GB2057500A - Improvements in electro magnetic steels - Google Patents
Improvements in electro magnetic steels Download PDFInfo
- Publication number
- GB2057500A GB2057500A GB8028651A GB8028651A GB2057500A GB 2057500 A GB2057500 A GB 2057500A GB 8028651 A GB8028651 A GB 8028651A GB 8028651 A GB8028651 A GB 8028651A GB 2057500 A GB2057500 A GB 2057500A
- Authority
- GB
- United Kingdom
- Prior art keywords
- temperature
- steel
- anneal
- range
- decarburising
- 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.)
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Links
Classifications
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- 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
- C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
- C21D8/1222—Hot rolling
-
- 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
- C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest
Abstract
A method for producing non- oriented steel for electromagnetic applications comprises hot rolling a steel containing a nitride/carbide former and coiling the hot band at a temperature of not less than 680 DEG C before cold reduction and annealing in a non-decarburising atmosphere at 900 DEG C to 1000 DEG C. The range of composition of the sheets is as follows: <IMAGE>
Description
SPECIFICATION
Improvements in electro magnetic steels
This invention relates to steels for electromagnetic applications and is particularly directed to non-oriented steels displaying magnetic ageing resistance.
Non-oriented silicon steels for electromagnetic applications are well known in the art and are produced generally in the form of sheet or strip in the fully annealed condition which is subsequently sheared or stamped into laminations. These laminations are stacked to form the cores of static or rotating electrical machines such as transformers and alternators and are magnetically excited by current flow through conductors wound around the cores.
In conventional non-oriented silicon steel particular attention must be paid to the processing of the material to avoid deterioration in the magnetic properties after processing has been completed. This deterioration of magnetic properties with time is termed magnetic ageing and is usually expressed as a percentage increase in total power loss (Watts/kg) at a specified induction. (e.g. 1.5 Tesla).
It is now accepted practice to reduce magnetic ageing by a decarburising anneal; decarburising is thus a vitally important but unfortunately expensive stage in the production of a nonoriented silicon steel. The process requires an atmosphere of either pure hydrogen or one rich in hydrogen which has to be saturated with water to achieve a specific dew point. This atmosphere can be expensive and difficult to handle.
Temperature/times of annealing have to be closely controlled for optimum decarburisation rates.
It is an object of the present invention to provide a process route which will produce a magnetic ageing resistant, non-oriented silicon steel and which avoids a decarburising treatment in the finishing plant.
According to one aspect of the present invention, a method for producing non-oriented steel sheet for electromagnetic applications comprises hot rolling steel having less than 0.025% carbon, between 0.05% and 3.5% silicon, between 0.2% and 0.8% manganese, between 0.10% and 0.35% aluminium, between 0.003% and 0.008% nitrogen, together with a nitride/carbide former selected from the group consisting of titanium, niobium, tantalum, vanadium and zirconium, the remainder being iron except for incidental impurities, coiling the hot band at a temperature of not less than 6800C and subjecting the subsequently cold reduced material of substantially final gauge to a non-decarburising anneal at a temperature lying within the range 9000Cto 10000C.
Ideally, the non-decarburising final anneal should be carried out at a temperature in excess of 9400C and preferably within the temperature range 9500C to 10000C.
The steel of this invention may be produced by any conventional steelmaking process. For
example basic oxygen steelmaking, open hearth
refining or electric arc steelmaking may be
employed, with the required composition being
achieved by techniques well known in the art. In the case of steel produced by basic oxygen
steelmaking or open hearth refining, the carbon
concentration is conveniently reduced by vacuum degassing. Alloying of the melt to produce the required composition may occur during, or after the vacuum degassing operation.
Preferably the hot band, which ideally is hot rolled at a finishing temperature of not less than 9000C is coiled at a temperature in excess of 7000C to produce optimum results.
The concentration of nitride/carbide former in the material of the invention suitably is selected to lie within the range by weight of 0.05% to 0.2% for titanium, 0.06% to 0.3% for vanadium, 0.05% to 0.3% for nobium, 0.12% to 0.3% for zirconium, and 0.10% to 0.3% for tantalum.
