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采用硬度计SEM,EDS,TEM和XRD研究了经深冷处理和未经深冷处理Cr8Mo2SiV钢的回火硬度、残余奥氏体含量和碳化物析出行为.结果表明,Cr8Mo2SiV钢经1030℃淬火后,二次硬化峰值硬度出现在回火温度为520℃.深冷处理能够显著减少残余奥氏体含量,进而提高二次硬化峰温度之前的回火硬度,并使二次硬化峰向低温区移动20℃.在520℃回火处理,Cr8Mo2SiV钢的回火硬度随保温时间的延长而线性降低.Cr8Mo2SiV钢的二次硬化是残余奥氏体的转变和Mo_2C的析出前期共同作用的结果,残余奥氏体的作用更大.Mo_2C的析出前期合金元素Mo和C形成[Mo-C]偏聚团的G.P.区,随回火时间延长,Mo_2C析出并长大,均匀弥散分布于基体中.
The tempering hardness, residual austenite content and carbide precipitation behavior of Cr8Mo2SiV steel after cryogenic treatment and non-cryogenic treatment were investigated by SEM, EDS, TEM and XRD.The results show that after Cr8Mo2SiV steel quenched at 1030 ℃, The second hardening peak hardness occurs at a tempering temperature of 520 ° C. Cryogenic treatment can significantly reduce the retained austenite content, thereby increasing the tempering hardness before the secondary hardening peak temperature and allowing the secondary hardening peak to move 20 ° C. to the low temperature region. Tempering at 520 ℃, the tempering hardness of Cr8Mo2SiV steel decreases linearly with the increase of holding time.The secondary hardening of Cr8Mo2SiV steel is the result of the interaction between the retained austenite and the pre-precipitation of Mo_2C, the residual austenite Mo 2 C is more than that of Mo and C. The formation of [GP-Mo] clusters of Mo-C in the Mo 2 C pre-precipitation alloy forms the GP zone with segregation of Mo 2 C in the matrix as the tempering time prolongs.