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通过低碳微合金化的思路设计了Q125级ERW石油套管钢的成分,同时研究了调质热处理工艺对其组织和性能的影响。结果表明,采用920℃淬火+500℃回火调质处理后,Q125石油套管钢的屈服强度为975 MPa,抗拉强度990 MPa,伸长率为14.8%,0℃冲击功为43 J,具有良好综合力学性能和耐蚀性。通过电子背散射衍射(EBSD)分析发现,调质后以大角度晶界为边界的平均晶粒尺寸得到明显细化;扫描电镜及透射电镜分析显示,试验钢的组织为典型的回火索氏体,内含有50～160 nm残留的马氏体/贝氏体板条,且板条呈平束状或交错排列,板条内部存在对强度贡献较大的相互缠结的高密度位错亚结构。
The composition of Q125 grade ERW casing steel was designed through the idea of low-carbon micro-alloying, and the influence of quenching and tempering heat treatment on its microstructure and properties was also studied. The results show that the yield strength of Q125 oil casing steel is 975 MPa, the tensile strength is 990 MPa, the elongation is 14.8%, the impact energy at 0 ℃ is 43 J after tempered at 920 ℃ and tempered at 500 ℃, Has a good comprehensive mechanical properties and corrosion resistance. The electron backscatter diffraction (EBSD) analysis showed that the average grain size after quenching and tempering is greatly refined by the large-angle grain boundary. The SEM and TEM analyzes show that the microstructure of the test steel is typical tempered Soxhlet Containing 50 ~ 160 nm residual martensite / bainite lath, and the laths are flat beam or staggered arrangement, the lath has a greater contribution to the strength of intertwined high density dislocation sub structure.