Identification of material parameters from low cycle fatigue, thermomechanical fatigue and creep tests for damage prediction of thermomechanically loaded Ni-resist Type D-5S

Abstract

An experimental and numerical study of the mechanical behaviour of cast iron during a thermomechanical fatigue is presented here. The cast iron specimens under investigation were made of austenitic ductile iron Ni-resist Type D-5S which is mostly used for exhaust manifolds and turbocharger housings. Elastoplastic and viscoplastic material parameters were determined from low cycle fatigue tests at different strain rates and thermomechanical fatigue tests, respectively, and then compared to material parameters previously gained by a combination of low cycle fatigue tests at a single strain rate and creep tests. These material parameters were then used to perform thermal and structural finite element analyses from which fatigue and creep damages on the cast iron were calculated. While damage predictions calculated here vary, they are comparable to experimental observations.