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Influence of microstructure on the thermo-mechanical fatigue behavior and life of vermicular graphite cast irons

2019; Elsevier BV; Volume: 771; Linguagem: Inglês

10.1016/j.msea.2019.138617

1873-4936

M.X. Zhang, J.C. Pang, Y. Qiu, Shan Li, Meng Wang, Z.F. Zhang,

High Temperature Alloys and Creep

Cylinder head is subjected to the combination changes of temperature and mechanical loads in service. In such harsh condition, thermo-mechanical fatigue (TMF) failure is a main problem. In this study, two kinds of vermicular graphite cast irons were selected to reveal the TMF properties and life prediction. Vermicular graphite casts with different microstructures have different ferrite cluster morphologies, which result in different fracture mechanisms. The hysteresis loops of both materials display obvious asymmetry. Hysteresis energy and mechanical strain amplitude were selected as damage parameters to determine the fatigue life. It is found that the TMF performance of vermicular graphite cast iron with higher pearlite content is better; meanwhile, the life of TMF at different constraint ratios was also studied. Hysteretic energy related to constrain ratio is in a parabolic form, and the life of TMF decreases with the absolute value of constraint ratio increasing. Finally, the quantitative relationship between constraint ratio and TMF life was also discussed.