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采用SEM,TEM,XRD等方法研究了9Ni钢经两相区热处理(QLT)和调质处理(QT)后的精细组织,奥氏体含量,深冷冲击韧性和断口。结果表明,QLT处理有利于生成奥氏体。两相区加热温度TL为660℃时,试验钢中奥氏体的体积分数为12.2%,-196℃下的夏比冲击吸收能量为148 J。经QT处理的试样含有较高的位错密度,且伴有碳化物析出,冲击韧性降低。断口分析表明,QLT处理试样为等轴韧窝断裂特征,而QT处理试样为河流状解理断裂特征。示波冲击试验表明,QLT试样失稳断裂时,产生大量塑性变形,断裂吸收能远大于QT处理试样。
The microstructure, austenite content, cryogenic impact toughness and fracture of 9Ni steel after heat treatment (QLT) and quenching and tempering (QT) were studied by SEM, TEM and XRD. The results show that, QLT treatment is conducive to the formation of austenite. The heating temperature TL of the two-phase zone is 660 ° C, the volume fraction of austenite in the test steel is 12.2%, and the Charpy absorbed energy at 196 ° C is 148 J. The QT-treated samples contain higher dislocation density and carbide precipitation with lower impact toughness. Fracture analysis shows that QLT samples are equiaxed dimple fracture characteristics, while QT samples are river-like cleavage fracture characteristics. Oscillating impact tests show that when the QLT specimen is unstably broken, a large amount of plastic deformation occurs, and the breaking energy absorbed by the QLT specimen is far greater than that of the QT specimen.