Tungsten Inert Gas Weld Joint Research Articles

STUDY ON THE IMPACT OF POST WELD HEAT TREATMENT ON TIG AND A-TIG INCONEL 617 WELDMENTS

This study analyzes the effects of Post Weld Heat Treatment (PWHT) on the mechanical properties and microstructure of Inconel 617 weldments produced by the Activated Tungsten Inert Gas (A-TIG) welding and Tungsten Inert Gas (TIG) welding. The TIG weld joints considered for this study were in an as-welded condition and underwent two different conditions of heat treatment including 1050∘C for 3 and 5[Formula: see text]h, respectively. The A-TIG weld joints studied were the as-welded type and the weldment was heat-treated at 1050∘C for 3[Formula: see text]h. The microstructure and the characterization of mechanical properties were performed for all weldments and a comparative assessment was made. Tensile strength and the hardness of the heat-treated samples were considerably higher than that of the as-welded samples. Impact toughness was slightly reduced after PWHT. Improvement in tensile strength could be attributed to the precipitation of the carbides and segregation of Chromium (Cr) and molybdenum (Mo).

Evaluation of dissimilar TIG welded joints of novel high strength low alloy steel for automotive applications: Experiment and numerical comparative approach

Modern automotive, aerospace, and manufacturing sectors use tungsten inert gas (TIG) welding widely as a critical procedure due to the weld's quality and joint efficiency. In this study, mechanical characterization of TIG-welded joints of high strength low alloy (HSLA) steel with two different grades (S1 and S2) was performed experimentally and mechanical properties were calculated in terms of hardness profile along the weldment and load-displacement curves. True stress-strain curves of base metal, heat-affected zone, and melted zones were used for calibration of the 8-node solid numerical model. The highest hardness value of 386 HV was obtained in the melted zone whereas a softening zone was observed in the heat-affected zone (HAZ) of S2 where the Vicker's microhardness value was 270 HV. During the comparison of simulation results with experimental data, it was found that the overall error was less than 5% which reflects a good accuracy of material models used for numerical modeling. A higher ultimate tensile strength was found in similar S1-S1 steel joints as compared to similar S2-S2 and dissimilar S1-S2 steel joints. Furthermore, the results of simulations revealed that the maximum von Mises stress (1050 MPa) concentrations were found in the HAZ of a similar S1-S1 welded joint, whereas the minimum von Mises stresses (880 MPa) in S2-S2 welded joint, and intermediate von Mises stresses (1010 MPa) on the side of S1 HAZ in S1-S2 dissimilar welded joint. The results of simulations and experimental study of TIG welding joints show good agreement with reasonable accuracy.

Microstructure and Pitting Corrosion Characteristics of Tig Welded Joints of Super 304HCu Austenitic Stainless Steel

Abstract Super 304HCu is an advanced ultra-super critical (A-USC) boiler grade austenitic stainless steel with the distinct addition of 3 wt.-% of Copper. A-USC power plants intended to operate in chloride rich environments (sea shore, feed water residues, etc.) are susceptible to chloride assisted corrosion failures. In this study, the pitting corrosion behaviour of the Super 304HCu parent material and tungsten inert gas weld joints was studied using a potentiodynamic cyclic polarization test in 3.5 % NaCl solution at three different pH levels (pH = 3, pH = 7, and pH = 11). The Epit values of the parent material is found to be much nobler than that of the weld joints. The micrographs of the pitted weld joints and the oxalic acid etched structure of Super 304HCu joints are presented. From the micrographs it is revealed that the heat affected zone is the most susceptible region to pitting corrosion.

Fabrication of Aluminum 5083/SiC Surface Composite on Tungsten Inert Gas Weld Joint by Novel Direct Friction Stir Processing Technique

For the creation of surface reinforcement particles in the metal matrix, friction stir processing is frequently utilized. Formation of aluminum/SiC surface composite on Tungsten Inert Gas (TIG) butt weld of Al5083 by a novel technique of direct friction stir processing (DFSP) using a hollow tool is successfully demonstrated in this present work. Deposition of SiC in the stir zone of DFSP was confirmed by X-Ray diffraction (XRD) method. Micro analysis of weld joint was achieved using metallographic microscope and scanning electron microscope (SEM). Microstructure of stir zone of DFSP shows finely distributed SiC reinforcement particles in aluminum matrix. Absence of detrimental intermetallics was confirmed by energy dispersive spectroscopy (EDS) analysis. Tensile strength of DFSPed specimen was found to be 227.3 MPa which is 19.5% lower than UTS of autogenous TIG weld specimen. Microhardness of SZ of DFSP was found to be increased from TIG weld microhardness of 86 Hv to 107 Hv due to presence of SiC particles.

