Abstract
Generally, the Achilles’ Heel of welded structures is fatigue as evident in many case studies. Accordingly, in design, appraising a welded structure's integrity is incomplete without evaluating its fatigue behavior. Specifically, welded structures are susceptible to numerous stress concentrations introduced during welding. These structures also undergo degradation by thermomechanical loading caused by thermal transients and stratifications. In scientific literature, most of the studies deal with this problem under isothermal fatigue con- ditions, which is different from the typical service conditions that can result in thermal shock in addition to fatigue failure over time. Hence, as the world is gearing towards automating the welding of Pressure Vessels (PV) due to the improvement of laser beam welding technology, there is a doubt as to whether laser welded PVs will have the same or better fatigue strength as those from traditional welding processes such as Tungsten Inert Gas (TIG) welding, Submerged Arc Welding (SAW) and others. Therefore, this study analyzes the effect of laser beams on the Low Cycle Fatigue (LCF) resistance of PVs made from stainless steel AISI 347 by the Batelle Structural Stress Method (BSSM) coupled with Finite Element Analysis (FEA). However, after analyzing the user design specified pressure vessel, it was discovered that there is a nonlinear relationship between laser power and fatigue damage. For this reason, laser power should be accounted for in Miner's rule for accurate prediction of fatigue life.