ABSTRACT

The continuous cooling transformation (CCT) diagram of 30CrMo steel simulated by compact strip production process was constructed. And the effect of austenite deformation on the CCT behaviour was investigated. The results showed that the microstructure gradually transformed from proeutectoid ferrite and pearlite to bainite and martensite with the increase of cooling rate, accompanying a refined microstructure and an increasing hardness. When the cooling rate was lower than 0.1°C s⁻¹, the desired microstructure of ferrite and pearlite could be obtained. And the austenite deformation strongly promoted the formation of proeutectoid ferrite, which led to a decreasing hardness of deformed steel. When the cooling rate was larger than 10°C s⁻¹, the fully martensite microstructure was obtained. And the austenite deformation inhibited martensite transformation, resulting in a decrease of the martensite transformation starting (M_s) temperature from 391°C to 368°C.

摘要

构建了紧凑带钢生产工艺模拟的30CrMo钢连续冷却转变（CCT）图。并研究了奥氏体变形对 CCT 行为的影响。结果表明，随着冷却速度的增加，组织逐渐由先共析铁素体和珠光体转变为贝氏体和马氏体，组织细化，硬度增加。当冷却速度低于0.1°C s ^{-1 时}，可以获得所需的铁素体和珠光体组织。并且奥氏体变形强烈促进了先共析铁素体的形成，导致变形钢的硬度降低。当冷却速度大于 10°C s ^-1，获得完全马氏体组织。并且奥氏体变形抑制了马氏体转变，导致马氏体转变起始温度（M _s）从391℃降低到368℃。