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Obtaining method of large deformation pipe line steel double phase structure

A dual-phase microstructure and acquisition method technology, applied in heat treatment equipment, heat treatment process control, manufacturing tools, etc., can solve the problem of duplex microstructure photos and stress-strain curves without providing manufacturing process plans, large-deformation duplex microstructure, production methods and The process has not been publicly reported and other issues

Inactive Publication Date: 2015-02-04
XI'AN PETROLEUM UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

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

Method used

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  • Obtaining method of large deformation pipe line steel double phase structure
  • Obtaining method of large deformation pipe line steel double phase structure
  • Obtaining method of large deformation pipe line steel double phase structure

Examples

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Embodiment 1

[0027] A method for obtaining a dual-phase structure of X70 steel grade large deformation pipeline steel, comprising the following steps:

[0028] Step 1: Determine the chemical composition of the steel (as shown in the table below): the units of the following parameters are mass percentages

[0029]

[0030] Step 2: The continuous cooling transformation curve of steel, such as figure 1 The CCT curve shown;

[0031] Step 3: According to the continuous cooling transformation curve, the cooling rate of the moderately accelerated cooling for obtaining the dual-phase structure of the steel is determined to be in the range of 37-46°C / s;

[0032] Step 4, determining that the range of the phase transition point corresponding to the cooling rate range is 663-660°C;

[0033] Step 5. Determine the starting cooling temperature of the steel as 680° C. and the cooling rate as 40° C. / s according to the determined phase transition point and cooling rate range;

[0034] Step six, adopti...

Embodiment 2

[0046] A method for obtaining a dual-phase structure of X80 steel grade large deformation pipeline steel, comprising the following steps:

[0047] Step 1: Determine the chemical composition of the steel (as shown in the table below): the units of the following parameters are mass percentages

[0048]

[0049] Step 2: The continuous cooling transformation curve of steel, such as Figure 4 shown;

[0050] Step 3: According to the continuous cooling transformation curve, the cooling rate of the moderately accelerated cooling for obtaining the dual-phase structure of the steel is determined to be in the range of 45-55°C / s;

[0051] Step 4, determine the range of the phase transition point corresponding to the cooling rate range (700-708°C);

[0052] Step 5. Determine the starting cooling temperature of the steel as 720° C. and the cooling rate as 50° C. / s according to the determined phase transition point and cooling rate range;

[0053] Step six, adopting the moderately acc...

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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...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D8/02C21D8/10C21D11/00C22C38/58C22C38/50
Inventor 张骁勇高惠临刘文婷徐学利
Owner XI'AN PETROLEUM UNIVERSITY
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