暖通空调用钢的热变形行为与组织研究

Study on Thermal Deformation Behavior and Microstructure of HVAC Steel

采用Gleeble 3800型热模拟试验机对暖通空调用钢进行了变形温度950~1100℃、应变速率0.01~5 s^(-1)的热压缩变形,观察了不同热变形条件下的组织演变规律。结果表明,当变形温度为1150℃,应变速率为1 s^(-1)及以上时,暖通空调用钢中的等轴晶晶粒尺寸分布均匀且较为细小;当应变速率为1 s^(-1),变形温度达到1100℃及以上时,暖通空调用钢的软化机制主要以动态再结晶为主;暖通空调用钢的热压缩变形适宜在应变速率≥1 s^(-1)、变形温度≥1100℃的热变形条件下进行。暖通空调用钢的变形激活能Q为729.266 kJ/mol,通过热压缩变形建立了暖通空调用钢的流变应力方程;当应变速率为0.01~5 s^(-1)、变形温度950~1150℃时,暖通空调用钢的峰值应力计算值与实测值误差均在10%以内,表明暖通空调用钢的流变应力方程在实际热压缩过程中具有较好的适应性。

The hot compression deformation of steel for HVAC(namely ultra high carbon steel)with deformation temperature of 950~1100℃and strain rate of 0.01~5 s^(-1) was carried out by Gleeble 3800 thermal simulation tester,and the microstructure evolution under different thermal deformation conditions was observed.The results show:when the deformation temperature is 1150℃and the strain rate is 1 s^(-1) or above,the equiaxed grain size distribution in steel for HVAC is uniform and fine;when the strain rate is 1 s^(-1) and the deformation temperature reaches 1100℃or above,the softening mechanism of steel for HVAC is mainly dynamic recrystallization;the hot compression deformation of steel for HVAC is suitable under the hot deformation conditions of strain rate is 1 s^(-1) or above and deformation temperature is 1100℃or above.The deformation activation energy Q of steel for HVAC is 729.266 kJ/mol,and the flow stress equation of steel for HVAC is established;when the strain rate is 0.01~5 s^(-1) and the deformation temperature is 950~1150℃,the error between the calculated and measured peak stress of steel for HVAC is less than 10%,indicating that the flow stress equation of steel for HVAC has good adaptability in the actual thermal compression process.