This study explores the joining of AA6061-T6 aluminium alloy and AZ31B magnesium alloy using the Cold Metal Transfer (CMT) process with ER4043 aluminium filler wire. The influence of wire feed speed (WFS), welding speed (WS), and arc length correction (ALC) on weld bead geometry, microstructure, and mechanical properties of Al/Mg joints was investigated. The results indicate that WFS, WS, and ALC significantly affect weld characteristics. Increasing WFS leads to higher heat input, improving reinforcement height, penetration, and bead width. At 4700 mm/min WFS, optimal reinforcement height was achieved, while 5000 mm/min further enhanced penetration and bead width. Higher WS reduced heat input, resulting in narrower bead width, shallower penetration, and lower reinforcement height. ALC influenced arc behaviour, with 10% ALC minimising the weld metal area and 15% significantly increasing it. Microstructural analysis identified MgO, Mg solid solution, Mg2Al3, and Mg17Al12 at different joint regions. The optimized parameters (4700 mm/min WFS, 280 mm/min WS, 10% ALC) yielded the highest tensile strength of 34 MPa and hardness of 120 HV. Fracture occurred mainly at the Mg/weld interface and near the fusion line. This study underscores the importance of welding parameters in enhancing the mechanical properties of Al/Mg joints and provides insights for optimising aluminium-magnesium welding. Cette & eacute;tude explore l'assemblage de l'alliage d'aluminium (Al) AA6061-T6 et de l'alliage de magn & eacute;sium (Mg) AZ31B & agrave; l'aide du proc & eacute;d & eacute; de transfert de m & eacute;tal & agrave; froid (CMT) avec un fil d'apport en aluminium ER4043. La recherche examine l'influence des param & egrave;tres cl & eacute;s du proc & eacute;d & eacute; - vitesse d'alimentation du fil (WFS), vitesse de soudage (WS) et correction de la longueur de l'arc (ALC) - sur la g & eacute;om & eacute;trie du cordon de soudure, la microstructure et les propri & eacute;t & eacute;s m & eacute;caniques des joints Al/Mg dissemblables. Les r & eacute;sultats indiquent que l'interaction de WFS, WS et ALC influence significativement les caract & eacute;ristiques de la soudure. Une augmentation de WFS conduit & agrave; un apport de chaleur plus & eacute;lev & eacute;, r & eacute;sultant en une plus grande hauteur de renforcement, une profondeur de p & eacute;n & eacute;tration am & eacute;lior & eacute;e et un cordon plus large. & Agrave; une WFS de 4700 mm/min, on a observ & eacute; une hauteur du renforcement optimale, avec de nouvelles augmentations de WFS de 5000 mm/min am & eacute;liorant la p & eacute;n & eacute;tration et la largeur du cordon. Inversement, une WS plus & eacute;lev & eacute;e r & eacute;duit l'apport de chaleur, conduisant & agrave; un cordon plus & eacute;troit, une p & eacute;n & eacute;tration moins profonde et une hauteur de renforcement plus faible. Le param & egrave;tre ALC influence davantage le comportement de l'arc, avec un ALC de 10% minimisant la zone de m & eacute;tal fondu (WM) et un ALC plus & eacute;lev & eacute; (par exemple, 15%) l'augmente significativement. L'analyse microstructurale a r & eacute;v & eacute;l & eacute; la pr & eacute;sence de diff & eacute;rentes phases & agrave; des positions vari & eacute;es dans le joint. Au niveau du substrat de Mg, on a observ & eacute; du MgO et une solution solide de Mg. Pr & egrave;s de l'interface du m & eacute;tal fondu, on a & eacute;galement trouv & eacute; du MgO et une solution solide de Mg. L'interface a montr & eacute; la formation de phases de Mg2Al3 et de Mg17Al12, tandis que pr & egrave;s de l'interface du m & eacute;tal fondu, on a d & eacute;tect & eacute; du Mg2Si, du MgO et une solution solide d'Al. Dans le m & eacute;tal fondu, les phases pr & eacute;dominantes consistaient de Mg2Al3 et de solution solide d'Al. Les joints fabriqu & eacute;s a l'aide des param & egrave;tres optimis & eacute;s - 4700 mm/min WFS, 280 mm/min WS et 10% ALC - exhibaient la r & eacute;sistance & agrave; la traction de 34 MPa et la duret & eacute; de 120 HV les plus & eacute;lev & eacute;es. L'analyse des fractures a montr & eacute; que la rupture se produisait principalement & agrave; l'interface Mg/soudure et pr & egrave;s de la ligne de fusion du c & ocirc;t & eacute; du Mg. Cette & eacute;tude souligne le r & ocirc;le critique des param & egrave;tres de soudage dans l'am & eacute;lioration des propri & eacute;t & eacute;s m & eacute;caniques des joints dissemblables d'Al/Mg et offre un aper & ccedil;u des d & eacute;veloppements futurs du soudage des alliages aluminium-magn & eacute;sium.

