High-strength steel sheet

A high-strength steel plate and width technology, applied in the direction of furnace type, furnace, heat treatment furnace, etc., can solve the problem of reduced processability of steel materials, and achieve the effect of cost reduction and excellent corrosion resistance

Active Publication Date: 2012-07-25
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] In general, the workability of steel materials decreases as the strength increases

Method used

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  • High-strength steel sheet
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  • High-strength steel sheet

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0112] Steels having the compositions shown in Table 1 were smelted in a converter, and billets were produced by continuous casting. Next, these steel slabs were heated, hot-rolled, and coiled under the conditions shown in Table 2 to produce hot-rolled steel sheets with a thickness of 2.0 mm.

[0113] Table 1

[0114]

[0115] The microstructure of the obtained hot-rolled steel sheet was analyzed by the method shown below to determine the amount of Ti and V contained in precipitates smaller than 20 nm, and the amount of solid solution V. In addition, the tensile strength: TS, and stretch flange properties after processing: λ were obtained by the methods shown below 10 And corrosion resistance after painting: the maximum peeling width on one side of SDT, and evaluate it.

[0116] Microstructural Analysis

[0117] The hot-rolled steel sheet obtained above was cut into an appropriate size, and about 0.2 g was dissolved at 20 mA / cm 2 constant current electrolysis.

[0118]...

Embodiment 2

[0134] Steels having the compositions shown in Table 3 were smelted in a converter, and billets were produced by continuous casting. Next, under the conditions shown in Table 4, these steel slabs were heated, hot rolled, and coiled to produce hot-rolled steel sheets with a thickness of 2.0 mm.

[0135] table 3

[0136]

[0137] For the obtained hot-rolled steel sheet, the microstructure was analyzed by the same method as in Example 1, and the amount of Ti and V contained in precipitates smaller than 20 nm, and the amount of solid solution V were determined. In addition, the tensile strength: TS and the stretch flange property after processing: λ were obtained by the same method as in Example 1 10 And corrosion resistance after painting: the maximum peeling width on one side of SDT, and evaluate it.

[0138] Table 4 shows the results obtained above.

[0139]

[0140] According to Table 4, it can be seen that the TS of the example of the present invention is more than 7...

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Abstract

The invention provides a high-strength steel sheet excellent in stretch-flange characteristics after working and in corrosion resistance after coating. A steel sheet which has a composition containing by mass C: 0.02 to 0.20%, Si: 0.3% or below, Mn: 0.5 to 2.5%, P: 0.06% or below, S: 0.01% or below, Al: 0.1% or below, Ti: 0.05 to 0.25%, and V: 0.05 to 0.25% with the balance consisting of Fe and unavoidable impurities and a substantially ferrite single-phase structure wherein the contents of Ti, V, and solid-soluted V in precipitates of less than 20nm in size are 200 to 1750 mass ppm, 150 to 1750 mass ppm, and 200 to less than 1750 mass ppm respectively.

Description

technical field [0001] The present invention relates to a high-strength steel sheet excellent in stretch flangeability after processing and corrosion resistance after painting. Background technique [0002] Automobile chassis and truck frames require formability (mainly elongation and stretch flange properties), so steels with a tensile strength of 590 MPa have been used in the past. However, in recent years, from the viewpoint of reducing the environmental load of automobiles and improving impact properties, the strength of steel sheets for automobiles has been increased, and studies on the use of steels with a tensile strength of 780 MPa class have begun. [0003] In general, the workability of steel materials decreases as the strength increases. Therefore, studies on steel sheets having high strength and high workability have been started. Examples of techniques for improving elongation and stretch-flange properties include Patent Documents 1 to 6. [0004] Patent Docu...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/14C22C38/38C21D8/02C21D9/46
CPCC21D8/0426C22C38/04C22C38/14C22C38/06C21D9/48C22C38/28C22C38/12C21D2211/004C21D2211/005C22C38/24
Inventor 中川功一横田毅中村展之濑户一洋城代哲史山田克美
Owner JFE STEEL CORP
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