过共析钢在过冷奥氏体形变过程中的组织超细化

Ultra-refinement of hypereutectoid steel during deformation of undercooled austenite

用Gleeble1500热模拟试验机进行单轴热压缩实验,研究了过共析钢在过冷奥氏体形变过程中的组织演变规律.结果表明:过冷奥氏体变形可以抑制网状渗碳体的形成,过冷奥氏体动态相变只得到珠光体组织,在继续变形过程中珠光体发生动态球化,得到超细化(α+θ)复相组织.提高形变温度使过冷度降低,阻碍过冷奥氏体动态相变的进行;而降低应变速率使变形时间延长,有利于过冷奥氏体动态相变和珠光体动态球化的进行,但得到的超细化复相组织较为粗大.

The microstructure evolution of a hypereutectoid steel （0.97%C） during deformation of undercooled austenite was investigated by uniaxial hot compression simulation experiment. The results indicate that the proeutectoid network carbides were restrained by deformation of undercooled austenite and only pearlite was formed by dynamic transformation of undercooled austenite. Lamellar pearlite was spheroidized dynamically by hot deformation, resulting in the formation of ultrafine （α＋θ） microduplex micro.structures. The increase of deformation temperature, leading to the decrease of the degree of undercooling, has the retarding effect on dynamic transformation of undercooled austenite. The decrease of strain rate, leading to the prolonging of the deformation time, was beneficial to dynamic transformation of undercooled austentite and dynamic spheroidization of pearlite, but the resulted ultrafine microduplex microstructures was coarser.