The main objective of this study was to investigate the combined effect of microstructure and residual stresses on notch fatigue behaviour of friction stir-welded (FSW) AA 6061-T651 aluminium alloy joints. Two different microstructures of FSW joints were produced at different welding speeds. A completely reverse-rotating fatigue testing machine was utilized to investigate the fatigue properties of notched specimens. The test results showed that the notch fatigue strength of a welded joint made at a speed of 25 mm/min was 33 % of the welded joint's yield strength and 23 % of its tensile strength. To understand the overall fatigue behaviour of the welded joints, fatigue data were further analyzed using the Basquin equation variables. Microstructure investigation using optical and orientation imaging microscopy, transmission electron microscopy, and X-ray diffraction analysis of the joints was analyzed and discussed. The microstructure complexity and the weld zone tensile residual stress significantly affect the welded joints fatigue behaviour. It was found that the notch fatigue properties of the joints were extremely sensitive to their microstructural characteristics and residual stresses. An increase in tensile residual stresses decreases the notch fatigue life of the welded joints. The results of electron backscattered diffraction analysis indicated that joints with a fine grain microstructure exhibit higher microstructural stability and less initial damage. A fractography investigation showed that joints with fine grain microstructure have increased crack resistance in stage I and lower crack propagation in stage II.

This study examines the microstructural, mechanical, and fractographic characteristics of friction-welded (FW) joints between SA 213 T12 and SA 213 F12 low alloy steels at rotational speeds of 55, 60, and 65 rps. Microstructural analysis using optical and SEM imaging revealed distinct weld zones, including the interface (IF), partially deformed zone (PDZ), and heat-affected zone (HAZ). The IF exhibited refined bainite and acicular ferrite, with increased dynamic recrystallization at 60 rps, leading to enhanced mechanical properties. Elemental mapping through EDS confirmed uniform chromium and molybdenum diffusion across the IF, with greater mechanical mixing at higher speeds. Microhardness profiling showed peak values at the IF, particularly on the SA 213 F12 side, decreasing towards SA 213 T12. The hardness distribution narrowed at higher speeds due to increased flash generation. Tensile testing revealed that all joints exceeded the base metals in ultimate tensile strength (UTS), with the highest UTS at 60 rps. Fractographic analysis confirmed a predominantly ductile failure, with finer dimples at 60 rps, correlating with improved elongation and strength. These findings demonstrate that an optimal rotational speed of 60 rps yields superior mechanical performance and microstructural refinement, providing valuable insights for optimizing FW parameters in high-performance applications. Cette & eacute;tude examine les caract & eacute;ristiques microstructurales, m & eacute;caniques et fractographiques de joints soud & eacute;s par