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EP0106166A1
Expired / Lapsed
EP
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Method and apparatus for the continuous annealing of steel strips
Assignee: Italimpianti SpA
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Filing: 1983-09-15
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Granted: —
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Expires: 2003-09-15
Abstract
Abstract This invention relates to the continuous annealing of steel strips, and resides in the fact that a rapid or semi-rapid quenching between the annealing treatment proper and the overaging process is effected in an electrolytic pickling bath. After the overaging process and final cooling, the steel strip may be submitted to an electrolytic treatment in a sulfate-based neutral aqueous solution, preferably additivated with other anions, such as borates and/or phosphates.
Inventors
- 👤 Roberto Bruno
- 👤 Nazzareno Azzerri
- 👤 Pierluigi Antoniucci
- 👤 Giorgio Bocci
- 👤 Sandro Brizielli
- 👤 Paolo Berardi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 21:19
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: 16
Claim 1
Independent Claim
87 words
A method of continuous annealing of steel strips, comprising, orderly, the following steps: heating the steel strip to the annealing temperature, maintaining the annealing temperature, first controlled slow quenching, second controlled rapid or semirapid quenching, subsequent heating of the steel strip up to the overaging temperature, maintaining the overaging temperature, final cooling and optional surface-conditioning of the steel strip, characterized in that the rapid or semi-rapid quenching is carried out by dipping in an electrolytic pickling bath in which the steel strip is used as an electrode.
Claim 2
Independent Claim
87 words
A method of continuous annealing of steel strips, comprising, orderly, the following steps: heating the steel strip to the annealing temperature, maintaining the annealing temperature, first controlled slow quenching, second controlled rapid or semirapid quenching, subsequent heating of the steel strip up to the overaging temperature, maintaining the overaging temperature, final cooling and optional surface-conditioning of the steel strip, characterized in that the rapid or semi-rapid quenching is carried out by dipping in an electrolytic pickling bath in which the steel strip is used as an electrode.
Claim 3
Dependent Claim
51 words
A method according to claim 1, characterized in that in a first step, immediately after dipping, the still red-hot steel strip is used as a cathode in an electrolytic pickling bath, while in a subsequent second step the cooled steel strip is used as an anode in an electrolytic pickling bath.
Claim 4
Dependent Claim
26 words
A method according to claim 1, characterized in that the rapid or semi-rapid quenching is effected in an electrolytic pickling bath at a controlled quenching speed.
Claim 5
Dependent Claim
44 words
A method according to claim 3, characterized in that in order to control the quenching speed, the current density applied to the steel strip acting as a cathode is regulated, thereby regulating the amount of hydrogen which develops on the surface of said strip.
Claim 6
Dependent Claim
41 words
A method according to claim 1, characterized in that the surface-conditioning treatment of the steel strip at the end of the cycle is carried out electrolytically in a neutral aqueous sulfate-based solution, additivated with other anions, such as borates and/or phosphates.
Claim 7
Dependent Claim
27 words
A method according to claim 1, characterized in that the elimination of the rolling oils is effected by thermal means with simultaneous pre-heating of the steel strip.
Claim 8
Dependent Claim
97 words
A continuous annealing line of steel strips, comprising, orderly, an optional section for elimination of rolling oils applied on the strip, a section for heating up to the annealing temperature, a section for maintaining the annealing temperature, a slow quenching section, a rapid or semi-rapid quenching section, a section for heating up to the overaging temperature, a section for maintaining the overaging temperature, a final cooling section and an optional section for surface-conditioning the strip, characterized in.that the rapid or semi-rapid quenching section is formed by an electrolytic pickling bath wherein the steel strip constitutes an electrode.
Claim 9
Dependent Claim
97 words
A continuous annealing line of steel strips, comprising, orderly, an optional section for elimination of rolling oils applied on the strip, a section for heating up to the annealing temperature, a section for maintaining the annealing temperature, a slow quenching section, a rapid or semi-rapid quenching section, a section for heating up to the overaging temperature, a section for maintaining the overaging temperature, a final cooling section and an optional section for surface-conditioning the strip, characterized in.that the rapid or semi-rapid quenching section is formed by an electrolytic pickling bath wherein the steel strip constitutes an electrode.
Claim 10
Dependent Claim
52 words
A continuous annealing line according to claim 7, characterized in that the electrolytic quenching and pickling bath comprises an electrolytic cell wherein the steel strip travels first with a downward dipping movement during which it acts as a cathode, then with an upwardly emerging movement during which it acts as an anode.
Claim 11
Dependent Claim
46 words
A continuous annealing line according to claim 7, characterized in that the electrolytic quenching and pickling bath comprises two successive electrolytic cells, and in the first cell said steel strip acts as a cathode, while in the second cell said steel strip acts as an anode.
Claim 12
Dependent Claim
31 words
An annealing line according to claim 7, characterized in that the electrolytic solution in the electrolytic quenching and pickling bath is an aqueous 1 - 1.5 molar solution of sodium sulfate.
Claim 13
Dependent Claim
24 words
An annealing line according to claim 10, characterized in that the temperature of the electrolytic solution is between the ambient temperature and boiling temperature.
Claim 14
Dependent Claim
76 words
An annealing line according to claim 9, characterized in that said electrolytic cells are fed with a current density to the strip between 10 and 60 A/dm 2 which is selected, depending upon the temperature of the electrolytic solution, so that when the steel strip acts as a cathode hydrogen shall develop on the surface thereof, whereas when the steel strip acts as an anode the development of oxigen on the surface thereof is, preferably, prevented.
Claim 15
Dependent Claim
36 words
A continuous annealing line according to claim 7, characterized in that the optional final section for the surface-conditioning comprises an electrolytic tank with a neutral sulfate-based solution, additivated with other anions such as borates and/or phosphates.
Claim 16
Dependent Claim
34 words
An annealing line according to claim 7, characterized in that the section for eliminating the rolling oils is a furnace section with a reducing atmosphere and with burners which operate in scarcity of air.
References Cited (Backward Citations)
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