Numerical Study of Post Welds Residual Stress and Creep Behavior of Inconel 718 and 316 Stainless Steel Joints

Abstract

Numerical simulation is implemented to study the generation of residual stress and creep deformation behavior for different types of welded joints fabricated for 316 SS and IN 718 base metals using IN 625 filler metal. Residual stress is calculated numerically by executing mechanical analysis followed by thermal analysis. Cooling rate has been determined using Newton’s law of cooling considering convective heat transfer across the welded specimen. Creep analysis through numerical simulation requires specific creep coefficient from respective creep law. Time hardening creep law is formulated and implemented to simulate the creep behavior of the weld joints for one hour time duration. Parallel butt weld is found to be more unscathed as very low amount of residual stress generation is observed across the weld bead. On the contrary, large amount of residual stress is observed along the weld bead for T weld joint. Furthermore, primary and secondary creep stages are observed in simulated creep curve for one hour time duration in case of all types of butt weld joints studied here. On the other hand, tertiary creep stage in addition to primary and secondary creep stages is observed for lap and T weld joint during one hour simulated creep behavior. Parallel butt weld joints of 316 SS and IN 718 base metals with IN 625 filler metal observed to have very low amount of creep strain compared to creep strain generated in others welded joints for creep simulation of one hour duration.