friction (FW) en aciers faiblement alli & eacute;s (LAS) SA 213 T12 et SA 213 F12 & agrave; des vitesses de rotation vari & eacute;es (55, 60 et 65 tour/s). L'analyse de la microstructure & agrave; l'aide de micrographies optiques et MEB a r & eacute;v & eacute;l & eacute; des zones distinctes & agrave; travers la soudure, incluant l'interface (IF), une zone partiellement d & eacute;form & eacute;e (PDZ) et une zone thermiquement affect & eacute;e (HAZ). L'IF pr & eacute;sentait des microstructures raffin & eacute;es domin & eacute;es par la bainite et la ferrite aciculaire, avec une recristallisation dynamique accrue & agrave; 60 tour/s, ayant pour r & eacute;sultats des propri & eacute;t & eacute;s m & eacute;caniques sup & eacute;rieures. La cartographie & eacute;l & eacute;mentaire au moyen de balayages de lignes d'EDS a confirm & eacute; une diffusion uniforme du chrome et du molybd & egrave;ne & agrave; travers l'IF, avec un m & eacute;lange m & eacute;canique am & eacute;lior & eacute;, observ & eacute; & agrave; des vitesses de rotation plus & eacute;lev & eacute;es. Le profil de la microduret & eacute; a montr & eacute; que l'IF pr & eacute;sentait syst & eacute;matiquement une duret & eacute; plus & eacute;lev & eacute;e que les PDZ, HAZ et m & eacute;taux de base environnants, attribu & eacute;e & agrave; l'& eacute;crouissage et au raffinement de la microstructure. On a observ & eacute; les valeurs de pointe de duret & eacute; du c & ocirc;t & eacute; du SA 213 F12, avec une diminution progressive vers le c & ocirc;t & eacute; du SA 213 T12. La r & eacute;partition de la duret & eacute; & eacute;tait fortement influenc & eacute;e par la vitesse de rotation, les zones aux duret & eacute;s les plus & eacute;lev & eacute;es se r & eacute;tr & eacute;cissant aux vitesses plus & eacute;lev & eacute;es en raison de la g & eacute;n & eacute;ration accrue de bavures et de l'extrusion du mat & eacute;riau. Les essais de traction ont indiqu & eacute; que tous les joints surpassaient les m & eacute;taux de base en termes de r & eacute;sistance ultime & agrave; la traction (UTS), la valeur d'UTS la plus & eacute;lev & eacute;e atteinte & agrave; 60 tour/s. La rupture s'est produite syst & eacute;matiquement dans le m & eacute;tal de base, mettant en & eacute;vidence la r & eacute;sistance sup & eacute;rieure des joints soud & eacute;s. L'analyse fractographique a confirm & eacute; un mode de rupture principalement ductile, avec une morphologie plus fine & agrave; alv & eacute;oles & agrave; 60 tour/s en corr & eacute;lation avec un allongement et une r & eacute;sistance am & eacute;lior & eacute;s. L'& eacute;tude d & eacute;montre qu'une vitesse de rotation optimale de 60 tour/s produit des joints pr & eacute;sentant des propri & eacute;t & eacute;s m & eacute;caniques et des caract & eacute;ristiques de microstructure sup & eacute;rieures en raison des effets thermiques et m & eacute;caniques & eacute;quilibr & eacute;s. Ces r & eacute;sultats offrent un aper & ccedil;u valable sur l'optimisation des param & egrave;tres de la FW pour l'assemblage fiable des aciers faiblement alli & eacute;s dans les applications & agrave; hautes performances.

