OS12W0072 Creating highly triaxial stresses in stainless steel

Abstract

This paper presents results from an experimental and numerical study on generating triaxial residual stresses in stainless steel. The residual stresses were introduced by water quenching of spheres and cylinders. A series of finite element simulations were carried out to determine how process conditions and dimensions of solid cylindrical bars and spherical balls influence the residual stress distributions. The results show that high compressive residual stresses occur around the surfaces of the cylinders and spheres. Near the centre of the samples the residual stresses are tensile. Spray water quenching experiments were conducted using solid cylinders and spheres of a stainless steel. The temperature during quenching compared well with the finite element simulations. Surface residual stresses were measured using the incremental centre-hole technique. Overall there is good agreement between the predicted and measured residual stresses. However, the level of triaxial stress is found to be sensitive to heat transfer coefficients. By controlling the cooling conditions and changing the dimensions of the steel samples differing triaxial residual stress states can be achieved in a controlled manner. This differs from other processes, such as welding, and shot peening, where the magnitudes and distributions of residual stresses are ill defined and the volume of material subjected to triaxial residual stresses is relatively small.