30CrNi3MoV钢的热变形行为及热加工图

采用Gleeble-3500热模拟试验机对30CrNi3MoV钢进行单向热压缩试验,研究了其在变形温度950~1150 ℃、应变速率0.01~10 s^-1的热变形行为,构建了应变补偿型流变应力本构方程,并绘制出该钢的热加工图。结果表明,30CrNi3MoV钢真应力-真应变曲线有3种不同特征:高温小应变速率时,表现为典型的动态再结晶过程;低温小应变速率时,曲线为动态回复特征;应变速率较大时,应力随应变的增大而增大,无明显的峰值应力。采用5次多项式拟合构建的应变耦合流变应力本构方程具有高的精确度,采用该方程获得的预测值与试验值的平均相对误差为3.2%,相关性系数R值为0.993。从热加工图中得到试验钢最佳的热加工工艺参数范围是:变形温度为1020~1150 ℃、应变速率为0.03~0.35 s^-1。

Hot deformation behavior and hot processing map of 30CrNi3MoV steel

Unidirectional thermal compression tests on 30CrNi3MoV steel were carried out by using Gleeble-3500 thermal-mechanical simulator, the hot deformation behaviors at deformation temperatures of 950-1150 ℃ and strain rates of 0.01-10 s^-1 were studied, the strain-compensated flow stress constitutive equation and the processing map were established for the 30CrNi3MoV steel. The results show that the true stress-strain curves of the 30CrNi3MoV steel have three characteristics:(i)under conditions of high temperature and small strain rate, being typical dynamic recrystallization process; (ii) under conditions of low temperature and small strain rate,characterized as dynamic recovery; and (iii) when the strain rate is large, the stress increases with the increase of strain, and there is no obvious peak stress. The modified strain coupled flow stress constitutive equation displays highest accuracy when constructed by using the 5-degree polynomial fitting, by which the obtained mean relative error between the predicted and the experimental values is 3.2%, and the correlation coefficient R is 0.993.The hot processing map shows that the optimum deformation temperature and strain rate ranges for the 30CrNi3MoV steel are 1020-1150 ℃ and 0.03-0.35 s^-1, respectively.