Effect Of Heat Treatment Process Parameters On Decabonization Of Bainite Steel

The effect of heat treatment on the decarbonization behavior of bainitic steels and several commercial steels was studied by means of heat treatment process experiment,mechanical property test and microstructure analysis,and morphology observation on the impact specimen fraction through the Scanning Electron Microscopy.This paper laid the foundation for the research on the decarbonization of bainitic steelThe results show that the Ac1 and Ac3 phase-transition temperature of the BZ20 steel by the hardness-temperature method are 740? and 880?.With the increase of the austenitizing heating temperature,BZ20 bainite steel started to raise complete decarbonization layer at 960?.BZ30 bainite steel decarbonization layer does not occur completely at the different heating temperature,but the heating temperature over 920? grain boundary oxidation decarbonization on the sample surface.35 CrMo steel started to raise complete decarbonization layer at 840?.23CrNi3Mo steel started to raise complete decarbonization layer at 960?.FF710 steel started to raise complete decarbonization layer at 920?,the grain boundary oxidation phenomenon began to appear at the same time.BZ20 steel complete decarbonization layer appeared at heat preservation time 4 mm/min at 920?,the depth of decarbonization layer and heat preservation time linearly increased.At 880?,BZ30 steel grain boundary oxidation occurs after the heat preservation time 2 mm/min.At 850?,35CrMo steel complete decarbonization layer appeared at heat preservation time 2 mm/min.At 850?,23CrNi3Mo steel complete decarbonization layer appeared at heat preservation time 8 mm/min.At 850?,FF710 steel complete decarbonization layer and grain boundary oxidation appeared at heat preservation time 2 mm/min.At 1050?,the rest of the materials appeared complete decarbonization layer except BZ30 steel.With the increase of heating time,BZ20 steel complete decarbonization layer depth increased at 920?.920? secondary heating normalizing and 920? heating normalizing increased before 690? high temperature tempering preheat treatment can refine the organization,improve the comprehensive mechanical properties.920? normalizing and 250?tempering with the temper times increased,the experiments material hardness and mechanical properties tend to decrease.With the temper times increased after normalizing,the experiments material impact toughness increased.920? quenching and 250? tempering,the impact toughness decreased with the increase of quenching times.