淬火冷速对H13模具钢组织及力学性能的影响

Effect of quenching cooling rate on microstructure and mechanical properties of H13 die steel

采用光学显微镜（OM）、扫描电镜（SEM）和透射电镜（TEM）研究了不同淬火冷却速度对H13热作模具钢显微组织及力学性能的影响。结果表明：当淬火冷却速度从12.6℃/min提高到40.7℃/min,经590℃回火6 h后,试验钢中的马氏体板条束宽度从340 nm减小至150 nm。此外,条带状及球状碳化物沿晶界的析出量显著减少;试验钢的室温冲击性能和硬度值均有一定的提高。试验钢以40.7℃/min淬火冷却＋590℃回火6 h后在厚度方向的最低冲击吸收能量达到14.6 J;而试验钢以12.6℃/min淬火冷却＋590℃回火后,晶界处合金元素偏聚严重,其中Cr、Mo和V元素含量分别高出基体约16%、23%和210%。

Effects of quenching cooling rates on microstructure and mechanical properties of H13 hot working die steel were investigated by means of OM,SEM and TEM. The results show that with the increase of quenching cooling rate from 12. 6 ℃/min to 40. 7 ℃/min,the width of martensite lath of tested steel tempered at 590 ℃ for 6 h decreases from 340 nm to 150 nm. In addition,the precipitation of the stripped and globular carbides decreases remarkably along grain boundaries,and the impact property and hardness values of tested steel at room temperature are all improved obviously. The minimum impact absorbed energy of the tested steel at thick ness direction reaches 14. 6 J at quenching cooling rate of 40. 7 ℃/min and tempering at 590 ℃ for 6 h. However,the tested steel quenched with cooling rate of 12. 6 ℃/min and tempered at 590 ℃ for 6 h has severe segregation of alloy elements in the grain boundary,where the element content of Cr,Mo and V is approximately 16%,23% and 210% higher than that of the matrix,respectively.