为研究工程机械用Q690钢的高温热变形行为,采用Gleeble3800型热模拟试验机,对工程机械用Q690钢进行高温压缩试验。分析了Q690钢的真应力-真应变曲线;建立了Q690钢的热变形方程和热加工图。结果表明:随着变形温度的升高和变形速率的减小,Q690钢的流变应力减小;Q690钢的热变形激活能为432.3545kJ/mol;热加工图表明Q690钢在整个温度范围内均存在失稳区,实际生产过程中应尽量避免失稳区;在温度为1 080~1 150℃,应变速率为0.01~0.3s^-1时,Q690钢的功率耗散因子高于0.3,该参数为Q690钢最佳的热加工区域。

In order to study the high temperature hot deformation behavior of Q690 steel for construction machinery, the high temperature compression test of Q690 steel for construction machinery was carried out by using Gleeble3800 thermal simulation testing machine. The true stress-true strain curve of Q690 steel was analyzed. The hot deformation equation and hot processing map of Q690 steel were established. The results show that the flow stress of the Q690 steel decreased with the increase of deformation temperature and the decrease of deformation rate. The hot deformation activation energy of Q690 steel was 432.354 5 kJ/mol.The hot processing map showed that the Q690 steel had instability zone in the whole temperature range, and the instability zone should be avoided in the actual production process. When the temperature was 1 080-1 150℃ and the strain rate was 0.01-0.3 s^-1, the power dissipation factor of the Q690 steel was higher than 0.3, which was the best hot working area of the Q690 steel.