked visual loss, a pupillary abnormality, and a retinal injury accompanied by a dense central scotoma and peripheral field constriction. A residual, partially pigmented foveal lesion remained after 16 months, with normal visual acuity. Since the degree of keratoconjunctivitis and facial erythema was known, we substantiated the duration of exposure to the arc by weighting the known action spectrum of moderate ultraviolet erythema with the ultraviolet spectral irradiance measurements of the arc. From the radiometric measurements of the visible brightness and visible and near infrared spectrum of the arc and from knowledge of pupil size, we calculated the retinal exposure dose rate, which was less than normally considered necessary to produce a chorioretinal burn. This case may provide a clinical example of photic maculopathy recently reported in experimental investigations

Hybrid laser arc welding of a used fuel container

Energy Technology Data Exchange (ETDEWEB)

Boyle, C., E-mail: cboyle@nwmo.ca [Nuclear Waste Management Organization, Toronto, ON (Canada); Martel, P. [Novika Solutions, La Pocatiere, QC (Canada)

2015-07-01

The Nuclear Waste Management Organization (NWMO) has designed a novel Used Fuel Container (UFC) optimized for CANDU used nuclear fuel. The Mark II container is constructed of nuclear grade pipe for the body and capped with hemi-spherical heads. The head-to-shell joint fit-up features an integral backing designed for external pressure, eliminating the need for a full penetration closure weld. The NWMO and Novika Solutions have developed a partial penetration, single pass Hybrid Laser Arc Weld (HLAW) closure welding process requiring no post-weld heat treatment. This paper will discuss the joint design, HLAW process, associated welding equipment, and prototype container fabrication. (author)

Metal arc welding and the risk of skin cancer

DEFF Research Database (Denmark)

Heltoft, K N; Slagor, R M; Agner, T

2017-01-01

OBJECTIVES: Arc welding produces the full spectrum of ultraviolet radiation and may be a contributory cause of skin cancer; however, there has been little research into this occupational hazard. The aim of this study is to explore if metal arc welding increases the risk of malignant melanoma and....../or basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) on skin areas which may possibly be exposed (neck, head, and upper extremities). METHOD: A Danish national company-based historic cohort of 4333 male metal arc welders was followed from 1987 through 2012 to identify the risk of skin cancer....... An external reference group was established including all Danish skilled and unskilled male workers with similar age distribution. Occupational histories were gathered by questionnaires in 1986 and information about skin cancer diagnoses [BCC, SCC, cutaneous malignant melanoma (CMM), and precancerous...

Tests of arc-welding-related EMI effects on startup instrumentation

International Nuclear Information System (INIS)

Qian, T.; Kalechstein, W.; Cosgrove, D.

1996-01-01

The tests described in this paper were conducted to characterize the effects that electromagnetic interference (EMI), from arc welding, has on startup instrumentation (SUI). This paper reviews the results of a literature search on EMI resulting from arc welding and gives the objective and scope of the tests conducted and describes the test equipment and setting, and test procedure and results. Are-welding-related EMI levels in an SUI system were measured to determine the dominant source of interference, the coupling path and the susceptible part of the SUI system. The effectiveness of easily implemented improvements in reducing the level of EMI in the SUI system were also tested. Recommendations are provided on how to eliminate or reduce the EMI effects on sensitive nuclear instruments. (author)

Mechanical properties of 5083 aluminium welds after manual and automatic pulsed gas metal arc welding using E5356 filler

CSIR Research Space (South Africa)

Mutombo, K

2010-01-01

Full Text Available Semi-automatic and automatic pulsed gas metal arc welding (GMAW) of aluminium alloy 5083 with ER5356 filler wire causes considerable softening in the weld. The tensile strength of dressed automatic welds approaches that of the base metal...

Microstructure and abrasive wear properties of M(Cr,Fe7C3 carbides reinforced high-chromium carbon coating produced by gas tungsten arc welding (GTAW process

Directory of Open Access Journals (Sweden)

Soner BUYTOZ

2010-01-01

Full Text Available In the present study, high-chromium ferrochromium carbon hypereutectic alloy powder was coated on AISI 4340 steel by the gas tungsten arc welding (GTAW process. The coating layers were analyzed by optical microscopy, X-ray diffraction (XRD, field-emission scanning electron microscopy (FE-SEM, X-ray energy-dispersive spectroscopy (EDS. Depending on the gas tungsten arc welding pa-rameters, either hypoeutectic or hypereutectic microstructures were produced. Wear tests of the coatings were carried out on a pin-on-disc apparatus as function of contact load. Wear rates of the all coating layers were decreased as a function of the loading. The improvement of abrasive wear resistance of the coating layer could be attributed to the high hardness of the hypereutectic M7C3 carbides in the microstruc-ture. As a result, the microstructure of surface layers, hardness and abrasive wear behaviours showed different characteristics due to the gas tungsten arc welding parameters.

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.)

Development of a one side automatic TIG arc welding system in horizontal position for annular vessels in nuclear fuel cycle factory

International Nuclear Information System (INIS)

Ohtsuka, Takao; Ohsawa, Morihiko; Nakashima, Hiroyuki; Habuta, Susumu; Hori, Tomiji; Fujiwara, Katsusi; Kitaguchi, Yoshihisa.

1995-01-01

Various annular vessels are planned to be equipped as a part of the plutonium refining facility in the nuclear fuel cycle factory. For manufacturing the high quality vessels, a one side automatic TIG arc welding system which is applied to the circumferencial joints in horizontal welding position have been completed. The automatic welding system is confirmed to be effective for improving the joint qualities and saving the manufacturing cost by our Mockup test. The main points of our welding system are as follows. (1) Low pulsed TIG arc welding process with a mixed shielding gas of Ar+5%H 2 is being employed. (2) Mechanical seam trucking system for the carriage and welding torch is equipped in the welding machine. (3) Arc voltage controlling system is employed for stabilizing the welding condition. (4) Magnetic wheels are equipped at the carriage for travelling without rails. The weight of this welding machine is designed to be less than 15 kg. (author)

Optimization of arc-start performance by wire-feeding control for GMA welding

Energy Technology Data Exchange (ETDEWEB)

Kang, Jong Gu; Ryu, Gyeong Su; Rhee, Se Hun [Hanyang University, Seoul (Korea, Republic of); Kim, Dong Cheol; Kang, Mun Jin [Korea Institute of Industrial Technology, Incheon (Korea, Republic of); Park, Young Whan [Pukyong National University, Busan (Korea, Republic of)

2013-02-15

The wire feeding system for gas metal arc welding usually consists of a wire feeder and a torch. In many industries, the distance between the wire feeder and the torch is generally 3 m to 5 m. In a conventional wire feeder, a direct current (DC) motor is used for wire feeding. However, a significant problem with this system is the impossibility of feedback control because of inner or outer impedance. In this paper, a digital wire feeder was developed by using a DC encoder motor and a push-pull torch. An optimized wire-feeding system was also developed by experiment. The welding process was observed using a high-speed camera. The resulting wire-feeding system exhibits low spatter generation and arc stability.

Microstructure evolution of Al/Mg butt joints welded by gas tungsten arc with Zn filler metal

International Nuclear Information System (INIS)

Liu Fei; Zhang Zhaodong; Liu Liming

2012-01-01

Based on the idea of alloying welding seam, Gas tungsten arc welding method with pure Zn filler metal was chosen to join Mg alloy and Al alloy. The microstructures, phases, element distribution and fracture morphology of welding seams were examined. The results indicate that there was a transitional zone in the width of 80–100 μm between the Mg alloy substrate and fusion zone. The fusion zone was mainly composed of MgZn 2 , Zn-based solid solution and Al-based solid solution. The welding seam presented distinct morphology in different location owning to the quite high cooling rate of the molten pool. The addition of Zn metal could prevent the formation of Mg–Al intermetallics and form the alloyed welding seam during welding. Therefore, the tensile strengths of joints have been significantly improved compared with those of gas tungsten arc welded joints without Zn metal added. Highlights: ► Mg alloy AZ31B and Al alloy 6061 are welded successfully. ► Zinc wire is employed as a filler metal to form the alloyed welding seam. ► An alloyed welding seam is benefit for improving of the joint tensile strength.

Multi-objective Optimization of Pulsed Gas Metal Arc Welding Process Using Neuro NSGA-II

Science.gov (United States)

Pal, Kamal; Pal, Surjya K.

2018-05-01

Weld quality is a critical issue in fabrication industries where products are custom-designed. Multi-objective optimization results number of solutions in the pareto-optimal front. Mathematical regression model based optimization methods are often found to be inadequate for highly non-linear arc welding processes. Thus, various global evolutionary approaches like artificial neural network, genetic algorithm (GA) have been developed. The present work attempts with elitist non-dominated sorting GA (NSGA-II) for optimization of pulsed gas metal arc welding process using back propagation neural network (BPNN) based weld quality feature models. The primary objective to maintain butt joint weld quality is the maximization of tensile strength with minimum plate distortion. BPNN has been used to compute the fitness of each solution after adequate training, whereas NSGA-II algorithm generates the optimum solutions for two conflicting objectives. Welding experiments have been conducted on low carbon steel using response surface methodology. The pareto-optimal front with three ranked solutions after 20th generations was considered as the best without further improvement. The joint strength as well as transverse shrinkage was found to be drastically improved over the design of experimental results as per validated pareto-optimal solutions obtained.

Effect of Post Weld Heat Treatment on Microstructure and Mechanical Properties of Submerged Friction Stir Welded 7A04 Aluminum Alloy

Directory of Open Access Journals (Sweden)

HAO Ya-xin

2016-06-01

Full Text Available 7A04 aluminum alloy plate was jointed by submerged friction stir welding(SFSW, and welded joints were treated (Post Weld Heat Treatment, PWHT, and the effect of post weld heat treatment on the microstructure and mechanical properties in SFSW was investigated. The results show that PWHT joints exhibit dispersively distributed fine precipitates phase morphology, are significantly superior than the feature of the small amount of precipitates with dispersed distribution in SFSW joints. Compared with SFSW joints, the mechanical properties of joints are improved significantly by PWHT. The average hardness of the weld joints nugget zone is increased by 39.7HV, and the tensile strength is increased by 67MPa, reaches 96.1% of the base material, strain hardening capacity of the joints is also enhanced, the tensile fracture exhibits mixed fracture feature of microporous polymerization and cleavage.

Technical assistance to AECL: electron beam welding of thick-walled copper containers for nuclear fuel waste disposal

International Nuclear Information System (INIS)

Maak, P.Y.Y.

1984-01-01

This report describes the results of Phase Two of the copper electron beam welding project for the final closure of copper containers for nuclear fuel waste disposal. It has been demonstrated that single pass, electron beam square butt welds (depth of weld penetration > 25 mm) can be made without preheat in both electrolytic tough-pitch copper and oxygen-free copper plates. The present results show that oxygen-free copper exhibits better weldability than the electrolytic tough-pitch copper in terms of weld penetration and vulnerability to weld defects such as gas porosity, erratic metal overflow and blow holes. The results of ultrasonic inspection studies of the welds are also discussed

Molten pool characterization of laser lap welded copper and aluminum

Science.gov (United States)

Xue, Zhiqing; Hu, Shengsun; Zuo, Di; Cai, Wayne; Lee, Dongkyun; Elijah, Kannatey-Asibu, Jr.

2013-12-01

A 3D finite volume simulation model for laser welding of a Cu-Al lap joint was developed using ANSYS FLUENT to predict the weld pool temperature distribution, velocity field, geometry, alloying element distribution and transition layer thickness—all key attributes and performance characteristics for a laser-welded joint. Melting and solidification of the weld pool was simulated with an enthalpy-porosity formulation. Laser welding experiments and metallographic examination by SEM and EDX were performed to investigate the weld pool features and validate the simulated results. A bowl-shaped temperature field and molten pool, and a unique maximum fusion zone width were observed near the Cu-Al interface. Both the numerical simulation and experimental results indicate an arch-shaped intermediate layer of Cu and Al, and a gradual transition of Cu concentration from the aluminum plate to the copper plate with high composition gradient. For the conditions used, welding with Cu on top was found to result in a better weld joint.

