Effect of Axial Misalignment on Fatigue Properties and Fatigue Crack Growth Rate of Plasma Arc Butt Welded Joints

This paper investigated the effect of axial misalignment on the fatigue strength and fatigue crack propagation rate of butt weld joints made of SUS301L austenitic stainless steel thin sheets. The impact of axial misalignment on the fatigue performance of thin sheet welded joints was revealed through microstructure observation, tensile test, fatigue performance test and fatigue crack propagation rate test. The results indicated that the microstructure and tensile properties of both joints were similar. However, the misaligned joint exhibited a higher stress concentration, which caused the fatigue strength of the S–N curve to decrease significantly. After analyzing the fatigue data for misaligned welded joints with the IIW recommended stress amplification factor, the study found the amplified results were lower compared to butt joints. This suggested that the impact of axial misalignment on the fatigue properties of thin sheet welded structures was more significant than on thick plate welded structures. Furthermore, there was a considerable increase in the stress intensity factor at the fatigue crack tip of the misaligned joint, leading to a substantial rise in the propagation rate of the fatigue crack.