摘要:
研究了Ti对中碳高锰钢在不同加热温度和保温时间下的奥氏体晶粒长大规律的影响。结果表明,随着加热温度的升高和保温时间的延长,含Ti钢的奥氏体晶粒长大速率明显较慢,且相同温度下其晶粒尺寸更为细小。含Ti钢中含有较多的纳米级Ti(C,N)粒子,Thermo-calc计算表明其完全固溶温度约1 450℃,当温度逐渐升高时,Ti(C,N)虽有部分固溶,但尺寸小于100 nm的粒子比例依然较高,起到了阻碍奥氏体晶界迁移的作用,因此高温下含Ti钢的奥氏体晶界迁移速率较慢。建立了含Ti钢的高温奥氏体晶粒长大模型:$D_B=729.25 t^{0.16} \exp \left(-\frac{71 972.3}{R T}\right)$,根据拟合模型所得含Ti钢中的奥氏体晶界迁移能为72 kJ/mol,大于不含Ti钢的45 kJ/mol,同时生长指数n为0.16,而不含Ti钢为0.25,试验所得奥氏体晶粒尺寸与计算模拟值吻合较好。
Abstract:
Effect of Ti on austenite grain growth behavior in medium carbon manganese steel at different heating temperature and time were studied.The results show that Ti-bearing steel exhibited a much sluggish growth rate of austenite grain compared with Ti-free counterpart at higher heating temperature,which was attributed to the pinning effect of Ti(C,N) nanoparticles within size of 100 nm on austenite grain boundaries.The complete solid solution temperature was 1 450℃ calculated by Thermo-calc,and the amounts of nanoparticles Ti(C,N) were still large even at higher temperature.The austenite grain growth model of Ti-bearing steel was successfully established,ie.$D_B=729.25 t^{0.16} \exp \left(-\frac{71 972.3}{R T}\right)$,figuring the larger activation energy for migration of austenite grain boundary and the smaller grain growth index n,which were 72 kJ/mol and 0.16 respectively.The results predicted by the modified equation are found to be good agreement with the experimental results.The developed model could be employed to predict accurately the austenite grain growth of Ti-bearing medium carbon manganese steel.
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