热连轧工艺生产厚规格X80管线钢的工艺及组织性能

Process,Microstructure and Properties of Thick X80 Pipeline Steel Produced by Hot Continuous Rolling

研究了马钢热连轧生产厚规格X80管线钢的显微组织、析出物的种类、大小、分布和力学性能,研究表明:通过合理的成分设计和轧制工艺,传统热连轧生产的厚规格X80管线钢的组织均匀,合理;析出物细小弥散,其析出物为Nb、V、Ti的复合析出物,根据形态可以分为两类,第一类析出物是以含Ti为主的(Ti、Nb)(C、N)析出物,主要作用是阻止奥氏体晶粒长大;第二类析出物以含Nb为主的(Nb、Ti)C析出物,主要作用是析出强化。在充分发挥细晶强化、位错和亚晶强化和析出强化等强化机制的条件下,厚规格X80管线钢力学性能优良,屈服强度达到580 MPa,屈强比合适;-20℃的夏比冲击功和剪切面积分别为290 J和100%,-15℃的DWTT剪切面积为100%。各项性能均满足西气东输二线标准要求。

The microstructure, precipitates and mechanical properties of thick X80 pipeline steel produced by hot continuous rolling of Masteel were studied. The result shows that through reasonable composition design and rolling process , the microstructures of thick X80 pipeline steel produced by hot continuous rolling are uniform and reasonable, its precipitates are fine dispersion. The precipitates consist of Nb,V, Ti, they can be divided into two types based on their shape, one is （Ti,Nb）（C,N）in which Ti plays the main role, its main function is preventing austenite growth; another one is （Nb,Ti）C in which Nb plays the main role, its main function is precipitation strength. Under the circumstance of making full use of fine-grained strength, dislocation and sub-boundary strength, precipitation strength , the thick X80 pipeline steel has excellent mechanical properties： The yield strength is 580 MPa, the ratio of yield to strength is proper; the impact energy and shear area are respectively 290 J, 100% at -20℃ ,the DWTT shear area is 100% at - 15 ℃. All the performance meet the demand of the second West-East Gas Transmission.