Flow stress strongly affects the accuracy of FEM simulation, particularly for the fracture prediction of stretch forming. However, it is only possible to measure flow stress by tensile test in a small strain range before necking appears. The purpose of this study is to propose a measurement method for the flow stress of thin sheet metals in a large strain range, using ring compression test. In our previous study, by considering the strain distribution of the workpiece and the elastic deformation of dies through compression and friction between the workpiece and the dies, it is possible to measure the flow stress of sheet-shaped metals up to a strain of 1.0. In this study, the flow stress of high -strength steels and a mild-strength steel was measured by the method developed with considering plastic anisotropy using Hill's equation. Thus, the method developed is more effective than what for measuring flow stress in a variety of thin sheet metals.
