K390粉末冶金高速钢的热变形行为

Hot deformation behavior of K390 powder metallurgy high speed steel

在变形温度为1100~1200℃、应变速率为0.05~5 s^(-1)、最大变形量为70%的条件下,采用Gleeble-3800热模拟机对K390粉末冶金高速钢进行了等温压缩变形,并分析了不同变形温度和变形速率下实验钢的显微组织变化。结果表明:K390粉末冶金高速钢在变形初期表现出明显的加工硬化,流变应力急剧增大并迅速达到峰值;峰值应力随变形温度的降低和应变速率的增大而增大。随着变形温度的升高,晶粒尺寸增加。随着应变速率的增加,晶粒尺寸减小,碳化物分布趋于均匀。在变形温度为1150℃时,实验钢中出现了大量等轴晶,碳化物分布均匀。利用动态材料模型,建立了K390粉末冶金高速钢热变形失稳区热加工图。实验钢最佳的热加工参数为:变形温度1175℃、应变速率0.05 s^(-1)。

Under the conditions of deformation temperature ranging from 1100 to 1200℃,strain rate ranging from 0.05 to 5 s^(-1) and maximum deformation of 70%,isothermal compression deformation of K390 powder metallurgy high speed steel was carried out using a Gleeble-3800 thermal simulator.Microstructure changes of the experimental steel under different deformation temperatures and strain rates were analyzed.The results show that the K390 powder metallurgy high speed steel exhibits significant work hardening in the initial stage of deformation,with a sharp increase of the flow stress and rapidly reaching to peak value.The peak stress increases with the decrease of deformation temperature and the increase of strain rate.As the deformation temperature increases,the grain size increases.As the strain rate increases,the grain size decreases and the distribution of carbides tends to be uniform.At the deformation temperature of 1150℃,a large number of equiaxed grains appear in the experimental steel,and the distribution of carbides is uniform.Using the dynamic material model,the hot processing diagram of the K390 powder metallurgy high speed steel in the hot deformation instability zone is established.The optimal hot processing parameters of the experimental steel are:deformation temperature of 1175℃,strain rate of 0.05 s^(-1).