Study on Dissimilar Metals Welding of 15CDV6 and SAE 4130 Steels by Inter Pulse Gas Tungsten Arc Welding

AbstractIn aerospace scenario, ultra high strength steels like 15CDV6 steels and SAE 4130 steels are widely used because of their outstanding high strength to weight ratio. These steels differ from each other in their alloy composition. 15CDV6 steel contains lower bainate phase in hardened and tempered condition whereas SAE 4130 steel possess tempered martensite in hardened and tempered condition. 15CDV6 steel obtain their strength by austenizing at 975°C ± 5°C followed by Oil/Water/Forced air quenching and tempering at 650°C ± 5°C, while the strength of SAE 4130 steels is obtained by austenizing at 870°C ± 5°C followed by Oil/Water quenching and tempering at 260°C ± 5°C.In the present work, 3mm thick 15CDV6 alloy steel sheets were joined to SAE 4130 low alloy steel by Inter Pulse Gas Tungsten Arc welding using 8CD12 alloy filler wire, by taking both the base materials in different prior and post heat treatment conditions. Different welding parameters and heat- treatment cycles are employed. These weld coupons are evaluated by non-destructive tests like Dye penetrate test and X-ray radiography. The joints are evaluated for mechanical properties such as ultimate tensile strength, yield strength, percentage of elongation, and microhardness across weldment and measurement of residual stresses, both in as welded and post weld heat treated conditions. Evaluated mechanical properties were correlated to their weldment microstructures