This study investigates the influence of gas tungsten arc welding (GTAW) current modes on dissimilar joints between Inconel 718 and AISI 410 martensitic stainless steel, targeting aerospace applications. Welding these alloys is challenging due to their differing thermal and chemical properties, which lead to brittle Laves phase formation, elemental segregation, and residual stresses. To address this, constant current (CCGTAW) and pulsed current (PCGTAW) techniques were compared. Microstructural characterisation was performed using optical and scanning electron microscopy to examine fusion zones, interfaces, and heat-affected zones. Both weldments showed niobium-rich Laves phases; however, PCGTAW resulted in a lower volume fraction (7.06%) than CCGTAW (10.50%), indicating improved suppression. Tensile failures occurred in the AISI 410 base metal for both welds. Microhardness profiles revealed uniform fusion zone hardness, softening in the IN 718 HAZ, and martensitic hardening in the AISI 410 HAZ. Hot corrosion tests at 650 degrees C in a K2SO4-NaCl environment showed superior resistance in PCGTAW welds, with lower weight gain, reduced oxide spallation, and a smaller parabolic rate constant (Kp). These enhancements are attributed to grain refinement, reduced segregation, and a narrower partially melted zone. Overall, PCGTAW significantly improves joint integrity and corrosion resistance, making it ideal for aerospace-grade dissimilar welding applications. Cette & eacute;tude examine l'influence des modes de courant du soudage & agrave; l'arc sous gaz inerte avec & eacute;lectrode de tungst & egrave;ne (GTAW) sur les performances de soudures dissemblables entre l'inconel 718, un superalliage & agrave; base de nickel, et l'acier inoxydable martensitique AISI 410, & eacute;valuant leur aptitude pour applications a & eacute;rospatiales. Souder ces alliages constitue un d & eacute;fi technique en raison de leurs propri & eacute;t & eacute;s thermiques et chimiques diff & eacute;rentes, ce qui favorise la formation de phases de laves fragiles, la s & eacute;gr & eacute;gation & eacute;l & eacute;mentaire et les contraintes r & eacute;siduelles qui compromettent l'int & eacute;grit & eacute; du joint. Pour relever ces d & eacute;fis, ce travail compare les techniques GTAW & agrave; courant constant (CCGTAW) et & agrave; courant puls & eacute; (PCGTAW), visant & agrave; att & eacute;nuer la formation de phases nuisibles, & agrave; am & eacute;liorer la qualit & eacute; des soudures et & agrave; augmenter la r & eacute;sistance & agrave; la corrosion & agrave; haute temp & eacute;rature. On a r & eacute;alis & eacute; une analyse microstructurale par microscopie optique et & eacute;lectronique & agrave; balayage pour examiner les zones de fusion, les interfaces de soudure et les zones affect & eacute;es thermiquement (HAZ). On a r & eacute;alis & eacute; des essais de traction pour & eacute;valuer les performances m & eacute;caniques, tandis qu'on a r & eacute;alis & eacute; des essais de corrosion & agrave; chaud dans un environnement de sel fondu & agrave; 650 degrees C en utilisant un m & eacute;lange de K2SO4-NaCl. Les deux m & eacute;thodes de soudage ont donn & eacute; lieu & agrave; des zones de fusion avec des phases de laves riches en niobium et & agrave; une s & eacute;gr & eacute;gation & eacute;l & eacute;mentaire. Cependant, les soudures par PCGTAW ont pr & eacute;sent & eacute; une fraction volumique des phase de laves plus faible (7.06%) que les soudures par CCGTAW (10.50%), indiquant une meilleure suppression de la formation d'interm & eacute;talliques fragiles et une am & eacute;lioration de l'int & eacute;grit & eacute; de la soudure. Les ruptures en traction se sont produites dans le m & eacute;tal de base AISI 410 pour les deux assemblages soud & eacute;s. Les profils de microduret & eacute; des assemblages soud & eacute;s ont r & eacute;v & eacute;l & eacute; une duret & eacute; constante dans les zones de fusion et un ramollissement dans la zone affect & eacute;e thermiquement de l'In 718, tandis que l'on a observ & eacute; une augmentation significative de la duret & eacute; dans la HAZ de l'AISI 410 en raison de la formation de martensite induite par un refroidissement rapide. Notamment, les soudures de PCGTAW ont d & eacute;montr & eacute; une r & eacute;sistance sup & eacute;rieure & agrave; la corrosion & agrave; chaud, telle que mise en & eacute;vidence par un plus faible gain de poids, une spallation des oxydes r & eacute;duite et une constante de taux parabolique (Kp) plus faible. Ces am & eacute;liorations sont dues & agrave; un affinement du grain en raison de vitesses de refroidissement plus rapides, d'une s & eacute;gr & eacute;gation & eacute;l & eacute;mentaire r & eacute;duite et d'une zone partiellement fondue plus & eacute;troite, ce qui, collectivement, a supprim & eacute; la formation d'& eacute;cailles d Les r & eacute;sultats soulignent l'efficacit & eacute; du GTAW & agrave; courant puls & eacute; pour am & eacute;liorer l'int & eacute;grit & eacute; structurelle et la r & eacute;sistance & agrave; la corrosion des joints dissemblables d'Inconel 718-AISI 410, offrant des informations pr & eacute;cieuses pour le d & eacute;veloppement de composants a & eacute;rospatiaux durables expos & eacute;s & agrave; des environnements agressifs.

