FATIGUE PROPERTIES OF META-BAINITE IN STEEL 40CrMnSiMoVA

The microstructure,strength,toughness and fatigue properties of an ultra-high strength steel40CrMnSiMoVA have been investigated.The so-called meta-bainite,composed of thin re-tained austenite films within or between the bainitic ferrite lathes was found in the steel afterisothermally quenched at 300℃ for 1h.In comparison with the martensite structure obtainedby isothermally quenching in martensite range,the meta-bainite has more excellent strengthand plasticity,lower notch sensitivity,stronger strain harden ability,higher fatigue strength,longer strain or impact fatigue life,slower crack propagation rate and more remarkableoverload effect on increasing fatigue life.