Microstructure evolution in stress relaxation behavior of austenite AISI 304 stainless steel spring

In order to investigate the microstructure evolution of spring stress relaxation under different conditions, a microscopic analysis is carried out for the austenitic AISI 304 stainless steel spring. The microstructure and remanence of spring samples are obtained. Based on this, the stress relaxation mechanisms at different temperatures and loads are studied. The research shows that, for AISI 304 springs, the main stress relaxation mechanism at low temperatures and light loads is martensitic transformation. When the environmental temperature exceeds the creep temperature of spring material, the main stress relaxation mechanism is changed to the formation and growth of austenite twins. The rise of temperature will accelerate the spring stress relaxation. Within the elastic limit, the applied load only changes the relaxation rate instead of the relaxation mechanism. Thus, for the safety and reliability of springs, the environmental temperature should not exceed the creep temperature of spring material and the applied load should not exceed the spring elastic limit.