Accelerated material data generation for viscoplastic material models based on complex LCF and incremental creep tests

Abstract

Viscoplastic material models are quite important for realistic characterization of deformation behaviour of high-temperature components. However, their material parameter adjustment is expensive and usually requires extensive material testing. The high-temperature deformation behaviour of cast iron GJS X SiMo 4.1 was determined by accelerated complex material testing methods in order to establish a cost-effective identification of viscoplastic material model parameters. Incremental creep tests with mixed-load and temperature steps, together with relaxation and stepped-tensile tests, were carried out in order to determine the stress-dependent creep strain rate at characteristic temperatures and stresses. The cyclic plastic deformation behaviour was studied with complex low-cycle fatigue (C-LCF) evaluations at varying strain rates, amplitudes and temperatures. Thereafter, the results were employed to identify material model parameters of a Chaboche-type viscoplastic material model, which was applied to represent the cyclic deformation and creep behaviour with a correct representation of strain-rate effects at low strain rates.

Keywords:

• Cast iron GJS X SiMo 4.1
• viscoplastic deformation modelling
• creep, relaxation and cyclic deformation behaviour

Acknowledgements

The authors acknowledge the financial support of KBB-Turbocharger and for providing the test material for the investigations. Siempelkamp GmbH is recognised for carrying out the creep tests.