EP0312883A1 - Processing electrical steels - Google Patents

Processing electrical steels Download PDF

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Publication number
EP0312883A1
EP0312883A1 EP88116829A EP88116829A EP0312883A1 EP 0312883 A1 EP0312883 A1 EP 0312883A1 EP 88116829 A EP88116829 A EP 88116829A EP 88116829 A EP88116829 A EP 88116829A EP 0312883 A1 EP0312883 A1 EP 0312883A1
Authority
EP
European Patent Office
Prior art keywords
strip
corrosion inhibitor
processing electrical
coating
rolling
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP88116829A
Other languages
German (de)
French (fr)
Other versions
EP0312883B1 (en
Inventor
James Herbert Richard Page
Gwilym Leslie Woodman
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
British Steel PLC
Original Assignee
British Steel PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by British Steel PLC filed Critical British Steel PLC
Publication of EP0312883A1 publication Critical patent/EP0312883A1/en
Application granted granted Critical
Publication of EP0312883B1 publication Critical patent/EP0312883B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
    • C23F11/02—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in air or gases by adding vapour phase inhibitors
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
    • C21D8/1277—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties involving a particular surface treatment
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length

Definitions

  • This invention relates to the processing of steels for electromagnetic applications.
  • steels are styled electrical steels and may contain up to 3.25% silicon, e.g. non-oriented silicon steel, but the invention also embraces such steels having no added silicon, so called “non-silicon” steels which only contain silicon in very low concentrations, .e.g. ⁇ 0.05%
  • such steels produced via either an ingot route or a continuously cast route are rolled into hot band, descaled by pickling, cold rolled, continuously annealed in a decarburising atmosphere and then cold rolled again into the final gauge.
  • An optional further anneal may be made, e.g. by the customer to minimise deterioration of magnetic properties.
  • the cold reduction is carried out in the presence of a lubricant which reduces the mill load and also acts as a mill coolant.
  • this lubricant additionally includes a rust inhibitor necessary to protect the coil during storage and dispatch.
  • the present invention provides a method of processing electrical steel by hot rolling cast stock into strip and coiling same, descaling and then cold rolling the strip to its final gauge, continuously annealing said strip in a decarburising atmosphere, coating the strip with a corrosion inhibitor, and drying and coiling same for despatch.
  • the second stage rolling, or extension pass has been dispensed with and the provision of a rust inhibiting coating stage downstream of the annealing furnace has preserved the "coil protection" aspect.
  • the slight reduciton in hardness of the strip occasioned by dispensing with the second stage rolling, may be compensated by the use of steel grades having a higher phosphorus and/or manganese content.
  • the coating is preferably water-borne and oil free; one example of such a coating comprises a 1% solution in water of dicyclohexylammonium nitrite (typically the product VP1260) together with 0.1% of a wetting agent of the alcohol alkoxylate family (typically the product Synperonic LF/RA 30) having low foaming properties, and which does not react with or adversely affect the solubility of VP1260.
  • the solution is non-combustible and relatively non-toxic and cheap; further, it does not stain the strip.
  • the coating solution is applied to the strip in its dry state immediately on exiting from the continuous annealing furnace, via a pair of smooth coating rolls, whence it then passes through a drying oven before coiling.
  • a typical rate of usage is one gallon per tonne of steel strip of, say, 0.65 mm gauge. Tests on stored coils have shown that over 40 mg/sq.m of the residual corrosion inhibitor was still present after a storage period of six weeks.
  • the silicon content of the steel may conveniently be ⁇ 0.6% preferably ⁇ 0.05%.

Abstract

A method of processing electrical steel by hot rolling cast stock into strip and coiling same, descaling and then cold rolling the strip in a decarburising atmosphere, coating the strip with a corrosion inhibitor, and drying and coiling same for despatch.
Compared with the conventional process hitherto therefore, the second stage rolling, or extension pass, has been dispensed with and the provision of a rust inhibiting coating, which is preferably water-borne and oil free, downstream of the annealing furnace preserves the "coil protection" aspect.

Description

  • This invention relates to the processing of steels for electromagnetic applications. Such steels are styled electrical steels and may contain up to 3.25% silicon, e.g. non-oriented silicon steel, but the invention also embraces such steels having no added silicon, so called "non-silicon" steels which only contain silicon in very low concentrations, .e.g. <0.05%
  • Conventionally, such steels produced via either an ingot route or a continuously cast route are rolled into hot band, descaled by pickling, cold rolled, continuously annealed in a decarburising atmosphere and then cold rolled again into the final gauge. An optional further anneal may be made, e.g. by the customer to minimise deterioration of magnetic properties.
  • The cold reduction is carried out in the presence of a lubricant which reduces the mill load and also acts as a mill coolant. In the second cold rolling stage this lubricant additionally includes a rust inhibitor necessary to protect the coil during storage and dispatch.
  • It is an object of this invention to provide a more economical process route for such steels whilst still maintaining an adequate degree of protection (against rusting) to the product during storage and dispatch.
  • The present invention provides a method of processing electrical steel by hot rolling cast stock into strip and coiling same, descaling and then cold rolling the strip to its final gauge, continuously annealing said strip in a decarburising atmosphere, coating the strip with a corrosion inhibitor, and drying and coiling same for despatch.
  • Compared with the conventional process hitherto therefore, the second stage rolling, or extension pass, has been dispensed with and the provision of a rust inhibiting coating stage downstream of the annealing furnace has preserved the "coil protection" aspect.
  • Further, by dispensing with the separate second stage cold roll a better surface finish is maintained on the strip and with the coating developed for this process this finish is preserved for a longer period than hitherto and the strip surface is much cleaner and brighter.
  • The slight reduciton in hardness of the strip, occasioned by dispensing with the second stage rolling, may be compensated by the use of steel grades having a higher phosphorus and/or manganese content.
  • The coating is preferably water-borne and oil free; one example of such a coating comprises a 1% solution in water of dicyclohexylammonium nitrite (typically the product VP1260) together with 0.1% of a wetting agent of the alcohol alkoxylate family (typically the product Synperonic LF/RA 30) having low foaming properties, and which does not react with or adversely affect the solubility of VP1260. The solution is non-combustible and relatively non-toxic and cheap; further, it does not stain the strip.
  • It has been found that this solution readily wets the strip and has a relatively low temperature of evaporation thus leaving the VP1260 evenly distributed and bound to the strip surface by the "invisible" layer of Synperonic LF/RA 30.
  • The coating solution is applied to the strip in its dry state immediately on exiting from the continuous annealing furnace, via a pair of smooth coating rolls, whence it then passes through a drying oven before coiling.
  • A typical rate of usage is one gallon per tonne of steel strip of, say, 0.65 mm gauge. Tests on stored coils have shown that over 40 mg/sq.m of the residual corrosion inhibitor was still present after a storage period of six weeks. The silicon content of the steel may conveniently be <0.6% preferably <0.05%.

