大规格5CrNiMoV热作模具钢的硬度均匀性研究

Research on the Uniformity of the Hardness of Large Scale 5CrNiMoV Hot-Work Die Steel

摘要: 对5CrNiMoV热作模具钢锻后预处理工艺进行了研究。结果表明，按常规工艺处理后，5CrNiMoV热作模具钢的预处理金相组织存在大量未溶碳化物，属于欠热组织，同时锻造遗留下来的粗大组织未能消除，严重影响了后续的调质热处理，硬度均匀性难以满足客户需求。采用重结晶 + 高温固溶的预处理工艺，获得了均匀细小的伪共析组织，大大缩短了球化退火时间，为后续调质处理提供了良好的组织准备，实现了调质硬度 ≥ 42 HRC时，芯表硬度差 ≤ ±1.5 HRC。

Abstract: The 5CrNiMoV hot-work die steel pretreatment after forging process was studied. The results showed that there were many undissolved carbides founded in the pretreatment of metallographic organization under the conventional process, belonging to subcooled organization; meanwhile the coarse microstructure from forging failed to eliminate, seriously affecting the subsequent quenching process, and its hardness uniformity was difficult to meet customer demand. Adopting recrystallization + high temperature normalizing heat treatment process of preparation, homo-geneous and fine pseudo-eutectoid microstructure was gotten, and the time of spheroidizing an-nealing was also greatly shortened, providing a good pre-microstructure for subsequent quenching; thus it was realized that the uniformity of hardness from the surface to the core can be less than HRC 1.5, when the hardness is higher than 42 HRC.