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通过不同正火和回火处理获得不同状态的T91钢试样。采用金相、扫描电镜,硬度测试等方法,研究了不同回火条件下T91钢的组织演化过程与硬度变化规律。结果表明,随正火温度升高,T91钢中合金元素逐渐固溶,板条马氏体逐渐粗化,残留奥氏体减少,1050℃正火后获得最佳细小马氏体组织。670～820℃回火时,T91钢的再结晶点(790℃)和相变点(820℃)很近,随着回火温度的升高,正火板条马氏体开始发生回复和再结晶,带来硬度的逐渐降低,其中790℃回火时硬度最低。T91钢交货态采用760～780℃的回火工艺处理,保证了板条马氏体只发生高温回复,没有发生再结晶,所以从转变过程和组织形态看,称T91钢交货态的组织为回火马氏体更合理。
Through different normalizing and tempering to obtain different states of T91 steel samples. The evolution of microstructure and hardness of T91 steel under different tempering conditions were studied by means of metallographic examination, scanning electron microscopy and hardness testing. The results show that with the increase of normalizing temperature, alloying elements gradually dissolve in T91 steel, the lath martensite gradually coarsens and the retained austenite decreases, and the fine fine martensite is obtained after normalizing at 1050 ℃. When tempering from 670 ℃ to 820 ℃, the recrystallization point (790 ℃) and transformation temperature (820 ℃) of T91 steel are very close. With the increase of tempering temperature, the martensite of normalizing lamellae begins to recover and then Crystallization, bringing the gradual decrease in hardness, of which the lowest hardness when tempering 790 ℃. T91 steel delivery state using 760 ~ 780 ℃ tempering process to ensure that the lath martensitic only high temperature response, did not occur recrystallization, so from the transformation process and organizational form, said T91 steel delivery organization For the tempering martensitic more reasonable.