This research manuscript explores the residual stress analysis, mechanical and metallurgical aspects of dissimilar welded joints between AISI 316 and Monel 400 developed by constant, pulse and ...Interpulse current TIG welding processes. The induced residual stresses have been measured experimentally by employing X-ray diffraction. The mechanical properties of welded joints have been determined by conducting tensile and Vickers hardness testing. The metallurgical properties of weldments have been analyzed by employing optical and scanning electron microscopy. From the experimental results, lower residual stresses have been observed in Interpulse current TIG weldment than the other two weldments. The tensile properties of the Interpulse current TIG weldment were observed to be higher than the other two weldments. In Interpulse TIG weldments, grain refinement and reduced heat affected zone near the fusion zone have been observed.
In this paper, high-temperature impact fatigue (HTIF) was carried out on a Co-based surface layer cladded by TIG welding, and cracks emerged at 400-cycle condition. The reasons for cracking were ...investigated from three aspects: microstructure, stress distribution, and crystal orientation. Crack generation was induced by high stress distribution in eutectic carbides at grain boundaries and the great disparity in orientations between grains on two sides of the crack path. The microstructural advantage for cracking behavior played a key role in emergence of cracks, which was verified by the investigation and comparison of three distances from the weld interface. Moreover, the interface microstructure of Co-based layer and FB2 substrate was characterized by transmission electron microscopy, and the phase composition of the weld interface comprised FeCo and M23C6. The results presented that the addition of Ni-based transition layer caused the acquisition of the crack-free surface layer after HTIF. Finally, microhardness test was conducted on samples with and without a transition layer. The hardness of Co-based surface layer without the transition layer was mainly affected by the transformation of carbides, dilution of Fe, and work hardening during HTIF. The hardness of Co-based surface layer with the transition layer showed minimal change during HTIF, and this finding was attributed to the slight variation in the microstructure.
•The microstructural evolution of Stellite 6 layer was revealed.•Mechanisms of cracks generation during HTIF were illustrated.•Crack problem was solved by the addition of Inconel 625 transition layer.•The phase composition of interfacial layer was determined.•Reasons for hardness variation during HTIF was explained.
This research manuscript explores the residual stress analysis, mechanical and metallurgical aspects of dissimilar welded joints between AISI 316 and Monel 400 developed by constant, pulse and ...Interpulse current TIG welding processes. The induced residual stresses have been measured experimentally by employing X-ray diffraction. The mechanical properties of welded joints have been determined by conducting tensile and Vickers hardness testing. The metallurgical properties of weldments have been analyzed by employing optical and scanning electron microscopy. From the experimental results, lower residual stresses have been observed in Interpulse current TIG weldment than the other two weldments. The tensile properties of the Interpulse current TIG weldment were observed to be higher than the other two weldments. In Interpulse TIG weldments, grain refinement and reduced heat affected zone near the fusion zone have been observed.
Nitrogen loss is an important phenomenon in welding of super duplex stainless steels. In this study, a super duplex stainless steel was autogenously TIG-welded with one to four bead-on-plate passes ...with low or high heat inputs using pure argon shielding gas. The goal was to monitor nitrogen content and microstructure for each weld pass. Nitrogen content, measured by wavelength dispersive X-ray spectrometry, was after four passes reduced from 0.28wt% in the base metal to 0.17wt% and 0.10wt% in low and high heat input samples, respectively. Nitrogen loss resulted in a more ferritic structure with larger grains and nitride precipitates. The ferrite grain width markedly increased with increasing number of passes and heat input. Ferrite content increased from 55% in base metal to 75% at low and 79% at high heat inputs after four passes. An increasing amount of nitrides were seen with increasing number of weld passes. An equation was suggested for calculation of the final nitrogen content of the weld metal as functions of initial nitrogen content and arc energy. Acceptable ferrite contents were seen for one or two passes. The recommendation is to use nitrogen in shielding gas and proper filler metals.
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•A unique method was employed to produce controlled thermal cycles using robotic welding combined with thermal cycle analysis.•Ferrite content in autogeneous super duplex stainless steel (SDSS) welds were characterized as function of nitrogen content.•An equation was proposed to predict the nitrogen loss in SDSS welds as function of initial nitrogen content and arc energy.
