Temperature and Strain-Rate Effect to Mechanical Behavior of Mo-Cr Alloy Cast Iron

Abstract

Mo-Cr alloy cast iron is the most important material often used to make auto panel dies. To study high-speed machining process of auto panel dies, the material’s elastic modulus and fracture critical values of Mo-Cr alloy iron at 20°C-800°C were studied based on the high temperature elongation test. The material’s stress-strain relation curves at various temperatures (20°C-500°C) and various strain-rates (500/s-5000/s) were studied and the dynamic tensile yield strength values were obtained by dynamic SHPB(Split Hopkinson Pressure Bar) high-speed compression test. The test observation showed that Mo-Cr alloy iron has heat resistance and its behavior is between toughness and brittleness materials. Its toughness is enhanced with temperature increasing. At 20°C-500°C and strain-rates (500/s-5000/s) the dynamic tensile yield strength is decreased about 17％-24％ by temperature softening effect and is increased about 56％-70％ by strain-rate strengthening effect. The strain-rate strengthening effect prevails over temperature softening effect. Keywords: Auto panel die; Mo-Cr alloy cast iron; SHPB; Temperature softening effect; Strain-rate strengthening effect