High-strength steel plate and method for producing same

A high-strength steel plate and a technology for manufacturing methods, which are applied in the directions of manufacturing tools, metal rolling, coating, etc., can solve the problems of deterioration of delayed fracture resistance and delayed fracture, and achieve improved collision safety and excellent delayed fracture resistance. Effect

Active Publication Date: 2021-04-09
JFE STEEL CORP
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

When a steel plate with a tensile strength of 980 MPa or higher is formed by press forming, delayed fracture may occur due to an increase in residual stress in the part or deterioration of the delayed fracture resistance of the steel plate itself.

Method used

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  • High-strength steel plate and method for producing same
  • High-strength steel plate and method for producing same
  • High-strength steel plate and method for producing same

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Embodiment

[0178] Using the steel with the composition shown in Table 1, the ingot was melted and cast under the conditions shown in Table 2. The obtained steel ingots were hot-rolled under the conditions shown in Table 2 to obtain hot-rolled steel sheets with a thickness of 2.8 mm. In addition, the coiling temperature of hot rolling was performed at 480 degreeC. Next, cold rolling was performed so that the plate thickness was 1.4 mm, and heat treatment (annealing) under the annealing conditions shown in Table 2 was performed. After annealing, temper rolling with an elongation of 0.2% was performed. It should be noted that the casting temperatures in Table 2 were obtained by actually measuring the molten steel temperature in the tundish. In addition, the solidification temperature is calculated|required from the following formula by actually measuring the component composition of steel.

[0179] Solidification temperature (°C)=1539-(70×[%C]+8×[%Si]+5×[%Mn]+30×[%P]+25×[%S]+5×[%Cu] +4×...

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Abstract

The present invention addresses the problem of providing: a high-strength steel plate having excellent delayed fracture resistance and a tensile strength of at least 980 MPa; and a method for producing same. This high-strength steel plate has a specific composition, wherein the degree of Mn segregation in a specific region is 1.5 or less, the maximum concentration of P in a specific region is 0.08 mass% or less, the number of the specific MnS particles in a specific region is 2.0 or less per 1 mm2, the number of specific oxide inclusions is 8 or less per 1 mm2, at least 80% of the oxide inclusions by number have a composition comprising 50 mass% of alumina, 20 mass% or less of silica, and 40 mass% or less of calcia, and the microstructure of the steel comprises 30-95% in total of martensite and bainite, 5-70% of a ferrite phase, and less than 3% (including 0%) of an austenite phase by volume percentage, and the tensile strength is at least 980 MPa.

Description

technical field [0001] The present invention relates to a high-strength steel sheet that is excellent in delayed fracture resistance and is suitable for use as a material for automobile parts and the like, and to a method for producing the same. Background technique [0002] In recent years, with the increasing awareness of the protection of the earth's environment, it is urgent to improve fuel consumption to reduce CO 2 emissions. As a result, there has been a growing trend to increase the strength of steel sheets used as raw materials for automobile parts, to achieve thinner parts, and to reduce the weight of vehicle bodies. When a steel sheet with a tensile strength of 980 MPa or higher is formed by press forming, delayed fracture may occur due to an increase in residual stress in the part or deterioration of the delayed fracture resistance of the steel sheet itself. Here, delayed fracture means that when a component is placed in a hydrogen intrusion environment under a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00B22D11/00B22D11/11B22D11/12C21C7/10C21D9/46C22C38/06C22C38/60C23C2/06B22D11/115
CPCC21D9/46C22C38/06C22C38/60C23C2/06C22C38/005C22C38/008C22C38/002C22C38/02C22C38/04C22C38/58C22C38/54C22C38/12C22C38/14C22C38/16C22C38/08C22C38/42C22C38/48C22C38/50B22D11/16B22D11/182C21D2211/004C22C38/001C21D2211/005C21D2211/008C21D2211/002C21D8/021C21D8/0226C21D8/0247C21D8/0273C22C38/22C22C38/32C23C2/02B21B1/04B22D11/10C21D8/0236C21D6/005C21D6/008C21D6/02C21D8/0205C21D8/0263C23C2/40
Inventor 小野义彦本田佑马吉冈真平谷口公一中村展之村井刚
Owner JFE STEEL CORP
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