DB685钢的热变形行为及热加工图

为了研究DB685钢的热变形特性,选取并建立了DB685钢的高温应力应变本构方程,利用Gleeble-1500热模拟机对DB685钢在变形温度为900~1200℃、应变速率为0.01~10 s~(-1)、最大应变量70%条件下进行压缩实验,根据建立的本构方程,绘制DB685钢的热变形加工图,利用所建立的加工图,分析了不同温度和应变速率下合金的热成形性能,结果表明:随着变形温度的升高和应变速率的降低,合金的流变应力下降,动态再结晶更容易发生;DB685钢在1125℃温度以上,并且在对应的应变速率下,耗散系数存在峰值;随着应变的增大,其耗散系数略有增大,失稳区减小,但热加工图的整体趋势保持一定。因此对于工业热加工,建议变形温度为1125~1175℃,应变速率高于0.032 s~(-1)。

Heat deformation behavior and heat processing map of steel DB685

In order to study the thermal deformation behavior of the steel DB685, its flow stress constitutive equation at high-temperature was chosen and established, and the heat compression tests were conducted by Gleeble-1500 thermal mechanical simulator within a tem-perature range form 900℃ to 1200℃, strain range from 0. 01 s-1 to 10 s-1 and the maximum strain of 70%. Based on the above consti-tutive equation, processing map of steel DB685 was designed, and formability of steel DB685 was analyzed at various temperatures and strain rates. The result shows that with the increase of the deformation temperature and the decrease of stress rate, the flow stress decrea-ses obviously, and the possibility of dynamic recrystallization increases. When the temperature is above 1125 ℃, the dissipation factor of steel DB685 reaches a peak value under the related strain rate. With the strain rate increase, the dissipation factor increases slightly, and the wrinkle area reduces. Furthermore, the overall trend of heat processing map remains the same. Thus, the deformation temperature 1125-1175 ℃ and the strain rate more than 0. 032 s-1 are recommended to set in the industrial forming conditions.