用实验室的D450 mm试验轧机,通过控轧控冷工艺轧制了厚度为16 mm的X80纯高温轧制工艺管线钢,对试验钢的组织及性能进行了研究.结果表明:试验钢的屈服强度达到600 MPa以上时,其屈强比为0.87,韧脆转变温度低于-60 ℃,达到了很好的强韧性匹配;试验钢中低硫、磷和高锰含量及细小的组织有效地降低了韧脆转变温度;试验钢中存在两种典型的析出物,一种以铌、Ti(CN)为主,尺寸较大(50 nm~0.2 μm),另一种为以NbC为主,尺寸较小(小于30 nm);这些纳米级析出物对钢的组织细化和强化起到了重要作用.

The structure and mechanical properties of pipeline steel X80 produced in laboratory by means of D450mm mill through controlled rolling and controlled cooling were tested.The results show that the yield strength of tested steel has reached above 600 MPa,and the ratio of tensile strength to yield strength is 0.87,and ductile-brittle transition temperature is lower than -60 ℃,and good strength and toughness are obtained.Low content of P,S,high content of Mn and fine microstructure have good effect on reducing the ductile-brittle transition temperature.Two different precipitations are observed in pipeline steel X80,and the large ones are mainly Nb,Ti(CN)with size range of 50 nm to 0.2 μm,and the small ones are mainly NbC with size lower than 30 nm.Remarkable strengthening and grain refinement can be caused by these nano-precipitations.