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研究了铜含量以及热处理工艺对9%Ni钢屈强比的影响。采用光学显微镜(OM)、扫描电镜(SEM)观察了钢的组织特征,测试了钢的拉伸性能、硬度以及晶粒度。结果表明,经淬火+两相区淬火+回火(QLT)处理,随着Cu含量(0～1.5%)的增加,钢中马氏体量增加,铁素体量减少,同时还可细化晶粒,而且可能造成强烈的第二相强化,三者共同作用导致的屈强比增加。QLT处理较常规热处理可显著降低钢的屈强比,9%Ni钢中添加适量铜有利于钢强度及屈强比的匹配。
The effects of copper content and heat treatment on yield ratio of 9% Ni steel were studied. The microstructure of the steel was observed by optical microscope (OM) and scanning electron microscope (SEM). The tensile properties, hardness and grain size of the steel were tested. The results show that with the increase of Cu content (0-1.5%), the amount of martensite increases and the amount of ferrite decreases in the quenched + two-phase quenched and tempered (QLT) Grain, but also may cause strong second phase strengthening, the combination of the three leads to an increase in the yield ratio. Compared with conventional heat treatment, QLT treatment can significantly reduce the yield ratio of steel. Adding 9% Ni to 9% Ni steel is good for the matching of strength and yield ratio.