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通过对9NiCrMo钢在不同回火温度下常规力学性能的测试、扫描电镜、透射电镜观察和XRD分析,研究了回火温度对其力学性能和微观组织的影响。结果表明:该钢具有较高的强度和良好的低温韧性;随着回火温度的升高,屈服强度和抗拉强度分别在550℃附近和570℃附近出现高峰,峰时效状态细小的M2C型碳化物弥散析出起到了重要的强化作用。二次马氏体的析出也是导致强度增加的因素。其良好的低温韧性主要归因于极细小的二次马氏体板条束、铁素体、适量的逆转变奥氏体的出现。
The mechanical properties of 9NiCrMo steel at different tempering temperatures, the scanning electron microscopy, transmission electron microscopy and XRD were used to study the effects of tempering temperature on the mechanical properties and microstructure. The results show that the steel has high strength and good low temperature toughness. With the increase of tempering temperature, the yield strength and tensile strength peak around 550 ℃ and around 570 ℃ respectively. The M2C The dispersion of carbide has played an important role in strengthening. Secondary martensite precipitation is also a factor that leads to increased strength. Its good low temperature toughness is mainly due to the very small secondary martensite lath, ferrite, the amount of reverse austenite.