Determining the flow stress curve with yield and ultimate tensile strengths. Part I--Important data from the tensile test

摘要

Material suppliers often provide the yield stress and ultimate tensile strength for sheet materials. They don't, however, always provide the true stress-true strain (flow stress) curve. This curve is one of the most important variables for calculating input data for the finite element (FE) and analytical methods used to predict metal flow and defects. The flow stress curve, which reflects the sheet material's elastic and plastic properties, typically is obtained from a tensile test or bulge test.1 In a tensile test, a standard-size specimen is cut out from the sheet metal and pulled slowly until it breaks. An extensometer is attached to the specimen to measure the elongation over an original gauge length, l_0. Throughout the test, the load applied and the elongation of gauge length are recorded in real time (see Figure 1).