When phosphorus and sulphur generally are present at incidental impurity levels and can be tolerated at these levels, the concentration by weight of phosphorus should not exceed 0.04% while the concentration by weight of sulphur should not exceed 0.025%. In practice however where the steel of the invention before inoculation is produced by basic oxygen steelmaking, a lower concentration limit of 0.01% of phosphorus and 0.02% or possibly 0.015% of sulphur is likely to be achieved.
The hot band produced according to the present invention may be cold reduced to substantially final gauge in a single cold rolling operation or may be reduced to substantially final gauge in two stages with an intermediate anneal.
In the case where two stage cold reduction is employed, the intermediate anneal conveniently is at a temperature lying within the range 8500C to 10000C although a temperature lying within the range 9000C to 10000C is preferred. While the intermediate anneal may be in a decarburising atmosphere, a non-decarburising anneal may equally be used and will of course display a number of advantages including cost benefit.
The use of a non-decarburising atmosphere in the final anneal of the cold reduced material of substantially final gauge produces no reduction of carbon concentration. However in conventional silicon steels a decarburising atmosphere is necessary to produce the low level of carbon required to minimise magnetic ageing resistance.
If conventional silicon steels were processed in a non-decarburising atmosphere unsatisfactory levels of carbon would result which would be detrimental to the magnetic ageing characteristics.
The use of the process route according to the present invention displays the cost benefit of avoiding a decarburising anneal atmosphere previously necessary to achieve the low levels of carbon concentration essential to produce acceptable ageing and magnetic characteristics.
Embodiments of the invention will now be described with reference to the following examples.
EXAMPLES
EXAMPLE 1
A steel having the following composition by weight:
1.24% Si
0.34% Mn
0.015% C
0.025% S
0.014% P
0.095% Ti 0.15% at 0.0059% N - balance iron and incidental impurities, was
made, cast into ingots, hot rolled into slabs and subsequently hot rolled to strip of nominal thickness 2.0 mm. The hot strip rolling was conventionally performed using a finishing temperature of 9350C (17200 F) and a coiling temperature of 6800C (12500F).
The hot rolled material was pickled and cold reduced in a single rolling operation to a final thickness of 0.50 mm. The cold rolled material was then subjected to a final anneal in a nondecarburising atmosphere at 9000C for approximately 2.5 minutes.
A typical power loss of 6.1 5 W/kg was obtained at 1.5T, 50 Hz on a longitudinal Epstein sample from material processed in this way.
Ageing tests, which consist of treating the samples at a temperature of 1 500C for 14 days followed by re-testing were carried out and substantially no deterioration in total power loss was found.
EXAMPLE 2
A steel was processed as in Example 1 to a final gauge of 0.50 mm. Non-decarburising annealing was carried out at a temperature of 9500C for approximately 2.5 minutes.
A typical total power loss of 5.53 W/kg was attained at 1 ST, 50 Hz on a longitudinal Epstein sample.
The sample again showed substantially no
magnetic ageing, within the testing limits detailed in Example 1.
EXAMPLE 3
A steel was processed as in Example 1 to a final
gauge of 0.50 mm. Non-decarburising annealing
was carried out at 100000 for approximately 2.5
minutes.
A typical power loss of 5.06 W/kg was
achieved at 1 .5T, 50 Hz on a longitudinal Epstein
sample; similar ageing characteristics as in
Examples 1 and 2 were obtained.
EXAMPLE 4
A steel having the following composition:
1.64% Si
0.014% C
0.31% Mn
0.019% S
0.25% Al
0.0060% N
0.083% Ti - the balance being iron except for incidental impurities, was made and hot rolled in the manner of the previous examples to a strip thickness of 2.0 mm. After pickling the material was cold reduced to a final thickness of 0.65 mm in a single cold rolling operation. Final annealing was carried out in a non-decarburising atmosphere at 10000C i for 2.5 minutes.
A typical total power loss of 5.40 W/kg at 1.5T, 50 Hz was obtained on a longitudinal sample. The sample again showed substantially no magnetic ageing, within the testing limits detailed in
Example 1.