Molten pool characterization of laser lap welded copper and aluminum

International Nuclear Information System (INIS)

Xue, Zhiqing; Hu, Shengsun; Zuo, Di; Cai, Wayne; Lee, Dongkyun; Elijah, Kannatey-Asibu Jr

2013-01-01

A 3D finite volume simulation model for laser welding of a Cu–Al lap joint was developed using ANSYS FLUENT to predict the weld pool temperature distribution, velocity field, geometry, alloying element distribution and transition layer thickness—all key attributes and performance characteristics for a laser-welded joint. Melting and solidification of the weld pool was simulated with an enthalpy-porosity formulation. Laser welding experiments and metallographic examination by SEM and EDX were performed to investigate the weld pool features and validate the simulated results. A bowl-shaped temperature field and molten pool, and a unique maximum fusion zone width were observed near the Cu–Al interface. Both the numerical simulation and experimental results indicate an arch-shaped intermediate layer of Cu and Al, and a gradual transition of Cu concentration from the aluminum plate to the copper plate with high composition gradient. For the conditions used, welding with Cu on top was found to result in a better weld joint. (paper)

Prediction of mechanical properties in friction stir welds of pure copper

International Nuclear Information System (INIS)

Heidarzadeh, A.; Saeid, T.

2013-01-01

Highlights: • Range of parameters for defect-free friction stir welded pure copper was reached. • Models were developed for predicting UTS, TE and hardness of pure copper joints. • Analysis of variance was used to validate the developed models. • Effect of welding parameters on mechanical behavior of welded joints was explored. • The microstructure and fracture surface of welded joints were investigated. - Abstract: This research was carried out to predict the mechanical properties of friction stir welded pure copper joints. Response surface methodology based on a central composite rotatable design with three parameters, five levels, and 20 runs, was used to conduct the experiments and to develop the mathematical regression model by using of Design-Expert software. The three welding parameters considered were rotational speed, welding speed, and axial force. Analysis of variance was applied to validate the predicted models. Microstructural characterization and fractography of joints were examined using optical and scanning electron microscopes. Also, the effects of the welding parameters on mechanical properties of friction stir welded joints were analyzed in detail. The results showed that the developed models were reasonably accurate. The increase in welding parameters resulted in increasing of tensile strength of the joints up to a maximum value. Elongation percent of the joints increased with increase of rotational speed and axial force, but decreased by increasing of welding speed, continuously. In addition, hardness of the joints decreased with increase of rotational speed and axial force, but increased by increasing of welding speed. The joints welded at higher heat input conditions revealed more ductility fracture mode

Effect of different electrode tip angles with tilted torch in stationary gas tungsten arc welding: A 3D simulation

International Nuclear Information System (INIS)

Abid, M.; Parvez, S.; Nash, D.H.

2013-01-01

In this study, the effect of different tip angles (30°, 60°, 90° and 120°) on the arc and weld pool behavior is analyzed in 2 mm and 5 mm arc lengths with tilted (70°) torch. Arc temperature, velocity, current density, heat flux and gas shear are investigated in the arc region and pool convection and puddle shapes are studied in the weld pool region. The arc temperature at the tungsten electrode is found the maximum with sharp tip and decreases as the tip angle increases. The arc temperature on the anode (workpiece) surface becomes concentrated with increase in tip angle. The arc velocity and gas shear stress are observed large with sharp tip and decreasing as the tip angle increases. Current density on the anode surface does not change with tip angle and observed almost the same in all the tip angles in both 2 mm and 5 mm arc lengths. Heat flux due to conduction and convection is observed more sensitive to the tip angle and decreases as the tip angle increases. The electromagnetic force is slightly observed increasing and the buoyancy force is observed slightly decreasing with increase in tip angle. Analyzing each driving force in the weld pool individually shows that the gas drag and Marangoni forces are much stronger than the electromagnetic and buoyancy forces. The weld pool shape is observed wide and shallow in sharp and narrow and deep in large tip angle. Increasing the arc length does not change the weld pool width; however, the weld pool depth significantly changes with arc length and is observed deep in short arc length. The arc properties and weld pool shapes are observed wide ahead of the electrode tip in the weld direction due to 70° torch angle. Good agreement is observed between the numerical and experimental weld pool shapes

Effect of heat input on the microstructure and mechanical properties of gas tungsten arc welded AISI 304 stainless steel joints

International Nuclear Information System (INIS)

Kumar, Subodh; Shahi, A.S.

2011-01-01

Highlights: → Welding procedure is established for welding 6 mm thick AISI 304 using GTAW process. → Mechanical properties of the weld joints are influenced strongly by the heat input. → Highest tensile strength of 657.32 MPa is achieved by joints using low heat input. → Welding parameters affect heat input and hence microstructure of weld joints. → Extent of grain coarsening in the HAZ increases with increase in the heat input. -- Abstract: Influence of heat input on the microstructure and mechanical properties of gas tungsten arc welded 304 stainless steel (SS) joints was studied. Three heat input combinations designated as low heat (2.563 kJ/mm), medium heat (2.784 kJ/mm) and high heat (3.017 kJ/mm) were selected from the operating window of the gas tungsten arc welding process (GTAW) and weld joints made using these combinations were subjected to microstructural evaluations and tensile testing so as to analyze the effect of thermal arc energy on the microstructure and mechanical properties of these joints. The results of this investigation indicate that the joints made using low heat input exhibited higher ultimate tensile strength (UTS) than those welded with medium and high heat input. Significant grain coarsening was observed in the heat affected zone (HAZ) of all the joints and it was found that the extent of grain coarsening in the heat affected zone increased with increase in the heat input. For the joints investigated in this study it was also found that average dendrite length and inter-dendritic spacing in the weld zone increases with increase in the heat input which is the main reason for the observable changes in the tensile properties of the weld joints welded with different arc energy inputs.

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.)

Effect of Cut Quality on Hybrid Laser Arc Welding of Thick Section Steels

Science.gov (United States)

Farrokhi, F.; Nielsen, S. E.; Schmidt, R. H.; Pedersen, S. S.; Kristiansen, M.

From an industrial point of view, in a laser cutting-welding production chain, it is of great importance to know the influence of the attainable laser cut quality on the subsequent hybrid laser arc welding process. Many studies have been carried out in the literature to obtain lower surface roughness values on the laser cut edge. However, in practice, the cost and reliability of the cutting process is crucial and it does not always comply with obtaining the highest surface quality. In this study, a number of experiments on 25 mm steel plates were carried out to evaluate the influence of cut surface quality on the final quality of the subsequent hybrid laser welded joints. The different cut surfaces were obtained by different industrial cutting methods including laser cutting, abrasive water cutting, plasma cutting, and milling. It was found that the mentioned cutting methods could be used as preparation processes for the subsequent hybrid laser arc welding. However, cut quality could determine the choice of process parameters of the following hybrid laser arc welding.

A comparative study of the microstructure and mechanical properties of HTLA steel welds obtained by the tungsten arc welding and resistance spot welding

International Nuclear Information System (INIS)

Ghazanfari, H.; Naderi, M.; Iranmanesh, M.; Seydi, M.; Poshteban, A.

2012-01-01

Highlights: ► Hardness mapping is a novel method to identify different phases. ► Surface hardness mapping, tabulates the hardness of a large area of weld. ► Hardness maps can be used to depict the strength map through the specimen. ► Hardness mapping is an easy way to identify the phase fractions within the specimen. - Abstract: Hardness tests are routinely employed as simple and efficient methods to investigate the microstructure and mechanical properties of steels. Each microstructural phase in steel has its own hardness level. Therefore, using surface hardness mapping data over a large area of weld zone would be a reasonable method to identify the present phases in steel. The microstructure distribution and mechanical properties variation through welded structures is inhomogeneous and not suitable for certain applications. So, studying the microstructure of weld zone has a significant importance. 4130 steel is classified in HTLA steels and it is widely used in marine industry due to its superior hardenability, good corrosion resistance and high strength. Gas tungsten arc and resistance spot welding are the most usable processes in joining of 4130 sheets. In this work a series of welds have been fabricated in 4130 steel tube by gas tungsten arc and resistance spot welding. The tube was subjected to quench-tempered heat treatment. Slices from the welds before and after heat treatment were polished and etched and the macrostructure and microstructure were observed. Hardness maps were then determined over the large area of weld zone, including the heat affected zone and base plate. Results show good relations between the various microstructures, strength and hardness values. It is also proved that this method is precise and applicable to estimate phase fraction of each phase in various regions of weld. In the current study some equations were proposed to calculate the ultimate tensile stress and yield stress from the weld. The calculated data were compared

Experimental investigation of the thickness effect for large as-welded SAW S355 steel specimens

DEFF Research Database (Denmark)

Ólafsson, Ólafur Magnús; Jensen, Jørgen Juncher; Berggreen, Christian

2016-01-01

The presented work aims to investigate and establish a pre-cise, thorough and detailed database from series of experi-mental testing of submerged arc welded (SAW) specimens of various thicknesses typically applied in ships and offshore structures and foundations. Welded structures of all sizes...... and shapes exhibit fatigue failure primarily in the welded region, rather than in the base material, due to imperfections and flaws relating to the welding procedure. The welded region has therefore received much attention from universities, re-search institutions along with industry as it is of significant...

Sensoring fusion data from the optic and acoustic emissions of electric arcs in the GMAW-S process for welding quality assessment.

Science.gov (United States)

Alfaro, Sadek Crisóstomo Absi; Cayo, Eber Huanca

2012-01-01

The present study shows the relationship between welding quality and optical-acoustic emissions from electric arcs, during welding runs, in the GMAW-S process. Bead on plate welding tests was carried out with pre-set parameters chosen from manufacturing standards. During the welding runs interferences were induced on the welding path using paint, grease or gas faults. In each welding run arc voltage, welding current, infrared and acoustic emission values were acquired and parameters such as arc power, acoustic peaks rate and infrared radiation rate computed. Data fusion algorithms were developed by assessing known welding quality parameters from arc emissions. These algorithms have showed better responses when they are based on more than just one sensor. Finally, it was concluded that there is a close relation between arc emissions and quality in welding and it can be measured from arc emissions sensing and data fusion algorithms.

Sensoring Fusion Data from the Optic and Acoustic Emissions of Electric Arcs in the GMAW-S Process for Welding Quality Assessment

Directory of Open Access Journals (Sweden)

Eber Huanca Cayo

2012-05-01

Full Text Available The present study shows the relationship between welding quality and optical-acoustic emissions from electric arcs, during welding runs, in the GMAW-S process. Bead on plate welding tests was carried out with pre-set parameters chosen from manufacturing standards. During the welding runs interferences were induced on the welding path using paint, grease or gas faults. In each welding run arc voltage, welding current, infrared and acoustic emission values were acquired and parameters such as arc power, acoustic peaks rate and infrared radiation rate computed. Data fusion algorithms were developed by assessing known welding quality parameters from arc emissions. These algorithms have showed better responses when they are based on more than just one sensor. Finally, it was concluded that there is a close relation between arc emissions and quality in welding and it can be measured from arc emissions sensing and data fusion algorithms.

Improved design bases of welded joints in seawater

DEFF Research Database (Denmark)

Ólafsson, Ólafur Magnús

The presented work aims to investigate and establish a precise, thorough and detailed database from series of experimental testing of submerged arc welded, SAW, specimens of various thicknesses typically applied in offshore structures and foundations. Additionally, the testing was performed in two...... environment on fatigue resistance. Furthermore, novelty 25 mm thick steel laser-hybrid welded specimens in the as welded condition were subjected to experimental testing. A fatigue resistance S-Ncurve was established for the laser hybrid welded joints in addition to a more detailed analysis. The laser hybrid...... different environments, i.e. under in-air conditions and in a corrosion environment. Welded structures of all sizes and shapes exhibit fatigue failure primarily in the welded region, rather than in the base material, due to imperfections and flaws relating to the welding procedure. The welded region has...

Evolution of weld metal microstructure in shielded metal arc welding of X70 HSLA steel with cellulosic electrodes: A case study

International Nuclear Information System (INIS)

Ghomashchi, Reza; Costin, Walter; Kurji, Rahim

2015-01-01

The microstructure of weld joint in X70 line pipe steel resulted from shielded metal arc welding with E6010 cellulosic electrodes is characterized using optical and electron microscopy. A range of ferritic morphologies have been identified ranging from polygonal inter- and intra-prior austenite grains allotriomorphic, idiomorphic ferrites to Widmanstätten, acicular and bainitic ferrites. Electron Backscatter Diffraction (EBSD) analysis using Image Quality (IQ) and Inverse Pole Figure (IPF) maps through superimposition of IQ and IPF maps and measurement of percentages of high and low angle grain boundaries was identified to assist in differentiation of acicular ferrite from Widmanstätten and bainitic ferrite morphologies. In addition two types of pearlitic structures were identified. There was no martensite detected in this weld structure. The morphology, size and chemistry of non-metallic inclusions are also discussed briefly. - Highlights: • Application of EBSD reveals orientation relationships in a range of phases for shielded metal arc welding of HSLA steel. • Nucleation sites of various ferrite morphologies identified • Formation of upper and lower bainite and their morphologies

Evolution of weld metal microstructure in shielded metal arc welding of X70 HSLA steel with cellulosic electrodes: A case study

Energy Technology Data Exchange (ETDEWEB)

Ghomashchi, Reza, E-mail: reza.ghomashchi@adelaide.edu.au; Costin, Walter; Kurji, Rahim

2015-09-15

The microstructure of weld joint in X70 line pipe steel resulted from shielded metal arc welding with E6010 cellulosic electrodes is characterized using optical and electron microscopy. A range of ferritic morphologies have been identified ranging from polygonal inter- and intra-prior austenite grains allotriomorphic, idiomorphic ferrites to Widmanstätten, acicular and bainitic ferrites. Electron Backscatter Diffraction (EBSD) analysis using Image Quality (IQ) and Inverse Pole Figure (IPF) maps through superimposition of IQ and IPF maps and measurement of percentages of high and low angle grain boundaries was identified to assist in differentiation of acicular ferrite from Widmanstätten and bainitic ferrite morphologies. In addition two types of pearlitic structures were identified. There was no martensite detected in this weld structure. The morphology, size and chemistry of non-metallic inclusions are also discussed briefly. - Highlights: • Application of EBSD reveals orientation relationships in a range of phases for shielded metal arc welding of HSLA steel. • Nucleation sites of various ferrite morphologies identified • Formation of upper and lower bainite and their morphologies.

