高温时效对P91钢组织及硬度的影响

对P91钢进行了650 ℃×2935 h的时效试验,测试了时效过程中的硬度变化,并分析了显微组织变化对硬度的影响。结果表明,在时效前期,由于M₂₃C₆的析出,导致硬度略有上升。在后续的时效中,M₂₃C₆发生熟化,数量密度降低;同时,亚晶缓慢长大,位错密度略微降低,使P91钢的硬度缓慢下降。根据时效过程中的组织和硬度变化,可以预测P91钢在不超过600 ℃的条件下服役时,有较好的组织和性能稳定性。

Effect of high temperature aging on microstructure and hardness of P91 steel

P91 steel was aged at 650 ℃ for 2935 h. The hardness change during aging was measured, and the influence of microstructure change on hardness was analyzed. The results show that in the early aging period, the hardness increases slightly due to the precipitation of M₂₃C₆. During the subsequent aging, M₂₃C₆ is matured and its quantity density decreases, at the same time, the hardness of the P91 steel decreases slowly due to the slow growth of sub crystal and slight decrease of dislocation density. According to the changes of microstructure and hardness during the aging process, it can be predicted that the P91 steel has better stability of microstructure and properties when it is in service at the temperature not exceeding 600 ℃.