EXAMPLE 5
A steel having the following composition:
1.60% Si
0.014% C
0.32% Mn
0.019% S 0.25% Al
0.078% Ti
0.0054% N - The balance being iron except for incidental impurities, was made and hot rolled in the conventional manner to a strip thickness of 2.0 mm. After pickling the material was cold reduced in a single rolling operation to a final thickness of 0.50 mm and given a final anneal at 9400C in a non-decarburising atmosphere for 2.5 minutes.
A typical total power loss of 5.59 W/kg at 1.5T, 50 Hz was obtained on a longitudinal sample. The sample again showed substantially no magnetic ageing, within the testing limits detailed in
Example 1.
EXAMPLE 6
A steel having following composition:
1.24% Si
0.34% Mn 0.011%C 0.025% S
0.017% P
0.10% Nb 0.13% Al 0.0059% N with the balance being iron except for incidental impurities, was made and hot rolled in a similar manner to that described in Example 1. In this case however the finishing temperature during hot rolling was 91 00C (1 6700F) and the coiling temperature 6800C (12500F).
The hot rolled material was pickled and subsequently cold reduced in a single cold rolling operation to a thickness of 0.50 mm and given a final annealing treatment in a non-decarburising atmosphere at 1000C for 2.5 minutes.
A typical power loss of 7.15 W/kg at 1.5T, 50 Hz was obtained on a longitudinal Epstein sample. The material was substantially resistant to magnetic ageing, with the testing limits applied in previous examples.
EXAMPLE 7
A steel having the following composition:
1.32% Si
0.34% Mn
0.012% C
0.025% S
0.013% P 0.013% Ta 0.1 1% Al 0.0063% N - balance being iron except for incidental impurities, was made and hot rolled in a similar manner to that described in Example 1. In this case however finishing temperature during hot rolling was 91000(1 7700F) and the coiling temperature 6800C (12500F).
The hot rolled strip was pickled and cold reduced to a final thickness of 0.50 mm in a single cold rolling operation. The cold rolled material was given a final anneal in a non-decarburising atmosphere at a temperature of '10000C for 2.5 minutes.
A typical power loss of 6.48 W/kg at 1.5T, 50 Hz was attained on a longitudinal Epstein sample. The material was substantially resistant to magnetic ageing, within the test limits imposed in previous examples.
EXAMPLE 8
A steel having the composition described with reference to Example 1 was made and hot rolled in the usual way. Hot rolled strip, nominally 2.0 mm in thickness, was produced using a finishing temperature of 9000C (166)OF) and a coiling temperature of 6800C (12500F).
After pickling the hot rolled material was cold reduced to an intermediate thickness of 0.55 mm and given an inter anneal at 9000C in a nondecarburising atmosphere.
The material was then cold reduced to a final thickness of 0.50 mm followed by final annealing in a non-decarburising atmosphere at 9000C for approximately 2.5 minutes.
A typical power loss for material processed in this manner is 4.97 W/kg at 1.5T, 50 Hz on a longitudinal sample. Magnetic ageing tests confirmed good ageing resistance.
EXAMPLE 9
A steel having the composition as detailed in
Example 6 was made and hot rolled in the manner described.
The hot rolled material was pickled, cold reduced to an intermediate thickness of 0.55 mm and given an inter anneal of 9000C in a nondecarburising atmosphere. The annealed material was then cold reduced to a final thickness of 0.50 mm and subsequently finally annealed at 9500C for about 2.5 minutes in a nondecarburising atmosphere.
A typical power loss for material processed in this way is 4.80 W/kg at 1.5T, 50 He on a longitudinal Epstein sample. Substantially no magnetic ageing was exhibited by the samples when tested in the manner previously described.
EXAMPLE 10
A steel having the composition as detailed in
Example 7 was made and hot rolled in the manner described.
The hot rolled material was pickled, cold reduced to an intermediate thickness of 0.55 mm and given an intermediate anneal at 8500C in a non-decarburising atmosphere. The annealed material was then cold reduced to a final thickness of 0.50 mm and subsequently finally annealed at 9000C for about 2.5 minutes in a nondecarburising atmosphere.
A typical power loss for material processed in this way is 5.08 W/kg at 1.5T, 50 Hz on a longitudinal Epstein sample. Substantially no magnetic ageing was exhibited by the sample, when tested as previously described.
