两相区淬火对10Ni5CrMo钢组织与性能的影响

Effect of intercritical quenching on microstructure and properties of 10Ni5CrMo steel

研究了10Ni5CrMo钢经调质处理和淬火+两相区淬火+回火(QLT)热处理后的组织与性能。结果表明,10Ni5CrMo钢经两相区淬火处理后,得到板条状的二次回火马氏体+铁素体的混合组织,并且在板条边界及板条内部析出逆转变奥氏体,该逆转变奥氏体与基体遵从K-S关系。10Ni5CrMo钢经QLT处理后改善了钢的回火稳定性,屈强比降低,尤其是低温韧性显著提高。随着回火温度的升高,逆转变奥氏体的含量增多。稳定的逆转变奥氏体提高了低温韧性。

Microstructure and mechanical properties of 10Ni5CrMo steel were studied during quenching-and-tempering and a special heat treatment （QLT） consisting of sequential quenching （Q） ,intercritical quenching （L） and tempering （T）. The results show that the mixed microstructure of lath-like secondary tempered martensite ＋ ferrite are obtained and a small amount of reverted austenite precipitate along the boundaries and inner of martensite in QLT-treated steel. The reverted austenite keeps the K-S relation with the matrix. QLT-treated 10Ni5CrMo steel improves the tempering stability and decreases the yield ratio, especially increases the low temperature impact toughness. With higher tempering temperatures,the content of reverted austenite becomes more. Stable reverted austenite improves low-temperature impact toughness.