两相区热处理工艺对9NiCrMo钢回火稳定性的影响

Effect of quenching,lamellarizing and tempering process on tempering stability of 9NiCrMo steel

运用OM、SEM和TEM对9NiCrMo钢经调质(QT)、两相区淬火(QLT)后的微观组织结构进行了观察,用X射线衍射测定了两相区淬火(QLT)试样的逆转变奥氏体含量,研究了调质(QT)、两相区淬火(QLT)工艺对9NiCrMo钢强度和韧性的影响及其机理。结果表明:两相区淬火处理过程中,二次淬火(L)温度对试验钢中析出稳定逆转变奥氏体的量有影响;本试验中,两相区淬火温度为750℃时,试验钢中析出稳定逆奥的量最多,即该温度下试验钢的韧性最好;两相区热处理能很大程度改善9NiCrMo钢的回火稳定性,利于工业生产。

Microstructure of 9NiCrMo steel after quenching and tempering（ QT） and quenching,lamellarizing and tempering（ QLT） was systematically studied by means of optical microscope（ OM）,scanning electron microscope（ SEM） and transmission electron microscopy（ TEM）. Moreover,quantity of reversed austenite in the steel after QLT treatment was measured by X-ray diffraction（ XRD）. Based on the experimental results,the effects of QT and QLT on strength and low temperature toughness of the 9NiCrMo steel were investigated and the mechanism was analyzed. The results show that the lamellarizing temperature affects the content of reverted austenite of the steel; when the lamellarizing temperature is 750 ℃,the content of reverted austenite in the tested steel reaches the maximum,which means that toughness of the steel is the best when lamellarized at this temperature; QLT treatment can greatly improve the tempering stability of 9NiCrMo steel effectively without reducing the strength,which is conducive to industrial production.