Abstract: 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.

Key words: 30CrNi3MoV steel, hot deformation behavior, true stress-strain curve, constitutive equation, hot processing map