高铁用U75V钢轨钢动态CCT曲线

用膨胀法结合显微组织观察及硬度测量方法,得到了U75V钢轨钢动态CCT曲线。结果表明:当冷却速度为0.05~3℃/s时的U75V钢轨钢的显微组织为珠光体组织,而且随着冷却速度的加快珠光体片层间距逐渐减小;冷却速度为5℃/s时主要的显微组织为珠光体组织,但出现少量马氏体组织;当冷却速度为15~50℃/s时的显微组织为马氏体和残余奥氏体组织。随着冷却速度的增大,硬度呈增加趋势。高铁用U75V钢轨钢奥氏体向珠光体开始转变温度不超过700℃,相变结束温度不低于500℃,当冷却速度为2~3℃/s时珠光体片层间距最为细小。

Dynamic CCT Curve of U75V Steel for High-Speed Railway

The expansion curves of continuous cooling transformation at different cooling rates of U75V steel for sigh-speed railway were got by dilatometric change referencing microscopic test and hardness measurement. The results show that the product of austenite transformation is pearlite when the cooling rate is lower than 3??/s, and the pearlite interlamellar spacing decreases as the cooling rate increasing. Pearlite and little martensite is obtained at the cooling rate of 5??/s, martensite and retained austenite is got if the cooling rate is in the range of 15-50??/s. The hardness of the steel increases with the increase of cooling rate. The starting transformation temperature from austenite to pearlite of U75V steel for high-speed railway is less than 700??, and the finishing transformation temperature is higher than 500??. The pearlite has the minimum interlamellar spacing when the cooling rate is 2-3??/s.