US4618379A
Expired / Lapsed
US
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Method for the continuous annealing of steel strips
Assignee: Italimpianti SpA
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Filing: 1985-07-12
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Granted: 1986-10-21
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Expires: 2005-07-12
Abstract
Abstract This invention relates to the continuous annealing of moving steel strips. A rapid quenching between the annealing treatment and the overaging process is effected in an electrolytic pickling bath, in which the steel strip acts first as a cathode and thereafter as an anode. The current density applied to the steel strip acting as a cathode in the electrolytic pickling bath is regulated so as to control the amount of hydrogen developed on the strip surface and, concurrently, to control the quenching speed of said steel strip.
Inventors
- 👤 Roberto Bruno
- 👤 Nazzareno Azzeri
- 👤 Pierluigi Antoniucci
- 👤 Giorgio Bocci
- 👤 Sandro Brizielli
- 👤 Paolo Barardi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 09:54
CPC Classifications
C; C25; C25F; C25F1/00; C25F1/02; C25F1/04; C25F1/06; C21; C21D; C21D1/00; C21D1/56; C21D1/60; C21D9/00; C21D9/52; C21D9/54; C21D9/56; C21D9/573
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
193 words
A method for continuously annealing a moving steel strip comprising the following sequential steps: (a) heating the steel strip to annealing temperature; (b) maintaining the annealing temperatures; (c) first slow quenching the steel strips; (d) second rapid quenching of the steel strip which comprises: dipping the steel strip in an electrolytic pickling bath; feeding said steel strip through liquid in said bath at a feeding rate effective to promote a laminar motion in layers of the liquid pickling bath at boundaries of the surface of the steel strip; regulating current density applied to the steel strip, while it is being used as a cathode, to control the amount of hydrogen thus developed on its surface and, concurrently, to control the quenching speed of said steel strip; increasing the current density applied to the steel strip while it is being used as a cathode, while maintaining the said laminar motion conditions in said pickling bath, in order to increase the quenching rates; thereafter using the steel strip as an annode in said pickling bath; (e) heating the steel strip to overaging temperature; (f) maintaining said overaging temperature, and (g) finally cooling the steel strip.
Claim 2
Independent Claim
193 words
A method for continuously annealing a moving steel strip comprising the following sequential steps: (a) heating the steel strip to annealing temperature; (b) maintaining the annealing temperatures; (c) first slow quenching the steel strips; (d) second rapid quenching of the steel strip which comprises: dipping the steel strip in an electrolytic pickling bath; feeding said steel strip through liquid in said bath at a feeding rate effective to promote a laminar motion in layers of the liquid pickling bath at boundaries of the surface of the steel strip; regulating current density applied to the steel strip, while it is being used as a cathode, to control the amount of hydrogen thus developed on its surface and, concurrently, to control the quenching speed of said steel strip; increasing the current density applied to the steel strip while it is being used as a cathode, while maintaining the said laminar motion conditions in said pickling bath, in order to increase the quenching rates; thereafter using the steel strip as an annode in said pickling bath; (e) heating the steel strip to overaging temperature; (f) maintaining said overaging temperature, and (g) finally cooling the steel strip.
Claim 3
Independent Claim
197 words
A method for continuously annealing a moving steel strip comprising the following sequential steps: (a) heating the steel strip to an annealing temperature; (b) maintaining the annealing temperature; (c) first slow quenching the steel strip; (d) second rapid quenching of the steel strip which comprises: dipping the steel strip in an electrolytic pickling bath; promoting turbulent motion of liquid in layers of the electrolytic pickling bath which are adjacent surfaces of the strip; using the steel strip, while the pickling bath, first as a cathode which develops hydrogen on its surface; regulating current density applied to the steel strip while it is being used as a cathode to control the amount of hydrogen thus developed on its surface and, concurrently, to control the quenching speed of said steel strip; increasing the current density applied to the steel strip while it is being used as a cathode, while maintaining the said turbulent motion of liquid in said pickling bath, in order to reduce the quenching rate; thereafter using the steel strip as an annode in said pickling bath; (e) heating the steel strip to overaging temperature; (f) maintaining said overaging temperature, and (g) finally cooling the steel strip.
Claim 4
Independent Claim
197 words
A method for continuously annealing a moving steel strip comprising the following sequential steps: (a) heating the steel strip to an annealing temperature; (b) maintaining the annealing temperature; (c) first slow quenching the steel strip; (d) second rapid quenching of the steel strip which comprises: dipping the steel strip in an electrolytic pickling bath; promoting turbulent motion of liquid in layers of the electrolytic pickling bath which are adjacent surfaces of the strip; using the steel strip, while the pickling bath, first as a cathode which develops hydrogen on its surface; regulating current density applied to the steel strip while it is being used as a cathode to control the amount of hydrogen thus developed on its surface and, concurrently, to control the quenching speed of said steel strip; increasing the current density applied to the steel strip while it is being used as a cathode, while maintaining the said turbulent motion of liquid in said pickling bath, in order to reduce the quenching rate; thereafter using the steel strip as an annode in said pickling bath; (e) heating the steel strip to overaging temperature; (f) maintaining said overaging temperature, and (g) finally cooling the steel strip.
