电阻焊接用高强Q125级石油套管钢组织及其性能

设计了一种低合金含量的Q125级高强度石油套管用钢，研究了热处理工艺对实验钢组织和力学性能的影响．与870℃淬火＋500℃回火工艺相比，实验钢在850℃淬火＋500℃回火工艺下具有更好的强韧性配合．与870℃淬火相比，850℃淬火处理的奥氏体晶粒尺寸较小，使决定钢力学性能的晶区、板条束尺寸细化，因此其性能更优异．淬火温度对实验钢的析出行为影响不大．尺寸较大的TiN以及TiC和TiN复合析出物对奥氏体晶界起到钉扎作用，可以抑制奥氏体晶粒的长大；含有Mo的尺寸较小的TiC可以起到钉扎位错的作用，阻止位错移动，对强度的提高贡献很大．

Microstructure and mechanical properties of Q125 grade high-strength oil well casing steel used for electric resistance welding

A type of Q125 grade high-strength low-alloy oil well casing steel was designed and the effects of heat treatment processes on its microstructure and properties were investigated.Compared with the process of quenching at 870 ℃ and tempering at 500 ℃,the steel quenched at 850 ℃ and tempered at 500 ℃ has preferable combination of strength and toughness.In comparison with quenching at 870 ℃,the steel quenched at 850 ℃ has better mechanical properties because of smaller original austenite grains,which lead to a smaller size of packets and blocks.Quenching temperature has little influence on the precipitation behavior.TiN with a larger size or TiC and TiN associated precipitations can restrain original austenite grain coarsening through pitting austenite grain boundaries;TiC with a smaller size,which is rich Mo,can be an effective barrier to dislocation motion,and therefore has great contributions to improve the strength of the steel.