High-strength hot-rolled steel sheet and method for producing same

A technology of hot-rolled steel plate and manufacturing method, applied in the direction of manufacturing tools, metal rolling, heat treatment furnace, etc., can solve the problems of reduced ductility, poor processability, difficult part forming, etc., and achieve excellent bending processability and remarkable effect Effect

Active Publication Date: 2014-09-17
JFE STEEL CORP
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

[0003] However, in general, the ductility of steel materials decreases with increasing strength, and the workability deteriorates. Therefore, when a steel plate with a tensile strength of 980 MPa or more is formed into a desired part shape, various problems may occur. Such failure
For example, when a steel plate with a tensile strength of 980 MPa or more is press-worked, cracks and necking in the bent portion become noticeable, making it difficult to form parts

Method used

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  • High-strength hot-rolled steel sheet and method for producing same
  • High-strength hot-rolled steel sheet and method for producing same
  • High-strength hot-rolled steel sheet and method for producing same

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Embodiment

[0129] Under the hot rolling conditions shown in Table 2, steel raw materials (slabs) having a wall thickness of 250 mm having the composition shown in Table 1 were hot rolled to produce hot rolled steel sheets with a thickness of 1.4 to 3.2 mm. In addition, the cooling rate described in Table 2 is the average cooling rate from finish rolling temperature to coiling temperature.

[0130] In addition, for a part of the obtained hot-rolled steel sheet, it was passed through a hot-dip galvanizing line with an annealing temperature of 720° C., and then immersed in a 460° C. plating bath (plating bath composition: Zn-0.13% by mass Al), Made of hot-dip galvanized material (GI material). In addition, for a part of the hot-dip galvanized material (GI material), it is passed through the hot-dip galvanizing production line, dipped in a plating bath, and then alloyed at 520 ° C to make an alloyed hot-dip galvanized material (GA material ). The coating weight of GI material and GA materi...

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Abstract

The present invention addresses the problem of providing: a high-strength hot-rolled steel sheet which has excellent strength and excellent processability (in particular, bending processability) at the same time; and a method for producing the high-strength hot-rolled steel sheet. In order to solve the above-mentioned problem, the present invention is characterized by: having a specific composition; having an area ratio of a ferrite phase of 95% or more; having an average crystal grain diameter of the ferrite phase of 8 mum or less; having a structure wherein the average particle diameter of carbides within the crystal grains of the ferrite phase is less than 10 nm; and having a tensile strength of 980 MPa or more.

Description

technical field [0001] The present invention relates to a high-strength hot-rolled steel sheet useful for automotive components, having a high tensile strength (TS) of 980 MPa or more and excellent workability (especially bending workability) and a method for producing the same. Background technique [0002] In recent years, from the viewpoint of protecting the global environment, in order to limit CO 2 emissions, the entire automotive industry aims to improve vehicle fuel efficiency. In order to improve the fuel efficiency of automobiles, it is most effective to reduce the weight of automobiles by reducing the thickness of used components. Therefore, the use of high-strength hot-rolled steel sheets as raw materials for automotive components has been increasing in recent years. On the other hand, since automobile parts made of steel sheets are often formed by press working or the like, steel sheets for automobile parts are required to have excellent bendability (bending wor...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00B21B3/00C21D9/46C22C38/14C22C38/60C23C2/02C23C2/06C23C2/28
CPCC23C2/28C23C2/06C22C38/54C22C38/14C21D8/0284C22C38/04C21D9/46C22C38/001C22C38/10C22C38/00C22C38/60C22C38/06B21B3/00C21D2211/005C22C38/008C22C38/002C21D8/0263C22C38/02C22C38/46C22C38/12C22C38/005C22C38/007C22C38/42C23C2/02C22C38/50C21D8/0226C21D2211/004Y10T428/12799C23C2/0224
Inventor 高坂典晃船川义正重见将人大久保英和金村笃谦
Owner JFE STEEL CORP
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