某大口径厚壁12Cr1MoVG钢制高压锅炉管硬度偏高，采用硬度测试、力学性能试验、金相检验等方法对硬度偏高问题进行了分析。结果表明：热处理后的钢管组织不均匀，导致钢管的力学性能不均匀，部分区域硬度不符合设计要求。根据电站机组特点，设计了正火后旋转内淋外喷冷却、正火后直接水冷和正火后“预冷+水冷+空冷”3种热处理工艺方案，最终通过选用“预冷+水冷+空冷”工艺，将回火温度和预冷时间控制在合理范围，使钢管硬度符合设计要求。

The hardness of 12Cr1MoVG steel pipes with large diameter and thick wall for high pressure boiler was too high. The problems of high hardness were analyzed by means of hardness test, mechanical property test and metallographic examination. The results show that the structure of steel pipes were not uniform after heat treatment, which resulted in the mechanical performance of steel pipes was not uniform, and the hardness of some areas did not meet the design requirements. According to the characteristics of the power plant unit, three heat treatment process schemes were designed including rotating internal spray cooling after normalizing, direct water cooling after normalizing and "precooling+water cooling+air cooling" after normalizing. Finally, the tempering temperature and precooling time were controlled within the reasonable range by selecting the process of "precooling+water cooling+air cooling", so that the steel pipe hardness met the design requirements.