High-strength hot-dip galvanized steel sheet and method for producing the same

A technology of hot-dip galvanized steel sheet and manufacturing method, which can be applied to manufacturing tools, hot-dip galvanizing process, heat treatment furnace, etc., and can solve the problems of reduced workability and the like

Active Publication Date: 2010-02-24
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] However, there is a tendency that the workability decreases as the strength of the steel sheet increases.

Method used

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  • High-strength hot-dip galvanized steel sheet and method for producing the same
  • High-strength hot-dip galvanized steel sheet and method for producing the same
  • High-strength hot-dip galvanized steel sheet and method for producing the same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0127] The steels with the compositions shown in Tables 1 and 2 were melted to form steel slabs, and then hot-rolled, pickled, cold-rolled at a rolling ratio of 50%, and Continuous annealing and plating treatment, the thickness of the manufactured plate is 1.4mm and the coating weight per single side is 45g / m 2 Hot-dip galvanized steel sheet and alloyed hot-dip galvanized steel sheet.

[0128] The obtained galvanized steel sheets and alloyed galvanized steel sheets were subjected to the following material tests to study material properties.

[0129] The obtained results are shown in Tables 7 to 10.

[0130] In addition, the material test and evaluation methods of material properties are as follows.

[0131] (1) Structure of steel plate

[0132] The cross-section in the rolling direction and the sheet thickness: 1 / 4 plane position were studied by an optical microscope or a scanning electron microscope (SEM). The grain size of the ferrite phase is measured according to the m...

Embodiment 2

[0179] Hot-dip galvanized steel sheets were manufactured in the same manner as in Example 1 using steels having the composition shown in Table 11. Here, the manufacturing conditions were determined as follows.

[0180] Billet Heating Temperature SRT: 1200°C Finishing Rolling Temperature FT: 910°C

[0181] ·Average cooling rate from finish rolling temperature to (finish rolling temperature -100°C): 40°C / sec

[0182] Coiling temperature CT: 500°C

[0183] ·One-time average heating rate: 20°C / s ·Intermediate temperature: 700°C

[0184] Secondary average heating rate: 5°C / sec

[0185] ·Annealing temperature: 800℃ ·Holding time: 60 seconds

[0186] ・Average cooling rate from holding the annealing temperature: 10°C / sec

[0187] ·Cooling stop temperature: 500℃

[0188] Alloying treatment conditions: plating bath temperature 460°C, alloying treatment conditions 520°C for 20 seconds

[0189] ·Skin pass rate%: 0.3%

[0190] Table 12 and Table 13 show the properties of each hot-d...

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Abstract

Disclosed is a high-strength hot-dip galvanized steel sheet having a composition consisting of not less than 0.05% but less than 0.12% of C, not less than 0.01% but less than 0.35% of Si, 2.0-3.5% ofMn, 0.001-0.020% of P, 0.0001-0.0030% of S, 0.005-0.1% of Al, 0.0001-0.0060% of N, more than 0.5% but not more than 2.0% of Cr, 0.01-0.50% of Mo, 0.010-0.080% of Ti, 0.010-0.080% of Nb and 0.0001-0.0030% of B and the balance of Fe and unavoidable impurities, while having a structure containing a ferrite phase having a volume fraction of 20-70% and an average crystal grain size of not more than 5 ¢mu!m. This high-strength hot-dip galvanized steel sheet has a high tensile strength of not less than 980 MPa (TS = 980 MPa), while being excellent in processability and weldability.

Description

technical field [0001] The present invention relates to a high-quality steel sheet suitable for use in automobile parts and the like that require press forming into a strict shape, excellent in formability and weldability, and having a tensile strength (TS: tensile strength) of 980 MPa or more. Strength hot-dip galvanized steel sheet (hightensile-strength (zinc) galvanized steel sheet). The present invention also relates to a method for manufacturing the above-mentioned high-strength hot-dip galvanized steel sheet. [0002] Furthermore, the galvanized steel sheet of the present invention includes a so-called galvannealed steel sheet subjected to an alloying heat treatment (galvannealing) after hot-dip galvanizing. Background technique [0003] High-strength hot-dip galvanized steel sheets used for automobile parts and the like are required to have excellent workability in addition to high strength in terms of their application characteristics. [0004] Recently, high-stren...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/38C23C2/06C23C2/28C21D8/02C21D9/46
CPCC23C2/28C22C38/32C21D2211/008C22C38/22C22C38/28C21D9/46C22C38/26C22C38/02C21D8/0426C21D8/0478C21D8/0473C22C38/06C23C2/02C22C38/38C21D6/005C23C2/06C21D2211/005C22C38/001C21D9/48C21D2211/002Y10T428/12799C23C2/024C23C2/0224C21D8/02
Inventor 高木周作川边英尚长谷川浩平大居利彦冲田泰明樱井理孝
Owner JFE STEEL CORP
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