Investigation of Evaluation Method of Mechanical Properties of Machined Surface Layer of Austenitic Stainless Steel Using X-Ray Diffraction Method

Abstract

Machined surface layer, which consist of a fine grained layer and plastically deformed layer, has significant effects on the fatigue strength on the austenitic stainless steel. Therefore, the mechanical properties of the machined surface layer are important for accurate prediction of the fatigue life. However, slight thickness of the machined surface layer makes difficult to evaluate the mechanical properties of the machined surface layer. The objective of this paper is to investigate the mechanical properties of thin machined surface layer. For this purpose, we proposed the method for evaluating the stress-strain relationship of the machined surface layer by using the surface residual axial and circumferential stresses of the as-machined round specimen obtained by X-ray diffraction. Our measurement revealed that reducing grain size and thickness of the machined surface layer make the strength higher. The increase rate in the strength of the machined surface layer is inversely proportional to the cutting speed.