Manufacturing method capable of improving plasticity of pipeline steel plate

A manufacturing method and steel plate technology, which is applied in the field of high-strength steel production, can solve unresolved problems such as yield strength ratio, and achieve the effects of stable production process, strong operability, and improved plasticity

Inactive Publication Date: 2013-08-21
NANJING IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the problem of yield ratio has not been solved by the above-mentioned process method

Method used

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  • Manufacturing method capable of improving plasticity of pipeline steel plate
  • Manufacturing method capable of improving plasticity of pipeline steel plate
  • Manufacturing method capable of improving plasticity of pipeline steel plate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] The product is commercial pipeline steel (thickness 21mm), the chemical composition is shown in Table 1, and the structure is bainite. Reheat to 810°C in the heat treatment furnace, and then hold it at this temperature for 42 minutes. Through the precipitation of Nb, V, N, etc., the loss of yield strength of the steel during heat treatment can be reduced, and the tensile strength can be greatly improved. Quenching, the cooling rate is 18°C / s. The mechanical properties of the treated plate are shown in Table 2, and the microstructure is shown in Table 2. figure 1 , ferrite has a bimodal grain size distribution structure, in which the volume fraction of grains with a diameter below 1 μm accounts for about 50%, the volume fraction of 5-10 μm grains accounts for about 35%, and the volume fraction of grains in the rest size range Fractions account for about 15%.

[0021] Table 1 Chemical composition of pipeline steel in Example 1 (wt%)

[0022] C Si mn P S ...

Embodiment 2

[0026] The product is commercial pipeline steel (plate thickness 21mm), the chemical composition is shown in Table 3, and the structure is bainite. Reheat to 780°C in a heat treatment furnace, then keep it at this temperature for 42 minutes, and cool it by air cooling after the heat preservation is over. The mechanical properties of the treated plate are shown in Table 4, the microstructure figure 2 , ferrite also exhibits a bimodal grain size distribution structure, in which the volume fraction of grains with a diameter below 1 μm accounts for about 55%, the volume fraction of 5-10 μm grains accounts for about 30%, and the volume fraction of grains in the rest size range The volume fraction accounts for about 15%.

[0027] Table 3 The chemical composition (wt%) of the pipeline steel in the example

[0028] C Si mn P S Nb V Ti Cu Cr Ni Al t 0.080 0.25 1.35 0.013 0.0027 0.026 0.020 0.012 0.25 0.15 0.16 0.025

[0029] Table 4 Mec...

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Abstract

The invention discloses a manufacturing method capable of improving the plasticity of a pipeline steel plate. The manufacturing method comprises the following steps of: reheating the pipeline steel plate at 780 to 830 DEG C, wherein the heat-preserving time is based on 2 min / mm*plate thickness; and performing water quenching or air cooling, wherein the cooling speed is 1 to 20 DEG C / s. The obtained pipeline steel metallographic structure is of a ferrite ultrafine grain structure, so the defect of low plasticity of pure ultrasonic grain steel is overcome. The volume percentage of the crystal grains with the diameter being less than 1 micron is about 50 to 55 percent, the volume percentage of the crystal grains with the diameter being 5 to 10 microns is about 30 to 35 percent, and the volume percentage of the crystal grains with other sizes is about 10 to 15 percent. According to the obtained pipeline steel plate, the yield strength is 450 to 530 MPa, the tensile strength is 670 to 760 MPa, the extension rate is more than or equal to 27 percent, and the yield ratio Rt0.2 / Rm is less than or equal to 0.70. The manufacturing method is stable in production process, high in operability and low cost, and the obtained material has excellent comprehensive performance.

Description

Technical field [0001] The present invention involves a high -strength steel production, which is specifically a manufacturing method to improve the steel plate of the pipeline. Background technique [0002] In the 21st century, steel is still the dominant structural material, and no material can fully replace steel.With the development of society and economy, the steel industry is facing three major pressures to save resources, save energy, and protect the environment.Therefore, improving steel quality, reducing costs, and developing steel materials that are friendly with human beings have greatly improved their comprehensive mechanical properties, which has become the main direction of steel material research.Among them, the use of thermal mechanical control rolling technology (TMCP) and degeneration -induced ferrite phase transformation technology (DIFT) to produce fine crystal high -strength steel at low cost is the current development direction of the metallurgical industry....

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D6/00C21D1/18C22C38/50
Inventor 崔强刘朝霞李恒坤
Owner NANJING IRON & STEEL CO LTD
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