Abstract: The continuous cooling transformation (CCT) curves of S690 steel tube (/% : 0.15C, 0.25Si, 1.32Mn, 0.012P, 0. 005S, 0.20Cr, 0.04Al, 0.08V) with cooling rate 0. 01 ~30℃/s are measured and the effect of quenching at 890 〜970 ℃ and tempering at 600 〜690℃ on structure and mechanical properties of the steel has been studied. Results show that the phase transformation points of steel S690 seamless tube are Ac₃ 828 °C , Ac₁ 753 ℃, Ms 395 ℃, and the critical cooling rate of steel is 13 ℃/s, and there are ferrite, pearlite, bainite and martensite four transformation zone； with selecting quenching at 910 ~930 ℃, the structure of steel tube is uniform and fine with average grain size 13.9μm, and the steel has higher hardness with HRC value 42.5 ；with tempering at 615 - 675 ℃，the steel tube has uniform tempered sorbite structure and better comprehensive mechanical properties.

摘要： 测定了S690钢管（/%:0.15C,0.25Si,1.32Mn,0.012P,0.005S,0.20Cr,0.04Al,0.08V）0.01～30℃/s冷却速率下连续冷却转变（CCT）曲线,并研究了890～970℃淬火,600～690℃回火对其组织和力学性能的影响。结果表明,S690钢管相变点Ac₃为828℃,Ac₁为753℃,Ms为395℃,临界冷却速率为13℃/s,存在铁素体、珠光体、贝氏体,马氏体4个相变区;选择910～930℃淬火,钢管的组织较细小均匀,平均晶粒尺寸13.9μm,具有较高的硬度,HRC值42.5;在615～675℃回火,钢管可得到均匀的回火索氏体组织,其综合力学性能优良。