Journal of Welding Science

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Fusion welding is widely used in heavy industries to join different parts together. But sometimes welding-induced distortions cause problems like misalignment during assembling and make costs to remove them. Thus it is imperative to predict and mitigate them to improve weldments quality and also reduce in fabrication costs. This study at first will introduce inherent deformation method for prediction of welding-induced distortion. In following a relatively large panel will be simulated by finite element software ANSYS and its distortion will be calculated. The results will be compared by experimental measurement. Afterward this investigation will present an efficient welding sequence which produce minimal distortion.

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In this paper, maximum value of energy to break at Charpy impact test as a criterion of fracture toughness of AISI 316/A387 Gr.91 weld joints with ERNiCrMo-3 filler metal were obtained by optimization of pulesd current gas tungsten arc welding process parameters. The selected parameters were peak current, background current, frequency and on time percentage that were changed in three levels. Therefore a L₉ orthogonal array of Taguchi design including nine experiments for four parameters with three levels (3⁴) was used. Analysis of signal to noise (S/N) ratio indicated that optimized values of peak current, background current, frequency and on time percentage were 120A, 90A, 10Hz and 80%, respectively. The welded specimen with optimized parameters showed an energy to break at Charpy impact test value of 65J at -20°c. The obtained results also demonstrated that the most influence on energy to break values belonged to background current, frequency, peak current and on time percentage, respectively. 

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In this research in order to improve the mechanical properties of Aluminium alloy 2024, nanostructure Aluminum sheets were first produced by Cryorolling process and then was welded by resistance spot welding method. For this purpose, the samples solution treated at 495˚C for 55 minute and subsequently cryorolled up to 85% reduction in thickness. For obtaining simultaneous strength and ductility, the cryorolled sheets were then subjected to aged. In this regard the produced samples were then resistance spot welded with different welding parameters, including welding current 60 to 105 KA, electrode force of 3 KN, and welding time of 0.1 s. The highest tensile shear peak load was obtained through welding with 95 KA current.

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Dissimilar welding of AISI 304L austenitic stainless steel to AISI 409 ferritic stainless steel with GMAW process usingtwo Ar-O2 and Ar-CO2 shielding gas mixtures was studied. ER316LSi and ER309LMo filler metals were chosen by considering 5 and 15% delta ferrite according to the Schaeffler equations and diagram. Based on the observations, both filler metals accompanied by Ar-2%O₂ shielding gas resulted in acceptable weldments. Yield strength and UTS of tensile samples were 288 and 424 MPa, respectively. All tensile samples fractured in the ferritic base metal. Microhardness test results demonstrated that the maximum hardness of 190-200 HV was obtained from ER316LSi weld metal. The minimum hardness of 145 HV was found in the HAZ of 409 side mainly due to the grain coarsening. Microstructural examinations revealed needle-like precipitates formed perpendicular to each other in the HAZ of 409 stainless steel. It seemed that the pre-existing TiC precipitates evolved into the needle shape precipitates as a result of rapid heating and cooling rates during the welding process.
 

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Friction stir spot welding (FSSW) is a type of solid state welding that is used in the connection of small pieces and light metals such as aluminum alloy especially. The technical problem during melting of aluminum alloys is one of the most important reasons for developing application of friction stir welding for aluminum alloys. In this research, the effects of important processing parameters such as tool rotation speed, dwell time, plunge depth of tool and sheets thickness on the mechanical properties such as failure force and energy of FSS welded AA-3105 alloy have been experimentally studied using micro hardness and tensile tests. Tensile-shear tests show four different fracture modes of weld failure which consist of shear fracture, circumferential fracture, nugget pull out fracture and fracture in base material modes. The results show that the weld strength drops with increasing the tool rotation speed. Strength and hardness of weld and weld zone increase and then decrease with increasing dwell time of rotational tool which it can be obtained an optimum value of dwell time. Strength and fracture energy and load of welds increases with increasing the sheet thickness

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Magnesium alloys are very attractive materials owing to their properties of low density, high specific strength and stiffness, good castability, and weldability. AZ31 magnesium alloys in terms of weldability has better situation than the other, so it has more applications than other magnesium alloys. In this study, TIG and pulsed TIG welding method was used to welding the AZ31 alloy and finally microstructure and mechanical properties of welds with metallography, scanning electron microscopy (SEM), tensile test were examined. The results showed that the heat input affected the size of grains that are leading to changes in mechanical properties. Sample was welded with TIG welding with minimum current has maximum strength among the samples both pulsed TIG welding and TIG method. It is observed that with increasing frequency in TIG welding, strength is reduced. Despite the same I_P and I_B, higher frequency has created a stronger welding. Also increases the frequency leads to more fine-grained samples, resulting in increased strength.

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Today in addition to Join by friction stir welding, the composite fabrication process is also performed simultaneously. The main purpose of the present research is to investigate the effect of pin geometry on the property of Aluminum 6061- alumina nanocomposite created by friction stir welding. For this purpose friction stir welding was carried out by selecting five types of pin geometries on Aluminum 6061 in which Al2O3 particles were deposited and the samples were examined by tensile and hardness tests, optical and electron microscope. Samples were investigated by tensile and hardness test, optical and electronic microscopy. Regular hexagonal pins due to having six smooth face and impulsive movement during rotation, caused a good perturbation which resulted in maximum tensile strength and elongation percentage of 198 MPa and 10.25 and minimum grain size of 13.3 micron, respectively. In the sample welded by a threaded cylindrical pin due to non-impact during rotation, inappropriate flow of reinforcing particles and its accumulation at perturbation the lowest tensile strength and elongation percentage of 133.5 MPa and 1.95%, respectively, were observed.