Claim 5
Dependent Claim
46 words
A method according to claim 2, in which the turbulent motion is promoted by feeding the steel strip through said bath at a feeding rate effective to promote turbulent motion in layers of the liquid pickling bath at boundaries of the surface of the steel strip.
Claim 6
Dependent Claim
23 words
A method according to claim 2 in which the turbulent motion conditions are promoted by a forced stirring of the electrolytic pickling bath.
Claim 7
Dependent Claim
63 words
A method according to claim 1, in which the liquid of the electrolytic pickling bath is maintained at room temperature and the current density applied to the steel strip is adjusted to between 10 and 50 A/square dm in order to control the quenching rate of the steel strip between 300° and 650° C./second while the steel strip is being used as cathode.
Claim 8
Dependent Claim
62 words
A method according to claim 2, in which the liquid of the electrolytic pickling is maintained at boiling temperature and the current density applied to the steel strip is adjusted between 10 and 60 A/square dm in order to control the quenching rate of the said steel strip between 50° and 200° C./second while the steel strip is being used as cathode.
Claim 9
Dependent Claim
244 words
A method according to claim 1 for continuously annealing a moving steel strip comprising the following sequential steps: (a) preheating the steel strip and eliminating rolling oil thereon by thermal treatment in a reducing atmosphere; (b) heating the steel strip to annealing temperature; (c) maintaining the annealing temperature; (d) first slow quenching the steel strip; (e) second rapid quenching of the steel strip which comprises: dipping the steel strip in an electrolytic pickling bath; feeding said steel strip through said liquid in said bath at a feeding rate effective to promote a laminar motion in layers of the liquid pickling bath at boundaries of the surface of the steel strip; using the steel strip, while in the pickling bath, first as a cathode which develops hydrogen on its surface; regulating current density applied to the steel strip while it is being used as a cathode, to control the amount of hydrogen thus developed on its surface and, concurrently, to control the quenching speed of said steel strip; increasing the current density applied to the steel strip while it is being used as a cathode while maintaining the laminar motion conditions in said pickling bath, in order to increase the quenching rate; thereafter using the steel strip as an annode in said pickling bath; (f) heating the steel strip to overaging temperature; (g) maintaining said overaging temperature; (h) finally cooling the steel strip, and (i) surface conditioning the said steel strip by an electrolytic treatment.
Claim 10
Independent Claim
223 words
A method for continuously annealing a moving steel strip comprising the following sequential steps: (a) preheating the steel strip and eliminating rolling oil thereon by thermal treatment in a reducing atmosphere; (b) heating the steel strip to an annealing temperature; (c) maintaining the annealing temperature; (d) first slow quenching the steel strip; (e) second rapid quenching of the steel strip which comprises: dipping the steel strip in an electrolytic pickling bath; promoting turbulent motion conditions in liquid in layers of the electrolytic pickling bath which are adjacent surfaces of the strip; using the steel strip, while in the pickling bath, first as a cathode which develops hydrogen on its surface; regulating the current density applied to the steel strip while it is being used as a cathode to control the amount of hydrogen developed on its surface and, concurrently, to control the quenching speed of said steel strip; increasing the current density applied to the steel strip while it is being used as a cathode, while maintaining the turbulent motion conditions in said pickling bath, in order to reduce the quenching rate; thereafter using the steel strip as an anode in the pickling bath; (f) heating the steel strip to overaging temperature; (g) maintaining said overaging temperature; (h) finally cooling the steel strip, and (i) surface conditioning steel strip by an electrolytic treatment.
Claim 11
Independent Claim
223 words
A method for continuously annealing a moving steel strip comprising the following sequential steps: (a) preheating the steel strip and eliminating rolling oil thereon by thermal treatment in a reducing atmosphere; (b) heating the steel strip to an annealing temperature; (c) maintaining the annealing temperature; (d) first slow quenching the steel strip; (e) second rapid quenching of the steel strip which comprises: dipping the steel strip in an electrolytic pickling bath; promoting turbulent motion conditions in liquid in layers of the electrolytic pickling bath which are adjacent surfaces of the strip; using the steel strip, while in the pickling bath, first as a cathode which develops hydrogen on its surface; regulating the current density applied to the steel strip while it is being used as a cathode to control the amount of hydrogen developed on its surface and, concurrently, to control the quenching speed of said steel strip; increasing the current density applied to the steel strip while it is being used as a cathode, while maintaining the turbulent motion conditions in said pickling bath, in order to reduce the quenching rate; thereafter using the steel strip as an anode in the pickling bath; (f) heating the steel strip to overaging temperature; (g) maintaining said overaging temperature; (h) finally cooling the steel strip, and (i) surface conditioning steel strip by an electrolytic treatment.
Claim 12
Dependent Claim
46 words
A method according to claim 8, in which the turbulent motion conditions are promoted by feeding the steel strips through said bath at a feeding rate effective to promote turbulent motion in liquid layers of the pickling bath at boundaries of surfaces of the steel strip.
Claim 13
Dependent Claim
23 words
A method according to claim 8 in which the turbulent motion conditions are promoted by a forced stirring of the electrolytic pickling bath.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-10-20 | 1990-04-21 | 1990-10-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-10-20 | 1994-04-21 | 1994-10-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-10-20 | 1998-04-21 | 1998-10-21 | $7700.00 | Window Closed / Lapsed |