大直径X90M管线钢的开发与试制

采用超低碳Mn-Mo-Ni-Cr-Cu合金设计和TMCP工艺,开发了板厚为16.3 mm和19.6 mm大直径(1 219 mm)X90M管线钢。结果表明,两种试验钢轧态性能较好,以细小粒状贝氏体+针状组织+细小弥散分布M-A岛的组织构成,具有较佳的强韧性匹配。屈服强度为603~641 MPa,抗拉强度为761~815 MPa,屈强比在0.81以下,-15℃冲击功大于300 J,-20℃落锤撕裂(DWTT)剪切面积大于85%;并且16.3 mm X90M韧塑性明显优于19.6 mm X90M;制管后随着扩径率的提高,强度与屈强比上升,同时均匀延伸率与低温韧性下降,但屈强比仍小于0.93,其均匀延伸率大于5%,且-15℃冲击功大于220 J。

Development and Trial Production of X90M Pipeline Steel with Large Diameter

An uhra-low carbon Mn-Mo-Ni-Cr-Cu for pipeline steel was designed to produce two kinds of 1 219 mm diameter X90M （thickness of 16.3 mm and 19.6 ram） by means of using thermo-mechanical controlled process. The results showed that the performance of these hot rolled X90M were fine and the microstructure composed with fine granular bainite＋acicular structure＋ uniformly distributed M-A island organization, which provided better strength and low temperature toughness. The yield strength could reach 603-641 MPa and tensile strength improved to761~815 MPa; The value of Rp02/Rm was below than 0.81 and the Charpy V-notch impact energy measured at -15 ℃ was over than 300 J and the shear area of DWTT specimens tested at -20 ℃ was greater than 85%; The toughness and plasticity of 16.3 mm X90M was over 19.6mm; However, with diameter expansion rate increasing, the strength and yield ratio increased, simuhaneously, the uniform elongation and low temperature toughness decreased, but the yield ratio was less than 0.93 and the uniform elongation rate was more than 5%, and impact energy at -15 ℃ was still above than 220 J.