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Hot-rolled and annealed ferritic stainless steel sheet and method for manufacturing the same

a technology of ferritic stainless steel and which is applied in the direction of manufacturing tools, heat treatment equipment, furnaces, etc., can solve the problems of insufficient hot-rolled ferritic stainless steel sheet to be used as thick flanges, and cannot obtain predetermined thicknesses, etc., to achieve the effect of improving the threshold stress intensity factor kic and sufficient corrosion resistan

Inactive Publication Date: 2020-12-10
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention solves the problem of cracks occurring during the blanking of a thick flange by increasing the threshold stress intensity factor of a steel sheet, which prevents the need for high levels of stress to initiate cracks. This is achieved by hot-rolling and annealing the steel sheet to improve its strength and toughness, making it more suitable for use in thick flanges. The resulting hot-rolled and annealed ferritic stainless steel sheet has sufficient corrosion resistance and excellent toughness, preventing cracks during blanking.

Problems solved by technology

However, when the present inventors tried to work the hot-rolled ferritic stainless steel sheet described in Patent Literature 1 into the shape of a thick flange having a burring working part, in spite of the fact that the steel sheet had a sufficient Charpy impact value, in some cases, cracks occurred in the burring working part, in particular, at the central part in the sheet thickness direction, and it was not possible to obtain a predetermined flange shape, revealing that the hot-rolled ferritic stainless steel sheet was not sufficient enough to be used as a thick flange.

Method used

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Examples

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examples

[0099]Aspects of the present invention will be described in more detail below on the basis of examples.

[0100]Molten stainless steels having the chemical compositions shown in Table 1 were each melted and refined in a converter with a capacity of 150 tons by a strong stirring-vacuum oxygen decarburization (SS-VOD) process, and a steel slab with a width of 1,000 mm and a thickness of 200 mm was formed by continuous casting. Except for No. 36, each of the slabs was heated at 1,150° C. for one hour, and then subjected to rough rolling, as hot rolling, using a three-stand reversing mill to form a steel sheet with a thickness of about 40 mm. Subsequently, by subjecting the steel sheet to finish rolling with seven passes, in which final three passes (5th pass, 6th pass, and 7th pass) were performed under the conditions shown in Table 2, a hot-rolled steel sheet was obtained. Regarding No. 36, the slab was heated at 1,300° C. for one hour, and then subjected to hot rolling. The resulting ho...

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Abstract

The present invention provides a hot-rolled and annealed ferritic stainless steel sheet which has sufficient corrosion resistance and in which cracks can be prevented during blanking into a thick flange, and a method for manufacturing the same. A hot-rolled and annealed ferritic stainless steel sheet has a chemical composition containing, in percent by mass, C: 0.001% to 0.020%, Si: 0.05% to 1.00%, Mn: 0.05% to 1.00%, P: 0.04% or less, S: 0.01% or less, Al: 0.001% to 0.100%, Cr: 10.0% to 19.0%, Ni: 0.65% to 1.50%, Ti: 0.10% to 0.40%, and N: 0.001% to 0.020%, with the balance being Fe and unavoidable impurities, and has a threshold stress intensity factor KIC of 35 MPa·m1 / 2 or more.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This is the U.S. National Phase application of PCT / JP2018 / 016545, filed Apr. 24, 2018, which claims priority to Japanese Patent Application No. 2017-087756, filed Apr. 27, 2017, the disclosures of these applications being incorporated herein by reference in their entireties for all purposes.FIELD OF THE INVENTION[0002]The present invention relates to a hot-rolled and annealed ferritic stainless steel sheet having excellent workability and being suitable for use in flanges and the like and a method for manufacturing the same.BACKGROUND OF THE INVENTION[0003]In recent years, there has been increased tightening of regulations on exhaust gas in automobiles and there has been an urgent need to improve the fuel efficiency. Accordingly, an exhaust gas recirculation (EGR) system, in which exhaust gas from an automobile engine is used again as intake air of the engine, has been increasingly used. The exhaust gas from the engine is passed through a...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C21D9/46B21B3/02C22C38/54C22C38/52C22C38/50C22C38/48C22C38/46C22C38/44C22C38/42C22C38/06C22C38/04C22C38/02C22C38/00C21D8/02C21D6/00
CPCC22C38/001C22C38/48C22C38/06C21D6/008C22C38/005C21D8/0205C22C38/52C21D9/46C22C38/04C22C38/002C22C38/54C22C38/50C21D6/004C22C38/02B21B3/02C21D8/0226C21D8/0263C21D6/005C22C38/44C22C38/42C22C38/46C21D6/007C22C38/00C22C38/004C21D8/0273C21D2211/005
Inventor YOSHINO, MASATAKAINOUE, KEISHIFUJISAWA, MITSUYUKI
Owner JFE STEEL CORP
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