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对9Ni钢厚板进行了4种热处理工艺试验,分别是终轧后直接淬火+回火(DQ+T)、淬火+回火(QT)、淬火+双相区淬火+回火(QLT)和热轧后空冷到双相区淬火+回火(LT),分析了热处理工艺对9Ni钢组织与性能的影响规律。结果表明,9Ni钢采用DQ+T工艺热处理可获得最高的强度,但-196℃低温下的冲击功只有139 J;采用传统的QT和QLT能保持较高的低温韧性,低温冲击功分别为198 J和223 J。采用QT工艺的强度和屈强比高,伸长率较QLT处理的要低。采用QLT工艺获得铁素体,钢板低温韧性显著提高的同时强度则有较大幅度的降低,而伸长率最高;采用LT工艺热处理的钢板低温冲击功为225 J,达到QLT工艺水平,其屈服强度、抗拉强度和伸长率均比QT处理的钢板的同类指标要高,是一种兼有高韧性和高强度的新工艺。
Four kinds of heat treatment process tests were carried out on 9Ni steel plate, including direct quenching and tempering (DQ + T), quenching and tempering (QT), quenching and double phase quenching and tempering (QLT) and After hot rolling and air cooling to dual phase quenching and tempering (LT), the influence of heat treatment process on microstructure and properties of 9Ni steel was analyzed. The results show that 9Ni steel can obtain the highest strength by DQ + T heat treatment, but the impact energy at -196 ℃ is only 139 J at lower temperature. Conventional QT and QLT can maintain high low temperature toughness, the impact energy at low temperature is 198 J and 223 J. QT process using the strength and yield ratio high elongation than QLT treatment to be low. Using QLT process to obtain ferrite, the ductility of the steel is significantly improved while the strength is greatly reduced, while the elongation is the highest; the low temperature impact energy of LT steel is 225 J, reaching QLT process level, yielding The strength, tensile strength and elongation are all higher than similar indicators of QT-treated plates, a new process that combines high toughness and high strength.