在线控冷对热轧L360管线管组织和性能的影响

摘要 针对热轧无缝钢管组织性能调控手段单一，依赖添加合金元素和离线热处理的问题，以轧板模拟轧管的方式，通过实现在线控制冷却将离线热处理工艺在线化，研究分析了热轧L360高温轧制后在线控冷条件下显微组织演变及力学性能变化规律.结果表明:高温轧制后空冷时实验钢中含有粗大的魏氏组织，而轧后控制冷却工艺下实验钢组织显著细化，有利于微合金碳氮化物析出.实验钢轧后控冷至650℃时，能够避开魏氏组织形成的区间，同时屈服强度为478MPa，抗拉强度为641MPa，伸长率达到25.3%，屈强比0.74，0℃冲击功高达164J，实现了强度、韧性和塑性的平衡，各项力学性能指标均能满足API SPEC 5L—2012标准要求.
Abstract：In the view of the hot-rolled seamless steel pipe problems which lacks the way to control microstructure and mechanical properties， depends on the addition of alloying element excessively and uses an off-line heat treatment， an online cooling after rolling treatment is used to replace off-line treatment by means of the plate rolling instead of tube rolling. The effects of different cooling strategy on the microstructure and mechanical properties of a typical hot-rolled L360 steel pipe is studied. The results show that compared with air cooling treatment which easily causes a coarse Widmanstatten structure in L360 steel， the cooling after rolling treatment can promote the precipitation of microalloying elements， refine Widmanstatten structure and improve mechanical properties of the steel. When cooling temperature is controlled at 650℃， the formation of Widmansatten structure is reduced effectively and the balance of strength， toughness and plasticity of L360 steel can be achieved with the yield strength of 478MPa， the tensile strength of 641MPa， the elongation of 25.3%， the yield ratio of 0.74 and the impact energy at 0℃ of 164J， respectively， which meet the requirements of the standard of API SPEC 5L—2012.