X80管线钢成分工艺与组织性能研究

Effect of Composition and Process on Microstructure and Property of X80 Pipeline Steel

研究了不同成分及终轧温度对X80管线钢组织和性能的影响。结果表明,按照不同Cr/Mo成分比和终轧温度进行试验,试验钢均获得了优异的拉伸性能,但冲击性能稍差,成分对Rt0.5有显著影响,终轧温度对性能影响不显著;在Mo和Cr总含量不变时,随Cr含量增加,屈服强度增加,但韧性有所降低;基体组织为贝氏体,晶粒细小,晶粒度为ASTM13-14级,同时在基体上均匀分布着大量细小的M-A组元;析出相为(Nb,Ti)(C,N),数量较少,颗粒尺寸大多超过150 nm,析出强化效果不大,且其破坏基体的连续性,是导致冲击性偏差的重要原因之一。

The effects of composition and final rolling temperature on the microstructure and properties of X80 pipeline steel were studied. The results indicate that the tensile strength of all the samples performs well, while the impact property of those is poor. The effect of composition on Ro.5 is notable, while the effect of final rolling temperature on the property is not notable. When the total content of Mo and Cr is fixed, the yield strength increases and impact property reduces with the content of Cr increasing. The dominating microstructure is bainite, and crystal grain size whose level between ASTM 13 and 14 is very fine. Many small M-A constituents on matrix disperse homogeneously. A few precipitates of（Nb, Ti） （C, N） appear in the steel, most of which are larger than 150 nm, so they are too big to improve the tensile properties conspicuously. The continuity of matrix is destroyed by the presence of coarse precipitates which is one of the major reasons why the impact property is poor.