Weld metal microstructures of hardfacing deposits produced by self-shielded flux-cored arc welding

International Nuclear Information System (INIS)

Dumovic, M.; Monaghan, B.J.; Li, H.; Norrish, J.; Dunne, D.P.

2015-01-01

The molten pool weld produced during self-shielded flux-cored arc welding (SSFCAW) is protected from gas porosity arising from oxygen and nitrogen by reaction ('killing') of these gases by aluminium. However, residual Al can result in mixed micro-structures of δ-ferrite, martensite and bainite in hardfacing weld metals produced by SSFCAW and therefore, microstructural control can be an issue for hardfacing weld repair. The effect of the residual Al content on weld metal micro-structure has been examined using thermodynamic modeling and dilatometric analysis. It is concluded that the typical Al content of about 1 wt% promotes δ-ferrite formation at the expense of austenite and its martensitic/bainitic product phase(s), thereby compromising the wear resistance of the hardfacing deposit. This paper also demonstrates how the development of a Schaeffler-type diagram for predicting the weld metal micro-structure can provide guidance on weld filler metal design to produce the optimum microstructure for industrial hardfacing applications.

Effect of chemical composition of copper alloys on their hot-brittleness and weldability

International Nuclear Information System (INIS)

Zakharov, M.V.

1985-01-01

Effect of different alloying elements on the hot crack formation in argon-arc welding of M1 copper has been studied. It is shown that the effective crystallization interval has a determining influence on hot-brittleness of low-alloyed high-thermal- and electric conducting welded copper alloys. The narrow is this interval the lower is linear schrinkage and the alloys inclined to the formation of crystallization cracks in welding to a lesser degree. Alloying elements with low solubility in copper in solid state broadening the crystallization interval affect negatively the alloy hot-brittleness. Such additives as zirconium are useful at 0.02-0.O5% content and at > 0.1% content are intolerable. As to cadmium, tin, magnesium, cerium and antimony additives they don't practically strengthen copper and its alloys at 700-800 deg C and they should not be introduced

An analysis of the joints’ properties of thick-grained steel welded by the SAW and ESW methods

Directory of Open Access Journals (Sweden)

Krawczyk R.

2017-03-01

Full Text Available The article presents an analysis of properties of welded joints of thick-grained steel of P460NH type used more and more often in the modern constructions. A process of examining a technology of welding has been carried out on the thick-walled butt joints of sheet metal by two methods of welding namely submerged arc welding (SAW - 121 and electroslag (ESW - 722. The article deals with a topic of optimizing a process of welding thick-walled welded joints of fine-grained steel due to their mechanical properties and efficiency.

A comparative study of multiple regression analysis and back ...

Indian Academy of Sciences (India)

Abhijit Sarkar

artificial neural network (ANN) models to predict weld bead geometry and HAZ width in submerged arc welding ... Keywords. Submerged arc welding (SAW); multi-regression analysis (MRA); artificial neural network ..... Degree of freedom.

Application of Expectation Maximization Method for Purchase Decision-Making Support in Welding Branch

Directory of Open Access Journals (Sweden)

Kujawińska Agnieszka

2016-06-01

Full Text Available The article presents a study of applying the proposed method of cluster analysis to support purchasing decisions in the welding industry. The authors analyze the usefulness of the non-hierarchical method, Expectation Maximization (EM, in the selection of material (212 combinations of flux and wire melt for the SAW (Submerged Arc Welding method process. The proposed approach to cluster analysis is proved as useful in supporting purchase decisions.

The use of neutron diffraction for the determination of the in-depth residual stresses profile in weld coatings

International Nuclear Information System (INIS)

Marques, Maria Jose; Batista, A.C.; Nobre, J.P.; Loureiro, Altino; Kornmeier, Joana R.

2013-01-01

The neutron diffraction is a non-destructive technique, particularly suitable for the analysis of residual stress fields in welds. The technique is used in this article to study ferritic samples, coated by submerged arc welding using stainless steel filler metals. This procedure is often used for manufacturing process equipment for chemical and nuclear industries, for ease of implementation and economic reasons. The main disadvantage of that processes is the cracking phenomenon that often occurs at the interface between the base material and coatings, which can be minimized by performing post-weld stress relief heat treatments. The samples analyzed in this study were made of carbon steel plates, coated by submerged arc welding two types of stainless steel filler metals. For the first layer was used one EN 12 072 - S 2 U 23 12 electrode, while for the second and third layers were used an EN 12 072 - 19 12 3 S L electrode. After cladding, the samples were submitted to a post-weld heat treatment for 1 hour at 620 deg C. The residual stress profiles obtained by neutron diffraction evidence the relaxation of residual stress given by the heat treatment. (author)

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

Braze welding of cobalt with a silver–copper filler

Directory of Open Access Journals (Sweden)

Everett M. Criss

2015-01-01

Full Text Available A new method of joining cobalt by braze-welding it with a silver–copper filler was developed in order to better understand the residual stresses in beryllium–aluminum/silicon weldments which are problematic to investigate because of the high toxicity of Be. The base and filler metals of this new welding system were selected to replicate the physical properties, crystal structures, and chemical behavior of the Be–AlSi welds. Welding parameters of this surrogate Co–AgCu system were determined by experimentation combining 4-point bending tests and microscopy. Final welds are 5 pass manual TIG (tungsten inert gas, with He top gas and Ar back gas. Control of the welding process produces welds with full penetration melting of the cobalt base. Microscopy indicates that cracking is minimal, and not through thickness, whereas 4-point bending shows failure is not by base-filler delamination. These welds improve upon the original Be–AlSi welds, which do not possess full penetration, and have considerable porosity. We propose that utilization of our welding methods will increase the strength of the Be–AlSi weldments. The specialized welding techniques developed for this study may be applicable not only for the parent Be–AlSi welds, but to braze welds and welds utilizing brittle materials in general. This concept of surrogacy may prove useful in the study of many different types of exotic welds.

Experimental investigations of tungsten inert gas assisted friction stir welding of pure copper plates

Science.gov (United States)

Constantin, M. A.; Boșneag, A.; Nitu, E.; Iordache, M.

2017-10-01

Welding copper and its alloys is usually difficult to join by conventional fusion welding processes because of high thermal diffusivity of the copper, alloying elements, necessity of using a shielding gas and a clean surface. To overcome this inconvenience, Friction Stir Welding (FSW), a solid state joining process that relies on frictional heating and plastic deformation, is used as a feasible welding process. In order to achieve an increased welding speed and a reduction in tool wear, this process is assisted by another one (WIG) which generates and adds heat to the process. The aim of this paper is to identify the influence of the additional heat on the process parameters and on the welding joint properties (distribution of the temperature, hardness and roughness). The research includes two experiments for the FSW process and one experiment for tungsten inert gas assisted FSW process. The outcomes of the investigation are compared and analysed for both welding variants. Adding a supplementary heat source, the plates are preheated and are obtain some advantages such as reduced forces used in process and FSW tool wear, faster and better plasticization of the material, increased welding speed and a proper weld quality.

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

Energy Technology Data Exchange (ETDEWEB)

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

2017-03-15

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

Study of verification and validation of standard welding procedure specifications guidelines for API 5L X-70 grade line pipe welding

Directory of Open Access Journals (Sweden)

Qazi H. A. A.

2017-12-01

Full Text Available Verification and validation of welding procedure specifications for X-70 grade line pipe welding was performed as per clause 8.2, Annexure B and D of API 5L, 45th Edition to check weld integrity in its future application conditions. Hot rolled coils were imported from China, de-coiling, strip edge milling, three roller bending to from pipe, inside and outside submerged arc welding of pipe, online ultrasonic testing of weld, HAZ and pipe body, cutting at fixed random length of pipe, visual inspection of pipe, Fluoroscopic inspection of pipe, welding procedure qualification test pieces marking at weld portion of the pipe, tensile testing, guided bend testing, CVN Impact testing were performed. Detailed study was conducted to explore possible explanations and variation in mechanical properties, WPS is examined and qualified as per API 5L 45th Edition.

The variable polarity plasma arc welding process: Characteristics and performance

Science.gov (United States)

Hung, R. J.; Zhu, G. J.

1991-01-01

Significant advantages of the Variable Polarity Plasma Arc (VPPA) Welding Process include faster welding, fewer repairs, less joint preparation, reduced weldment distortion, and absence of porosity. The power distribution was analyzed for an argon plasma gas flow constituting the fluid in the VPPA Welding Process. The major heat loss at the torch nozzle is convective heat transfer; in the space between the outlet of the nozzle and the workpiece; radiative heat transfer; and in the keyhole in the workpiece, convective heat transfer. The power absorbed at the workpiece produces the molten puddle that solidifies into the weld bead. Crown and root widths, and crown and root heights of the weld bead are predicted. The basis is provided for an algorithm for automatic control of VPPA welding machine parameters to obtain desired weld bead dimensions.

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.

Vision of the Arc for Quality Documentation and for Closed Loop Control of the Welding Process

DEFF Research Database (Denmark)

Kristiansen, Morten; Kristiansen, Ewa; Jensen, Casper Houmann

2014-01-01

For gas metal arc welding a vision system was developed, which was robust to monitor the position of the arc. The monitoring documents the welding quality indirectly and a closed loop fuzzy control was implemented to control an even excess penetration. For welding experiments on a butt......-joint with a V-groove with varying root gapthe system demonstrated increased welding quality compared to the system with no control. The system was implemented with a low cost vision system, which makes the system interesting to apply in industrial welding automation systems....

Modeling macro-and microstructures of Gas-Metal-Arc Welded HSLA-100 steel

Science.gov (United States)

Yang, Z.; Debroy, T.

1999-06-01

Fluid flow and heat transfer during gas-metal-arc welding (GMAW) of HSLA-100 steel were studied using a transient, three-dimensional, turbulent heat transfer and fluid flow model. The temperature and velocity fields, cooling rates, and shape and size of the fusion and heat-affected zones (HAZs) were calculated. A continuous-cooling-transformation (CCT) diagram was computed to aid in the understanding of the observed weld metal microstructure. The computed results demonstrate that the dissipation of heat and momentum in the weld pool is significantly aided by turbulence, thus suggesting that previous modeling results based on laminar flow need to be re-examined. A comparison of the calculated fusion and HAZ geometries with their corresponding measured values showed good agreement. Furthermore, “finger” penetration, a unique geometric characteristic of gas-metal-arc weld pools, could be satisfactorily predicted from the model. The ability to predict these geometric variables and the agreement between the calculated and the measured cooling rates indicate the appropriateness of using a turbulence model for accurate calculations. The microstructure of the weld metal consisted mainly of acicular ferrite with small amounts of bainite. At high heat inputs, small amounts of allotriomorphic and Widmanstätten ferrite were also observed. The observed microstructures are consistent with those expected from the computed CCT diagram and the cooling rates. The results presented here demonstrate significant promise for understanding both macro-and microstructures of steel welds from the combination of the fundamental principles from both transport phenomena and phase transformation theory.

Sub-arc narrow gap welding of Atucha 2 RPV closure head

International Nuclear Information System (INIS)

Hantsch, H.; Million, K.; Zimmermann, H.

1982-01-01

Narrow gap technology was used for reasons of design and fabrication when welding the closure-head dome to its flange. Preliminary tests had yielded the necessary improvements of the well-proven sub-arc practice. New facilities had to be developed for welding proper and for the accompanying machining work (finishing in the narrow gap). Special measures were adopted for monitoring the welding process and for recording the welding parameters. The new method was tried out on several large test coupons before welding of the final product was started. No difficulties were encountered during the welding job. Fabrication of the closure head is shown in a short film sequence. (orig.)

