摘要
对经淬火+回火(QT)与淬火+两相区淬火+回火(QLT)工艺处理后的9Ni钢中的逆转变奥氏体含量和其对原位拉伸时裂纹形成和扩展时所起到的作用进行了观察和分析。结果表明:经QT工艺处理的钢中的逆转变奥氏体含量为2%,在裂纹扩展过程中,裂纹尖端成锐角,加剧了应力集中;经QLT处理后,钢中的逆转变奥氏体含量提高为6%,在裂纹扩展的过程中,裂纹尖端成钝角,弱化了应力集中。逆转变奥氏体并不能直接阻碍裂纹的扩展,通过提高基体的韧性,间接地阻碍裂纹的扩展,从而优化实验钢的低温韧性。
The volume fraction of reversed austenite and low temperature impact energy of 9Ni steel treated by quenching ＋ tempering （QT） and quenching＋intercritical quenching ＋ tempering （QLT） were measured in virtue of XRD and CVN. The initiation and propagation behavior of crack was observed by in-situ tensile test. The results show that the volume fraction of reversed austenite in QT-treated 9Ni steel is about 2%; the crack tip is acute angle, which can aggravate the stress concentration. However, the amount of reversed austenite in, QLT-treated steel exhibit up to 6%; the crack tip is obtuse angle, diminishes stress concentration. The reversed austenite can not hinder the propagation of crack directly, it fimctioned by toughening the matrix so as to improve the cryogenic impact toughness effectively.
出处
《热加工工艺》
CSCD
北大核心
2012年第8期177-179,183,共4页
Hot Working Technology