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In the present study, the corrosion behavior and microstructural changes of 5000 series aluminum and copper sheets after the explosive welding process have been investigated. Explosive welding is performed with a fixed stop interval and change of explosive load. Dynamic potential polarization tests and electrochemical impedance spectroscopy, light microscopy, and scanning electron microscopy were used. The results of TOEFL polarization curves show that the lowest corrosion velocity was related to the sample with an explosive load of 1.5 and the highest corrosion velocity was related to the sample with an explosive load of 2.5. The corrosion resistance of a sample with an explosive load of 2.5 is less than that of a sample with an explosive load of 1.5 due to more severe plastic deformation at the joint. The metallographic results show a wave-vortexing of the joint due to the increase in the explosive charge. The results of the impedance test in welded samples showed that the value of n (experimental power parameter) decreased with wave-vortexing of the joint and the sample with 2.5 explosive load had the highest corrosion rate. Based on the results of scanning electron microscopy, it was observed that with an increasing explosive charge, the thickness of the local melting layer gradually increases.

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In this study, laser direct deposition was employed to fabricate a functionally graded transition between 17‑4PH stainless steel and Stellite 6. Specimens were designed and produced such that the chemical composition varied incrementally from 100 % 17‑4PH to 100 % Stellite 6, with each step involving a 25 % decrease in the 17‑4PH content and a corresponding 25 % increase in Stellite 6. Microstructural evolution and elemental distribution were characterized by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), while mechanical properties were assessed via Vickers microhardness testing and uniaxial tensile tests. The microstructural analysis revealed a needle‑like martensitic matrix in the substrate, which transformed into cellular dendrites upon reaching the 25 % Stellite 6 layer. As the Stellite 6 fraction increased, along with corresponding rises in Cr and W content, grain boundaries broadened and carbides accumulated within interdendritic regions. At the 50 % composition, oriented columnar dendrites became prominent, and at higher Stellite 6 levels the dendritic structure refined further, ultimately evolving into an equiaxed morphology. Microhardness measurements showed a continuous increase from approximately 300 HV in the 17‑4PH substrate to 490 HV in the pure Stellite 6 layer. Tensile testing demonstrated that both yield strength (σᵧ) and ultimate tensile strength (σᵤ) remained within 1102–1159 MPa across all compositions, with no evidence of brittle phases or manufacturing defects. Elongation increased from 7 % in pure Stellite 6 to 19 % in pure 17‑4PH, with the 50 %–50 % gradient exhibiting an optimal balance of strength and ductility (14.5 % elongation).
 

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Nickel-based superalloys are among the most critical materials used in high-temperature components of gas turbines, where their replacement costs and potential turbine damage necessitate effective protection and repair strategies. Optimizing repair methods to enhance efficiency and reduce costs has therefore been a continuous focus. The aim of this study is to improve the repair process of Inconel 738LC superalloy by reducing the susceptibility to liquation cracking. Activated tungsten inert gas (A-TIG) welding was performed on Inconel 738LC using a welding current of 60 A. Titanium dioxide (TiO₂) powder was employed as an activating flux, and weldments with four flux concentrations were examined. The microstructure w:::::as char:::::acterized using optical microscopy and scanning electron microscopy. The results revealed that flux concentration had a significant influence on penetration depth, with a concentration of 1 g/mL producing the maximum effect. At this concentration, weld penetration increased by 68% and weld pool volume by 63%, while the heat-affected zone width decreased by 12%. Arc imaging and quantitative/qualitative analysis demonstrated a constricted and focused plasma arc column in the presence of TiO₂ flux. Microstructural examinations further revealed suppression of columnar dendrite growth. It was found that TiO₂ flux enhances weld penetration and pool volume by constricting the arc and activating a reversed Marangoni flow, while simultaneously reducing HAZ width. However, the increased weld pool volume also intensified contraction stresses, leading to liquation cracking in the weld with the largest pool volume.

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In this study, the effect of gas tungsten arc welding (GTAW) in both constant and pulsed current modes with frequencies of 5 and 20 Hz was investigated on the weldability, microstructure, and mechanical properties of Inconel 738LC superalloy. The main objective was to evaluate the susceptibility to liquation cracking in the heat-affected zone (HAZ) and to identify the mechanisms responsible for improving weldability. The results revealed that applying pulsed current, particularly at a higher frequency of 20 Hz, significantly reduced the extent of liquation cracking and improved the overall joint quality. The average crack length decreased by more than 50% compared to the constant current condition. Increasing the pulse frequency transformed the solidification morphology from columnar dendritic to equiaxed, reduced interdendritic segregation, and led to a more uniform and finer distribution of MC carbides. The ultimate tensile strength increased from 751 MPa (constant current) to 802 MPa (20 Hz pulsed current), representing an improvement of approximately 6.7%, while the total elongation improved from 7.96% to 9.83% (about 23% increase). The weld metal hardness also increased from 446 to 468 HV. Overall, pulsed GTAW at a moderate frequency (20 Hz) effectively reduced solidification stresses and thermal gradients, providing an efficient approach to mitigate liquation cracking and enhance the mechanical performance of Inconel 738LC welds.