淬火温度对刀剪用M390粉末冶金不锈钢组织和性能的影响

Effect of quenching temperature on microstructure and properties of M390 powder metallurgical stainless steel for chopping knives and scissors

通过对M390粉末冶金不锈钢进行不同温度下的平衡相计算和真空气淬+低温回火处理,研究了淬火温度对回火后显微组织和力学性能的影响。结果表明,随着淬火温度的升高,M390钢回火后的碳化物尺寸不断长大,单位面积的颗粒数量减少而所占面积分数提高,碳化物分布均匀性降低。硬度随淬火温度的升高呈先上升后略微下降趋势,在1130℃淬火时达到最大值60.2 HRC,回火后降为58.5 HRC。抗弯强度受淬火温度的影响不大,为4000 MPa级水平。为获得良好性能,淬火温度应控制在1200℃以下,1130~1180℃真空气淬+200℃低温回火是刀剪用M390钢的最佳热处理工艺制度。

Through calculation of equilibrium phases at different temperatures and carrying out vacuum quenching+low temperature tempering for powder metallurgical stainless steel M390,the effect of quenching temperature on microstructure and mechanical properties of the steel was analyzed.The results show that with the increase of quenching temperature,the size of carbides in the tempered M390 steel increases,the number of carbide particles per unit area decreases but the area fraction increases,thus the distribution uniformity of carbide decreases.Meanwhile,the hardness increases first and then decreases slightly,reaching the maximum value of 60.2 HRC after quenching at 1130℃and decreases to 58.5 HRC after tempering.However,the flexural strength is little affected by quenching temperature,which is at the level of 4000 MPa.In order to obtain good properties,the quenching temperature should be controlled below 1200℃.In conclusion,vacuum gas quenching at 1130-1180℃and tempering at 200℃is the optimum heat treatment process for the M390 steel used for chopping knives and scissors.