中文摘要：

利用Gleeble 1500热模拟试验机进行单轴热压缩实验,研究了含Al过共析钢和不含Al过共析钢过冷奥氏体形变过程中,形变温度和应变速率对组织演变的影响。结果表明：过共析钢过冷奥氏体形变过程中的动态转变经历动态相变和相变所得珠光体的动态球化、超细化。过冷奥氏体动态相变抑制晶界网状渗碳体的形成。动态转变所经历的两个过程均为热激活过程,受形变温度和应变速率的影响。降低形变温度,使过冷度增加;降低应变速率,使完成应变的时间延长,两者均减小了过冷奥氏体完成动态相变所需的应变量,使相变所得的珠光体经历的变形程度增加,有利于珠光体实现球化、超细化。合金元素Al的添加阻碍铁、碳原子的扩散,推迟过冷奥氏体动态相变的发生,细化所得的球化、超细化复相组织。

英文摘要：

The effect of processing parameters （deformation temperature and strain rate） during deformation of undercooled austenite on the microstructure evolution of hypereutectoid steel was investigated by uniaxial hot compression simulation experiment. The results indicate that microstructure evolution during deformation of undercooled austenite include dynamic phase transformation and dynamic spheroidization of pearlite. During dynamic phase transformation, the proeutectoid net-cementites at grain boundary are suppressed and the pearlite is obtained. Dynamic phase transformation and dynamic spheroidization of pearlite are thermal activation process, which is influenced by deformation temperature and strain rates. Decreasing deformation temperature or strain rates, leading to the smaller strain for the completion of dynamic phase transformation of undercooled austenite, is of benefit to the formation of ultra-refined and spheroidized pearlite during hot deformation of undercooled austenite. With addition of Al, diffusion of carbon and iron atoms are impeded, retarding the formation of pearlite and refining the duplex microstructure.