Thin steel sheet, plated steel sheet, method for producing hot-rolled steel sheet, method for producing cold-rolled full-hard steel sheet, method for producing thin steel sheet, and method for producing plated steel sheet

A manufacturing method and technology of hot-rolled steel sheets, applied in the direction of manufacturing tools, heat treatment furnaces, hot-dip coating processes, etc., can solve problems such as reduced workability, achieve improved collision safety, excellent bendability and coating properties, and fuel efficiency Improved effect

Active Publication Date: 2018-11-23
JFE STEEL CORP
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, strengthening of the material usually results in a reduction in processability

Method used

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  • Thin steel sheet, plated steel sheet, method for producing hot-rolled steel sheet, method for producing cold-rolled full-hard steel sheet, method for producing thin steel sheet, and method for producing plated steel sheet
  • Thin steel sheet, plated steel sheet, method for producing hot-rolled steel sheet, method for producing cold-rolled full-hard steel sheet, method for producing thin steel sheet, and method for producing plated steel sheet
  • Thin steel sheet, plated steel sheet, method for producing hot-rolled steel sheet, method for producing cold-rolled full-hard steel sheet, method for producing thin steel sheet, and method for producing plated steel sheet

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Embodiment 1

[0158] Hereinafter, the present invention will be specifically described based on examples. The technical scope of the present invention is not limited to the following examples.

[0159] Steel with the composition shown in Table 1 (the balance being Fe and unavoidable impurities) was melted in a vacuum melting furnace in a laboratory, and rolled to form a billet. These billets were heated to 1200° C., rough-rolled, and then hot-rolled under the conditions shown in Table 2 to obtain hot-rolled steel sheets (HR). Next, a part was cold-rolled to 1.4 mm to make a cold-rolled full-hard steel sheet (CR). The obtained hot-rolled steel sheets and cold-rolled full-hard steel sheets were subjected to annealing. Next, a galvanizing treatment and, if necessary, a galvanizing treatment are performed to produce a galvanized steel sheet (GI) and a galvannealed steel sheet (GA). Annealing was carried out in the laboratory under the conditions shown in Table 2 using a heat treatment and pl...

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Abstract

Provided are: a thin steel sheet and a plated steel sheet having a TS of 1180 MPa or higher and excellent bendability and plating properties; and methods for producing a hot-rolled steel sheet, a cold-rolled full-hard steel sheet, and a thin steel sheet. This thin steel sheet has a predetermined component composition and comprises at least one element selected from 0.003-0.100% of Ti, 0.003-0.100%of Nb, and 0.005-0.500% of Mo. In a range up to 20 [mu]m from the surface in the sheet thickness direction, polygonal ferrite accounts for 0-60%, and the total of martensite, bainite, and retained austenite is 40-100%. The amount of Mn in martensite present in a range up to 20 [mu]m from the steel sheet surface in the sheet thickness direction ([Mn]SM) and the amount of Mn in the bulk ([Mn]B) satisfies an equation that is [Mn]SM/[Mn]B <= 1.5. At a position 300 [mu]m from the surface in the sheet thickness direction, the area percentage of martensite is 40-80%, and the average crystal grain size of polygonal ferrite and that of bainite are less than 15 [mu]m.

Description

technical field [0001] The present invention relates to a thin steel sheet, a coated steel sheet, a method for manufacturing a hot-rolled steel sheet, a method for manufacturing a cold-rolled full-hard steel sheet, a method for manufacturing a thin steel sheet, and a method for manufacturing a coated steel sheet. Background technique [0002] From the viewpoint of improving the crash safety of automobiles and improving fuel efficiency, higher strength is required for steel sheets used in automobile parts. However, strengthening of the material usually results in a decrease in processability. Therefore, it is necessary to develop a steel sheet excellent in both strength and workability. In particular, high-strength steel sheets with a tensile strength (hereinafter sometimes referred to as TS) exceeding 1,180 MPa are difficult to form. Therefore, the bending body is often processed in a rigid shape like beams and edge beam parts, and excellent bendability is required. steel ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C21D9/46C22C38/14C22C38/60
CPCC21D9/46C22C38/00C22C38/14C22C38/60C21D8/00C21D8/02C21D8/0236C21D8/0263C22C38/001C22C38/04C21D2211/002C21D2211/008C21D8/0226C21D2211/005C22C38/02C22C38/06C22C38/12C23C2/28C23C2/29C23C2/024C23C2/02C23C2/26C23C2/0224C23C2/06C23C2/40Y02P10/20
Inventor 长谷川宽船川义正
Owner JFE STEEL CORP
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