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.