Research on Microstructure and Mechanical Properties of Square Wave Alternating Current Tungsten Inert Gas Welded Joints in 2219-T6 Aluminum Alloy

Research on Microstructure and Mechanical Properties of Square Wave Alternating Current Tungsten Inert Gas Welded Joints in 2219-T6 Aluminum Alloy

Characterization of the microstructure and mechanical properties of activated tungsten inert gas welded and hot-wire tungsten inert gas welded super austenitic stainless steel AISI 904L

Super austenitic stainless steel AISI 904L is a premium stainless steel variant known for its superior properties and ability to retain the same in highly challenging conditions. This study investigates the feasibility of welding 10-mm thick plates of AISI 904L through activated tungsten inert gas welding and hot-wire tungsten inert gas welding methods. The fabricated joints are then subjected to solidification mode study, ferrite number analysis, microstructural characterization, and mechanical tests. Results of the solidification mode study indicated primary austenitic solidification in both the weld joints. The ferrite number measurement revealed that the hot-wire tungsten inert gas weld joint had a higher δ-ferrite content of 1.58 over 0.99 of the activated tungsten inert gas weld joint. A microstructure study confirmed the presence of refined equiaxed grains in the fusion zone of the hot-wire tungsten inert gas weld joint, while the activated tungsten inert gas weld joint displayed equiaxed grains crammed between the columnar grains and dendrites. Liquid penetrant inspection of bend-tested samples proved the soundness and quality of both weld joints. The hot-wire tungsten inert gas weld joint excelled over the activated tungsten inert gas weld joint with a higher microhardness value. During tensile tests, activated tungsten inert gas and hot-wire tungsten inert gas weld joints displayed average ultimate tensile strength values of 521 and 514 MPa, respectively. The impact toughness of the activated tungsten inert gas weld joint was 248 J, while it was 220 J for the hot-wire tungsten inert gas weld joint. Field emission scanning electron microscope analysis equipped with energy-dispersive spectroscopy and elemental color mapping provided details about weld microstructure and the reasons for the material's failure. The study proved the efficiency and soundness of the 10-mm thick joints of AISI 904L fabricated by activated tungsten inert gas and hot-wire tungsten inert gas welding techniques.

Welding of Super Duplex Stainless Steel and Austenitic Stainless Steel:#xd; Influence and Role of Bicomponent Fluxes

ABSTRACT This study investigated dissimilar tungsten inert gas and activated tungsten inert gas welding experimental results of austenitic 202 with a super duplex 32760 stainless steel. Their microstructural study revealed a balanced austenite-ferrite morphology that mainly consisted of Widmanstatten austenite (WA), grain boundary austenite (GA), and intergranular austenite (IGA). The study showed that the use of flux reduced the heat input necessary to achieve complete penetration, which tends to increase ferrite count in the heat-affected zone and the weld zone of weldment, resulting in minimizing the hot cracking propensity. Further, structure-property connections were also established by evaluating these two weldments’ tensile strength, impact strength, and microhardness. It was determined that weldments of activated tungsten inert gas weldment had better mechanical properties than traditional tungsten inert gas weldment. A weld zone fracture occurred near the austenitic weld interface in both weldments. It was noticed that unmixed zone formation on the side of the austenitic steel was to blame for the poor mechanical properties and failure of tungsten inert gas and activated tungsten inert gas weld joints. In both cases, the hardness distribution in the weld zones is ranked as super duplex stainless steel base metal > heat-affected zone of super duplex steel side > welded zone > heat-affected zone of austenitic steel side > austenitic base metal.

