High-tension/hot-rolled steel sheet having excellent workability, and method for producing same

A technology of hot-rolled steel sheets with excellent workability, applied in the direction of manufacturing tools, chemical instruments and methods, heat treatment furnaces, etc., can solve the problems of insufficient workability, extension flange, etc., and achieve excellent workability and remarkable effects

Active Publication Date: 2013-03-06
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In addition, in the technique proposed in Patent Document 1, it was found that when the tensile strength (TS) of the steel sheet is increased to 590 MPa level, the workability, especially the stretch flangeability, is insufficient for the current requirements. (refer to the embodiment of Patent Document 1)

Method used

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  • High-tension/hot-rolled steel sheet having excellent workability, and method for producing same
  • High-tension/hot-rolled steel sheet having excellent workability, and method for producing same
  • High-tension/hot-rolled steel sheet having excellent workability, and method for producing same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0129] The molten steel having the composition shown in Table 1 was smelted and continuously cast by a generally known method to produce a slab (steel material) having a wall thickness of 250 mm. After heating these billets to 1250°C, rough rolling was carried out, and finish rolling was performed at the finish rolling temperature shown in Table 2. After finishing rolling, the temperature range from 880°C to the coiling temperature was carried out. Cooling was performed at the average cooling rate shown in Table 2, and coiling was performed at the coiling temperature shown in Table 2 to obtain a hot-rolled steel sheet having a thickness of 2.3 mm. In addition, for some hot-rolled steel sheets (hot-rolled No. 2 of steel No.A), they were immersed in a galvanizing bath (0.1%Al-Zn) at 480°C to form a coating weight of 45g / m 2 After the hot-dip galvanized film, the alloying treatment is carried out at 520 ° C to make an alloyed hot-dip galvanized steel sheet.

[0130] [Table 1]

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Embodiment 2

[0156] The molten steel having the composition shown in Table 4 was smelted and continuously cast by a generally known method to produce a billet (steel material) having a wall thickness of 250 mm. After heating these billets to 1250°C, rough rolling was carried out, and finish rolling was performed at the finish rolling temperature shown in Table 5. After finish rolling, the temperature ranged from 880°C to coiling temperature Cooling was performed at an average cooling rate shown in Table 5, and coiling was performed at a coiling temperature shown in Table 5 to obtain a hot-rolled steel sheet having a thickness of 2.3 mm. In addition, for some hot-rolled steel sheets (hot-rolled No. 13 of steel No. H and hot-rolled No. 15 of steel No. I), they were immersed in a galvanizing bath (0.1% Al-Zn) at 480°C to form an adherent Amount 45g / m 2 The hot-dip galvanized film is made into hot-dip galvanized steel sheet. In addition, for another part of the hot-rolled steel sheet (hot-ro...

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Abstract

Provided is a high-tension / hot-rolled steel sheet which has both strength and workability (stretch flangeability). The high-tension / hot-rolled steel sheet has: a composition comprising, by mass%, 0.005% to 0.050% of C, 0.2% or less of Si, 0.8% or less of Mn, 0.025% or less of P, 0.01% or less of S, 0.01% or less of N, 0.06% or less of Al, and 0.05% to 0.10% of Ti such that S, N, and Ti satisfy Ti>=0.04+(N / 1448+S / 3248), and with Fe and inevitable impurities as the balance; a matrix in which the ferrite phase is 95% or more by surface area percentage with respect to the overall structure; a structure in which carbide microparticles comprising Ti and having an average grain size of less than 10 nm are dispersed and precipitated, and the volume ratio of the carbide microparticles with respect to the overall structure is 0.0007 or greater; a tensile strength of 590 MPa or greater; and excellent workability.

Description

technical field [0001] The present invention relates to a high-strength hot-rolled steel sheet excellent in workability (stretch flangeability) suitable as a raw material for transportation machinery materials and structural materials such as automobile parts and a method for producing the same. Background technique [0002] From the viewpoint of protecting the global environment, in order to reduce CO 2 Emissions, while maintaining the strength of the car body, reducing its weight to improve the fuel efficiency of the car is often regarded as an important issue in the automotive industry. In order to reduce the weight of the automobile body while maintaining the strength of the automobile body, it is effective to increase the strength of the steel sheet used as a raw material for automobile parts and reduce the thickness of the steel sheet. For example, reducing the thickness of high-strength steel sheets for automobile running parts leads to significant weight reduction o...

Claims

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Application Information

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IPC IPC(8): C22C38/14C22C38/54C21D8/02C21D9/46
CPCC21D9/46C22C38/14C22C38/002B32B15/01C22C38/12C22C38/04C21D2211/004C22C18/04C22C38/004C22C38/06C22C38/008C21D8/0226C22C38/02B32B15/013C21D8/0205C22C38/10C22C38/08C22C38/16C22C38/001C22C38/18C23C2/06C23C2/285C22C38/54C21D8/02
Inventor 有贺珠子中岛胜己船川义正森安永明村田贵幸
Owner JFE STEEL CORP
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