Experimental study on crack propagation of stainless steel 304 material under amplitude overloads

Abstract

Fatigue mechanisms caused by dynamic loadings starts with cracks that occurred in a material. Under conditions such as transient conditions, an earthquake or instantaneous external loads, some parts of nuclear reactor that initially receive operating loads can be overloaded. The purpose of this research is to investigate the change of crack propagation in stainless steel 304 material related with amplitude overloads. The crack propagation test used the axial dynamic testing with the maximum stress (σ max) of 145 MPa, stress ratio R = 0.1 and over loading ratio (OVR) of 1.5, 1.75, 2. The results showed that the amplitude overloads caused the crack to propagate slowly as the crack tip formed a branch. The higher crack growth rate also showed the higher stress intensity factors in the crack tip.