Experimental investigation on the weld pool formation process in plasma keyhole arc welding

Science.gov (United States)

Van Anh, Nguyen; Tashiro, Shinichi; Van Hanh, Bui; Tanaka, Manabu

2018-01-01

This paper seeks to clarify the weld pool formation process in plasma keyhole arc welding (PKAW). We adopted, for the first time, the measurement of the 3D convection inside the weld pool in PKAW by stereo synchronous imaging of tungsten tracer particles using two sets of x-ray transmission systems. The 2D convection on the weld pool surface was also measured using zirconia tracer particles. Through these measurements, the convection in a wide range of weld pools from the vicinity of the keyhole to the rear region was successfully visualized. In order to discuss the heat transport process in a weld pool, the 2D temperature distribution on the weld pool surface was also measured by two-color pyrometry. The results of the comprehensive experimental measurement indicate that the shear force due to plasma flow is found to be the dominant driving force in the weld pool formation process in PKAW. Thus, heat transport in a weld pool is considered to be governed by two large convective patterns near the keyhole: (1) eddy pairs on the surface (perpendicular to the torch axis), and (2) eddy pairs on the bulk of the weld pool (on the plane of the torch). They are formed with an equal velocity of approximately 0.35 m s-1 and are mainly driven by shear force. Furthermore, the flow velocity of the weld pool convection becomes considerably higher than that of other welding processes, such as TIG welding and GMA welding, due to larger plasma flow velocity.

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

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.

Eutectic structures in friction spot welding joint of aluminum alloy to copper

International Nuclear Information System (INIS)

Shen, Junjun; Suhuddin, Uceu F. H.; Cardillo, Maria E. B.; Santos, Jorge F. dos

2014-01-01

A dissimilar joint of AA5083 Al alloy and copper was produced by friction spot welding. The Al-MgCuAl 2 eutectic in both coupled and divorced manners were found in the weld. At a relatively high temperature, mass transport of Cu due to plastic deformation, material flow, and atomic diffusion, combined with the alloy system of AA5083 are responsible for the ternary eutectic melting

Assessment of the Biological Effects of Welding Fumes Emitted From Metal Active Gas and Manual Metal Arc Welding in Humans.

Science.gov (United States)

Dewald, Eva; Gube, Monika; Baumann, Ralf; Bertram, Jens; Kossack, Veronika; Lenz, Klaus; Reisgen, Uwe; Kraus, Thomas; Brand, Peter

2015-08-01

Emissions from a particular welding process, metal inert gas brazing of zinc-coated steel, induce an increase in C-reactive protein. In this study, it was investigated whether inflammatory effects could also be observed for other welding procedures. Twelve male subjects were separately exposed to (1) manual metal arc welding fumes, (2) filtered air, and (3) metal active gas welding fumes for 6 hours. Inflammatory markers were measured in serum before, and directly, 1 and 7 days after exposure. Although C-reactive protein concentrations remained unchanged, neutrophil concentrations increased directly after exposure to manual metal arc welding fumes, and endothelin-1 concentrations increased directly and 24 hours after exposure. After exposure to metal active gas and filtered air, endothelin-1 concentrations decreased. The increase in the concentrations of neutrophils and endothelin-1 may characterize a subclinical inflammatory reaction, whereas the decrease of endothelin-1 may indicate stress reduction.

A comparative study of the microstructure and mechanical properties of HTLA steel welds obtained by the tungsten arc welding and resistance spot welding

Energy Technology Data Exchange (ETDEWEB)

Ghazanfari, H., E-mail: ghazanfari@aut.ac.ir [AmirKabir University of Technology, Department of Mining and Metallurgy, 424 Hafez Ave, Tehran (Iran, Islamic Republic of); Naderi, M., E-mail: mnaderi@aut.ac.ir [AmirKabir University of Technology, Department of Mining and Metallurgy, 424 Hafez Ave, Tehran (Iran, Islamic Republic of); Iranmanesh, M., E-mail: imehdi@aut.ac.ir [AmirKabir University of Technology, Department of Maritime Engineering, 424 Hafez Ave, Tehran (Iran, Islamic Republic of); Seydi, M., E-mail: afsan_sy@yahoo.com [Zarin Joosh Aria Co., Tehran (Iran, Islamic Republic of); Poshteban, A., E-mail: ali_poshtiban@yahoo.com [Hamyar Sanat Eghbal Co., Tehran (Iran, Islamic Republic of)

2012-02-01

Highlights: Black-Right-Pointing-Pointer Hardness mapping is a novel method to identify different phases. Black-Right-Pointing-Pointer Surface hardness mapping, tabulates the hardness of a large area of weld. Black-Right-Pointing-Pointer Hardness maps can be used to depict the strength map through the specimen. Black-Right-Pointing-Pointer Hardness mapping is an easy way to identify the phase fractions within the specimen. - Abstract: Hardness tests are routinely employed as simple and efficient methods to investigate the microstructure and mechanical properties of steels. Each microstructural phase in steel has its own hardness level. Therefore, using surface hardness mapping data over a large area of weld zone would be a reasonable method to identify the present phases in steel. The microstructure distribution and mechanical properties variation through welded structures is inhomogeneous and not suitable for certain applications. So, studying the microstructure of weld zone has a significant importance. 4130 steel is classified in HTLA steels and it is widely used in marine industry due to its superior hardenability, good corrosion resistance and high strength. Gas tungsten arc and resistance spot welding are the most usable processes in joining of 4130 sheets. In this work a series of welds have been fabricated in 4130 steel tube by gas tungsten arc and resistance spot welding. The tube was subjected to quench-tempered heat treatment. Slices from the welds before and after heat treatment were polished and etched and the macrostructure and microstructure were observed. Hardness maps were then determined over the large area of weld zone, including the heat affected zone and base plate. Results show good relations between the various microstructures, strength and hardness values. It is also proved that this method is precise and applicable to estimate phase fraction of each phase in various regions of weld. In the current study some equations were proposed to

Generation rate of carbon monoxide from CO2 arc welding.

Science.gov (United States)

Ojima, Jun

2013-01-01

CO poisoning has been a serious industrial hazard in Japanese workplaces. Although incomplete combustion is the major cause of CO generation, there is a risk of CO poisoning during some welding operations. The aim of the present study was to evaluate the generation rate of CO from CO2 arc welding under controlled laboratory conditions and estimate the ventilation requirements for the prevention of CO poisoning. Bead on plate welding was carried out with an automatic welding robot on a rolled steel base metal under several conditions. The concentration of emitted CO from the welding was measured by a real-time CO monitor in a well-ventilated laboratory that was free from ambient CO contamination. The generation rate of CO was obtained from the three measurements-the flow rate of the welding exhaust gas, CO concentration in the exhaust gas and the arcing time. Then the ventilation requirement to prevent CO poisoning was calculated. The generation rate of CO was found to be 386-883 ml/min with a solid wire and 331-1,293 ml/min with a flux cored wire respectively. It was found that the CO concentration in a room would be maintained theoretically below the OSHA PEL (50 ppm) providing the ventilation rate in the room was 6.6-25.9 m3/min. The actual ventilation requirement was then estimated to be 6.6-259 m3/min considering incomplete mixing. In order to prevent CO poisoning, some countermeasures against gaseous emission as well as welding fumes should be taken eagerly.

Experimental Investigations on Pulsed Nd:YAG Laser Welding of C17300 Copper-Beryllium and 49Ni-Fe Soft Magnetic Alloys

International Nuclear Information System (INIS)

Mousavi, S. A. A. Akbari; Ebrahimzadeh, H.

2011-01-01

Copper-beryllium and soft magnetic alloys must be joined in electrical and electro-mechanical applications. There is a high difference in melting temperatures of these alloys which cause to make the joining process very difficult. In addition, copper-beryllium alloys are of age hardenable alloys and precipitations can brittle the weld. 49Ni-Fe alloy is very hot crack sensitive. Moreover, these alloys have different heat transfer coefficients and reflection of laser beam in laser welding process. Therefore, the control of welding parameters on the formation of adequate weld puddle composition is very difficult. Laser welding is an advanced technique for joining of dissimilar materials since it can precisely control and adjust the welding parameters. In this study, a 100W Nd:YAG pulsed laser machine was used for joining 49Ni-Fe soft magnetic to C17300 copper-beryllium alloys. Welding of samples was carried out autogenously by changing the pulse duration, diameter of beam, welding speed, voltage and frequency. The spacing between samples was set to almost zero. The ample were butt welded. It was required to apply high voltage in this study due to high reflection coefficient of copper alloys. Metallography, SEM analysis, XRD and microhardness measurement was used for survey of results. The results show that the weld strength depends upon the chemical composition of the joints. To change the wells composition and heat input of the welds, it was attempted to deviate the laser focus away from the weld centerline. The best strength was achieved by deviation of the laser beam away about 0.1mm from the weld centerline. The result shows no intermetallic compounds if the laser beam is deviated away from the joint.

Optimizing friction stir weld parameters of aluminum and copper using conventional milling machine

Science.gov (United States)

Manisegaran, Lohappriya V.; Ahmad, Nurainaa Ayuni; Nazri, Nurnadhirah; Noor, Amirul Syafiq Mohd; Ramachandran, Vignesh; Ismail, Muhammad Tarmizizulfika; Ahmad, Ku Zarina Ku; Daruis, Dian Darina Indah

2018-05-01

The joining of two of any particular materials through friction stir welding (FSW) are done by a rotating tool and the work piece material that generates heat which causes the region near the FSW tool to soften. This in return will mechanically intermix the work pieces. The first objective of this study is to join aluminum plates and copper plates by means of friction stir welding process using self-fabricated tools and conventional milling machine. This study also aims to investigate the optimum process parameters to produce the optimum mechanical properties of the welding joints for Aluminum plates and Copper plates. A suitable tool bit and a fixture is to be fabricated for the welding process. A conventional milling machine will be used to weld the aluminum and copper. The most important parameters to enable the process are speed and pressure of the tool (or tool design and alignment of the tool onto the work piece). The study showed that the best surface finish was produced from speed of 1150 rpm and tool bit tilted to 3°. For a 200mm × 100mm Aluminum 6061 with plate thickness of 2 mm at a speed of 1 mm/s, the time taken to complete the welding is only 200 seconds or equivalent to 3 minutes and 20 seconds. The Copper plates was successfully welded using FSW with tool rotation speed of 500 rpm, 700 rpm, 900 rpm, 1150 rpm and 1440 rpm and with welding traverse rate of 30 mm/min, 60 mm/min and 90 mm/min. As the conclusion, FSW using milling machine can be done on both Aluminum and Copper plates, however the weld parameters are different for the two types of plates.

Numerical Modeling of Fluid Flow, Heat Transfer and Arc-Melt Interaction in Tungsten Inert Gas Welding

Science.gov (United States)

Li, Linmin; Li, Baokuan; Liu, Lichao; Motoyama, Yuichi

2017-04-01

The present work develops a multi-region dynamic coupling model for fluid flow, heat transfer and arc-melt interaction in tungsten inert gas (TIG) welding using the dynamic mesh technique. The arc-weld pool unified model is developed on basis of magnetohydrodynamic (MHD) equations and the interface is tracked using the dynamic mesh method. The numerical model for arc is firstly validated by comparing the calculated temperature profiles and essential results with the former experimental data. For weld pool convection solution, the drag, Marangoni, buoyancy and electromagnetic forces are separately validated, and then taken into account. Moreover, the model considering interface deformation is adopted in a stationary TIG welding process with SUS304 stainless steel and the effect of interface deformation is investigated. The depression of weld pool center and the lifting of pool periphery are both predicted. The results show that the weld pool shape calculated with considering the interface deformation is more accurate.

