Pipeline steel plate for HIC (hydrogen induced cracking)-resistant X80 elbow pipes and manufacturing method thereof

Abstract

The invention discloses a pipeline steel plate for HIC (hydrogen induced cracking)-resistant X80 elbow pipes. A component design principle is characterized in that a proper amount of C (carbon) and Mn (manganese) is added, a trace amount of microalloying elements of Nb (niobium), V (vanadium), Ti (titanium) and the like is added, a small amount of Mo (molybdenum), Cu (copper), Ni (nickel) and the like is added, and a particular TMCP (thermo mechanical control process) technology is combined, so as to finally ensure the mechanical properties, especially HIC-resistant property at high carbon equivalent. The manufacturing process comprises the following steps of preparing materials according to a proportional ratio; sending into a converter or an electric furnace to smelt; refining outside the converter or the electric furnace; continuously casting; reheating a plate blank; performing TMCP technology and stack cooling after water cooling; straightening. The pipeline steel plate for the X80 elbow pipe has the advantages that the particular TMCP comprises two-phase rolling and intermediate blank cooling, so that the problem of HIC-resistant property at high carbon equivalent is solved; and the HIC-resistant property of pipeline steel plate for X80 elbow pipes is excellent.

Description

technical field [0001] The invention belongs to the technical field of manufacturing steel plates for X80 bent pipes, in particular to HIC-resistant steel plates for X80 bent pipes and a manufacturing method thereof. Background technique [0002] At present, fossil energy still occupies a dominant position in the energy structure in the energy demanded by the world. The rapid growth of the world economy in recent years has greatly driven the rapid growth of fossil energy demand, which has also greatly promoted the development of long-distance transmission pipelines. Transmission efficiency, lower investment, and the development trend of steel for long-distance oil and gas pipelines is to develop towards high-strength or ultra-high steel grades. At present, the highest steel grade of pipeline steel used in countries all over the world is X80 steel grade. In addition to the straight pipe section, a pipeline project also includes elbow sections used to change the direction of ...

AI Technical Summary

Problems solved by technology

The patent application number is CN201310477888.9 The patent application mentions a heat treatment method to improve the HIC resistance of the elbow through the heat treatment process. This method is completely different from the heat simmering process commonly used at present. And because it involves two large-span temperature group intervals heat treatment , so the actual industrial production is very difficult and the production efficiency is very low, it does not have the feasibility of industrial production

[0004] Considering that the entire austenite deformation and subsequent cooling are relatively simple and insufficient in the heat simmering process, compared with the steel plate for straight pipe, when designing the steel plate for bending pipe, only high carbon equivalent composition design can be used at present.

High carbon equivalent composition design and high HIC sensitivity

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