This study analyzes the failure modes and fracture mechanisms of resistance spot welding (RSW) in dissimilar thickness DP800 and AISI1040 steels for automotive chassis applications. Shear fracture characteristics were examined by varying welding current parameters. The observed lap-shear failure modes in dissimilar joints included Pull-out fracture (PF), Interfacial (IF) failure, and Partial interfacial (P-IF) failure. Additionally, a correlation between welding current and fracture modes in dissimilar joints was established. The maximum shear fracture strengths observed were 23 kN for lap-tensile shear fracture load (L-TSFL) and 19 kN for cross-tensile shear fracture load (C-TSFL), both associated with pull-out fractures. Maximum hardness was recorded at the weld interface, reaching approximately 570 HV at a welding current of 6 kA. The changes in failure mode primarily resulted from severe stress concentration at the weld interface, with fluctuating microhardness also contributing to different failure modes in dissimilar joints.

In this research paper, the ±45 biaxially oriented woven flax and its hybrid flax/carbon composite laminates are manufactured by the vacuum bag technique using vinyl ester as the resin binder and the samples are characterized to evaluate their tensile, flexural and impact properties. Combining natural fibers with conventional materials typically creates a hybrid composite that shows optimal mechanical properties with partial sustainability. The flax/carbon variant exhibited superior tensile strength values of 383.88 MPa and 32.60 GPa, which are about 3.5 and 2.7 times higher than the flax composites, their flexural strengths are around 415.57 MPa and 25.02 GPa, respectively, and they have an impact resistance of 12.67 J.

This study investigates the effect of forging pressure on the microstructural evolution, mechanical properties, and fracture behaviour of rotary friction welded (RFW) low-alloy steel (LAS) joints. Three forging pressures—0.76, 0.84, and 0.91 MPa/s—were applied to evaluate their influence on hardness, tensile strength, and ductility. Microstructural analysis revealed that at 0.84 MPa/s, significant grain refinement occurred in the heat-affected zone, promoting superior mechanical properties. The ultimate tensile strength increased from 473 MPa at 0.76 MPa/s to 488 MPa at 0.84 MPa/s, before slightly decreasing to 482 MPa at 0.91 MPa/s due to grain coarsening. A maximum elongation of 40.01% was achieved at 0.84 MPa/s, representing a 27.05% improvement compared to 0.76 MPa/s. Hardness variations followed a similar trend, with peak values observed at intermediate forging pressure. Fractographic analysis confirmed a ductile fracture mode at 0.84 MPa/s, characterised by deep equiaxed dimples, while coarser fracture features were noted at higher pressures. These results demonstrate that an optimal forging pressure enhances strength–ductility synergy by refining the microstructure and preventing excessive grain growth. The findings provide valuable insights into optimising forging conditions for high-performance RFW LAS joints in structural and industrial applications.

This study explores the influence of plasma gas flow rate (PGFR) on the defects, microstructure evolution and mechanical properties during plasma arc welding of Ti6Al4V titanium alloy thin sheets using microscopic analysis, spectroscopic analysis, tensile and microhardness tests. The variation in PGFR affects the welding arc in terms of its stability, pressure and constriction which results in transformation of arc from conduction mode to keyhole mode and changes in microstructure as well. All the other welding process parameters were kept constant except for PGFR which was varied to investigate its significance. Excess weld metal was observed under the weld bead is an attribute of keyhole formation. Macrographs exhibits increments in weld geometry measurements whereas weld defects such as lack of penetration and porosity decreased with increased PGFR. The microstructural examination showed a variety of phase formations that includes majorly with acicular alpha and Widmanst & auml;tten alpha morphologies. Tensile strength and hardness at the weld region of the welded joints increases with increase in PGFR. An oxygen rich brittle subsurface layer called alpha-case morphology was observed at the weld region of 1 L/min joint causes significant reduction in ductility.

