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High-strength molten-zinc-plated steel sheet having excellent bendability and weldability, and process for production thereof

A technology for hot-dip galvanized steel sheet and weldability, which is applied in the field of high-strength hot-dip galvanized steel sheet and its manufacture, can solve the problems of reduced workability and steel sheet fracture, and achieves the effect of improving weldability

Active Publication Date: 2013-02-06
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] However, in general, as the strength of the steel sheet increases, the workability tends to decrease. Therefore, when the high-strength steel sheet is applied to the vehicle body, there are problems such as cracking of the steel sheet during press forming.

Method used

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  • High-strength molten-zinc-plated steel sheet having excellent bendability and weldability, and process for production thereof
  • High-strength molten-zinc-plated steel sheet having excellent bendability and weldability, and process for production thereof
  • High-strength molten-zinc-plated steel sheet having excellent bendability and weldability, and process for production thereof

Examples

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Embodiment

[0155] The steel with the composition shown in Table 1 is smelted. Under the conditions shown in Tables 2-1 and 2-2, slab heating, hot rolling, coiling, cold rolling with a rolling rate of 50%, and continuous Annealing and plating treatment, the thickness of the manufactured plate is 2.0mm, and the coating adhesion per single side is 45g / m 2 Hot-dip galvanized steel sheet and alloyed hot-dip galvanized steel sheet. It should be noted that the rolling reduction rate during cold rolling was all 50%. In addition, the air ratio in the furnace during continuous annealing was set to the air ratio shown in Tables 2-1 and 2-2 during the primary temperature rise, and the range of 0.8 to 1.0 after the secondary temperature rise.

[0156] With respect to the hot-dip galvanized steel sheet and galvannealed steel sheet obtained in this way, the following material tests were performed to examine the material properties.

[0157] The results are shown in Tables 3-1, 3-2, and Table 4.

[0158] It ...

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Abstract

A steel sheet is coated with a molten zinc plating layer, wherein the steel sheet comprises, in mass%, not less than 0.05% and less than 0.12% of C, 0.001 to 0.040% of P and 0.0050% or less of S, has a steel sheet surface layer part (which is a part lying between each of surfaces of the steel sheet and a depth of 10 [mu]m of the steel sheet) and a steel sheet inner layer part (which is a inside part from the depth of 10 [mu]m from each of the surfaces of the steel sheet), and has a tensile strength of 980 MPa or more, wherein the steel sheet surface layer part has a structure that contains a ferrite phase at a volume fraction of more than 70% and the steel sheet inner layer part has a structure that contains a ferrite phase having an average crystal particle diameter of 5 [mu]m or less at a volume fraction of at least 20 to 70%. In this manner, it is possible to produce a high-strength molten-zinc-plated steel sheet having a tensile strength (TS) as high as 980 MPa or more and also having excellent bendability and weldability.

Description

Technical field [0001] The present invention relates to a high-strength hot-dip galvanized steel sheet suitable for automobile parts requiring strict bending processing and the like, excellent in bendability and weldability, and having a tensile strength (TS) of 980 MPa or more, and a manufacturing method thereof. [0002] It should be noted that the hot-dip galvanized steel sheet in the present invention includes a so-called galvannealed steel sheet that has been subjected to alloying heat treatment after hot-dip galvanizing. Background technique [0003] High-strength hot-dip galvanized steel sheets used for automobile parts, etc., are required to be excellent in workability in addition to high strength in terms of their use characteristics. [0004] Recently, from the viewpoint of improving fuel efficiency and ensuring crash safety by using body weight reduction, high-strength steel sheets are required for automobile bodies, and their applications are expanding. In addition, in t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/38C21D9/46C23C2/06C23C2/40
CPCC21D9/46C21D8/005C23C2/02C23C2/28C23C2/06C23C2/40C21D2211/005C21D2211/004C22C38/22C21D2211/002B32B15/18C23C2/26C21D2211/008C22C38/06C22C38/26C22C38/02C21D8/0226B32B15/013B32B15/043C22C38/28C21D8/0473C22C38/001C22C38/32C22C38/38Y10T428/12799C21D6/002C21D6/005C21D6/008C21D8/0236C21D8/0247C21D8/0278C22C38/04C22C38/12C22C38/14C23C2/024C23C2/0224
Inventor 高木周作长谷川浩平
Owner JFE STEEL CORP
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