Method for production of non-oriented electrical steel strip
View Patent ↗The present invention relates to a method for producing a non-oriented electrical steel with improved magnetic properties and improved resistance to ridging, brittleness, nozzle clogging and magnetic aging. The chromium bearing steel is produced from a steel melt which is cast as a thin slab or conventional slab, cooled, hot rolled and/or cold rolled into a finished strip. The finished strip is further subjected to at least one annealing treatment wherein the magnetic properties are developed, making the steel sheet of the present invention suitable for use in electrical machinery such as motors or transformers.
1. A method for producing a non-oriented electrical steel comprising the steps of:
(a) preparing a non-oriented electrical steel melt having a composition in weight % comprising:
up to about 6.5% silicon,
up to about 5% chromium,
up to about 0.05% carbon,
up to about 3% aluminum,
up to about 3% manganese, and
the balance being substantially iron and residuals;
(b) casting a steel slab from said steel melt;
(c) heating said steel slab to a temperature less than T max and greater than T min as defined by:
T min , ° C.=921−5998(%C)−106(%Mn)+135(%P)+78.5(%Si)+107(%Al)−11.9(%Cr)+896(%N)+8.33(%Cu)−146(%Ni)+173(%Mo)
T max , ° C.=1479+3480(%C)+158(%Mn)−347(%P)−121(%Si)−275(%Al)+1.42(%Cr)−195(%N)+44.7(%Cu)+140(%Ni)−132(%Mo)
(d) hot rolling said slab to a hot rolled strip wherein said hot rolling provides a nominal strain of at least 700 using the equation:
ɛ
nominal
=
[
2
π
n
t
i
D
(
t
i
-
t
f
)
(
1.25
-
t
f
4
t
i
)
]
0.15
exp
(
7616
T
)
ln
(
t
i
t
f
)
;
and
,
(e) finish annealing said strip at a temperature less than T as defined by:
T , ° C.=759−4430(%C)−194(%Mn)+445(%P)+181(%Si)+378(%Al)−29.0(%Cr)−48.8(%N)−68.1(%Cu)−235(%Ni)+116(%Mo).
2. The method of claim 1 wherein the finish annealing temperature is less than T as defined by:
T , ° C.=921−5998(%C)−106(%Mn)+135(%P)+78.5(%Si)+107(%Al)−11.9(%Cr)+896(%N)+8.33(%Cu)−146(%Ni)+173(%Mo).
3. The method of claim 1 wherein the non-oriented electrical steel melt comprises:
about 1% to about 3.5% silicon,
about 0.1% to about 3% chromium,
up to about 0.01% carbon,
up to about 1% aluminum,
about 0.1% to about 1% manganese,
up to about 0.01% of a metal selected from the group consisting of sulfur, selenium and mixtures thereof,
up to about 0.01% nitrogen, and
the balance being substantially iron and residuals.
4. The method of claim 2 wherein the non-oriented electrical steel melt comprises:
about 1% to about 3.5% silicon,
about 0.1% to about 3% chromium,
up to about 0.01% carbon,
up to about 1% aluminum,
about 0.1% to about 1% manganese,
up to about 0.01% of a metal selected from the group consisting of sulfur, selenium and mixtures thereof,
up to about 0.01% nitrogen, and
the balance being substantially iron and residuals.
5. The method of claim 1 wherein the non-oriented electrical steel melt comprises:
about 1.5% to about 3% silicon,
about 0.15% to about 2% chromium,
up to about 0.005% carbon,
up to about 0.5% aluminum,
about 0.1% to about 0.35% manganese,
up to about 0.005% sulfur;
up to about 0.007% selenium;
up to about 0.002% nitrogen, and
the balance being substantially iron and residuals.
6. The method of claim 2 wherein the non-oriented electrical steel melt comprises:
about 1.5% to about 3% silicon,
about 0.15% to about 2% chromium,
up to about 0.005% carbon,
up to about 0.5% aluminum,
about 0.1% to about 0.35% manganese,
up to about 0.005% sulfur;
up to about 0.007% selenium;
up to about 0.002% nitrogen, and
the balance being substantially iron and residuals.