Single-walled nanohorns and other nanocarbons generated by submerged arc discharge between carbon electrodes in liquid argon and other media

International Nuclear Information System (INIS)

Vasu, K; Pramoda, K; Govindaraj, A; Rao, C N R; Moses, K

2014-01-01

Arc discharge between two graphite electrodes submerged in different liquid media yields various dimensional nanocarbon structures such as 1D carbon nanotubes and 2D graphene. Single-walled carbon nanohorns (SWNHs) prepared by submerged arc discharge in liquid nitrogen medium are found to have nitrogen impurities. Here, we report the structure and properties of pure and nitrogen-doped SWNHs obtained by submerged arc discharge in a liquid argon medium. The absence of an XPS N 1s signal, which is present in nanohorns obtained in liquid nitrogen, indicate that the nanohorns are free from nitrogen impurities. Raman spectra show a strong defect-induced D band and current–voltage characteristics show a slight nonlinear behavior. N 2 adsorption of pure SWNHs shows type-IV isotherms with a surface area of 300 m 2 g −1 . Adsorption of CO 2 and H 2 in pure SWNHs has also been measured. Arc discharge in other liquid media such as water, ethanol, dimethylformamide (DMF), n-methyl pyrrolidone (NMP), formamide, benzene, heptane and acetone yields different nanocarbon structures including multi-walled carbon nanotubes (MWNTs), few-layer graphene, carbon onions and carbon nanoparticles. (papers)

Characterization of gas metal arc welded hot rolled DP600 steel

Energy Technology Data Exchange (ETDEWEB)

Mukherjee, K.; Ramazani, A.; Yang, L.; Prahl, U.; Bleck, W. [RWTH Aachen University, Institute for Ferrous Metallurgy (IEHK) (Germany); Reisgen, U.; Schleser, M.; Abdurakhmanov, A. [RWTH Aachen University, Welding and Joining Institute (ISF) (Germany)

2011-12-15

Dual-phase (DP) steels are suitable candidates for automotive applications due to their high strength and ductility. These advanced mechanical properties result from the special microstructure of the DP steel with 5{proportional_to}20% martensite phase in a soft ferrite matrix. However, during welding, which is an important process in automotive industry, this special microstructure is destroyed. In this research the characterization of Gas Metal Arc (GMA) welded joining zones was performed by optical microscopy and hardness mapping. Tensile tests were also performed keeping the welded portion in the gauge length. Scanning Electron Microscopy (SEM) was used for the fracture investigation. From the characterization and tensile tests, the soften zones were found, which are caused by the tempered martensite and larger ferrite grain size than that in base metal. Furthermore, GMA welding make a large Heat Affected Zone (HAZ). (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Development of high productivity pipeline girth welding

International Nuclear Information System (INIS)

Yapp, David; Liratzis, Theocharis

2010-01-01

The trend for increased oil and gas consumption implies a growth of long-distance pipeline installations. Welding is a critical factor in the installation of pipelines, both onshore and offshore, and the rate at which the pipeline can be laid is generally determined by the speed of welding. This has resulted in substantial developments in pipeline welding techniques. Arc welding is still the dominant process used in practice, and forge welding processes have had limited successful application to date, in spite of large investments in process development. Power beam processes have also been investigated in detail and the latest laser systems now show promise for practical application. In recent years the use of high strength steels has substantially reduced the cost of pipeline installation, with X70 and X80 being commonly used. This use of high strength pipeline produced by thermomechanical processing has also been researched. They must all meet three requirments, high productivity, satisfactory weld properties, and weld quality

Residual stress investigation of copper plate and canister EB-Welds Complementary Results

International Nuclear Information System (INIS)

Gripenberg, H.

2009-03-01

The residual stresses in copper as induced by EB-welding were studied by specimens where the weld had two configurations: either a linear or a circumferential weld. This report contains the residual stress measurements of two plates, containing linear welds, and the full-scale copper lid specimen to which a hollow cylinder section had been joined by a circumferential EB-weld. The residual stress state of the EB-welded copper specimens was investigated by X-ray diffraction (XRD), hole drilling (HD) ring core (RC) and contour method (CM). Three specimens, canister XK010 and plates X251 and X252, were subjected to a thorough study aiming at quantitative determination of the residual stress state in and around the EB-welds using XRD for surface and HD and RC for spatial stress analysis. The CM maps one stress component over a whole cross section. The surface residual stresses measured by XRD represent the machined condition of the copper material. The XRD study showed that the stress changes towards compression close to the weld in the hollow cylinder, which indicates shrinkage in the hoop direction. According to the same analogy, the shrinkage in the axial direction is much smaller. The HD measurements showed that the stress state in the base material is bi-axial and, in terms of von Mises stress, 50 MPa for the plates and 20 MPa for the cylinder part of the canister. The stress state in the EB-welds of all specimens differs clearly from the stress state in the base material being more tensile, with higher magnitudes of von Mises stress in the plate than in the canister welds. The HD and RC results were obtained using linear elastic theory. The RC measurements showed that the maximum principal stress in the BM is close to zero near the surface and it becomes slightly tensile, 10 MPa, deeper under the surface. Welding pushed the general stress state towards tension with the maximum principal stress reaching 50 MPa, deeper than 5 mm below the surface in the weld. The

Cracking generated by arc welding; La fissuration consecutive a l'operation de soudage a l'arc

Energy Technology Data Exchange (ETDEWEB)

Carpreau, J.M. [LaMSID UMR EDF-CNRS-CEA 2832, 78 - Chatou (France)

2010-07-01

During welding, rapid localized heat transients lead to thermal cycles, resulting in changes in the local metallurgy and mechanical loading of the components to be joined. Depending on the materials, these changes may generate cracks, making the weld structure unable to resist in-service loading. Analysis of various cracking mechanisms showed the role of the thermomechanical loading of the weld or HAZ during cooling after arc welding. Hence, prediction of cracking is based on the calculation of the thermomechanical stress, which often gives an estimated range, or from a mechanistically-based phenomenological approach. (author)

Automatic orbital GTAW welding: Highest quality welds for tomorrow's high-performance systems

Science.gov (United States)

Henon, B. K.

1985-01-01

Automatic orbital gas tungsten arc welding (GTAW) or TIG welding is certain to play an increasingly prominent role in tomorrow's technology. The welds are of the highest quality and the repeatability of automatic weldings is vastly superior to that of manual welding. Since less heat is applied to the weld during automatic welding than manual welding, there is less change in the metallurgical properties of the parent material. The possibility of accurate control and the cleanliness of the automatic GTAW welding process make it highly suitable to the welding of the more exotic and expensive materials which are now widely used in the aerospace and hydrospace industries. Titanium, stainless steel, Inconel, and Incoloy, as well as, aluminum can all be welded to the highest quality specifications automatically. Automatic orbital GTAW equipment is available for the fusion butt welding of tube-to-tube, as well as, tube to autobuttweld fittings. The same equipment can also be used for the fusion butt welding of up to 6 inch pipe with a wall thickness of up to 0.154 inches.

Investigation of fracture in pressurized gas metal arc welded beryllium

International Nuclear Information System (INIS)

Heiple, C.R.; Merlini, R.J.; Adams, R.O.

1976-01-01

Premature failures during proof testing of pressurized-gas-metal-arc (PGMA) welded beryllium assemblies were investigated. The failures were almost entirely within the beryllium (a forming grade, similar to HP-10 or S-240), close to and parallel to the weld interface. The aluminum-silicon weld filler metal deposit was not centered in the weld groove in the failed assemblies, and failure occurred on the side of the weld opposite the bias in the weld deposit. Tensile tests of welded samples demonstrated that the failures were unrelated to residual machining damage from cutting the weld groove, and indicated small lack-of-fusion areas near the weld start to be the most likely origin of the failures. Acoustic emission was monitored during tensile tests of the welds. The majority of acoustic emission was probably from crack propagation through the weld filler metal. Tensile bars cut from the region of the weld start behaved differently; they failed at lower loads and exhibited an acoustic emission behavior believed to be from cracking in the weld metal-beryllium interface. Improvement in the quality of these and similar beryllium welds can therefore most likely be made by centering the weld deposit and reducing the size of the weld start defect. 21 fig

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

Comparative assessment of filler wires for argon-arc welding of refractory alloys

International Nuclear Information System (INIS)

Sorokin, L.I.; Bagdasarov, Yu.S.; Tupikin, V.I.

1993-01-01

It is recommended to use wires of similar composition as filler material during argon-arc welding of heat resisting alloys, and Sv-08Kh20N57M8V8T3R wire - for welding of dispersion hardening alloys. Sv-06Kh15N60M15, Sv-KhN64KBMYuVF or Kh11N60M23 wires should be used as filler materials to decrease tendency of welded joints to cracking during welding and heat treatment

Comparisons of irradiation-induced shifts in fracture toughness, crack arrest toughness, and Charpy impact energy in high-copper welds

International Nuclear Information System (INIS)

Corwin, W.R.; Nanstad, R.K.; Iskander, S.K.

1991-01-01

The Heavy-Section Steel Irradiation (HSSI) Program is examining relative shifts and changes in shape of fracture and crack-arrest toughness versus temperature behavior for two high-copper welds. Fracture toughness 100-MPa√m temperature shifts are greater than Charpy 41-J shifts for both welds. Mean curve fits to the fracture toughness data provide mixed results regarding curve shape changes, but curves constructed as lower boundaries indicate lower slopes. Preliminary crack-arrest toughness results indicate that shifts of lower-bound curves are approximately the same as CVN 41-J shifts with no shape changes

The Effect of Welding Energy on the Microstructural and Mechanical Properties of Ultrasonic-Welded Copper Joints

Science.gov (United States)

Yang, Jingwei; Cao, Biao; Lu, Qinghua

2017-01-01

The effects of welding energy on the mechanical and microstructural characteristics of ultrasonic-welded pure copper plates were investigated. Complex dynamic recrystallization and grain growth occurred inside the weld zone during ultrasonic welding. At a low welding energy, a thin band of straight weld interfaces was observed and had an ultra-fine grain structure. With an increase in welding energy, the weld interface progressively changed from flat to sinusoidal, and eventually turned into a convoluted wavy pattern, bearing similarities to shear instabilities, as observed in fluid dynamics. The lap shear load of the joints initially increased and then remained stable as the welding energy increased. The tensile characteristics of the joints significantly depended on the development of plastic deformation at the interface. The influence of the microstructure on the hardness was also discussed. PMID:28772553

Creep properties of welded joints in OFHC copper for nuclear waste containment

International Nuclear Information System (INIS)

Ivarsson, B.; Oesterberg, J.O.

1988-08-01

In Sweden it has been suggested that copper canisters are used for containment of spent nuclear fuel. These canisters will be subjected to temperatures up to 100 degrees C and external pressures up to 15 MPa. Since the material is pure (OFHC) copper, creep properties must be considered when the canisters are dimensioned. The canisters are sealed by electron beam welding which will affect the creep properties. Literature data for copper - especially welded joints - at the temperatures of interest is very scare. Therefore uniaxial creep tests of parent metal, weld metal, and simulated HAZ structures have been performed at 110 degrees C. These tests revealed considerable differences in creep deformation and rupture strength. The weld metal showed creep rates and rupture times ten times higher and ten times shorter, respectively, than those of the parent metal. The simulated HAZ was equally strongen than the parent metal. These differences were to some extent verified by results from creep tests of cross-welded specimens which, however, showed even shorter rupture times. Constitutive equations were derived from the uniaxial test results. To check the applicability of these equations to multiaxial conditions, a few internal pressure creep tests of butt-welded tubes were performed. Attemps were made to simulate their creep behaviour by constitutive equations were used. These calculations failed due to too great differences in creep deformation behaviour across the welded joint. (authors)

Carbothermic reduction of pyrolusite for obtaining carbon bearing ferromanganese and slags, adequated to the development of welding materials; Reduccion carbotermica de pirolusita para la obtencion de ferromanganeso y escoria, adecuados al desarrollo de materiales de soldadura

Energy Technology Data Exchange (ETDEWEB)

Cruz-Crespo, A.; Garcia-Sanchez, L. L.; Quintana-Puchol, R.; Perdomo Gonzalez, L.; Gomez-Perez, C. R.; Jimenez-Vielsa, G. E.; Cores-Sanchez, A.

2004-07-01

The high carbon ferromanganese obtained by means of carbothermic reduction in an electric arc furnace of direct current is proposed. the ideal composition of slag oxides to achieve a flux to be used in the submerged arc welding (SAW) is established. Calculation for charge components (pyrolusite, coke, steel wool, lime, rutile and fluorite) for no fluxes technology for FeMn is carried out taking into account the welding fluxes characteristics of the SiO{sub 2}-MnO-CaO system. Change materials reduction experiments to obtain FeMn and slag are used to develop a SAW flux. (Author) 21 refs.