Improvement of mechanical and microstructural properties of AA 5052-H32 TIG weldment using friction stir processing approach

The effect of Friction Stir Process (FSP) on the weld bead of Tungsten Inert Gas (TIG) welded 5052-H32 Aluminium alloy is investigated in this work in terms of mechanical and microstructural characterization. A comparison study was conducted on the FSP treated and unprocessed TIG-welded Aluminium alloy joints. Optical and scanning electron microscopes were used to study the microstructure of the welded joints. Electron backscattered diffraction (EBSD) analysis was performed to analyze the grain size and orientation. The mechanical properties of the weldment were investigated using tensile strength and hardness measurements. The yield strength of unprocessed TIG welded joints was 79.5 MPa, but following friction stir processing, it improved to 129.5 MPa. The tensile strength of TIG-welded joints was 176.5 MPa. However, after post friction stir processing, it was increased to 201 MPa. On friction stir treated TIG welded joints, the elongation values improved from 8.5 percent in TIG welds to 20.75 percent. The refinement of fine grain structure is noticed in the stir zone due to the influence of high stirring action, intense plastic deformation, and frictional heat by Friction stir processing, which improves the mechanical characteristics of the weldment and decreases weld flaws. The tensile fractured surface of the joints was examined using SEM analysis. Brittle failure was seen in the TIG weld joints, and ductile failure with dimples was found in FSPed TIG junctions. The results show that the friction stir processed weldment has better mechanical properties than unprocessed TIG welded joints.

Effects of Plasma Sintering on the Post TIG Weld Joint of Fe-15Cr-25Ni Austenitic Stainless Steel

Arc-plasma sintering (APS) for 5 s has been applied to the post tungsten inert gas (TIG) weld joint of Fe–15Cr–25Ni austenitic stainless steel (ASS). The treatment is intended to observe the effect of heat generated by plasma on micro-crystal structures around the fusion zone (FZ), especially internal stress relief in steel after being subjected to welding. The effect of stress relief in weld was measured using the neutron diffraction technique. ASS that is predominantly composed of Fe, Cr, and Ni elements, with contents of 57%, 15%, and 25%wt. respectively, was cut into two parts. Both parts were then welded with TIG without filler with a current and voltage of 60 A and 50 V, respectively. After APS for 5 s, the sample was characterized and analyzed using high-resolution powder neutron diffractometer at a high-temperature laboratory facility. The results show that the tensile residual stress decreased with the APS heat input. The residual stresses significantly decreased from 82.40 MPa to 1.21 MPa in the FZ and continued almost evenly from 65.92 MPa to 1.24 MPa in the heat-affected zone (HAZ). The residual stress is a tensile stress that can reduce the mechanical strength of materials. This condition is also applicable to applied loads. A microstructure gives a confirmation that the C element migrates from the FZ to HAZ. The content was very high in dark traces. The C element reacts to Cr and O to form chromium carbide (Cr23C6) and chromium carbonyl (CrC6O6), respectively. It rapidly migrates among its grain boundaries. It may also weaken materials and probably initiate intergranular cracks.

Effect of Pulse Current Frequency on Microstructure and Hot Corrosion Behavior of Tungsten Inert Gas-Welded Joints of N155 Superalloy

Effect of Pulse Current Frequency on Microstructure and Hot Corrosion Behavior of Tungsten Inert Gas-Welded Joints of N155 Superalloy

Microstructure and mechanical properties of 9Cr-0.5Mo-1.8W–VNb (P92) steel weld joints processed by fusion welding

Abstract Grade P92 steel is used for making steam generator components of thermal and nuclear power plants at temperatures up to 923 K. Microstructures, mechanical properties and the service life of the welded components are influenced by the welding process employed. In the present investigation, the effect of Tungsten Inert Gas (TIG) and Activated TIG (A-TIG) welding processes on the microstructure and mechanical properties of P92 steel weld joints are studied. Optical microscope, SEM and TEM were used for characterizing the microstructures. Application of the activated flux on the joint area during A-TIG welding significantly increases the depth of penetration. Due to high current density peak temperature is higher in the weld pool and steep temperature gradient is observed across the joint interface. Therefore, the microstructure is relatively coarse in the A-TIG weld metal. TEM investigations have confirmed that the precipitates present at the grain and lath boundaries are carbides of the form M23C6 and the precipitates seen within the matrix of the lath are niobium and vanadium rich carbides and nitrides of type MX. The tensile strength of the A-TIG weld joint both at room temperature and at 923 K is higher than that of the TIG weld joint. In comparison to the base metal and TIG weld joint, a decrease in the Charpy impact toughness is observed in the A-TIG weld joint due to the formation of δ-ferrite along the fusion interface. However, in contrast to the TIG weld metal, tensile residual stresses at the A-TIG weld are very low.

