热变形对耐蚀重轨钢动态再结晶及组织的影响

Influence of Heat Deformation on Dynamic Recrystallization and Microstructure of Corrosion Resistant Rail Steel

高强耐蚀重轨U68CuCr是国内新近研制开发的钢轨新品种,通过在Gleeble-1500热模拟试验机上对耐蚀重轨钢进行单道次压缩试验,测定了在不同变形温度、变形量和变形速率条件下的真应力-真应变曲线,分析了热变形参数对珠光体动态再结晶行为的影响。利用金相显微镜和扫描电镜观察了不同变形条件下空冷得到的珠光体显微组织,测定了珠光体片间距和珠光体球团等显微组织参数,分析了热变形参数对珠光体组织影响的规律。研究表明:变形温度升高、变形速率降低、变形量增大的条件下,利于耐蚀重轨钢动态再结晶的发生;当变形温度和变形量一定时,变形速率越低,发生动态再结晶的可能性越大,应力峰值和临界应变减小;发生动态再结晶后得到珠光体组织,其珠光体片层间距和珠光体球团尺寸比未发生再结晶得到的珠光体更细小。

High stress corrosion resistance heavy rail U68CuCr is a kind of new rail steel, the true stress and strain curve of the heavy rail under different deformation temperature, different deformation, different deformation speed were measured by one-pass compression tests With Gleeble-1500. The influences Of heat deformation parameters on the dynamic recrystallization of the rail steel were analyzed. Air cooling pearlite microstructure after deformation was observed by OM and SEM, the pearlite nodule size and interlamella spacing were also measured to analyze the influence rule of heat deformation parameters on the microstructure of the rail steel. The results show that the dynamic recrystallization of U68CuCr mainly happens at higher deformed temperature, lower deformed speed and heavier deformation. With the certain deformed temperature and deformation, the dynamic recrystallzation can happen with more possibility when We deformation speed gets lower, the stress peak as well as critical strain reduces. When austenitic grain is obtained after dynamic recrystallzation, the pearlite nodule size and interlamella spacing is smaller than the one unrecrystallzation.