This study focuses on the multi-response optimization of rotary friction welding for joining identical austenitic stainless steel tubes. The study utilized Response Surface Methodology to optimize the welding process parameters, including rotational speed, friction pressure per time, and forging pressure per time. The objective was to enhance the Tensile Strength (MPa), Notch Tensile Strength (MPa), and Impact Toughness (J) of stainless steel tube joints. The experiment was conducted using a central composite design, which involved three components and five levels. The study's findings indicated that the rotating speed was the most influential process parameter, with friction pressure/time and forging pressure/time following closely behind. The optimal process parameters for enhancing the tensile characteristics of the rotary friction welded joint are determined to be a rotating speed of 27.6 rps, a friction pressure per time of 7.13 MPa/s, and a forging pressure per time of 7.83 MPa/s The Tensile Strength, Notch Tensile Strength, and Impact Toughness achieved under optimal conditions are 619.2 MPa, 734.1 MPa, and 41.29 MPa, respectively.

The joining of aluminum alloys using fusion welding often leads to issues such as hot tears, porosity, distortion, and solidifying cracks. To address these challenges, solid-state welding processes like Friction Stir Welding (FSW) are preferable. This study investigates the FSW of dissimilar aluminum alloys AA 5083 and AA 6061-T6, employing Acoustic Emission (AE) techniques for real-time monitoring. FSW was conducted under conditions with no defects, pinhole defects, and piping defects. The resulting joints were evaluated for their mechanical properties and metallurgical characteristics. Microstructural analysis was performed using an optical microscope, revealing that the defect-free condition achieved the highest tensile strength of 256 MPa and superior hardness of 93 HV at the stir zone. Tensile failure commonly manifested within the heat-affected zone (HAZ) of AA 6061-T6, primarily due to grain enlargement and the impact of Mg2Si precipitates. Examination of the fractured regions via scanning electron microscopy revealed ductile-mode fractures featuring elongated dimples and microvoids. AE parameters such as hits, amplitude RMS, and energy were analyzed, demonstrating that defect-free welds had consistent AE signal patterns, while significant variations were observed in pinhole and piping defect conditions due to larger defect areas. The findings suggest that AE monitoring is effective in detecting and analyzing welding defects, providing valuable insights into the FSW process for dissimilar aluminum alloys.

In the present investigation, the effect and role of plasma gas flow rate on the formation of microstructure during plasma arc welding of Ti6Al4V titanium alloy were studied using microscopic observation, energy dispersive spectroscopic analysis, tensile tests and microhardness measurements. Plasma gas flow rate influences the arc pressure, arc constriction, and stability. The transformation of plasma arc from conduction mode to keyhole mode causes severe changes to the microstructural characteristics of the titanium welds. This transformation takes place with slight variations of PGFR. Weld geometries increase with an increase in the PGFR. The microstructural examination shows that there are various phases formed during the variation in PGFR. Fusion zone had acicular α and widmanstätten α. Mechanical properties (i.e) strength and hardness of the joints increase with an increase in plasma gas flow rate. In the joint welded with 1 L/min, there is the formation of α-case which is an oxygen rich brittle subsurface structure and found detrimental to the ductility of the joints.

The purpose of this research is to examine the influence of temperature of preheating on mechanical performance and microstructure of FSW joints of DMR249A steel. The FSW joints were produced with no preheating and preheating at 100, 150, 200 and 250 °C respectively. Tensile properties and toughness of FSW joints were reduced when the temperature of preheating was raised from 100 to 250 °C. This is primarily related to an increased input of heat that results in inclusions of tungsten due to the wear of W99 tool and grain coarsening in stir zone (SZ) of FSW joints. The FSW joints produced with no preheating and preheating at 100 °C displayed greater tensile properties and toughness compared to the FSW joints produced with preheating at 150, 200 and 250 °C. This refers to the greater refinement of SZ microstructure of FSW joints which is made up of greater bainite regions and acicular ferrite.

