低碳钢20CrNi2Mo的高温热变形行为及热加工图

Hot deformation behavior and hot processing map of 20CrNi2Mo low carbon steel at elevated temperature

以20CrNi2Mo低碳钢为研究对象,采用DIL805A/T热模拟试验机在变形温度为900~1050℃、应变速率为0.001~1s^(-1)条件下进行等温单道次轴向热压缩试验,建立了20CrNi2Mo钢高温压缩的最大变形抗力本构方程和热加工图,并观察了热变形组织。结果表明:真应变值为0.1~0.5的热加工图中均存在两个功率耗散峰区,且随着应变量的增加峰区I逐渐向变形温度较高的区域移动,峰区II向应变速率增大的区域移动。热加工图中失稳区域随着应变量的增加先逐渐减小后又逐渐增大,在ε=0.4时,失稳区域最小,此应变量下20CrNi2Mo钢较优的热加工工艺区间为:变形温度940~960℃、应变速率0.001 s^(-1)或温度1025~1050℃、应变速率0.01~0.06 s^(-1)。

In order to establish the constitutive equation of the maximum deformation resistance and hot working processing maps of 20 CrNi2Mo low carbon steel,the isothermal single-pass compression tests for the steel were carried out on a DIL805A/T thermomechanical simulator under the different conditions in which temperature changes from 900 to 1050 ℃ and strain rate changes from 0.001 to 1 s（-1）,and the evolution of thermal deformation microstructure during the process was observed.The results show that there are two peaks in the energy dissipation processing maps of the tested steel with the true strain at the range of 0.1 s（-1） to 0.5 s（-1）.With the increasing of the true strain,peak area I moves gradually to higher deformation temperature region,and peak area II moves gradually to the higher strain rate region.However,the area of the instability zone of the hot working processing maps decreases first and then increases gradually with the increase of the strain,and has minimum value at the true strain of 0.4.Under this strain,the optimum hot working processes of the tested steel are as follows：the deformation temperature is 940-960 ℃ with the strain rate of 0.001 s（-1） or the temperature is 1025-1050 ℃ with the strain rate of 0.01-0.06 s（-1）.