Claims (4)

1. A method of processing electrical steel by hot rolling cast stock into strip and coiling same, descaling and then cold rolling the strip to its final gauge,characterised in that the strip is rolled at this stage, the strip then being continuously annealed in a decarburising atmosphere, coated with a corrosion inhibitor, and dried and coiled for despatch.
2. A method according to claim 1, characterised in that the corrosion inhibitor is applied to the strip in its dry state immediately on exiting the annealing furnace via a pair of smooth coating rolls.
3. A method according to claim 1 or claim 2 characterised in that the corrosion inhibitor is water-borne and oil free.
4. A method according to claim 3, characterised in that the corrosion inhibitor includes a dicyclohexylammonium nitrate and a wetting agent of the alkoxylate family.
EP88116829A 1987-10-17 1988-10-11 Processing electrical steels Expired - Lifetime EP0312883B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB878724387A GB8724387D0 (en) 1987-10-17 1987-10-17 Processing electrical steels
GB8724387 1987-10-17

Publications (2)

Publication Number Publication Date
EP0312883A1 true EP0312883A1 (en) 1989-04-26
EP0312883B1 EP0312883B1 (en) 1993-03-31

Family

ID=10625494

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88116829A Expired - Lifetime EP0312883B1 (en) 1987-10-17 1988-10-11 Processing electrical steels

Country Status (3)

Country Link
EP (1) EP0312883B1 (en)
DE (1) DE3879863T2 (en)
GB (2) GB8724387D0 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0662527A1 (en) * 1994-01-11 1995-07-12 Cortec Corporation Vapor phase corrosion inhibitor-desiccant material

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2449962A (en) * 1946-03-26 1948-09-21 Shell Dev Dicyclohexylammonium nitrite and its preparation
DE861702C (en) * 1951-06-21 1953-01-05 Armco Int Corp Process for the production of electrical steel strip
GB1354480A (en) * 1970-05-06 1974-06-05 Croda Chemicals Ltd Wet temper rolling emulsion
BE864899A (en) * 1978-03-14 1978-09-14 Centre Rech Metallurgique PROCESS FOR THE SURFACE TREATMENT OF A METAL STRIP
US4116701A (en) * 1977-03-08 1978-09-26 Conner Alvin James Sen Metal corrosion inhibitor
EP0140027A1 (en) * 1983-09-02 1985-05-08 Nippon Steel Corporation Aqueous solution for cooling cold-rolled steel strip in a continuous annealing process

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5224499B2 (en) * 1973-01-22 1977-07-01
JPS5945730B2 (en) * 1979-08-22 1984-11-08 新日本製鐵株式会社 Hot rolling method for high magnetic flux density unidirectional silicon steel sheet
EP0162710B1 (en) * 1984-05-24 1989-08-09 Kawasaki Steel Corporation Method for producing grain-oriented silicon steel sheets

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2449962A (en) * 1946-03-26 1948-09-21 Shell Dev Dicyclohexylammonium nitrite and its preparation
DE861702C (en) * 1951-06-21 1953-01-05 Armco Int Corp Process for the production of electrical steel strip
GB1354480A (en) * 1970-05-06 1974-06-05 Croda Chemicals Ltd Wet temper rolling emulsion
US4116701A (en) * 1977-03-08 1978-09-26 Conner Alvin James Sen Metal corrosion inhibitor
BE864899A (en) * 1978-03-14 1978-09-14 Centre Rech Metallurgique PROCESS FOR THE SURFACE TREATMENT OF A METAL STRIP
EP0140027A1 (en) * 1983-09-02 1985-05-08 Nippon Steel Corporation Aqueous solution for cooling cold-rolled steel strip in a continuous annealing process

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0662527A1 (en) * 1994-01-11 1995-07-12 Cortec Corporation Vapor phase corrosion inhibitor-desiccant material

Also Published As

Publication number Publication date
GB8824059D0 (en) 1988-11-23
EP0312883B1 (en) 1993-03-31
GB2211116A (en) 1989-06-28
DE3879863T2 (en) 1993-07-22
GB8724387D0 (en) 1987-11-18
DE3879863D1 (en) 1993-05-06
GB2211116B (en) 1991-06-26

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