The effect of angular distortion on the fatigue behavior of non-penetrating laser welded lap specimens of 301LN stainless steel

Abstract

In this work, the fatigue behaviors of non-penetrating laser welded lap specimens of cold-rolled 301LN austenitic stainless steel were investigated based on experiments and numerical analyses. The experiments showed the unequal-thickness specimens failed in the thicker bottom sheet under low fatigue loads, even though the mean stress in the thinner top sheet was higher, when the applied loads were high enough, the failure location changed from the bottom sheet to the top sheet. This phenomenon could be successfully explained through traction stress analysis considering the effect of angular distortion. However, the equivalent traction stress representation of fatigue data is below the ASME master S-N curve scatter band since the stress exceeds the yield limit of the base metal at low-cycle fatigue regime. The structural strain approach was then used to consider the effect of plastic deformation, and all fatigue data fall into ASME master E-N curve scatter band. This indicates the structural strain approach in conjunction with the master E-N curve is suitable for correlating both low-and high-cycle fatigue data of the non-penetrating laser welded lap specimens.