热轧屈服强度550MPa高强度钢板组织性能

Microstructure and Mechanical Properties of 550MPa Yield-Strength-Class Hot Rolled Plate Steel

为开发屈服强度大于550 MPa、-60℃冲击功高于37 J的高强度热轧厚钢板,开展了系列试验研究。提出2种试验钢,即CSiMnCuNiMo(A)和CSiMnCuNiCrMo(B)低合金钢。采用Gleeble 3800热模拟试验机,系统研究了钢A在热机变形条件下奥氏体连续冷却相变动力学和显微组织变化规律。在二辊可逆试验轧机上,进行了宽厚板控制轧制和控制冷却试验,研究了2种钢的显微组织和力学性能变化规律。确定了TMCP技术路线:采用再结晶区和未再结晶区两阶段控制轧制,随后快速冷却。2种钢在热轧时精轧压下率均不小于65%。钢A以20℃/s的速率冷却至500℃;钢B以13℃/s的速率冷却至400℃。-80℃夏氏低温冲击韧性平均值分别达到307 J和164 J。

Two test steels,i.e.,microalloyed CSiMnCuNiMo（A） and CSiMnCuNiCrMo（B） were investigated to develop a 550MPa yield-strength-class high strength hot plate steel with an assured CVN energy of 37J at-60℃.The continuous cooling transformation（CCT） kinetics in the designed thermomechanical processing conditions was investigated for the test steel A employing a Gleeble 3800 thermomechanical simulator.A series of thermomechanical rolling and accelerated cooling operations were exercised employing a two high reversing pilot rolling mill coupled with accelerated cooling system.The thermomechanical rolling specification is that the minimum reduction rate of 65% during finishing rolling is necessary followed by accelerated cooling at 20℃/s interrupted at 500℃ for the steel A and 13℃/s interrupted at 400℃/s for steel B,respectively.Minimum yield strength of 550 MPa and average Charpy V impact energy values of 307J and 164J were attained in the test steels A and B,respectively.