Fe-1C钢离异共析转变行为

离异共析转变(DET)是高碳钢实现快速球化退火的重要理论依据。为了深入理解离异共析转变机理,采用定量金相方法,通过奥氏体中断淬火和等温转变试验对Fe-1C钢离异共析转变行为进行研究。结果表明,在共析温度以下,Fe-1C钢中离异共析转变与珠光体转变存在竞争, DET相体积分数与奥氏体化后残留的渗碳体粒子间距L_θ以及珠光体片层间距λ有关,DET相体积分数随λ/L_θ值的增加而增大。用基于JMAK方程的离异共析转变动力学模型计算了DET相体积分数随λ/L_θ的变化关系并与试验结果进行了比较拟合,试验测量值与计算拟合曲线吻合较好。λ/L_θ的值越大,离异共析转变时碳原子扩散所需距离相对于珠光体转变越短,就越有利于离异共析转变的发生。

Divorced eutectoid transformation behavior in Fe-1C steel

Divorced eutectoid transformation (DET) is an important theoretical basis for rapid spheroidization annealing of high carbon steels. In order to understand the mechanism of DET, quantitative metallographic method was used, the DET behavior of Fe-1C steel was investigated by means of austenitic interrupted quenching and isothermal transformation experiments. The results show that the DET competes with pearlite transformation in Fe-1C steel below eutectoid temperature, and the volume fraction of DET phase is related to the cementite particles spacing L_θ and the pearlite interlamellae spacing λ. The volume fraction of DET phase increase with the increment of λ/L_θ. The relationship between the volume fraction of DET phase and λ/L_θ was calculated by the DET kinetic model based on JMAK equation and compared with the experimental results. The calculated fitting results agree well with the experimental data. The greater the value of λ/L_θ, the shorter the distance required for the diffusion of carbon atoms during DET relative to the pearlite transformation, and the more favorable it is for the occurrence of DET.