Effect of pulsed current welding on fatigue behaviour of high strength aluminium alloy joints

International Nuclear Information System (INIS)

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

2008-01-01

High strength aluminium alloys (Al-Zn-Mg-Cu alloys) have gathered wide acceptance in the fabrication of light weight structures requiring high strength-to weight ratio, such as transportable bridge girders, military vehicles, road tankers and railway transport systems. The preferred welding processes of high strength aluminium alloy are frequently gas tungsten arc welding (GTAW) process and gas metal arc welding (GMAW) process due to their comparatively easier applicability and better economy. Weld fusion zones typically exhibit coarse columnar grains because of the prevailing thermal conditions during weld metal solidification. This often results inferior weld mechanical properties and poor resistance to hot cracking. In this investigation, an attempt has been made to refine the fusion zone grains by applying pulsed current welding technique. Rolled plates of 6 mm thickness have been used as the base material for preparing single pass welded joints. Single V butt joint configuration has been prepared for joining the plates. The filler metal used for joining the plates is AA 5356 (Al-5Mg (wt%)) grade aluminium alloy. Four different welding techniques have been used to fabricate the joints and they are: (i) continuous current GTAW (CCGTAW), (ii) pulsed current GTAW (PCGTAW), (iii) continuous current GMAW (CCGMAW) and (iv) pulsed current GMAW (PCGMAW) processes. Argon (99.99% pure) has been used as the shielding gas. Fatigue properties of the welded joints have been evaluated by conducting fatigue test using rotary bending fatigue testing machine. Current pulsing leads to relatively finer and more equi-axed grain structure in gas tungsten arc (GTA) and gas metal arc (GMA) welds. In contrast, conventional continuous current welding resulted in predominantly columnar grain structures. Grain refinement is accompanied by an increase in fatigue life and endurance limit

Copper contamination in thin stainless steel sheet

International Nuclear Information System (INIS)

Holbert, R.K. Jr.; Dobbins, A.G.; Bennett, R.K. Jr.

1986-01-01

The standard welding technique used at Oak Ridge Y-12 Plant for joining thin stainless sheet is the gas tungsten arc (GTA) welding process. One of the reoccurring problems with the sheet welds is surface cracking in the heat-affected zone (HAZ). Metallography shows that the cracks are only about 0.05 mm (0.002 in.) deep which is significant in a 0.25 mm (0.01 in.) thick sheet. Thus, welding requirements do not permit any surfacing cracking as detected by a fluorescent dye penetrant test conducted on every part after welding. Surface cracks have been found in both of the two most common weld designs in the thin sheet fabricated at the Oak Ridge Y-12 Plant. These butt joints are welded between two 0.25 mm thick stainless steel sheets and a tube with eyelet welded to a 25 mm (0.98 in.) thick sheet. The weld between the two sheets is made on a semiautomatic seam welding unit, whereas the tube-to-eyelet-to-sheet welds are done manually. The quality of both welds is very dependent on the welding procedure and the way the parts are placed in the weld fixturing. Metallographic examination has indicated that some welded parts with surface cracking in the weld region had copper particles on the surface, and the question of copper contamination has been raised. With the aid of a scanning electron microscope and an electron microprobe, the existence of copper in an around the surface cracks has been verified. The copper is on the surface of the parts prior to welding in the form of small dust particles

Mathematical Modeling of Optical Radiation Emission as a Function of Welding Power during Gas Shielded Metal Arc Welding.

Science.gov (United States)

Bauer, Stefan; Janßen, Marco; Schmitz, Martin; Ott, Günter

2017-11-01

Arc welding is accompanied by intense optical radiation emission that can be detrimental not only for the welder himself but also for people working nearby or for passersby. Technological progress advances continuously in the field of joining, so an up-to-date radiation database is necessary. Additionally, many literature irradiance data have been measured for a few welding currents or for parts of the optical spectral region only. Within this paper, a comprehensive study of contemporary metal active gas, metal inert gas, and cold metal transfer welding is presented covering optical radiation emission from 200 up to 2,700 nm by means of (spectro-) radiometric measurements. The investigated welding currents range from 70 to 350 A, reflecting values usually applied in industry. Based upon these new irradiance data, three mathematical models were derived in order to describe optical radiation emission as a function of welding power. The linear, exponential, and sigmoidal emission models depend on the process variant (standard or pulsed) as well as on the welding material (mild and stainless steel, aluminum). In conjunction with the corresponding exposure limit values for incoherent optical radiation maximum permissible exposure durations were calculated as a function of welding power. Typical times are shorter than 1 s for the ultraviolet spectral region and range from 1 to 10 s for visible radiation. For the infrared regime, exposure durations are of the order of minutes to hours. Finally, a validation of the metal active gas emission models was carried out with manual arc welding.

High quality joining techniques: in-process assurance (IPA) welding system

Energy Technology Data Exchange (ETDEWEB)

Kaihara, Shoichiro [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan)

1996-08-01

On July 1, 1995, the Product Liability Law was enforced, and in industrial world, further reliability has been demanded. Recently, accompanying the progress of electronics, the proportion taken by automatic welders and robots increased in welding. By memorizing proper welding conditions, the welding from initial to final passes can be done fully automatically. Also feedback mechanism was equipped to mechanized welders, and the in-process control has become to be feasible. The way of thinking on confirming in process welding quality in arc welding is explained. IPA welding system utilizes the multi-media collecting images and sound, samples the change of welding conditions and the state of arc on a same screen, and monitors the deviation from the range of proper welding conditions. At the time of abnormality, inspector or a computer carries out image diagnosis and welding control, and the system indicates the soundness of welded parts. The basic concept and the flow chart of this system are shown. The experiment of applying the system to arc welding is reported. The correlation of welding phenomena and welding conditions is examined. (K.I.)

High quality joining techniques: in-process assurance (IPA) welding system

International Nuclear Information System (INIS)

Kaihara, Shoichiro

1996-01-01

On July 1, 1995, the Product Liability Law was enforced, and in industrial world, further reliability has been demanded. Recently, accompanying the progress of electronics, the proportion taken by automatic welders and robots increased in welding. By memorizing proper welding conditions, the welding from initial to final passes can be done fully automatically. Also feedback mechanism was equipped to mechanized welders, and the in-process control has become to be feasible. The way of thinking on confirming in process welding quality in arc welding is explained. IPA welding system utilizes the multi-media collecting images and sound, samples the change of welding conditions and the state of arc on a same screen, and monitors the deviation from the range of proper welding conditions. At the time of abnormality, inspector or a computer carries out image diagnosis and welding control, and the system indicates the soundness of welded parts. The basic concept and the flow chart of this system are shown. The experiment of applying the system to arc welding is reported. The correlation of welding phenomena and welding conditions is examined. (K.I.)

Heat input properties of hollow cathode arc as a welding heat source

International Nuclear Information System (INIS)

Nishikawa, Hiroshi; Shobako, Shinichiro; Ohta, Masashi; Ohji, Takayoshi

2005-01-01

In order to clarify whether a hollow cathode arc (HCA) can be used as a welding heat source in space, investigations into the fundamental characteristics of HCA were experimentally performed under low pressure conditions. The HCA method enables an arc discharge to ignite and maintain under low pressure conditions; in contrast, low pressure conditions make it extremely difficult for the conventional gas tungsten arc method to form an arc discharge. In an earlier paper, it was shown that the melting process by HCA is very sensitive to process parameters such as the gas flow rate and arc length, and a deep penetration forms when the arc length is long and the gas flow rate is low. In this paper, the distribution of the arc current on the anode surface and the plasma properties of the HCA under low pressure conditions have been made clear and the total heat energy to the anode has been discussed in order to understand the heat input properties of the HCA. The result shows that the HCA in the case of a low gas flow rate is a high and concentrated energy source, and the high energy input to the anode contributes to the deep penetration

Numerical aspects for efficient welding computational mechanics

Directory of Open Access Journals (Sweden)

Aburuga Tarek Kh.S.

2014-01-01

Full Text Available The effect of the residual stresses and strains is one of the most important parameter in the structure integrity assessment. A finite element model is constructed in order to simulate the multi passes mismatched submerged arc welding SAW which used in the welded tensile test specimen. Sequentially coupled thermal mechanical analysis is done by using ABAQUS software for calculating the residual stresses and distortion due to welding. In this work, three main issues were studied in order to reduce the time consuming during welding simulation which is the major problem in the computational welding mechanics (CWM. The first issue is dimensionality of the problem. Both two- and three-dimensional models are constructed for the same analysis type, shell element for two dimension simulation shows good performance comparing with brick element. The conventional method to calculate residual stress is by using implicit scheme that because of the welding and cooling time is relatively high. In this work, the author shows that it could use the explicit scheme with the mass scaling technique, and time consuming during the analysis will be reduced very efficiently. By using this new technique, it will be possible to simulate relatively large three dimensional structures.

Modelling of gas-metal arc welding taking into account metal vapour

Energy Technology Data Exchange (ETDEWEB)

Schnick, M; Fuessel, U; Hertel, M; Haessler, M [Institute of Surface and Manufacturing Technology, Technische Universitaet Dresden, D-01062 Dresden (Germany); Spille-Kohoff, A [CFX Berlin Software GmbH, Karl-Marx-Allee 90, 10243 Berlin (Germany); Murphy, A B [CSIRO Materials Science and Engineering, PO Box 218, Lindfield NSW 2070 (Australia)

2010-11-03

The most advanced numerical models of gas-metal arc welding (GMAW) neglect vaporization of metal, and assume an argon atmosphere for the arc region, as is also common practice for models of gas-tungsten arc welding (GTAW). These models predict temperatures above 20 000 K and a temperature distribution similar to GTAW arcs. However, spectroscopic temperature measurements in GMAW arcs demonstrate much lower arc temperatures. In contrast to measurements of GTAW arcs, they have shown the presence of a central local minimum of the radial temperature distribution. This paper presents a GMAW model that takes into account metal vapour and that is able to predict the local central minimum in the radial distributions of temperature and electric current density. The influence of different values for the net radiative emission coefficient of iron vapour, which vary by up to a factor of hundred, is examined. It is shown that these net emission coefficients cause differences in the magnitudes, but not in the overall trends, of the radial distribution of temperature and current density. Further, the influence of the metal vaporization rate is investigated. We present evidence that, for higher vaporization rates, the central flow velocity inside the arc is decreased and can even change direction so that it is directed from the workpiece towards the wire, although the outer plasma flow is still directed towards the workpiece. In support of this thesis, we have attempted to reproduce the measurements of Zielinska et al for spray-transfer mode GMAW numerically, and have obtained reasonable agreement.

Friction stir welding (FSW process of copper alloys

Directory of Open Access Journals (Sweden)

M. Miličić

2016-01-01

Full Text Available The present paper analyzes the structure of the weld joint of technically pure copper, which is realized using friction stir welding (FSW. The mechanism of thermo-mechanical processes of the FSW method has been identified and a correlation between the weld zone and its microstructure established. Parameters of the FSW welding technology influencing the zone of the seam material and the mechanical properties of the resulting joint were analyzed. The physical joining consists of intense mixing the base material along the joint line in the “doughy” phase. Substantial plastic deformations immediately beneath the frontal surface of tool provide fine-grained structure and a good quality joint. The optimum shape of the tool and the optimum welding regime (pressure force, rotation speed and the traverse speed of the tool in the heat affected zone enable the achievement of the same mechanical properties as those of the basic material, which justifies its use in welding reliable structures.

Analysis of microstructural variation and mechanical behaviors in submerged arc welded joint of high strength low carbon bainitic steel

Energy Technology Data Exchange (ETDEWEB)

Lan, Liangyun, E-mail: lly.liangyun@gmail.com [State Key Laboratory of Rolling Technology and Automation, Northeastern University, Shenyang 110819 (China); Qiu, Chunlin; Zhao, Dewen; Gao, Xiuhua; Du, Linxiu [State Key Laboratory of Rolling Technology and Automation, Northeastern University, Shenyang 110819 (China)

2012-12-15

Microstructural variation in high strength low carbon bainitic steel weldment was investigated in detail by means of optical microscope, transmission electron microscope and scanning electron microscope equipped with electron backscattered diffraction. The results showed that the welded joint has various microstructures such as acicular ferrite, coarse granular ferrite and fine polygonal ferrite. The martensite-austenite (MA) constituent has a variable structure in each sub-zone, which includes fully martensite and fully retained austenite. Meanwhile, the fine grained heat affected zone has higher content of retained austenite than the welded metal (WM) and coarse grained heat affected zone (CGHAZ). The orientation relationship between retained austenite and product phases in the WM and CGHAZ is close to Kurdjumov-Sachs relationship. However, the polygonal ferrite in the fine grained HAZ has no specific orientation relationship with the neighboring retained austenite. The toughness of the coarse grained region is much lower than that of the WM because the coarse bainite contains many large MA constituents to assist the nucleation of microcracks and coarse cleavage facet lowers the ability to inhibit the crack propagation.

Prediction of deformations during gas-tungsten-arc stationary welds

International Nuclear Information System (INIS)

Duncan, D.B.; Giedt, W.H.

