Accurate measurement of flow stress curves at high temperatures for low strain ranges

The present paper reports a comparison of flow stresses obtained by tension , plane strain compression, and axisymmetric compression testing in differe nt machines with or without extensometers in the gage length section. Flow stress curves obtained from different test systems suggest machine and spec imen geometry dependence, when the strain is computed based on gross specim en deformation. Finite element simulations give some insight into the inter pretation and use of each mechanical testing technique, revealing the distr ibution of the strain field in each case. The results show that careful cal ibration of every testing machine and, in some cases, finite element modeli ng of the tests, are essential to give a similar curve for the same nominal deformation conditions.