High strength steel plate with excellent delayed destruction resistance characteristics and low temperature toughness, and high strength member manufactured using same

A high-strength steel plate and high-strength technology, which is applied in the manufacture of tools, transportation and packaging, chemical instruments and methods, etc., can solve the problems of insufficient low-temperature toughness, inability to be used for rolling, and reduced yield, so as to expand the scope of application , Excellent delayed fracture resistance and low temperature toughness

Active Publication Date: 2015-12-23
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the low-temperature toughness is not necessarily sufficient, and especially when the C (carbon) concentration is high, casting defects occur frequently, which means that it cannot be used for rolling, or even if it can be used for rolling, the yield is significantly reduced.
[0015] In t

Method used

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  • High strength steel plate with excellent delayed destruction resistance characteristics and low temperature toughness, and high strength member manufactured using same
  • High strength steel plate with excellent delayed destruction resistance characteristics and low temperature toughness, and high strength member manufactured using same
  • High strength steel plate with excellent delayed destruction resistance characteristics and low temperature toughness, and high strength member manufactured using same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0134] Using a small melting furnace, experiments were carried out to melt and cast raw materials. The composition is adjusted so that it contains C: 0.36%, Mn: 1.3%, P: 0.02%, S: 0.004%, Cr: 0.2%, B: 0.0025%, Ti: 0.01%, Al: 0.002%, N: 0.003%, O: 0.0150%, and the rest are Fe and unavoidable impurities.

[0135] Thereafter, a predetermined amount of Si was added, and 90 seconds later, it was poured into a mold having an inner dimension (in mm) of 110×220×400 (maximum height). The amount of added Si is calculated from the concentration when generated in the total amount of slab, and is set to 0 (no addition) to 0.3%. The 220×400 solidification surface (two surfaces) of the slab was ground by 5 mm each, and the occurrence of defects due to air bubbles was examined. Furthermore, the slab was hot-rolled from 110 to 30 mm. The hot-rolled material is analyzed to examine the concentration of the main components. Table 1 shows the above results.

[0136]

[0137] A large number...

Embodiment 2

[0140] Using a small melting furnace, the raw materials are melted and the composition is adjusted so that it contains C: 0.3%, Mn: 1.3%, P: 0.02%, S: 0.004%, Cr: 0.2%, B: 0.0020%, Ti: 0.01 %, Al: 0.002%, N: 0.004%, O: 0.0150%, and the remainder is Fe and unavoidable impurities.

[0141] Thereafter, Si was added to the molten metal at a concentration of 0.15%, and the time from addition to casting was changed at intervals of 30 seconds, and casting was repeated 5 times in the mold.

[0142] Each obtained slab was heated to 1250° C. for hot rolling, and a hot-rolled steel sheet having a thickness of 2.8 mm was produced at a finishing temperature of 900° C. The coiling temperature was set to 600°C. After pickling, cold rolling was performed to obtain a cold-rolled steel sheet with a thickness of 1.4 mm.

[0143] Table 2 shows the results of chemical component analysis of the cold-rolled steel sheets. The compositions of steel symbols 2a-1, 2a-2, 2a-3, 2a-4, 2a-5 are all withi...

Embodiment 3

[0161] Using a small melting furnace, melt the raw materials and adjust the composition so that C: 0.36%, Mn: 1.2%, P: 0.01%, S: 0.002%, Cr: 0.2%, B: 0.0025%, Ti, 0.02% , Al: 0.002%, N: 0.003%, O: 0.0160%, and the remainder is Fe and unavoidable impurities. Thereafter, Si was added to the molten metal in such an amount that its concentration became 0.16%, and casting was repeated 5 times in a mold at short time intervals after the addition for 20 seconds. They are heated to 1200° C. for hot rolling, and hot-rolled steel sheets with a thickness of 2.8 mm are produced at a finishing temperature of 900 to 910° C. The coiling temperature was set to 600°C. After pickling, cold rolling was performed to obtain a cold-rolled steel sheet with a thickness of 1.4 mm. Table 4 shows the results of chemical component analysis of the cold-rolled steel sheets. The compositions of steel symbols 3a-1, 3a-2, 3a-3, 3a-4, 3a-5 are all within the scope of the present invention.

[0162] Anneali...

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Abstract

A high strength steel plate obtained from, in mass%, the chemical components of C: 0.20-0.42%, Si: 0.06-0.5%, Mn: 0.2-2.2%, Cr: 0.1-2.5%, B: 0.0005-0.01%, O: 0.0020-0.020%, Al: 0.001-0.03%, Ti: 0.001-0.05%, N: 0.1% or less, P: 0.03% or less, and S: 0.02 or less, with the remainder being Fe and unavoidable impurities. In the steel, 5 X103/mm2 to 1 X 105/mm2 of Mn oxide with a maximum length of 1 um to 5 um are present and 1.7 X 102/mm2 to 5 X 103/mm2 of complex oxides of Mn and Si with short axial direction lengths of 1 um or more and long axial direction lengths of 10 um or less are present.

Description

technical field [0001] The present invention relates to, for example, a high-strength steel sheet suitable for a hot stamping method, and more specifically, to a high-strength steel sheet excellent in delayed fracture resistance and low-temperature toughness. This application claims priority based on Japanese Patent Application No. 2013-051953 for which it applied in Japan on March 14, 2013, and takes in the content here. Background technique [0002] In general, in the field of transportation equipment such as automobiles, efforts are being made to reduce mass using high-strength materials. In recent years, in the field of automobiles, the weight of the vehicle body has tended to increase as crash safety is ensured and new functions are installed. The amount of high-strength steel plates used is steadily increasing to offset a part of the increase in vehicle body weight, slightly improve fuel efficiency and reduce carbon dioxide emissions. [0003] In the trend of expandi...

Claims

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Application Information

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IPC IPC(8): C22C38/00C22C38/38C22C38/58C23C2/12C23C2/40C21D1/18C21D9/46
CPCB22D1/00B32B15/012C21D1/18C21D1/26C21D6/002C21D6/004C21D6/005C21D6/008C21D6/02C21D7/13C21D8/0236C21D8/0247C21D8/0436C21D8/0447C21D9/46C21D2211/001C21D2211/004C22C38/00C22C38/001C22C38/002C22C38/02C22C38/04C22C38/06C22C38/22C22C38/24C22C38/26C22C38/28C22C38/32C22C38/38C22C38/42C22C38/50C22C38/54C22C38/58C23C2/12C23C2/40Y10T428/12757Y10T428/12799Y10T428/12958Y10T428/12972Y10T428/12979B32B15/20
Inventor 棚桥浩之友清寿雅
Owner NIPPON STEEL CORP
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