两相区热处理工艺对9NiCrMo钢强韧性的影响

 研究了淬火＋回火（QT）和淬火＋两相区淬火＋回火（QLT）2种热处理工艺对9NiCrMo钢力学性能的影响，分别采用OM和SEM观察了微观组织结构，利用X射线衍射和透射电镜研究了不同热处理后逆转变奥氏体的含量及其分布，进而分析了该工艺对9NiCrMo钢力学性能的影响规律及其机理。结果表明：两相区热处理能够在保证强度级别的同时，有效改善9NiCrMo钢的低温韧性，生成的双相组织及改变了逆转变奥氏体的分布状态是其提高钢低温韧性的主要原因。

Effect of Quenching,Lamellarizing and Tempering Process on Strength and Toughness of 9NiCrMo Steel

The mechanical properties of 9NiCrMo steel subjected to quenching and tempering (QT) and quenching, lamellarizing and tempering (QLT) heat treatments was investigated, and the microstructure was systematically studied by means of optical microscope(OM) and scanning electron microscope (SEM). Moreover, quantity and distribution of reversed austenite in 9NiCrMo steel after QLT heat treatment was studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Based on the experimental results, the effect and mechanism of QLT heat treatment on mechanical properties of 9NiCrMo steel were analyzed. The results indicate that QLT heat treatment can improve the cryogenic toughness of 9NiCrMo steel effectively without reducing the strength. And dual phase structure and the changed distribution of the reversed austenite after QLT heat treatment are the main reasons which improve the cryogenic toughness.