Tungsten Inert Gas (TIG) welding is also known as Gas Tungsten Arc Welding (GTAW) process which is an arc based welding process that uses the arc between a non-consumable tungsten electrode and a ...work piece with the help of a shielding gas 1-6. The TIG welding is used to produce high quality welds and isone of the most popular technologies for welding in manufacturing industries 7-12. The main disadvantage of TIG welding process is low weld penetration. The purpose of this review was to look into various techniques that may improve the weld penetration and weld quality in a TIG welding. In this review we discuss the influence of various types methods such as ATIG (Activated Flux TIG), FBTIG (Flux Bounded TIG), PCTIG (Pulsed Current Tungsten Inert Gas) Welding.It was observed during the review that use of flux or fluxes and pulsed current method improve the weld penetration with weld quality.
The dissimilar joints of AZ61 and ZK60 magnesium alloys were obtained by tungsten inert gas arc (TIG) welding and activating tungsten inert gas arc (A-TIG) welding processes. Microstructure ...characterization shows that, the fine α-Mg equiaxed dendrite crystals contained Mg17Al12 and MgZn2 particles in the fusion zone. The average size of the α-Mg grains in the fusion zone was refined to 19 μm at welding current of 80 A, which resulted in the largest tensile strength of 207 MPa. The tensile strength and the width of the beam of the A-TIG welded AZ61/ZK60 joints showed strong dependence on the amount of TiO2. However, the inhomogeneity of the heat-affected zone near different base metals presented no significant effect on the mechanical properties of the welded joint.
Dissimilar welds of Monel 400 and AISI 316 are extensively used in boiler feedwater heat exchanges, petrochemical industries, nuclear industries where moderate weld strength and high corrosion ...resistance are required. In this paper, dissimilar welded joint between Monel 400 and AISI 316 have been developed by employing Tungsten Inert Gas (TIG), pulsed TIG and Interpulse TIG welding techniques. The heat input rates and filler wire for joining the base metals were same for three welding techniques. The developed weldments have been inspected by employing X-ray Radiography Test (XRT) to determine the macro/micro defects. The tensile properties of weldments have been evaluated. The ultimate strength of TIG, pulsed TIG and Interpulse TIG weldments were observed to be 528 MPa, 542 MPa and 588 MPa, respectively. The tensile properties of Interpulse TIG weldments are superior to that of welds made of other two welding techniques.
Aluminium alloys are widely used in the fields of electric module packaging, electronic technology, automotive body structure, wind and solar energy management, due to the advantages of high specific ...strength, high processability, predominantly anti-erosion, increased conductivity, eco-friendly nature and recoverability. The objective of the study is to review the previous papers on aluminium usages, application, and workability parameters. The methodology adopted for the study is to use the structure literature review technique, and the time period selected for the study is 2008–2019 from the Scopus database. The findings of the study concluded that there are various types of aluminium alloys has been used by the previous researchers, and only 6061 is least explored aluminium alloy among all of them. The future scope of the study is to investigate using distinct activating fluxes for raising penetration & to understand consequences on mechanical components & rust behaviour of TIG-welded aluminium metal welds.
In present study, we investigated the effect of welding technique on resistance of hydrogen (H) embrittlement in Fe–18Mn-0.6C (wt.%) twinning-induced plasticity (TWIP) steel by using an ...electrochemical H-charging, thermal desorption spectroscope, and electron microscope. The friction-stir welding (FSW) specimen was less sensitive to H embrittlement relative to base metal and tungsten inert-gas (TIG) welding specimens by differences in microstructure and deformation mechanism. During H-charging of the FSW specimen, numerous dislocations/Σ3 boundaries reduced H diffusion into specimen interior, causing shallowest depth of brittle fracture. In contrast, the depth of brittle fracture in the H-charged TIG specimen was much larger due to rapid H diffusion by decreased grain boundaries including Σ3 annealing twin boundaries. During tensile deformation, the H-charged FSW specimen underwent the reduction in stress concentration by inactive TWIP as well as strong resistance of boundary decohesion. It was because of alleviation of H-enhanced localized plasticity (HELP) mechanism, leading to suppression of H-induced crack growth. Conversely, the H-charged base metal and TIG specimens revealed large stress concentration by active TWIP and weak boundaries owing to strong effects of HELP + H-enhanced decohesion (HEDE) mechanisms, exhibiting rapid H-induced crack propagation.
•FSW gives grain refinement and accumulation of dislocations/Σ3 boundaries.•TIG provides grain coarsening and reduction of Σ3 annealing twin boundaries.•For FSW, H diffusion is hindered by a lot of dislocations and Σ3 boundaries.•For FSW, suppressed twinning and HELP lead to delay H-induced cracking.•For TIG, extra ε-TRIP coupled with HELP + HEDE facilitates the boundary cracking.
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