High strength thin steel sheet excellent in hole expansibility, ductility and chemical treatment characteristics, and method for production thereof

A chemical conversion and treatment performance technology, applied in heat treatment furnaces, manufacturing tools, heat treatment equipment, etc., can solve the problems of poor adhesion of coating films, inability to form chemical conversion films well, etc.

Active Publication Date: 2006-02-08
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, sometimes there are problems such as: the chemical conversion film cannot be formed well (the performance of the chemical conversion film is poor), and the adhesion of the coating film after painting is poor.

Method used

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  • High strength thin steel sheet excellent in hole expansibility, ductility and chemical treatment characteristics, and method for production thereof
  • High strength thin steel sheet excellent in hole expansibility, ductility and chemical treatment characteristics, and method for production thereof
  • High strength thin steel sheet excellent in hole expansibility, ductility and chemical treatment characteristics, and method for production thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0046] Converter smelting steel with the chemical composition shown in Table 1-1 and Table 1-2 (content is mass %, blank composition column means no addition) is made into billet by continuous casting. Hot-rolling conditions Rolling and cooling were performed to produce hot-rolled steel sheets with a plate thickness of 2.6 mm (Examples 1-16, Comparative Examples 1-3) and 3.2 mm (Examples 17-32, Comparative Examples 4-6). In addition, the speed of rapid cooling is respectively set to 40°C / sec (Examples 1-15, Comparative Examples 1-4), 120°C / sec (Examples 16-30, Comparative Example 5), and 300°C / sec ( Examples 31, 32, Comparative Example 6), the air cooling time was set to 10 seconds (Examples 1-32, Comparative Examples 1-6). Among them, the finishing temperature of hot rolling was 900° C. (Examples 1 to 32, Comparative Examples 4 to 9) and 930° C. (Comparative Examples 1 to 3).

[0047] The hot-rolled steel sheets thus obtained were subjected to tensile tests, hole expansion t...

Embodiment 2

[0064] Steels having the compositions shown in Table 3-1 and Table 3-2 were melted, and slabs were produced by continuous casting according to a conventional method. Examples 33 to 58 are steels with components according to the present invention, the steel of Comparative Example 10 has the addition amount of C and P outside the range of the present invention, and the steel of Comparative Example 11 has the addition amount of Mn outside the range of the present invention In addition, the steel of Comparative Example 12 has an addition amount of Al outside the scope of the present invention, the steel of Comparative Example 13 has an addition amount of Si and Al outside the scope of the present invention, and the steel of Comparative Example 14 has Si, Ti, The addition amount of V is outside the range of the present invention, the addition amount of Si and Nb in the steel of Comparative Example 15 is outside the range of the present invention, and the addition amount of Al in the...

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Abstract

This invention Provides a hot-rolled high strength thin steel sheet which is excellent in hole expansibility, ductility and chemical treatment characteristics. Said steel sheet has a chemical composition, in mass %: C: 0.02 to 0.08 %, Si: 0.50 % or less, Mn: 0.50 to 3.50 %, P: 0.03 % or less, S: 0.01 % or less, Al: 0.15 to 2.0 %, and the balance: Fe and inevitable impurities, with the proviso that the formula: Mn + 0.5 X Al < 4 is satisfied, and has a metal structure wherein ferrite having a particle size of 2 Mum or more accounts for 40 area % or more. The thin steel sheet has a tensile strength of 590 N/mm<2> or more.

Description

technical field [0001] The invention relates to a high-strength hot-rolled steel sheet with excellent hole expandability, ductility, and chemical conversion film-forming performance and a manufacturing method thereof. The hot-rolled steel sheet is mainly used for press-processed automobile running parts, etc. It is about 0.6~6.0mm, with 590N / mm 2 or above strength. Background technique [0002] In recent years, taking advantage of the environmental issues of automobiles, there has been an increasing demand for reducing the weight of the vehicle body, integral molding of parts, and rationalization of the processing process as a measure to reduce fuel costs, thereby promoting the development of excellent press workability Development of high-strength hot-rolled steel sheets. In the prior art, as a high-strength hot-rolled steel sheet with such excellent workability, the well-known structures of this steel sheet include: ferrite-martensite structure, ferrite-bainite structure...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C22C38/06C22C38/14C21D9/46B21B1/26B21B3/00
Inventor 冈本力谷口裕一
Owner NIPPON STEEL CORP
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