7. The method of claim 1 wherein the non-oriented electrical steel melt further comprises up to about 0.15% antimony, up to about 0.005% niobium, up to about 0.25% phosphorus, up to about 0.15% tin, up to about 0.01% sulfur and/or selenium, and up to about 0.01% vanadium.
8. The method of claim 2 wherein the non-oriented electrical steel melt further comprises up to about 0.15% antimony, up to about 0.005% niobium, up to about 0.25% phosphorus, up to about 0.15% tin, up to about 0.01% sulfur and/or selenium, and up to about 0.01% vanadium.
9. A method for producing a non-oriented electrical steel comprising the steps of:
(a) preparing a non-oriented electrical steel melt having a composition in weight % comprising:
up to about 6.5% silicon,
up to about 5% chromium,
up to about 0.05% carbon,
up to about 3% aluminum,
up to about 3% manganese, and
the balance being substantially iron and residuals;
(b) casting a steel slab from said steel melt;
(c) heating said steel slab to a temperature less than T max and greater than T min as defined by:
ti T min , ° C.=759−4430(%C)−194(%Mn)+445(%P)+181(%Si)+378(%Al)−29.0(%Cr)−48.8(%N)−68.1(%Cu)−235(%Ni)+116(%Mo)
ti T max , ° C.=1633+3970(%C)+236(%Mn)−685(%P)−207(%Si)−455(%Al)+9.64(%Cr)−706(%N)+55.8(%Cu)+247(%Ni)−156(%Mo)
(d) hot rolling said slab to a hot rolled strip wherein said hot rolling provides a nominal strain of at least 700 using the equation:
ɛ
nominal
=
[
2
π
n
t
i
D
(
t
i
-
t
f
)
(
1.25
-
t
f
4
t
i
)
]
0.15
exp
(
7616
T
)
ln
(
t
i
t
f
)
;
and
,
(e) finish annealing said strip at a temperature less than T min as defined by:
ti T min , ° C.=759−4430(%C)−194(%Mn)+445(%P)+181(%Si)+378(%Al)−29.0(%Cr)−48.8(%N)−68.1(%Cu)−235(%Ni)+116(%Mo).
10. The method of claim 9 wherein the finish annealing temperature is less than T as defined by:
ti T , ° C.=921−5998(%C)−106(%Mn)+135(%P)+78.5(%Si)+107(%Al)−11.9(%Cr)+896(%N)+8.33(%Cu)−146(%Ni)+173(%Mo).
11. The method of claim 9 wherein the non-oriented electrical steel melt comprises:
about 1% to about 3.5% silicon,
about 0.1% to about 3% chromium,
up to about 0.01% carbon,
up to about 1% aluminum,
about 0.1% to about 1% manganese,
up to about 0.01% of a metal selected from the group consisting of sulfur, selenium and mixtures thereof,
up to about 0.01% nitrogen, and
the balance being substantially iron and residuals.
12. The method of claim 10 wherein the non-oriented electrical steel melt comprises:
about 1% to about 3.5% silicon,
about 0.1% to about 3% chromium,
up to about 0.01% carbon,
up to about 1% aluminum,
about 0.1% to about 1% manganese,
up to about 0.01% of a metal selected from the group consisting of sulfur, selenium and mixtures thereof,
up to about 0.01% nitrogen, and
the balance being substantially iron and residuals.
13. The method of claim 9 wherein the non-oriented electrical steel melt comprises:
about 1.5% to about 3% silicon,
about 0.15% to about 2% chromium,
up to about 0.005% carbon,
up to about 0.5% aluminum,
about 0.1% to about 0.35% manganese,
up to about 0.005% sulfur;
up to about 0.007% selenium;
up to about 0.002% nitrogen, and
the balance being substantially iron and residuals.
14. The method of claim 10 wherein the non-oriented electrical steel melt comprises:
about 1.5% to about 3% silicon,
about 0.15% to about 2% chromium,
up to about 0.005% carbon,
up to about 0.5% aluminum,
about 0.1% to about 0.35% manganese,
up to about 0.005% sulfur;
up to about 0.007% selenium;
up to about 0.002% nitrogen, and
the balance being substantially iron and residuals.
15. The method of claim 9 wherein the non-oriented electrical steel melt further comprises up to about 0.15% antimony, up to about 0.005% niobium, up to about 0.25% phosphorus, up to about 0.15% tin, up to about 0.01% sulfur and/or selenium, and up to about 0.01% vanadium.
