Flow stress measurement in upsetting test with grooved platens

Abstract

For practical determination of flow stress curve under forming conditions, i.e. at large strains, high strain rates and at elevated temperatures, a method is proposed based on the upsetting test with grooved platens. The procedure of the method is to measure the load and stroke during upsetting test, and transform them to average flow stress and average equivalent strain. This method was proved to be applied up to 700C with measuring error within 5% for various metals, and was employed as a standard material testing method for cold forging steels in Japan.