38MnVTi非调质钢的高温热压缩变形特性及加工图

Thermal Compression Deformation Performance at High Temperature and Processing Maps of Non-quenched and Tempered Steel 38MnVTi

采用Gleeble-1500D型热模拟试验机对38MnVTi非调质钢进行热压缩试验,研究了其在950~1 200℃和应变速率为0.01~10s-1条件下的热变形行为,基于Parasd和Murty两种失稳判据分别建立了动态材料模型（DMM）的加工图,利用加工图确定了试验钢在应变为0.8下的流变失稳区,并分析了两种加工图的差别。结果表明：两种加工图中失稳区域的面积大小相近,功率耗散系数的数值变化趋势相似,但它们的失稳区位置有差异;低的功率耗散系数可以作为一种识别热变形失稳的方法,应避免试验钢在高应变速率下进行大应变量变形;试验钢的热变形最佳工艺参数为变形温度1 050~1 200℃、应变速率0.04~1s-1。

The hot compression tests were carried out on non-quenched and tempered steel 38 MnVTi by using Gleeble-1500 Dthermal simulation system,and the thermal deformation behavior of the tested steel at temperature of950-1 200 ℃and strain rates of 0.01-10s-1 was studied.Based on Parasd criterion and Murty criterion,the processing maps of dynamic material model（DMM）were built.The instability regions of flow behavior with strain of 0.8could be recognized by the maps and the differences of the maps were also analyzed.The result show that the instability regions in the two maps were almost equal in area,and the change of numerical feature for the power dissipation coefficient also was similar,but the positions of instability regions were different.The low power dissipation coefficient could identify the instability for hot deformation and the deformation with large strain and high strain rate should be avoided for the tested steel.The best hot deformation progress parameters were the temperature range of 1 050-1 200 ℃ and strain rates of 0.04-1s-1.