Abstract: The production flow sheet for Nb-Ti microalloying pipeline steel X65 (/%: 0. 07C, 1. 60Mn, 0. 35Mo) is 130 t top and bottom combined blown converter-ladle argon blowing-LF-RH-250 mm X 1 500 mm slab casting-continuous rolling to 30mm plate-control cooling process. The effect of beginning rolling temperature (890 ~940 °C) in II rolling passes, cooling temperature (780 ~ 850℃) and cooling speed (8 ~ 20 ℃/s) after rolling on tensile properties, drop-weight tear test (DWTT) performance and structure of X65 steel heavy plate has been studied. Results show that with beginning rolling temperature 940 ℃ in II rolling passes and cooling speed 20 ℃/s after rolling the main structure in X65 steel heavy plate is acicular ferrite and granular bainite, the tensile strength and yield strength of plate are respectively 665 ~ 695 MPa and 495 〜520 MPa and the DWTT fibre structure ratio of plate is about 92% to meet the requirement of standard.

摘要： Nb-Ti微合金化X65管线钢(/%:0.07C、1.60Mn、0.35Mo)的生产工艺流程为130 t顶底复吹转炉-钢包吹氩-LF-RH-250 mm×1500 mm板坯连铸-连轧至30 mm板-控冷工艺。研究了第Ⅱ阶段开轧(890～940℃)轧后冷却温度(780～850℃)和冷却速度(8～20℃/s)对X65钢厚板拉伸、落锤性能和组织的影响。结果表明,Ⅱ阶段开轧温度为940℃,轧后冷却速度为20℃/s可以使X65钢厚板得到以针状铁素体和粒状贝氏体为主的组织,钢板抗拉强度665～695 MPa,屈服强度495～520 MPa,落锤纤维组织率约为92%,满足标准要求。