A Comparison between Tungsten Inert Gas Welded Joints Welded by Commercial ER5183 Filler and Al–Mg–Zn–Sc–Zr–Mn Filler on Microstructure and Properties in 7075-T651 Aluminum Alloys

A 7075-T651 aluminum alloy was successfully welded by tungsten inert gas welding using commercial ER5183 wire and Al–5Mg–1Zn–0.3Sc–0.15Zr welding wire containing different contents of Mn. The microstructure, corresponding mechanical properties, and the corrosion behavior of the welded joint were investigated by microscopy methods, tensile tests, and corrosion tests. The results revealed that Al3(Sc,Zr) particles were distributed in a small amount in the welds and refined the primary α-Al grain. The addition of Mn gives a strong interaction of improving fracture strength, micro-hardness, and corrosion resistance reducing the harmful influence of iron, as a result, the properties of the welded joint were enhanced. And the increase of Mn content improves the tensile strength and hardness of welds, which could be attributed to the refinement of eutectic T phase by Mn. Potentiodynamic polarization tests revealed that the corrosion resistance of welds increased with the increase of Mn content. Compared with the welded joint using commercial filler, the welded joint with Al–Mg–Zn–Sc–Zr–Mn filler exhibited a higher resistance to stress corrosion cracking (SCC). In conclusion, Al–Mg–Zn–Sc–Zr–Mn filler can be using for welding 7XXX aluminum alloys.

Unveiling the Residual Stresses, Local Micromechanical Properties and Crystallographic Texture in a Ti-6Al-4V Weld Joint

In this work, the micromechanical properties, crystallographic texture, welding residual stresses and their evolution after plastic strain were investigated in a Ti–6Al–4 V alloy tungsten inert gas weld joint. It was found that the welding process affected the Young modulus and microhardness values in both α and β phases in the different regions of the weld joint. The highest microhardness and Young modulus values of α phase were recorded in the heat-affected zone, whereas the highest values of these characteristics for the β phase were found in the fusion zone (FZ). The change in the micromechanical properties was accompanied by a change in the crystallographic texture components of the dominant α phase from (0001) and (11–20) components in the base material to (10–10) and (11–20) components in the FZ. The introduction of tensile testing resulted in a continuous stress relaxation and improved the weld joint performances.

Computation of residual stresses, distortion, and thermogravimetric analysis of Inconel 625 weld joints

In the current investigation, Inconel 625 weld joints were fabricated by Activated tungsten inert gas (A-TIG) and Tungsten inert gas (TIG) welding techniques. The joint configurations employed square butt and V groove edge preparations. Residual stresses measurement was carried out by X-ray diffraction using the Proto iXRD measurement system. Distortion in weld joints was estimated by measuring the vertical displacement on the grids marked on the weld joints before and after welding by using an electronic height gauge. Weldment revealed distinctive microstructure, peak tensile residual stress, and angular distortion. A-TIG weld joint exhibited lower residual stresses and distortion compared to the TIG weld joint. Thermogravimetric analysis (TGA) has inferred that the fusion zone of A-TIG and TIG weldments revealed better hot corrosion resistance at high temperatures.

Effects of Preheating and Cooling Rate on the Microstructure and Mechanical Properties of Tungsten Inert Gas Welded Joints of AA5083-H321 Aluminum Alloy

Various preheating treatment and cooling rates conditions were carried out in Tungsten Inert Gas welding to study mechanical behavior and microstructural evolution of AA5083-H321 aluminum alloy welded joints. The microstructural analysis illustrated the diverse grain size during welding at different preheating and cooling rate. The highest preheat temperature caused to enlarge dendritic grains and during the fastest cooling rate formed the smaller grains. Also, the texture and grain size impressed on tensile behavior and hardness welds. Grain structure of the heat-affected zone, partially melted zone, and weld metal appeared to have a tangible relationship with preheating and cooling rate conditions. The microhardness of these regions increased by increasing the cooling rate and decreasing the preheating temperature. The high preheating had a negative effect on the hardness and width of different zones of welded joints. The results showed that the cooling rate has remarkable effects on the mechanical properties of the welded specimen.

Microstructure and Mechanical Properties of Tungsten Inert Gas Weld Joints of Sprayed and Cast Aluminium-Lithium Alloy.

