G0310204 押込み法によるステンレス鋼の塑性特性と残留応力推定法(材料力学部門一般セッション:変形・ひずみ(2))

Abstract

This study proposed a method to evaluate the residual stress and plastic strain of stainless steel using Berkovich indentation test. This method deals with austenitic stainless steel, SUS316L that obeys the Ludwik work hardening law and involves in-plane equi-biaxial residual stress. Numerical experiment with finite element method (FEM) was carried out in order to simulate Berkovich indentation test for SUS316L having various plastic strain (pre-strain) and residual stress. It was found that indentation force increases with the increasing in pre-strain as well as compressive residual stress. Next, parametric FEM study by changing of residual stress σ_<res> and pre-strain ε_<pre> was conducted in order to deduce relationship between indentation curve and materials parameter of ε_<pre> and σ_<res> (Which was employed for the FEM study). This relationship can be expressed by dimensionless function with simple formulae. Thus, the present method can estimate both ε_<pre> and σ_<res> from an indentation curve of SUS316L. In addition, micro indentation test was conducted for several SUS316L steels including as-received, cold rolled steel, and shot peened steel. It is found that the proposed method can estimate the values of ε_<pre> and σ_<res> acculately.