Abstract: Microstructure and properties of Φ457 mm×70 mm 12Cr1MoVG steel pipe （/% ： 0.13C， 0.21Si， 0.56Mn， 1.07Cr， 0.31Mo， 0.20V， 0.008P， 0.004S， 0.02Ni， 0.004Cu， 0.012 4Al） after 1 000 ℃ normalizing plus using water mist accelerated cooling and 740 ℃ tempering were studied by means of microstructure observation， tensile test ， impact test at room temperature， hardness test and high temperature durability test. The results showed that the microstructure consisted of ferrite and bainite， with the volume of bainite accounting for 65%， and the grain size of 7-5 grade. Yield strength was 416 MPa， tensile strength was 575 MPa， impact energy at room temperature was 206-244 J， brinell hardness was 187HBW. The endurance strength under 575 ℃×10⁵ h was 86 MPa. It lasted 51 480 hours at 575 ℃/100 MPa unbroken. After 27 198 hours， it cracked under 575 ℃/120 MPa， and the crack originated from grain boundary creep pores， no serious spheroidization was found in the bainite matrix surrounding. The structure stability was excellent.

Key words: 12Cr1MoVG Steel Pipe with Thick-wall, Microstructure and Properties Control, Bainite, High Temperature Endurance Strength

摘要： 通过显微组织观察和室温拉伸试验、室温冲击试验、硬度试验和高温持久性能试验，研究了Φ457 mm×70 mm 12Cr1MoVG（/%：0.13C，0.21Si，0.56Mn，1.07Cr，0.31Mo，0.20V，0.008P，0.004S，0.02Ni，0.004Cu，0.012 4Al）钢管在1 000 ℃正火后采用水雾加速冷却和740 ℃回火的组织和性能。结果表明：显微组织为铁素体+贝氏体，贝氏体量约占65%，晶粒度7～5级；屈服强度为416 MPa，抗拉强度为575 MPa，室温冲击功为206～244 J，布氏硬度187HBW；575 ℃×10⁵ h持久强度为86 MPa；575 ℃/100 MPa持久51 480 h未断；575 ℃/120 MPa持久27 198 h断裂，试样开裂起源于晶界蠕变孔洞，周边贝氏体基体没有发现严重的球化等现象，组织稳定性优异。

关键词: 12Cr1MoVG厚壁钢管, 组织与性能控制, 贝氏体, 高温持久强度