The weld joints of sprayed 2195-T6 and cast 2195-T8 aluminium–lithium alloy were created using tungsten inert gas with filler wire. The microstructures and mechanical properties of the weld joints were examined. The results of the microstructure analysis showed that the width of the equiaxed grain zone (EQZ) and the amount of the second phase θ’(Al2Cu) was greater in the weld joint of the cast 2195-T8 Al–Li alloy than that of the sprayed 2195-T6 Al–Li alloy. Tensile testing indicated that failures occurred in the EQZ and partially melted zone (PMZ) for both weld joints. The tensile strength and elongation of the weld joints of the sprayed 2195-T6 and cast 2195-T8 Al–Li alloys were about 68.2%, 89.7%, and 50.7% and 28.3% those of the base metal in the joint, respectively. The cast 2195-T8 Al–Li alloy joint had more pores and cracks, resulting in lower tensile strength and elongation than those in the sprayed alloy. Further, the tensile fracture surface morphology indicated that the fracture mode of the sprayed 2195-T6 Al–Li alloy was a mixed fracture mode dominated by plastic fracture and that of the cast 2195-T8 Al–Li alloy joints was a mixed fracture mode dominated by brittle fracture.

Effect of Welding Processes on the Microstructure and Mechanical Properties of Duplex Stainless Steel Weld Joints

Abstract The objective of the present investigation involves studying the microstructure and mechanical properties of duplex stainless steel (DSS) alloy 2205 and super DSS (SDSS) alloy 2507 weld joints fabricated by tungsten inert gas (TIG) welding and its variant, activated TIG (A-TIG) welding. Square butt weld joints were fabricated from 10-mm-thick plates of DSS and SDSS using single pass A-TIG and multi-pass TIG welding processes. The filler wire ER2209 was used for multi-pass TIG welding of DSS 2205, and ER2594 filler wire was used for multi-pass TIG welding of SDSS 2507. The microstructure in the A-TIG weld metals was found to be coarser, which was caused by high peak temperatures during A-TIG welding. The microstructures exhibited different forms of austenite, including grain boundary allotriomorphs, Widmanstätten side plates, and intragranular precipitates in the weld metal. In the A-TIG weld metals, the microstructure exhibited a balanced ferrite-to-austenite ratio. The hardness values of multi-pass TIG weld joints were higher compared to A-TIG weld joints. The tensile and yield strengths of multi-pass TIG weld joints were higher compared to A-TIG weld joints, which was mainly due to higher delta ferrite content and finer microstructure. The toughness values obtained by Charpy impact testing were higher in A-TIG weld joints compared with multi-pass TIG weld joints at room temperature, which was mainly due to the balanced ferrite-to-austenite ratio in the weld microstructure. However, at subzero temperatures, the A-TIG weld joints exhibit lower impact toughness because of their coarser weld metal structure.

Microstructure and Impact Toughness of Local-Dry Keyhole Tungsten Inert Gas Welded Joints

In this paper, the microstructure and impact toughness of a S32101 duplex stainless steel underwater local-dry keyhole tungsten inert gas welded joint were studied. The impact toughness value of the underwater weld metal reached 78% of the onshore weld metal, which is in accordance with the underwater welding standards. The proportion of austenite in the underwater weld metal was 0.9% lower than that of the onshore weld metal. The proportion of the Σ3 coincidence site lattice boundaries and random phase boundaries in the underwater weld metal, which significantly influence the impact toughness of the weld metal, were smaller than that of the onshore weld metal.

Microstructure and Mechanical properties of Tungsten Inert Gas Welded Joints of Cast Al-Mg-Sc alloy

Abstract Aluminum-Magnesium-Scandium Cast alloy was Tungsten Inert Gas (TIG) welded, and the microstructure and mechanical properties of the global joint were examined and analyzed. The global joint fractured in the base metal, and thus possessed slightly greater tensile strength than the base metal. These results clearly show that Tungsten Inert Gas welding is an optimum / suitable welding process for cast Aluminum-Magnesium-Scandium alloys.

Ispitivanje zamorne čvrstoće i normi emisije štetnih supstanci u vazduhu tokom MIG i TIG zavarivanja 1460 legure aluminijum-litijum

This work presents the results of studying harmful substances in the air, released in the case of tungsten inert gas (TIG) and metal inert gas (MIG) welding of 1460 aluminum alloy (Al-Cu-Li). It is shown that the TIG process is accompanied by smaller evolution of the solid component and gas component of welding fumes than in MIG welding. Ozone concentrations during TIG and MIG welding are significantly (1.3 and 7.4 times, respectively) higher than the maximum permissible concentration. It is found that ultraviolet radiation, accompanying the welding process, is the main factor of toxic gas generation in the working zone of the studied aluminum-lithium alloys. Also, this paper presents analyses of microstructure, hardness, strength characteristics and fatigue behavior of 1460 TIG weld joints.