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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690MPa,其伸长率为12%,-20℃夏比冲击功不低于195J。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。
With the appropriate TMCP process, reducing the content of Mn, Mo, Cr and other elements, the successful preparation of a low carbon equivalent pipeline steel. The results show that the yield strength of the developed ultra high strength pipeline steel can reach 690MPa, the elongation is 12%, and the Charpy impact energy at -20 ℃ is not less than 195J. The match of high strength and toughness of the pipeline steel mainly comes from the effect of phase transformation and grain refinement. The base metal of steel is composed of bainite and MA component, and the coarsening zone and fine grain zone of heat affected zone Compared with the base metal, there was no decrease in hardness and impact toughness. The ductile low in the whole heat-affected zone was only 40 J lower than the base metal in the (α + γ) two-phase region, indicating that the 690 MPa grade Pipeline steel has good toughness match.