Method for manufacturing of stainless steel strips

Patent metadata

Field	Value
Publication number	US-2022177989-A1
Application number	US-202017310291-A
Country	US
Kind code	A1
Filing date	Jan 24, 2020
Priority date	Jan 28, 2019
Publication date	Jun 9, 2022
Grant date	—

Abstract

The invention relates to a method for manufacturing strips of stainless steel, comprising hot rolling in an initial process (A) and subsequently cold rolling in a cold rolling line (B). The hot rolling is stopped when the strip thickness has been reduced to a thickness between 2.0 mm and 6.5 mm. The subsequent cold rolling is passed at least one time through said cold rolling line, which comprises in the following order: At least one cold rolling mill (11-13) in the initial part of the line, at least one annealing section (17), a scale breaking step (21), a shot blasting step (23) and at least one pickling section (26, 27) utilizing a mixture of nitric acid HNO3, hydrofluoric acid HF and optionally sulphuric acid H2SO4.

First claim

1 . A method for manufacturing strips of stainless steel, comprising hot rolling in an initial process (A) and subsequently cold rolling in a cold rolling line (B), wherein the hot rolling is stopped when the strip thickness has been reduced to a thickness between 2.0 and 6.5 mm, that the thus hot rolled strip is cooled from the final hot rolling temperature through quenching to below 700 degrees ° C., that at the subsequent cold rolling is passed at least one time through said cold rolling line, which comprises at least one cold rolling mill in the initial part of the line and after said initial cold rolling mill(s), in the following order:
at least one annealing section, a scale breaking step, a shot blasting step and at least one pickling section utilizing a mixture of nitric acid HNO 3 , hydrofluoric acid HF and optionally sulphuric acid H 2 SO 4 ; said strip, as it for the first time is passing the at least one cold rolling mills in the initial part of the line, being rolled with the dark coloured oxides remaining, which oxides the strip has obtained in the hot condition of the strip during the initial process.

2 . Method according to claim 1 , wherein the thickness of the stainless-steel strip is reduced by 10-60% as it passes through said at least one cold rolling mill for the first time and by max 15% as it passes through the terminating cold rolling mill for the first time.

3 . Method according to claim 2 , wherein the strip is cold rolled, reducing its thickness by at least 3%, preferably at least 8%, and max 12% as it passes through said terminating cold rolling mill for the first time.

4 . Method according to claim 1 , wherein the thickness of the strip is reduced by 20-60% as it passes through said at least one cold rolling mill for the second time.

5 . Method according to claim 2 , wherein the strip is skin-pass rolled about 0.5% as it passes through said terminating cold rolling mill for the second time.

6 . Method according to claim 1 , wherein the strip is hard-rolled 2-15%, preferably 8-12%, as it passes through said terminating cold rolling mill for the second time.

Assignees

• Outokumpu Oy

Inventors

• Puukko Esa
• Aula Leeni

Classifications

• C21D8/02

  during manufacturing of plates or strips (C21D8/12 takes precedence) · CPC title

• B21B3/02

  Rolling special iron alloys {, e.g. stainless steel} · CPC title

• C21D8/0242

  Flattening; Dressing; Flexing · CPC title

• B21B45/06

  of strip material (B21B45/08 takes precedence) · CPC title

• C21D1/02

  Hardening articles or materials formed by forging or rolling, with no further heating beyond that required for the formation · CPC title