1980-10-01

Local temperature measurements on the heated and unheated surfaces, and strain measurements on the unheated surfaces of unrestrained circular weld specimens of annealed and cold-rolled Nitronic 40 stainless steel during stationary welding, are compared with values predicted from finite-element programs for temperature and strain variations. Experimental and predicted temperature histories agree within 10%. Predicted and measured hoop strain profiles (using a moire fringe technique), for the unheated surface are compared, showing significant deviations near the central region. Transient deflection measurements of the unheated specimen surfaces show good agreement with theory during the period the arc is operating. Close agreement in deflection behavior was observed during the cooling portion of the weld cycle for the annealed specimen, whereas substantial deviations occurred for the cold-rolled specimens

Electron Beam Welding of Thick Copper Material

Energy Technology Data Exchange (ETDEWEB)

Broemssen, Bernt von [IVF Industriforskning och utveckling AB, Stockholm (Sweden)

2002-08-01

The purpose of this study was to review the two variants of the Electron Beam Welding (EBW) processes developed (or used) by 1- SKB, Sweden with assistance from TWI, England and 2 - POSIVA, Finland with assistance from Outokumpu, Finland. The aim was also to explain the principle properties of the EBW method: how it works, the parameters controlling the welding result but also giving rise to benefits, and differences between the EBW variants. The main conclusions are that both SKB and POSIVA will within a few years succeed to qualify their respective EBW method for welding of copper canisters. The Reduced Pressure EBW that SKB use today seems to be very promising in order to avoid root defects. If POSIVA does not succeed to avoid root defects with the high vacuum method and the beam oscillation technique it should be possible for POSIVA to incorporate the Reduced Pressure technique albeit with significant changes to the EBW equipment. POSIVA has possibly an advantage over SKB with the beam oscillation technique used, which gives an extra degree of freedom to affect the weld quality. The beam oscillation could be of importance for closing of the keyhole. Before EBW of lids, the material certification showing the alloy content (specifying min and max impurity percentages) and the mechanical properties should be checked. The welded material needs also to be tested for mechanical properties. If possible the weld should have a toughness level equal to that of the unwelded parent material. Specifically some conclusions are reported regarding the SKB equipment. Suggestions for further development are also given in the conclusion chapter.

Electron Beam Welding of Thick Copper Material

International Nuclear Information System (INIS)

Broemssen, Bernt von

2002-08-01

The purpose of this study was to review the two variants of the Electron Beam Welding (EBW) processes developed (or used) by 1- SKB, Sweden with assistance from TWI, England and 2 - POSIVA, Finland with assistance from Outokumpu, Finland. The aim was also to explain the principle properties of the EBW method: how it works, the parameters controlling the welding result but also giving rise to benefits, and differences between the EBW variants. The main conclusions are that both SKB and POSIVA will within a few years succeed to qualify their respective EBW method for welding of copper canisters. The Reduced Pressure EBW that SKB use today seems to be very promising in order to avoid root defects. If POSIVA does not succeed to avoid root defects with the high vacuum method and the beam oscillation technique it should be possible for POSIVA to incorporate the Reduced Pressure technique albeit with significant changes to the EBW equipment. POSIVA has possibly an advantage over SKB with the beam oscillation technique used, which gives an extra degree of freedom to affect the weld quality. The beam oscillation could be of importance for closing of the keyhole. Before EBW of lids, the material certification showing the alloy content (specifying min and max impurity percentages) and the mechanical properties should be checked. The welded material needs also to be tested for mechanical properties. If possible the weld should have a toughness level equal to that of the unwelded parent material. Specifically some conclusions are reported regarding the SKB equipment. Suggestions for further development are also given in the conclusion chapter

Universal gas metal arc welding - a cost-effective and low dilution surfacing process

International Nuclear Information System (INIS)

Shahi, AS.; Pandey, Sunil

2006-01-01

This paper describes the use of a new variant of the gas metal arc welding (GMAW) process, termed u niversal gas metal arc welding (UGMAW), for the weld cladding of low carbon steels with stainless steel. The experimental work included single layer cladding of 12 mm thick low carbon steel with austenitic stainless steel 316L solid filler wire of 1.14 mm diameter. Low dilution conditions were employed using both mechanised GMAW and UGMAW processes. Metallurgical aspects of the as welded overlays were studied to evaluate the suitability of these processes for service conditions. It was found that UGMAW claddings contained higher ferrite content; higher concentrations of chromium, nickel and molybdenum; and lower carbon content compared to GMAW claddings. As a result, the UGMAW overlays exhibited superior mechanical and corrosion resistance properties. The findings of this study establish that the new process is technically superior and results in higher productivity, justifying its use for low cost surfacing applications

Research on Kinematic Trajectory Simulation System of KUKA Arc Welding Robot System

Science.gov (United States)

Hu, Min

2017-10-01

In this paper, the simulation trajectory simulation of KUKA arc welding robot system is realized by means of VC platform. It is used to realize the teaching of professional training of welding robot in middle school. It provides teaching resources for the combination of work and study and integration teaching, which enriches the content of course teaching.

Micro friction stir welding of copper electrical contacts

Directory of Open Access Journals (Sweden)

D. Klobčar

2014-10-01

Full Text Available The paper presents an analysis of micro friction stir welding (μFSW of electrolytic tough pitch copper (CuETP in a lap and butt joint. Experimental plan was done in order to investigate the influence of tool design and welding parameters on the formation of defect free joints. The experiments were done using universal milling machine where the tool rotation speed varied between 600 and 1 900 rpm, welding speed between 14 and 93 mm/min and tilt angle between 3° and 5°. From the welds samples for analysis of microstructure and samples for tensile tests were prepared. The grain size in the nugget zone was greatly reduced compared to the base metal and the joint tensile strength exceeded the strength of the base metal.

Influence of the composition and microstructure on the mechanical properties of single pass weld metal obtained with two-run multipower submerged arc welding of 35 MM Fe 510 quality steels

International Nuclear Information System (INIS)

Berkhout, C.F.; Sipkes, M.P.

1977-01-01

For three 35 mm Fe 510 quality steels (with and without niobium) experiments have been carried out to establish a relationship between composition, microstructure and mechanical properties of weldmetal obtained with two-run multipower submerged arc welding. The most striking aspects are summarized in the following. The weldmental composition can influence the toughness both, directly by matrix alloying or indirectly through the grainsize and constituents of the microstructure such as the perlite-cementite and martensite fraction. In the range of compositions investigated Mn for instance has a beneficial, while Nb and N have a detrimental effect on notch toughness. For nitrogen the concentration in the weldmetal is determined by the type of weldingflux used. The unfavourable effect of Nb in the weldmetal depends mainly on the Nb content of the plate material (dilution effect). Niobium introduced by the flux is not active and in all probability only present as non metallic inclusions. Remarkable is the strong interaction found between Nb and N. The influence of Nb decreases when the N content of the weldmetal increases. This effect may probably also be an explanation for the great differences in the interpretation of the influence of Nb on weldmetal ductility as mentioned in the literature. A change in the concentration of these elements does not have any influence on the grainsize of the weldmetal. The influence of Mo is quite remarkable. In the first place it has a grain-refining effect, which strongly predominates its detrimental effect in promoting the martensite formation. From quantitative measurements it also appears that Mo reduces the amount of perlite in the weldmetal and suppresses entirely the influence of Mn on the Charpy-V transition temperature and the uppershelf-energy level

Sustainability assessment of shielded metal arc welding (SMAW) process

Science.gov (United States)

Alkahla, Ibrahim; Pervaiz, Salman

2017-09-01

Shielded metal arc welding (SMAW) process is one of the most commonly employed material joining processes utilized in the various industrial sectors such as marine, ship-building, automotive, aerospace, construction and petrochemicals etc. The increasing pressure on manufacturing sector wants the welding process to be sustainable in nature. The SMAW process incorporates several types of inputs and output streams. The sustainability concerns associated with SMAW process are linked with the various input and output streams such as electrical energy requirement, input material consumptions, slag formation, fumes emission and hazardous working conditions associated with the human health and occupational safety. To enhance the environmental performance of the SMAW welding process, there is a need to characterize the sustainability for the SMAW process under the broad framework of sustainability. Most of the available literature focuses on the technical and economic aspects of the welding process, however the environmental and social aspects are rarely addressed. The study reviews SMAW process with respect to the triple bottom line (economic, environmental and social) sustainability approach. Finally, the study concluded recommendations towards achieving economical and sustainable SMAW welding process.

Advances of orbital gas tungsten arc welding for Brazilian space applications – experimental setup

Directory of Open Access Journals (Sweden)

José A. Orlowski de Garcia

2010-08-01

Full Text Available The present work describes details of the several steps of the technology involved for the orbital Gas Tungsten Arc Welding (GTAW process of pure commercially titanium tubes. These pieces will be used to connect the several components of the propulsion system of the China-Brazilian Satellite CBERS, and is part of the Brazilian aerospace industry development. The implantation involved the steps of environment control; cut and facing of the base metal; cleaning procedures; piece alignment; choice of the type, geometry and installation of the tungsten electrode; system for the pressure of the purge gas; manual tack welding; choice of the welding parameters; and, finally, the qualification of welding procedures. Three distinct welding programs were studied, using pulsed current with increasing speed, continuous current and pulsed current with decreasing amperage levels. The results showed that the high quality criteria required to the aerospace segment is such that usual welding operations must be carefully designed and executed. The three welding developed programs generated welds free of defects and with adequate morphology, allowing to select the condition that better fits the Brazilian aerospace segment, and to be implanted in the welding of the CBERS Satellite Propulsion System.

Computational Modeling of Microstructural-Evolution in AISI 1005 Steel During Gas Metal Arc Butt Welding

Science.gov (United States)

2013-05-01

H.K.D.H. Bhadeshia, A Model for the Microstruc- ture of Some Advanced Bainitic Steels , Mater. Trans., 1991, 32, p 689–696 19. G.J. Davies and J.G. Garland...REPORT Computational Modeling of Microstructural-Evolution in AISI 1005 Steel During Gas Metal Arc Butt Welding 14. ABSTRACT 16. SECURITY...Computational Modeling of Microstructural-Evolution in AISI 1005 Steel During Gas Metal Arc Butt Welding Report Title ABSTRACT A fully coupled (two-way

Effect of Post Weld Heat Treatment on Corrosion Behavior of AA2014 Aluminum – Copper Alloy Electron Beam Welds

Science.gov (United States)

Venkata Ramana, V. S. N.; Mohammed, Raffi; Madhusudhan Reddy, G.; Srinivasa Rao, K.

2018-03-01

The present work pertains to the study of corrosion behavior of aluminum alloy electron beam welds. The aluminium alloy used in the present study is copper containing AA2014 alloy. Electron Beam Welding (EBW) was used to weld the alloys in annealed (O) condition. Microstructural changes across the welds were recorded and the effect of post weld heat treatment (PWHT) in T4 (Solutionized and naturally aged) condition on pitting corrosion resistance was studied. A software based PAR basic electrochemical system was used for potentio-dynamic polarization tests. From the study it is observed that weld in O condition is prone to more liquation than that of PWHT condition. This may be attributed to re-melting and solidification of excess eutectic present in the O condition of the base metal. It was also observed that slightly higher hardness values are recorded in O condition than that of PWHT condition. The pitting corrosion resistance of the PMZ/HAZ in PWHT condition is better than that of O condition. This is attributed to copper segregation at the grain boundaries of PMZ in O condition.

Effects of microplasma arc AISI 316L welds on the corrosion behaviour of pipelines in LiBr cooling systems

International Nuclear Information System (INIS)

Sánchez-Tovar, R.; Montañés, M.T.; García-Antón, J.

2013-01-01

Highlights: •SECM tests reveal differences in electrochemical activity of base and welded alloys. •The highest electrochemical activity is obtained for the welded alloy. •Microplasma arc welding process hinders passivation in lithium bromide. •Microplasma arc welding increases corrosion rate and susceptibility to pitting. •The galvanic pair between base and welded alloys in LiBr is weak. -- Abstract: The effect of microplasma arc welding (MPAW) on the electrochemical and corrosion behaviour of AISI 316L stainless steel tubes has been studied. Scanning electrochemical measurements were performed in sodium chloride to evaluate the difference in the electrochemical activity of base (non-welded) and welded samples. Oxygen reduction rates increase in AISI 316L due to the heat treatment effect induced by welding, indicating a higher electrochemical activity in the welded samples. Additionally, the use of MPA weldments in lithium bromide (LiBr) absorption machines was also analysed at typical operating temperatures and Reynolds numbers. The welding process increases corrosion rates, hinders passivation and increases the susceptibility to pitting attack in LiBr. However, zero-resistance ammeter and localization index measurements show that the galvanic pair generated between the base and welded alloys is weak, both electrodes being in their passive state. Temperature greatly affects the corrosion process

Reliability of copper based alloys for electric resistance spot welding

International Nuclear Information System (INIS)

Jovanovicj, M.; Mihajlovicj, A.; Sherbedzhija, B.

