High-strength steel sheet, high-strength hot-dip galvanized steel sheet, high-strength hot-dip aluminized steel sheet, and high-strength electro-galvanized steel sheet, and their manufacturing methods

A high-strength steel plate and a manufacturing method technology, which are applied in the field of high-yield-ratio steel plates, can solve the problems of reduced formability of steel plates, cracks, and the inability to simply achieve thin-walled steel plates, and achieve the effects of high utilization value and improved fuel efficiency.

Active Publication Date: 2019-01-08
JFE STEEL CORP
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  • Abstract
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Problems solved by technology

[0003] However, in general, increasing the strength of the steel sheet leads to a decrease in the formability. Therefore, if the increase in strength is to be achieved, the formability of the steel sheet will decrease, and problems such as cracks during forming will occur.
Therefore, it is not possible to simply reduce the thickness of the steel plate

Method used

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  • High-strength steel sheet, high-strength hot-dip galvanized steel sheet, high-strength hot-dip aluminized steel sheet, and high-strength electro-galvanized steel sheet, and their manufacturing methods
  • High-strength steel sheet, high-strength hot-dip galvanized steel sheet, high-strength hot-dip aluminized steel sheet, and high-strength electro-galvanized steel sheet, and their manufacturing methods
  • High-strength steel sheet, high-strength hot-dip galvanized steel sheet, high-strength hot-dip aluminized steel sheet, and high-strength electro-galvanized steel sheet, and their manufacturing methods

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Embodiment

[0165] Steel having the composition shown in Table 1, with the balance consisting of Fe and unavoidable impurities, was melted in a converter and cast into slabs by continuous casting. The obtained slabs were made into the following various steel plates under the conditions shown in Table 2.

[0166] That is, after hot rolling, at Ac 1 Phase transition point above +20°C and Ac 1 Annealing below the transformation point +120°C, after cold rolling, in Ac 1 Above the phase transition point and Ac 1 Annealing is performed below the transformation point +100°C. Then, high-strength cold-rolled steel sheet (CR) is obtained, and further galvanized to obtain hot-dip galvanized steel sheet (GI), alloyed hot-dip galvanized steel sheet (GA), hot-dip aluminum-steel sheet (Al) and electro-galvanized steel sheet (EG )Wait.

[0167] It should be noted that, as a hot-dip galvanizing bath, a zinc bath containing 0.19% by mass of Al was used for a hot-dip galvanized steel sheet (GI), and a ...

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Abstract

Consisting of a predetermined composition, the steel structure is polygonal ferrite: 35% to 80%, unrecrystallized ferrite: 5% and martensite: 5% to 25% in terms of area ratio , Retained austenite in terms of volume ratio: 8% or more, and the average grain size of the polygonal ferrite is 6 μm or less, the average grain size of the martensite is 3 μm or less, and the retained austenite The average grain size of the tenite is 3 μm or less, and the value obtained by dividing the Mn amount (mass %) in the retained austenite by the Mn amount (mass %) in the polygonal ferrite is 2.0 or more, Thereby, a high-strength steel sheet having a TS of 590 MPa or more and a YR of 68% or more having excellent formability and a high yield ratio can be obtained.

Description

technical field [0001] The present invention relates to high-strength steel sheets, high-strength hot-dip galvanized steel sheets, high-strength hot-dip aluminized steel sheets, high-strength electro-galvanized steel sheets, and their manufacturing methods, and particularly aims to obtain components suitable for use in automotive, electrical and other industrial fields Steel sheet with excellent formability and high yield ratio. Background technique [0002] In recent years, improvement of fuel efficiency of automobiles has become an important issue from the viewpoint of preservation of the global environment. Therefore, there is an active movement to reduce the weight of the vehicle body itself by increasing the strength of the vehicle body material to achieve thinning. [0003] However, in general, increasing the strength of a steel sheet leads to a decrease in formability. Therefore, if the increase in strength is to be achieved, the formability of the steel sheet decrea...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/00C21D9/46C22C38/14C22C38/60C23C2/02C23C2/06C23C2/12C23C2/28C25D5/26
CPCC23C2/06C23C2/12C23C2/28C22C38/00C22C38/14C22C38/60C21D9/46C21D8/0205C21D8/0226C21D8/0236C21D8/0278C22C38/001C22C38/002C22C38/005C22C38/008C22C38/02C22C38/04C22C38/06C22C38/08C22C38/12C22C38/16C22C38/28C23C2/024C23C2/0224C21D2211/005Y02P10/20C25D3/22
Inventor 川崎由康松田广志山下孝子横田毅濑户一洋
Owner JFE STEEL CORP
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