Effect of Hot Stamping on Flexural Fatigue Property of QSS400 Axle Housing Steel

The four point flexural fatigue curves of the QSS400 steel including initial hot rolled plate and hot pressed shell at 800 ℃ were measured under asymmetry circle-load conditions with stress ratio of R=-0.8.The effect of hot pressing on microstructure and fatigue property of QSS400 steel was investigated.The results show that the recrystallization of QSS400 steel hot pressed at 800 ℃ took place but the microstructure of the steel didnt become coarsened and still kept fine grain degree of grade 11 due to the addition of Nb which restrained the forming of carbide.However,the fatigue strength decresed slightly,just about 4%.