Cr8钢的动态再结晶行为及组织转变

Dynamic Recrystallization Behavior and Microstructure Transformation of Cr8 Steel

利用Gleeble-3500热/力模拟试验机对Cr8支承辊用钢在应变速率0.01～1s-1、变形温度950～1 200℃条件下进行了热压缩变形试验,研究了其热变形力学行为和再结晶规律,并对该钢热变形后的显微组织及物相变化进行了分析。结果表明:在应变速率较低为0.01s-1,当变形温度低于1 050℃时,Cr8钢热变形后的组织主要为动态回复型,当变形温度高于1 100℃时,热变形后的组织为动态再结晶型,且随着变形温度的升高,动态再结晶晶粒逐渐长大;当应变速率增加到0.1s-1时,热变形后的组织在温度低于1 050℃时为动态回复型,在温度高于1 100℃时为动态再结晶型;当应变速率增加到1s-1时,变形温度高于1 050℃时,热变形后的组织即发生了明显的再结晶,奥氏体晶粒大部分已长成为等轴的再结晶晶粒;Cr8钢热变形后的物相主要为α-Fe和γ-Fe,显微组织主要为马氏体和残余奥氏体。

Thermal compression deformation test of Cr8 roller steel was done by using Gleeble-3500 thermal/ power simulation test machine under the condition of strain rate of 0. 01 ～ 10 s^-1 and deformation temperature of 950～1 200℃ to study its thermal deformation mechanical behavior and recrystallization law, and the change of microstructure and phase compositions after thermal deformation test was also analyzed. The results show that when strain rate was low of 0. 01 s^-1 and the deformation temperature was lower than 1 050℃, the thermal deformation mierostructure of Cr8 steel was mainly dynamic recovery, and when the deformation temperature was higher than 1 100 ℃ it was dynamic recrystallization, and the dynamic recrystallization grain size gradually grew with the increase of deformation temperature. When the strain rate increased to 0. 1 s^1- the thermal deformation microstructure was dynamic recovery when the temperature was below 1 050 ℃, it was dynamic recrystallization when the temperature was higher than 1 100 ℃. When the strain rate increased to 1 s^-1 and the deformation temperature was higher than 1 050 ℃, thermal deformation microstructure underwent significant recrystallization, and most of the austenite grains had grown to equiaxial recrystallized grains. The phases of Cr8 steel after thermal deformation test were α-Fe and γ-Fe, and the microstructure was martensite and retained austenite.