1977-01-01

Durability of copper based alloys (B-5 and B-6) for electric resistance spot-welding was examined. The total amount of Be, Ni and Zr was up to 2 and 1 wt.% respectively. Good durability and satisfactory quality of welded spots were obtained in previous laboratory experiments carried out on the fixed spot-welding machine of an industrial type (only B-5 alloy was examined). Electrodes made of both B-5 and B-6 alloy were tested on spot-welding grips and fixed spot-welding machines in Tvornica automobila Sarajevo (TAS). The obtained results suggest that the durability of electrodes made of B-5 and B-6 alloys is more than twice better than of that used in TAS

Specification for corrosion-resisting chromium and chromium-nickel steel bare and composite metal cored and stranded arc welding electrodes and welding rods

International Nuclear Information System (INIS)

Anon.

1983-01-01

This specification prescribes requirements for corrosion or heat resisting chromium and chromium-nickel steel electrodes and welding rods. These electrodes and welding rods are normally used for arc welding and include those alloy steels designated as corrosion or heat-resisting chromium and chromium-nickel steels, in which chromium exceeds 4.0 percent and nickel does not exceed 50.0 percent

Effects of Mars Atmosphere on Arc Welds: Phase 2

Science.gov (United States)

Courtright, Z. S.

2018-01-01

Gas tungsten arc welding (GTAW) is a vital fusion welding process widely used throughout the aerospace industry. Its use may be critical for the repair or manufacture of systems, rockets, or facilities on the Martian surface. Aluminum alloy AA2219-T87 and titanium alloy Ti-6Al-4V butt welds have been investigated for weldability and weld properties in a simulated Martian gas environment. The resulting simulated Martian welds were compared to welds made in a terrestrial atmosphere, all of which used argon shielding gas. It was found that GTAW is a process that may be used in a Martian gas environment, not accounting for pressure and gravitational effects, as long as adequate argon shielding gas is used to protect the weld metal. Simulated Martian welds exhibited higher hardness in all cases and higher tensile strength in the case of AA2219-T87. This has been attributed to the absorption of carbon into the fusion zone, causing carbide precipitates to form. These precipitates may act to pin dislocations upon tensile testing of AA2219-T87. Dissolved carbon may have also led to carburization, which may have caused the increase in hardness within the fusion zone of the welds. Based on the results of this experiment and other similar experiments, GTAW appears to be a promising process for welding in a Martian gas environment. Additional funding and experimentation is necessary to determine the effects of the low pressure and low gravity environment found on Mars on GTAW.

Spectroscopic analysis technique for arc-welding process control

Science.gov (United States)

Mirapeix, Jesús; Cobo, Adolfo; Conde, Olga; Quintela, María Ángeles; López-Higuera, José-Miguel

2005-09-01

The spectroscopic analysis of the light emitted by thermal plasmas has found many applications, from chemical analysis to monitoring and control of industrial processes. Particularly, it has been demonstrated that the analysis of the thermal plasma generated during arc or laser welding can supply information about the process and, thus, about the quality of the weld. In some critical applications (e.g. the aerospace sector), an early, real-time detection of defects in the weld seam (oxidation, porosity, lack of penetration, ...) is highly desirable as it can reduce expensive non-destructive testing (NDT). Among others techniques, full spectroscopic analysis of the plasma emission is known to offer rich information about the process itself, but it is also very demanding in terms of real-time implementations. In this paper, we proposed a technique for the analysis of the plasma emission spectrum that is able to detect, in real-time, changes in the process parameters that could lead to the formation of defects in the weld seam. It is based on the estimation of the electronic temperature of the plasma through the analysis of the emission peaks from multiple atomic species. Unlike traditional techniques, which usually involve peak fitting to Voigt functions using the Levenberg-Marquardt recursive method, we employ the LPO (Linear Phase Operator) sub-pixel algorithm to accurately estimate the central wavelength of the peaks (allowing an automatic identification of each atomic species) and cubic-spline interpolation of the noisy data to obtain the intensity and width of the peaks. Experimental tests on TIG-welding using fiber-optic capture of light and a low-cost CCD-based spectrometer, show that some typical defects can be easily detected and identified with this technique, whose typical processing time for multiple peak analysis is less than 20msec. running in a conventional PC.

Determination of input/output characteristics of full-bridge AC/DC/DC converter for arc welding

OpenAIRE

Stefanov, Goce; Karadzinov, Ljupco; Sarac, Vasilija; Cingoski, Vlatko; Gelev, Saso

2016-01-01

This paper describes the design and practical implementation of AC/DC/DC converter in mode of arc welding. An analysis of the operation of AC/DC/DC converter and its input/output characteristics are determined with computer simulations. The practical part is consisted of AC/DC/DC converter prototype for arc welding with output power of 3 kW and switching frequency of 64 kHz. The operation of AC/DC/DC converter is validated with experimental measurements.

A comparative study of the SSC resistance of a novel welding process IEA with SAW and MIG

International Nuclear Information System (INIS)

Natividad, C.; Salazar, M.; Espinosa-Medina, M.A.; Perez, R.

2007-01-01

The Stress Sulphide Cracking resistance of X65 weldments produced by Indirect Electric Arc, Submerged Arc Welding (SAW) and Metal Inert Gas (MIG) processes were evaluated in a NACE solution saturated with H 2 S at 25 deg. C, 37 deg. C and 50 deg. C using Slow Strain Rate Tests (SSRT) and electrochemical measurements. Weldments produced by the Indirect Electric Arc presented the best Stress Sulphide Cracking resistance at 25 deg. C. This behavior is attributed to the microstructural modification of the weld bead from ferrite in a needlelike form to a fine grain microstructure, which was not observed at 37 deg. C and 50 deg. C. In addition, the hydrogen permeation flux increased with the temperature, this result is associated with the ferrite phase. The electrochemical results show a decrease of the trapping sites for the atomic hydrogen on this weldment. This behavior has not been observed for the other welding processes due to their microstructure (a typical columnar growth of coarse grain)

Effects of filler wire on residual stress in electron beam welded QCr0.8 copper alloy to 304 stainless steel joints

International Nuclear Information System (INIS)

Zhang, Bing-Gang; Zhao, Jian; Li, Xiao-Peng; Chen, Guo-Qing

2015-01-01

The electron beam welding (EBW) of 304 stainless steel to QCr0.8 copper alloy with or without copper filler wire was studied in detail. The temperature fields and magnitude and distribution of stress fields in the joints during the welding process were numerically simulated using finite element method. The temperature cycles and residual stresses were also experimentally measured by thermometric and hole-drilling methods, respectively. The accuracy of the modeling procedure was verified by the good agreement between the calculated results and experimental data. The temperature distribution in the joint was found to be asymmetric along the center of weld. In particular, the temperature in the copper alloy plate is much higher than that in the 304 SS plate owing to the great difference in thermal conductivity between the two materials. The peak three-dimensional residual stresses all appeared at the interface between the copper and steel in the two different joints. Furthermore, the weld was subjected to tensile stress. The longitudinal residual stress, generally the most harmful to the integrity of the structure among the stress components in EBW with filler wire (EBFW), was 53 MPa lower than that of autogenous EBW (AEBW), and the through-thickness residual stress was 12 MPa lower. The transverse residual stress of EBFW was 44 MPa higher than that of AEBW. However, analysis of the von Mises stress showed that the EBFW process effectively reduced the extent of the high residual stress region in the weld location and the magnitude of the residual stresses in the copper side compared with those of the AEBW joint. - Highlights: • Copper and steel was welded by electron beam welding with copper filler wire. • The copper wire fed into gap can reduce the peak value of residual stress. • The peak value of longitudinal stress can be reduced 53 MPa by the filler wire. • The range of nov Mises stress in the weld could be reduced by the wire

Use of narrow gap welding in nuclear power engineering and development of welding equipment at Vitkovice Iron Works (VZSKG), Ostrava

International Nuclear Information System (INIS)

Lehar, F.; Sevcik, P.

1988-01-01

Briefly discussed are problems related to automatic submerged arc welding into narrow gaps. The said method was tested for the first time at the Vitkovice Iron Works VZSKG for peripheral welds on pressurizers for WWER-440 reactors. The demands are summed up which are put on the welding workplace which must be met for the use of the said technology. The requirements mainly include the provision of the positioning of the welding nozzle towards the weld gap in order to maximally exclude the effect of the welder. An automatic device was designed and manufactured at the VZSKG plant for mounting the welding nozzle on the automatic welding machine manufactured by ESAB which operates on the principle of the flexible compression of the nozzle to the wall of the weld gap. In the bottom part the welding nozzle is provided with a pulley which rolls during welding thereby providing a constant distance to be maintained between the welding wire and the wall of the weld gap. The diameter of the pulley is ruled by the diameter of the welding wire. Provided the clamping part is appropriately adjusted the developed equipment may be used for any type of automatic welding machine with motor driven supports. (Z.M.). 8 figs., 5 tabs., 9 refs

Investigation and modelling of friction stir welded copper canisters

Energy Technology Data Exchange (ETDEWEB)

Kaellgren, Therese

2010-02-15

This work has been focused on characterisation of FSW joints, and modelling of the process, both analytically and numerically. The Swedish model for final deposit of nuclear fuel waste is based on copper canisters as a corrosion barrier with an inner pressure holding insert of cast iron. Friction Stir Welding (FSW) is the method to seal the copper canister, a technique invented by The Welding Institute (TWI). The first simulations were based on Rosenthal's analytical medium plate model. The model is simple to use, but has limitations. Finite element models (FEM) were developed, initially with a two-dimensional geometry. Due to the requirements of describing both the heat flow and the tool movement, three-dimensional models were developed. These models take into account heat transfer, material flow, and continuum mechanics. The geometries of the models are based on the simulation experiments carried out at TWI and at Swedish Nuclear Fuel Waste and Management Co (SKB). Temperature distribution, material flow and their effects on the thermal expansion were predicted for a full-scale canister and lid. The steady state solutions have been compared with temperature measurements, showing good agreement. In order to understand the material flow during welding a marker technique is used, which involves inserting dissimilar material into the weld zone before joining. Different materials are tested showing that brass rods are the most suitable material in these welds. After welding, the weld line is sliced, etched and examined by optical microscope. To understand the material flow further, and in the future predict the flow, a FEM is developed. This model and the etched samples are compared showing similar features. Furthermore, by using this model the area that is recrystallised can be predicted. The predicted area and the grain size and hardness profile agree well

INERT GAS SHIELD FOR WELDING

Science.gov (United States)

Jones, S.O.; Daly, F.V.

1958-10-14

S>An inert gas shield is presented for arc-welding materials such as zirconium that tend to oxidize rapidly in air. The device comprises a rectangular metal box into which the welding electrode is introduced through a rubber diaphragm to provide flexibility. The front of the box is provided with a wlndow having a small hole through which flller metal is introduced. The box is supplied with an inert gas to exclude the atmosphere, and with cooling water to promote the solidification of the weld while in tbe inert atmosphere. A separate water-cooled copper backing bar is provided underneath the joint to be welded to contain the melt-through at the root of the joint, shielding the root of the joint with its own supply of inert gas and cooling the deposited weld metal. This device facilitates the welding of large workpieces of zirconium frequently encountered in reactor construction.

Electron beam welding of aluminium components

International Nuclear Information System (INIS)

Maajid, Ali; Vadali, S.K.; Maury, D.K.

2015-01-01

Aluminium is one of the most widely used materials in industries like transportation, shipbuilding, manufacturing, aerospace, nuclear, etc. The challenges in joining of aluminium are distortion, cleanliness and quality. Main difficulties faced during fusion welding of aluminium components are removal of surface oxide layer, weld porosity, high heat input requirement, distortion, hot cracking, etc. Physical properties of aluminium such as its high thermal conductivity, high coefficient of thermal expansion, no change in colour at high temperature, large difference in the melting points of the metal and its oxide (∼ 1400 °C) compound the difficulties faced during welding. Gas Tungsten Arc Welding (GTAW), Gas Metal Arc Welding (GMAW), Plasma Arc Welding (PAW), etc are generally used in industries for fusion welding of aluminium alloys. However in case of thicker jobs the above processes are not suitable due to requirements of elaborate edge preparation, preheating of jobs, fixturing to prevent distortion, etc. Moreover, precise control over the heat input during welding and weld bead penetration is not possible with above processes. Further, if heat sensitive parts are located near the weld joint then high energy density beam welding process like Electron Beam Welding (EBW) is the best possible choice for aluminium welding.This paper discusses EB welding of aluminium components, typical geometry of components, selection/optimization of welding parameters, problems faced during standardization of welding and process parameters and their remedies etc.