Obtaining method of large deformation pipe line steel double phase structure

Abstract

The invention relates to an obtaining method of a large deformation pipe line steel double phase structure. The obtaining method comprises the following steps: 1, carrying out compound design on a small part of pipe line steel according to design requirements; 2, determining a continuous cooling transformation curve (CCT curve) of the small part of the designed steel, wherein the CCT curve reflects a structure transformation law of the steel at different cooling rates; 3, selecting a cooling rate range meeting a requirement of bainite and ferrite double phase structure formation on the CCT curve; 4, determining various phase change points corresponding to the cooling rate range; and 5, determining the most important process parameters during steel manufacturing according to the determined phase change points, wherein the two most important process parameters comprise a cooling temperature and a cooling rate. According to the present invention, according to the existing process, the obtained cooling temperature and the obtained cooling rate are adopted to carry out batch production of steel plates, wherein a uniform elongation rate of the obtained double phase structure large deformation pipe line steel can be more than 12%, a working hardening index can be more than 0.15, and a yield ratio can be less than 0.77 so as to meet requirements on the large deformation pipe line steel in the standard.

Description

technical field [0001] The invention relates to a production method of large-deformation pipeline steel for long-distance pipelines in the petroleum industry, in particular to a method for obtaining a dual-phase structure of large-deformation pipeline steel. Background technique [0002] Large-deformation pipeline steel is a new type of pipeline structural material developed for oil and gas long-distance pipelines passing through geologically complex areas (landslides, earthquakes, frozen soil, etc.), in order to reduce the possible deformation damage to the pipeline caused by stratum movement. The typical structure of this new type of pipeline steel is composed of a soft matrix phase and a hard second phase of the dual-phase structure, and its performance characteristics are based on high strength and toughness, with a high deformation strengthening index (>0.1), Larger uniform elongation (>8%) and lower yield ratio (<0.8), so it has the ultimate deformation abilit...

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Problems solved by technology

[0003] At present, in the world, large deformation pipeline steel is only produced in a small amount in Japan, the United States and other countries, but there is no public report on its production method and process

Relevant units in China have also conducted research, but the disclosed content only involves the composition and the final test performance, and neither provides a specific manufacturing process plan nor a dual-phase structure photo and stress-strain curve. The direct evidence of large deformation duplex structure

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