EXAMPLE 11
A steel having the following composition by weight:
0.89% Si
0.28% Mn
0.015% C
0.018% S
0.012% P
0.068% Ti 0.10% Al 0.0059% N - balance iron and incidental impurities, was made, cast into ingots, hot rolled into slabs and subsequently hot rolled to strip of nominal thickness 2.0 mm. The hot strip rolling was conventionally performed using a finishing temperature of 9350C (1 7200F) and a coiling temperature of 6800C (12500F).
The hot rolled material was pickled and cold reduced in a single rolling operation to a final thickness of 0.50 mm. The cold rolled material was then subjected to a final anneal in a nondecarburising atmosphere at 9.400C for approximately 1 minute.
A typical power loss of 5.56 W/kg was obtained at 1 .5T, 50 Hz on a longitudinal Epstein sample from material processed in this way.
The sample again showed substantially no magnetic ageing, within the testing limits detailed in Example 1.
EXAMPLE 12
A steel having the following composition by
weight:
2.34% Si
0.31% Mn 0.011%C 0.025% S 0.011% P 0.079% Ti 0.27% Al
0.0059% N - balance iron and incidental impurities, was
processed as in Example 11.
A typical power loss 4.60 W/kg was obtained
at 1.5T. 50 Hz on a longitudinal Epstein sample
from material processed in this way.
The sample again showed substantially no
magnetic ageing, within the testing limits detailed
in Example 1.
EXAMPLE 13
A steel having the following composition by
weight:
1.67% Si
0.33% Mn
0.010% C
0.016% S
0.013% P
0.085% V
0.23% Al
0.0059% N - balance iron and incidental impurities, was processed as in Example 11.
A typical power loss of 4.56 W/kg was obtained at 1.5T, 50 Hz on a longitudinal Epstein sample from material processed in this way.
The sample again shows substantially no magnetic ageing, within the testing limits detailed in Example 1.
Whilst in no way meant to be limiting, the normal method of production of the steels of the examples is by the basic oxygen process followed by vacuum degassing.
In the examples, where two stage cold reduction is employed, the thickness of the strip after the first cold rolling operation preferably lies within the range 0.55--0.75 mm.
Claims (18)
1. A method for producing non-oriented steel sheet for electromagnetic applications comprises hot rolling steel having less than 0.025% carbon, between 0.05% and 3.5% silicon, between 0.2% and 0.8% manganese, between 0.10% and 0.35% aluminium, between 0.003% and 0.008% nitrogen, together with a nitride/carbide former selected from the group consisting of titanium, niobium, tantalum, vanadium, and ziroconium, the remainder being iron except for incidental impurities, coiling the hot band at a temperature of not less than 6800C and subjecting the subsequently cold reduced material of substantially final gauge to a non-decarburising anneal at a temperature lying within the range 9000Cto 10000C.
2. A method as claimed in claim 1 in which the non-decarburising final anneal is at a temperature within the range 9400C to 100000.
3. A method as claimed in claim 1 or 2 wherein the non-decarburising final anneal is at a temperature within the range 9500C to 10000 C.
4. A method as claimed in any preceding claim in which the steel is produced by any conventional steel making process.
5. A method as claimed in claim 4wherein the steel is produced by basic oxygen or open hearth refining and is subject to vacuum degassing to reduce the carbon concentration to the selected level.
6. A method as claimed in any preceding claim in which the hot band is hot rolled at a finishing temperature greater than 9000 C.
7. A method as claimed in any preceding claim in which the hot band is coiled at a temperature greater than 7000 C.
8. A method as claimed in any preceding claim wherein the hot band is cold reduced to substantially final gauge in a single cold rolling operation.
9. A method as claimed in any one of claims 1 to 7 wherein the hot band is cold reduced to substantially final gauge in two stages of cold rolling with an intermediate anneal.
10. A method as claimed in claim 9 wherein the intermediate anneal is at a temperature within the range 8500C to 100000.
11. A method as claimed in claim 10 wherein the intermediate anneal is at a temperature within the range 9000Cto 100000.
12. A method as claimed in any one of claims 9 to 11 in which the intermediate anneal is in a nondecarburising atmosphere.
13. A method as claimed in any preceding claim wherein the nitride/carbide former is selected from the group consisting of titanium, vanadium, niobium, zirconium and tantalium.
