新型超高强管线钢的组织与性能研究
Microstructure and Properties of New Ultra-high Strength Pipeline Steel
刘文月, 任 毅, 张 帅, 王 爽
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作者单位：鞍钢股份有限公司 技术中心, 辽宁 鞍山 114009
中文关键字：管线钢； 组织； 热影响区； 性能
英文关键字：pipeline steel; microstructure; heat affected zone (HAZ); properties
中文摘要：通过配合合适的TMCP工艺，降低了Mn、Mo、Cr等元素的含量，成功制备了一种低碳当量管线钢。结果表明，所开发的超高强度管线钢的屈服强度可达690 MPa，其伸长率为12%， -20 ℃夏比冲击功不低于195 J。该管线钢的超高强度与高韧性匹配主要来源于相变与晶粒细化的作用；钢的母材组织由贝氏体以及MA组元构成，热影响区粗晶区与细晶区组织与母材组织相近，没有出现硬度降低与冲击韧性下降的现象；整个热影响区的韧性低谷在(α+γ)两相区，其冲击功仅比母材低40 J，这说明690 MPa级管线钢具有良好的强韧性匹配。
英文摘要：A low carbon pipeline steel was developed by appropriate TMCP, which can decrease the content of Mn,Mo and Cr. The results show that the yield strength of ultrahigh strength pipeline steel reaches 690 MPa. The Charpy impact toughness at -20 ℃ is not lower than 195 J and the tensile elongation is 12%. The combination of ultrahigh strength and good toughness is mainly derived from fine grain size and phase transformation. The microstructure is characterized by bainitic ferrite and martensite-austenite (MA) constituents. The microstructure and properties of heat-affected zone (HAZ) is similar to those of the base metal. The (α+γ) zone has the lowest toughness, which is 40 J lower than the base. So it can conclude that 690 MPa pipeline steel has an excellent strength-toughness combination.