新型S690低合金高强度钢Φ219 mm×14 mm无缝管的CCT曲线和调质工艺研究

A Study on CCT Curves and Quenching-Tempering Process of New HSLA Steel S690 Φ219 mm×14 mm Seamless Tube

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Ac_3为828℃,Ac_1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。

The continuous cooling transformation（CCT） curves of S690 steel tube（/% ： 0.15 C, 0. 25 Si, 1. 32 Mn,0. 012 P,0. 005 S,0. 20 Cr,0. 04 A1,0. 08 V） with cooling rate 0. 01 ～30 ℃/s are measured and the effect of quenching at890 ～ 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 ℃, 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. 9 μm, 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.