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研究了AMS 6308钢在不同温度回火过程中Cu的强化机制及其对力学性能的影响。结果表明,150~350℃回火,AMS6308钢的组织为回火马氏体,强度和硬度略有增加,韧性下降。400~450℃回火,强度和硬度逐渐增加,这是由大量细小(<10 nm)的ε-Cu相在基体内和位错线上析出造成。450℃回火,ε-Cu相析出数量显著增加,导致强度和硬度达到峰值,韧性最差。450℃以上回火,随温度提高,ε-Cu相长大粗化,析出数量减少,其形态由球状转变为棒状或短杆状,沉淀强化作用减弱,M6C碳化物长大,基体发生回复再结晶,强度和硬度显著下降,韧性逐渐提高。
The mechanism of Cu strengthening and its effect on the mechanical properties of AMS 6308 steel during tempering at different temperatures were studied. The results show that the microstructure of AMS6308 steel is tempered martensite after tempering at 150-350 ℃, the strength and hardness increase slightly, and the toughness decreases. After tempering at 400-450 ℃, the strength and hardness increase gradually, which is caused by a large number of fine (<10 nm) ε-Cu phases precipitating in the matrix and dislocation lines. After tempering at 450 ℃, the amount of precipitated ε-Cu phase increased significantly, leading to the peak of strength and hardness and the worst toughness. When the temperature is above 450 ℃, the ε-Cu phase coarsens as the temperature increases, the amount of precipitated ε-Cu phase decreases, and the morphology changes from spherical to rod-like or short rod-like shape. The strengthening effect of precipitation is weakened, the carbides of M6C grow up, Crystallization, strength and hardness decreased significantly, toughness gradually increased.