Wire arc additive manufacturing (WAAM) is an advanced additive manufacturing (AM) technology that offers low cost and high deposition rates, making it suitable for building large metal parts for structural engineering applications. However, various welding procedures result in differing heat inputs and repetitive heating treatments throughout the deposition process, which can affect the microstructural and mechanical characteristics of the parts. In the current study, cylindrical parts made of 304L austenitic stainless steel (ASS) were manufactured using the WAAM technique, employing both gas metal arc welding (GMAW) and cold metal transfer (CMT) processes. This study explores the correlation between WAAM techniques and their effects on the bead geometry, microstructure and mechanical properties. The microstructure of the cylinders consisted of vertically growing austenite dendrites with residual ferrite (μ) within the austenite (γ) matrix. Compared to the bottom region (region ①), the top region (region ②) contained more residual ferrite. Although the microstructural characteristics from region ① to region ② are similar, they exhibit different ferrite morphologies. The rapid cooling rate in the CMT-AM process resulted in finer structures and a greater presence of ferrite phases in both regions compared to the GMAW-AM method. Cylinders produced by the CMT process displayed nearly uniform properties across both regions and demonstrated superior tensile properties, hardness, and impact toughness relative to those made using the GMAW technique. The WAAM 304L ASS cylinders also showed enhanced performance compared to stainless steel manufactured using traditional industrial forging standards, indicating that WAAM-processed 304L ASS cylinders are suitable for industrial applications.

In this investigation, Ultra-high Hard Armor (UHA) steel plate by Shielded Metal Arc Welding (SMAW) process using the Austenitic Stainless Steel (ASS) electrode. In the first part of this investigation, using the finite element method (FEM), thermal analysis parameters were optimized using bead on plate welds in software code, known as SYSWELD. In the second part, using optimized parameters, a coupled thermo-mechanical analysis on multipass welded fabrication was carried out. Weld thermal cycles were analyzed by simulation and compared with experimentally measured temperature profiles. A double ellipsoidal heat source model was used to simulate the SMAW process. The heating rate and cooling rate were calculated along with residual stresses. This range of heating and cooling rate resulted in untempered martensite in the heat-affected zone (HAZ), confirmed by microstructure analysis and hardness mapping. Good validation was found between the measured and simulated 2D model with a 4-10% variation. This study suggests that numerical simulation is the capable technique in understanding the thermal and mechanical properties that influence the welding of ultra-high hard armor steels joints.

The present investigation deals with the detailed analysis of opto-structural, morphological, electrical properties and photoelectrochemical cell performances of thermally evaporated AgxBi2−xS3−y thin film prepared for various x and y values (x = y = 0, 0.25, 0.50, 0.75 and 1). The cubic-structured AgBiS2 along with orthorhombic-structured Bi2S3 as confirmed from X-ray diffraction (XRD) analysis. The AgxBi2−xS3−y (x = y = 0–1) films showed higher optical absorption coefficient (105 cm−1) in the visible region and band gap values were found to be decreased from 2.08 to 1.35 eV. Scanning electron microscope (SEM) images have visualized the uniform distribution of spherical particles. Carrier concentration of the films are better than x = y = 0 as observed from Mott–Schottky plots. The FTO/AgxBi2−xS3−y (x = y = 1) photoelectrochemical cell yields the photoconversion efficiency (PCE) of 7.03

The large structural components (304 L austenitic stainless steel) used in nuclear power plants are difficult and expensive to manufacture and machine using standard methods. Wire arc additive manufacturing (WAAM) is a low cost and high deposition method for fabricating large structural parts. Therefore, in this investigation, 304 L austenitic stainless steel (304 L ASS) cylindrical component was fabricated using WAAM technique. The mechanical and microstructural characteristics of the bottom (region ) and top (region ) of the WAAM 304 L ASS component are studied. The microstructure of region consists of austenite and ferrite with vermicular and lathy morphologies, while region consists of skeletal and reticular morphologies. In regions and , yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) were found to be 350 +/- 7 MPa, 562 +/- 10 MPa, and 75 +/- 1%, respectively. The impact toughness and hardness in regions and were found to be 112 +/- 2 J and 183 +/- 6 (Hv0.5), respectively. From the results, it is evident that the tensile properties of the WAAM 304 L ASS component were equal/greater than the values of the forged 304 L ASS material, wrought 304 L ASS alloy, and 304 L ASS filler wire. HIGHLIGHTS 304 L austenitic stainless steel (ASS) cylindrical components were additively manufactured by GMAW process. The tensile properties, impact toughness, hardness and microstructural characteristics were studied in the bottom and top regions of the manufactured 304 L austenitic stainless steel cylinder. In comparison to the wrought 304 L austenitic stainless steel alloy, 304 L ASS filler wire, the coupons tested from bottom and top regions of the WAAM 304 L ASS (in the present research) cylinder showed equal/better tensile properties. [GRAPHICS] .