14. A method as claimed in claim 13 wherein the concentration of nitride/carbide former is selected to lie within the range 0.05%--0.2% by weight for titanium, 0.06%--0.3% for vanadium, 0.05%0.3% for niobium, 0.1 2%-0.3% for zirconium and 0.1 0%-0.3% for tantalum.
15. A method as claimed in any preceding claim wherein the concentration by weight of phosphorus and sulphur is not greater than 0.04% and 0.025% respectively.
16. A method as claimed in any preceding claim in which the steel is subject to vacuum degassing and the nit;nde/carbide former is adding during or aftervaccum degassing.
17. A method for producing non-oriented steel sheet for electromagnetic applications substantially as herein described with reference to any of the examples.
18. A non-oriented steel sheet for electromagnetic applications herein produced by the method of any preceding claim.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8028651A GB2057500B (en) | 1979-09-07 | 1980-09-04 | Electro magnetic steels |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7931139 | 1979-09-07 | ||
| GB8028651A GB2057500B (en) | 1979-09-07 | 1980-09-04 | Electro magnetic steels |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2057500A true GB2057500A (en) | 1981-04-01 |
| GB2057500B GB2057500B (en) | 1983-05-18 |
Family
ID=26272793
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8028651A Expired GB2057500B (en) | 1979-09-07 | 1980-09-04 | Electro magnetic steels |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2057500B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0434641A2 (en) * | 1989-12-22 | 1991-06-26 | CENTRO SVILUPPO MATERIALI S.p.A. | Process for the production of semiprocessed non oriented grain electrical steel |
| EP0469980B1 (en) * | 1990-07-30 | 1996-07-10 | USINOR SACILOR Société Anonyme | Process for manufacturing grain non oriented magnetic steel sheet and sheet obtained thereby |
| EP2840157A1 (en) * | 2013-08-19 | 2015-02-25 | ThyssenKrupp Steel Europe AG | Non-grain oriented electrical steel or sheet metal, component produced from same and method for producing non-grain oriented electrical steel or sheet metal |
-
1980
- 1980-09-04 GB GB8028651A patent/GB2057500B/en not_active Expired
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0434641A2 (en) * | 1989-12-22 | 1991-06-26 | CENTRO SVILUPPO MATERIALI S.p.A. | Process for the production of semiprocessed non oriented grain electrical steel |
| EP0434641A3 (en) * | 1989-12-22 | 1992-10-14 | Centro Sviluppo Materiali S.P.A. | Process for the production of semiprocessed non oriented grain electrical steel |
| EP0469980B1 (en) * | 1990-07-30 | 1996-07-10 | USINOR SACILOR Société Anonyme | Process for manufacturing grain non oriented magnetic steel sheet and sheet obtained thereby |
| EP2840157A1 (en) * | 2013-08-19 | 2015-02-25 | ThyssenKrupp Steel Europe AG | Non-grain oriented electrical steel or sheet metal, component produced from same and method for producing non-grain oriented electrical steel or sheet metal |
| WO2015024723A1 (en) * | 2013-08-19 | 2015-02-26 | Thyssenkrupp Steel Europe Ag | Non-grain-oriented electrical steel strip or electrical steel sheet, component produced therefrom, and method for producing a non-grain-oriented electrical steel strip or electrical steel sheet |
| CN105473751A (en) * | 2013-08-19 | 2016-04-06 | 蒂森克虏伯钢铁欧洲股份公司 | Non-grain-oriented electrical steel strip or electrical steel sheet, component produced therefrom, and method for producing a non-grain-oriented electrical steel strip or electrical steel sheet |
| US20160203897A1 (en) * | 2013-08-19 | 2016-07-14 | Thyssenkrupp Steel Europe Ag | Non-grain-oriented electrical steel strip or electrical steel sheet, component produced therefrom, and methods for producing same |
| CN105473751B (en) * | 2013-08-19 | 2018-01-12 | 蒂森克虏伯钢铁欧洲股份公司 | The method of the electrical steel strip or electric steel plate of non grain orientation, the part being made from it and electrical steel strip or electric steel plate for manufacturing non grain orientation |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2057500B (en) | 1983-05-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |