Effects of Deformation and Alloy Elements on Continuous Cooling Transformation of NM400 Steel
The continuous cooling transformation behavior of low alloy wear-resistant steel NM400 was investigated by MMS-200 thermal simulator.The static CCT and dynamic CCT diagrams of different content steels were investigated.The influences of deformation and alloy elements on the microstructure transformation of the steels were analyzed.The results show that the hot deformation slightly promotes the formation of ferrite.The temperature of bainite transformation decreases.The critical cooling rate of martensite transformation increases.Addition of Mo depresses the diffusion of carbon and refines the grains.The critical cooling rate of martensite formation is decreased more effectively by adding Ni.The hardness of the steels is over 400 HV at the cooling rates above 10 ℃/s,and it is feasible to produce NM400 steel by traditional quenching or ultra fast cooling(UFC).