Aluminium (Al) and magnesium (Mg) alloys are extensively used in the automobile sector because of their high strength-to-weight ratio, excellent castability low density and simplicity of recycling. Al-Mg structures used in the automotive sector can potentially reduce their weight. Although there is a significant opportunity for substantial cost reduction, the use of magnesium in aluminium structures remains restricted. This study aims to weld 3 mm-thick rolled sheets of AA6061 Al and AZ31B Mg alloy using the cold metal transfer (CMT) arc welding process. Three different filler wires (ER1100, ER4043, and ER5356) were used in the experiment. In this article, the mechanical and microstructure characteristics of Al/Mg dissimilar joints manufactured by CMT are evaluated and discussed in detail. Optical microscope (OM), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), and x-ray diffraction (XRD) were used to analyze the CMT-welded Al/Mg dissimilar joints. Of the three filler wires used, ER4043 (Al-5%Si) filler wire yielded defect-free sound joints due to the presence of Si, which improves the flow ability of molten filler during welding. The presence of Mg-rich intermetallics-Al-12 Mg-17) and Al-rich intermetallics-Al-3 Mg-2 were observed. The fractured area of the CMT-welded Al/Mg dissimilar joints revealed the presence of the Mg-rich intermetallics (Al-12 Mg-17 ), which is responsible for the decrease in tensile strength. The reduction of intermetallics, particularly of Mg-rich intermetallics (Al-12 Mg-17 ) is important for improving joint strength. RESEARCH HIGHLIGHTS: Cold metal transfer (CMT) arc welding was used to control the Al-Mg-rich intermetallics in the Al/Mg dissimilar joints. The microstructure, morphology and phase composition of the welded joints were studied by OM, SEM, TEM, EDS and XRD. The weld metal and AL substrate bonded with a strong interface, while weld metal and Mg substrate were joined at the epitaxial solidification area where the intermetallic compounds of Mg-2 Al-3 , Mg-17 Al-12 and Mg-2 Si are generated. The weld metal on the Mg side experienced brittle fracture, with a continuous distribution of Mg-2 Al-3 , Mg-17 Al-12 and Mg-2 Si.

The study investigated the impact of cooling rate differences at the top and bottom regions of wire-arc additive manufactured (WAAM) high-strength low-alloy steel component. Cold metal transfer-based WAAM technique was used to deposit component with metal-cored wire. It was found that grain coarsening occurred in the top region, with grain oriented in a specific direction with the formation of lesser high-angle grain boundaries (HAGB). The bottom region had many randomly nucleated grains with a relatively higher proportion of HAGB. The refinement in the grains at the bottom region was due to the faster cooling rate experienced at this region. The ultimate strength of 951 ± 15 MPa and a hardness of 320 ± 3.5 HV0.5 were recorded in the bottom region. The increased HAGB and randomly oriented finer grains acted as pining points, impeded dislocation movement, and enhanced the bottom region’s strength.

In this study, AA6061-T651 Aluminium alloy was joined by gas metal arc welding (GMAW) and friction stir welding (FSW) processes. Both joints were compared and discussed in terms of their microstructure and fatigue properties. The microstructural evolution of the weldment was examined using optical microscopy (OM) and orientation image microscopy (OIM). FSW joints have finer grains than GMAW joints, which results in higher hardness. In GMAW and FSW joints, the tensile strength was 195 MPa and 230 MPa, respectively. This is 62% and 74% of the base metal. A fully reversible fatigue testing machine was used to investigate the fatigue properties of both joints. In comparison with GMAW joints, FSW joints have significantly better fatigue properties and reach infinite life at 90 MPa. Fractographic analysis shows that FSW joints had fewer crack initiation sites in stage I and better crack growth resistance in stage II than GMAW joints.