High-strength steel plate having excellent formability, and production method for same

A technology of high-strength steel sheet and manufacturing method, which is applied in the directions of manufacturing tools, furnace types, metal rolling, etc., can solve the problems of difficult hot-dip galvanized steel sheet manufacturing, sufficient stretch flange formability, etc., and achieves both formability and The effect of hot dip galvanizing

Active Publication Date: 2012-10-03
NIPPON STEEL CORP
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

Therefore, it is difficult to use it for the manufacture of hot-dip galvanized steel sheets using conventional production lines
[0006] Patent Documents 3 to 6 describe various indexes related to formability, but it is difficult to achieve sufficient formability in stretch flange forming of automotive parts only if these indexes are adjusted within a predetermined range.

Method used

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  • High-strength steel plate having excellent formability, and production method for same
  • High-strength steel plate having excellent formability, and production method for same
  • High-strength steel plate having excellent formability, and production method for same

Examples

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Embodiment

[0129]Next, experiments performed by the present inventors will be described.

[0130] First, steels of Example Nos. 1 to No. 34 and Comparative Examples No. 35 to No. 52 having the compositions shown in Table 1 were produced using a vacuum melting furnace. Next, after cooling and solidifying the steel, it is reheated to 1200° C. and then hot rolled at 880° C. for finish rolling. Thereafter, it was cooled to 500° C. and kept at 500° C. for 1 hour to obtain a hot-rolled sheet. This holding at 500° C. for 1 hour reproduces the heat treatment at the time of coiling for hot rolling. Next, the scale was removed from the hot-rolled sheet by pickling, and then cold-rolled at the cold-rolling ratio r shown in Table 4 to obtain a cold-rolled sheet. Next, using a continuous annealing simulator, the temperature of the cold-rolled sheet was raised at a temperature rise rate V shown in Table 4, and annealed at 770° C. for 60 seconds. Then, hot-dip galvanizing is performed, alloying trea...

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Abstract

Disclosed is a high-strength steel plate wherein the Al content (%) and the Si content (%) conform to the relationship delimited by formula (A), and the average value Yave as defined by formula (B), which relates to the hardness as measured at 100 or more locations by means of a nanoindenter is 40 or higher. Formula (A): 0.3 = <0.7 * [Si] + [Al] =< 1.5 Formula (B): Yave = Sigma(180 * (Xi - 3)-2 / n) (Therein, [Al] represents the Al content (%), [Si] represents the Si content (%), n represents the total number of hardness measurement locations, and Xi represents the hardness (GPa) at the i-th measurement location (with i being an integer not greater than n))

Description

technical field [0001] The present invention relates to a high-strength steel sheet having excellent formability suitable for vehicle bodies and the like, and a method for producing the same. Background technique [0002] In recent years, in order to improve the fuel consumption of automobiles, it is required to further reduce the weight of the vehicle body. In order to reduce the weight of the car body, it is sufficient to use a high-strength steel plate, but the higher the strength, the more difficult it is to press and form it. This is because generally the higher the strength of the steel plate, the more the yield stress of the steel plate increases, and thus the more the elongation decreases. In addition, as high-strength steel sheets for vehicle bodies, steel sheets subjected to chemical conversion treatment such as hot-dip galvanized steel sheets or phosphate treatments may also be used. Therefore, such high-strength steel sheets are also required to have good hot-d...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00B21B3/00C21D9/46C22C38/06C22C38/38C23C2/06C23C2/40
CPCC22C38/02C22C38/002C23C2/02C23C2/28C21D9/48C22C1/02C23C2/06C22C38/12C22C38/04C21D2211/005C21D8/0436C21D2211/002C21D9/46C23C2/26C21D2211/008C22C38/06C21D8/04C21D8/0473C22C38/001C22C38/18C22C38/00C22C38/38Y10T428/12799C23C2/024C23C2/0224
Inventor 野中俊树松谷直树小川登志男藤田展弘
Owner NIPPON STEEL CORP
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