Measurement of residual stress introduced by grinding in dual phase stainless steel by the method of the X-ray stress measurement

A dual phase stainless steel consists of almost the same amount of both ferrite and austenite phase, and possesses good corrosion proof as well as high strength characters, so that this material is used for ocean structures. Commonly, dual phase stainless steals are processed for industrial use by rolling, cutting, and grinding, etc. Residual stress generated during these processes play important role in fatigue fracturing of this material. Thus, measurement of residual stress in the dual phase stainless steel is very important. However, as this material is one of the composite materials in which different constituents with different physical properties such as the coefficient of thermal expansion (CTE) and a mechanical property are involved, each constituents will posses a different residual stress and plastic strain due to a heat-treatment and / or other mechanical processes during manufacturing. Such microscopic complex state may affect the macroscopic properties of the material. In this study, these problems were investigated using the X-ray stress measurement method by which the residual stress in each constituent of composite materials can be obtained. In addition, an influence of the depth of cut in case of the up-cut grinding on the residual stress and plastic strain were discussed in detail Key Words: Dual phase stainless steel, X-ray stress measurement, Macro- and microstress, Plastic strain.