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Investigation on the Effect of Post Weld Heat Treatment Temperature on Stress Corrosion Resistance of Inconel 625 Cladded on AISI 4130 Steel Using Hot Wire GTAW
M. Siddiqui, S. H. Razavi, H. Sabet,
Volume 4, Issue 1 (8-2018)
Abstract
In this research  the effect of heat treatment offer welding (PWHT) in 650,750 and 8500C for two hours on Sulfide stress corrosion cracking resistance (SSC), welding metal Inconel 625 to low alloy steel 4130 was analyzed that was welded using Automatic TIG welding process then the mechanical properties of the joint was observed using micro hardness measure experiment (weld metal, base metal and the welding heat-affected zone) and welding metal structure using light microscopy, electron SEM(EDX), also XRD. The comparison of the microstructure in different temperatures show the least effect on microstructure in 6500C. In micro hardness measure test after post-weld heat treatment (PWHT) with increasing temperature we observed decreasing hardness of base metal and heat-effected zon and alsoincreasing weld metal micro hardness. when the temperature of post-weld heat treatment reached to 8500C phase γ" changed quickly to delta phase δ.when temperature reached to 8500C secondary phases changed to needle form. After stress testing in Sulfide environment magnetic particles (MT) was done on the samples and results showed that in the post-weld heat treatment sample 8500C tension crack is made. Pictures of stress testing(SSC) SEM sample shows that tension cracks mode is base metal cracks along the grain boundaries and it also extends the base metal to weld metal.
Investigation of the effect of pulse frequency in gas tungsten arc welding (GTAW) of IN738LC nickel-based superalloy
R. Sahihi, S. M. A. Boutorabi, R. Ashiri,
Volume 11, Issue 2 (12-2025)
Abstract
The weldability of the superalloy Inconel 738LC is compromised by its susceptibility to heat-affected zone (HAZ) liquation cracking, a consequence of its high gamma-prime (γ') precipitate strength and the formation of low-melting-point eutectic phases. This study investigates the impact of Gas Tungsten Arc Welding (GTAW) current mode—comparing continuous current with pulsed current—on the microstructure, mechanical properties, and overall weldability of IN738LC. Through room-temperature tensile testing, Vickers hardness measurements, and microstructural analysis via optical and electron microscopy, it was demonstrated that pulsed current, particularly at higher frequencies, substantially mitigates liquation cracking and improves joint integrity. The pulsed technique introduces controlled thermal fluctuations that reduce the effective heat input, promoting a transition from columnar to equiaxed dendritic solidification, minimizing interdendritic segregation, and refining the distribution of MC carbides. Consequently, the weld metal exhibits enhanced tensile strength, ductility, and hardness. These findings establish pulsed GTAW as an effective strategy for suppressing cracking and improving the performance of IN738LC welded joints.

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