Research on Creep Test of Compacted Graphite Cast Iron and Parameter Identification of Constitutive Model under Wide Range of Temperature and Stress

With the increase in engine power density, temperature and stress carried by cylinder head during operation also increase. The thermal fatigue life prediction of needs to consider accurate reasonable creep-constitutive models parameters. In view wide range working conditions compacted graphite cast iron (CGI) head, creep test CGI under 450~550 °C 100~300 MPa was out, proposed characterize a model for minimum rate. Research indicated that conditions, more prone damage than low load, deformation dominated grain boundary sliding (GBS), intragranular dislocation glide (IDG), climb (IDC). mechanism-based true (DMTS) model, combined with multiobjective optimization method, constructed, 73% predicted values were within twice error range. Compared linear regression method could still fit parameters case small samples.