16. The method of claim 10 wherein the non-oriented electrical steel melt further comprises up to about 0.15% antimony, up to about 0.005% niobium, up to about 0.25% phosphorus, up to about 0.15% tin, up to about 0.01% sulfur and/or selenium, and up to about 0.0 1% vanadium.
17. A method for producing a non-oriented electrical steel comprising the steps of:
(a) preparing a non-oriented electrical steel melt having a composition in weight % comprising:
up to about 6.5% silicon,
up to about 5% chromium,
up to about 0.05% carbon,
up to about 3% aluminum,
up to about 3% manganese, and
the balance being substantially iron and residuals;
(b) casting a steel slab from said steel melt;
(c) heating said steel slab to a temperature less than T max as defined by:
T max , ° C.=1463+3401(%C)+147(%Mn)−378(%P)−109(%Si)−248(%Al)+0.79(%Cr)−78.8(%N)+28.9(%Cu)+143(%Ni)−22.7(%Mo)
(d) hot rolling said slab to a hot rolled strip wherein said hot rolling provides a nominal strain of at least 700 using the equation:
ɛ
nominal
=
[
2
π
n
t
i
D
(
t
i
-
t
f
)
(
1.25
-
t
f
4
t
i
)
]
0.15
exp
(
7616
T
)
ln
(
t
i
t
f
)
;
and
,
(e) finish annealing said strip at a temperature less than T min as defined by:
T min , ° C.=759−4430(%C)−194(%Mn)+445(%P)+181(%Si)+378(%Al)−29.0(%Cr)−48.8(%N)−68.1(%Cu)−235(%Ni)+116(%Mo).
18. The method of claim 17 wherein the finish annealing temperature is less than T as defined by:
T , ° C.=921−5998(%C)−106(%Mn)+135(%P)+78.5(%Si)+107(%Al)−11.9(%Cr)+896(%N)+8.33(%Cu)−146(%Ni)+173(%Mo).
19. The method of claim 17 wherein the non-oriented electrical steel melt comprises:
about 1% to about 3.5% silicon,
about 0.1% to about 3% chromium,
up to about 0.01% carbon,
up to about 1% aluminum,
about 0.1% to about 1% manganese,
up to about 0.01% of a metal selected from the group consisting of sulfur, selenium and mixtures thereof,
up to about 0.01% nitrogen, and
the balance being substantially iron and residuals.
20. The method of claim 18 wherein the non-oriented electrical steel melt comprises:
about 1% to about 3.5% silicon,
about 0.1% to about 3% chromium,
up to about 0.01% carbon,
up to about 1% aluminum,
about 0.1% to about 1% manganese,
up to about 0.01% of a metal selected from the group consisting of sulfur, selenium and mixtures thereof,
up to about 0.01% nitrogen, and
the balance being substantially iron and residuals.
21. The method of claim 17 wherein the non-oriented electrical steel melt comprises:
about 1.5% to about 3% silicon,
about 0.15% to about 2% chromium,
up to about 0.005% carbon,
up to about 0.5% aluminum,
about 0.1% to about 0.35% manganese,
up to about 0.005% sulfur;
up to about 0.007% selenium;
up to about 0.002% nitrogen, and
the balance being substantially iron and residuals.
22. The method of claim 18 wherein the non-oriented electrical steel melt comprises:
about 1.5% to about 3% silicon,
about 0.15% to about 2% chromium,
up to about 0.005% carbon,
up to about 0.5% aluminum,
about 0.1% to about 0.35% manganese,
up to about 0.005% sulfur;
up about 0.007% selenium;
up to about 0.002% nitrogen, and
the balance being substantially iron and residuals.
23. The method of claim 17 wherein the non-oriented electrical steel melt further comprises up to about 0.15% antimony, up to about 0.005% niobium, up to about 0.25% phosphorus, up to about 0.15% tin, up to about 0.01% sulfur and/or selenium, and up to about 0.01% vanadium.
24. The method of claim 18 wherein the non-oriented electrical steel melt further comprises up to about 0.15% antimony, up to about 0.005% niobium, up to about 0.25% phosphorus, up to about 0.15% tin, up to about 0.01% sulfur and/or selenium, and up to about 0.01% vanadium.