Abstract: The mechanical properties and micro structure of microalloying pipeline steel X70 ( % ：0. 04C, 1. 54Mn, 0. 05Nb, 0. 04V, 0. 01Ti, 0.003 9N) of 14. 6 mm sheet continuous rolled from 150 mm casting slab have been tested and analyzed. Results show that with adding micro niobium and after breakdown with control rolling by deformation N70% at ≤950 °C , finishing rolling at 800 ℃ , then cooling to 500 -550 °C with 20 ~30 ℃/s, the structure of X70 pipeline steel at ambient temperature is typical acicular ferrite with grain size 2 ~ 5 μm, which has excellent comprehensive mechanical properties i. e. σ_0.5≥565 MPa, σ_b≥655 MPa and Cv at -20℃≥212 J.

Key words: X70, Control-Rolling, Acicular Ferrite, Metal Strengthening

摘要： 测试和分析了由150 mm铸坯连轧成14.6 mm微合金化管线钢X70(%:0.04C、1.54Mn、0.05Nb、0.04V、0.01Ti、0.003 9N)的力学性能和显微组织。结果表明,通过加入微量Nb与开坯后≤950℃进行变形量≥70%的控制轧制,终轧800℃并以20～30℃/s冷至500～550℃,管线钢X70的室温组织为典型的针状铁素体,晶粒尺寸2～5μm,具有良好的综合力学性能,即σ_0.5≥565 MPa,σ_b≥655 MPa,Cv(-20℃)≥212 J。

关键词: X70, 控制轧制, 针状铁素体, 金属强化