High-strength composite steel sheet having excellent moldability and delayed fracture resistance

A composite structure, high-strength technology, used in furnace types, furnaces, heat treatment furnaces, etc., can solve the problem of insufficient delayed damage, and achieve excellent resistance to delayed damage, good tensile flanging, and excellent spot weldability. Effect

Inactive Publication Date: 2009-06-17
KOBE STEEL LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this type of steel has been studied mainly with a tensile strength of 900 MNPa or less, and for 980 MPa or higher, the delayed failure that is particularly a problem is not sufficiently considered.

Method used

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  • High-strength composite steel sheet having excellent moldability and delayed fracture resistance
  • High-strength composite steel sheet having excellent moldability and delayed fracture resistance
  • High-strength composite steel sheet having excellent moldability and delayed fracture resistance

Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0083]Hereinafter, the present invention will be described more specifically with examples, but the present invention is not limited by the following examples, and can be modified and implemented within the appropriate range of the present invention without departing from the scope of the preceding and following, which are all included in the technical scope of the present invention.

experiment example

[0085] After smelting the steel materials of the composition shown in Table 1, after continuous casting, hot rolling, pickling, and cold rolling were carried out under the following conditions, and then, according to Table 2 (refer to figure 1 ) under the conditions indicated by heat treatment (annealing), thereby obtaining a cold-rolled steel sheet.

[0086] hot rolled

[0087] Heating temperature: 1200℃×60 minutes

[0088] Completion temperature: 880°C

[0089] Cooling: cooling to 720°C at 40°C / sec, cooling to 500°C at 40°C / sec after air cooling for 10 seconds, followed by furnace cooling at 500°C for 60 minutes.

[0090] Finished plate thickness: 3.2mm

[0091] pickling, cold rolling

[0092] After pickling, it is cold rolled to a plate thickness of 1.2 mm.

[0093] Heat treatment (annealing)

[0094] As shown in Table 2, after heating to the specified annealing temperature for 180 seconds, cool to the specified cooling stop temperature at a specified rate, and keep a...

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Abstract

Disclosed is a high-strength composite steel sheet having a tensile strength of 980 MPa or greater and excellent in moldability, delayed fracture resistance and spot weldability. The steel sheet comprises a steel having the following chemical composition: C: 0.12-0.25%, Si: 1.0-3.0%, Mn: 1.5-3.0%, P: 0.15% or less, S: 0.02% or less, Al: 0.4% or less, and Cr: 1.0% or less, with the remainder being iron and unavoidable impurities, wherein the contents of Si, Al, Mn and Cr satisfy the relationship expressed by the following formula: (Si+Al) / Mn or (Si+Al) / (Mn+Cr)=0.74-1.26 and the steel sheet has a specified microstructure.

Description

technical field [0001] The present invention relates to, for example, having a tensile strength of 980 MPa or higher, excellent formability and delayed fracture resistance (anti-delayed fraction property), and excellent spot weldability, as automotive structural members (columns, beams, reinforcements, etc.) Useful high-strength composite tissue steel plates such as body skeleton materials, cushioning materials, door handles, plate parts, walking parts and other reinforcement members). Background technique [0002] In recent years, the demand for high-strength steel sheets has increased for the purpose of reducing fuel consumption by reducing the weight of automobiles and the like and ensuring safety during collisions. Followed by the requirements for the tensile strength of the steel plate, from the existing 590MPa level requirements to 980MPa level or more. However, forming a high-strength steel sheet of the 980 MPa class or higher inevitably reduces the formability, and ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C22C38/06C22C38/38C21D9/46
CPCC22C38/04C21D9/46C22C38/02C22C38/08C22C38/14C22C38/16C22C38/38C22C38/58C22C38/002C22C38/005C22C38/12
Inventor 中屋道治向井阳一杉本公一
Owner KOBE STEEL LTD
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