NZ756845B2 - Steel Sheet, Method of Manufacturing Same, Crown Cap, and Drawing and Redrawing (DRD) Can - Google Patents
Steel Sheet, Method of Manufacturing Same, Crown Cap, and Drawing and Redrawing (DRD) Can Download PDFInfo
- Publication number
- NZ756845B2 NZ756845B2 NZ756845A NZ75684518A NZ756845B2 NZ 756845 B2 NZ756845 B2 NZ 756845B2 NZ 756845 A NZ756845 A NZ 756845A NZ 75684518 A NZ75684518 A NZ 75684518A NZ 756845 B2 NZ756845 B2 NZ 756845B2
- Authority
- NZ
- New Zealand
- Prior art keywords
- steel sheet
- less
- crown cap
- drd
- sheet
- Prior art date
Links
- 238000004519 manufacturing process Methods 0.000 title claims description 13
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 178
- 239000010959 steel Substances 0.000 claims abstract description 178
- 239000000126 substance Substances 0.000 claims abstract description 13
- 239000000203 mixture Substances 0.000 claims abstract description 12
- 239000012535 impurity Substances 0.000 claims abstract description 8
- 238000005097 cold rolling Methods 0.000 claims description 51
- 238000005096 rolling process Methods 0.000 claims description 44
- 238000000137 annealing Methods 0.000 claims description 28
- 238000005098 hot rolling Methods 0.000 claims description 18
- 238000005554 pickling Methods 0.000 claims description 15
- 238000010438 heat treatment Methods 0.000 claims description 10
- 239000002994 raw material Substances 0.000 claims description 8
- 238000002441 X-ray diffraction Methods 0.000 claims description 4
- 229910052799 carbon Inorganic materials 0.000 abstract description 5
- 229910052698 phosphorus Inorganic materials 0.000 abstract description 3
- 229910052748 manganese Inorganic materials 0.000 abstract description 2
- 229910052757 nitrogen Inorganic materials 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 52
- 230000015572 biosynthetic process Effects 0.000 description 41
- 238000005755 formation reaction Methods 0.000 description 41
- 239000000463 material Substances 0.000 description 25
- 230000037303 wrinkles Effects 0.000 description 24
- 230000001603 reducing Effects 0.000 description 23
- 229910052751 metal Inorganic materials 0.000 description 18
- 239000002184 metal Substances 0.000 description 18
- 238000006722 reduction reaction Methods 0.000 description 18
- 238000000034 method Methods 0.000 description 10
- 230000000694 effects Effects 0.000 description 8
- 235000013405 beer Nutrition 0.000 description 7
- 238000007747 plating Methods 0.000 description 7
- 238000011156 evaluation Methods 0.000 description 6
- 239000006104 solid solution Substances 0.000 description 6
- 238000005728 strengthening Methods 0.000 description 6
- 229910017083 AlN Inorganic materials 0.000 description 4
- PIGFYZPCRLYGLF-UHFFFAOYSA-N aluminum nitride Chemical compound [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 3
- 238000007792 addition Methods 0.000 description 3
- 239000011651 chromium Substances 0.000 description 3
- 238000009749 continuous casting Methods 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- 238000009863 impact test Methods 0.000 description 3
- 238000011068 load Methods 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- 238000009628 steelmaking Methods 0.000 description 3
- KRVSOGSZCMJSLX-UHFFFAOYSA-L Chromic acid Chemical compound O[Cr](O)(=O)=O KRVSOGSZCMJSLX-UHFFFAOYSA-L 0.000 description 2
- 235000013361 beverage Nutrition 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000010960 cold rolled steel Substances 0.000 description 2
- 230000000875 corresponding Effects 0.000 description 2
- 229910000529 magnetic ferrite Inorganic materials 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 238000004080 punching Methods 0.000 description 2
- 238000003303 reheating Methods 0.000 description 2
- 238000004381 surface treatment Methods 0.000 description 2
- 229910052718 tin Inorganic materials 0.000 description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N tin hydride Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 2
- 239000005029 tin-free steel Substances 0.000 description 2
- 238000004642 transportation engineering Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 238000010306 acid treatment Methods 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- REDXJYDRNCIFBQ-UHFFFAOYSA-N aluminium(3+) Chemical class [Al+3] REDXJYDRNCIFBQ-UHFFFAOYSA-N 0.000 description 1
- 235000014171 carbonated beverage Nutrition 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000003009 desulfurizing Effects 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 239000004800 polyvinyl chloride Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 235000014214 soft drink Nutrition 0.000 description 1
- 230000037373 wrinkle formation Effects 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
- B65D41/00—Caps, e.g. crown caps or crown seals, i.e. members having parts arranged for engagement with the external periphery of a neck or wall defining a pouring opening or discharge aperture; Protective cap-like covers for closure members, e.g. decorative covers of metal foil or paper
- B65D41/02—Caps or cap-like covers without lines of weakness, tearing strips, tags, or like opening or removal devices
- B65D41/10—Caps or cap-like covers adapted to be secured in position by permanent deformation of the wall-engaging parts
- B65D41/12—Caps or cap-like covers adapted to be secured in position by permanent deformation of the wall-engaging parts made of relatively stiff metallic materials, e.g. crown caps
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
-
- 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
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
-
- 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
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—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
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0236—Cold 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
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0278—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips 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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0405—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing of ferrous alloys
-
- 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
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
- C21D8/0426—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
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
- C21D8/0436—Cold 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
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0447—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment
- C21D8/0468—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment between cold rolling steps
-
- 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
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
-
- 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
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
- C21D9/48—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals deep-drawing sheets
-
- 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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- 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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
-
- 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
- C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
-
- 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
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- 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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
Abstract
Provided is a steel sheet with a chemical composition consisting of, in mass%, C: more than 0.006% but not exceeding 0.012%, Si: 0.02% or less, Mn: 0.10% to 0.60%, P: 0.020% or less, S: 0.020% or less, Al: 0.01% to 0.07%, N: 0.0080%to 0.0200%, balance: Fe and unavoidable impurities. With the dislocation density at half depth from the steel sheet surface set between 2.0 x 1014/m2and 1.0 x 1015/m2, the steel sheet has sufficient formability and strength even when the gauge is made thinner. tion density at half depth from the steel sheet surface set between 2.0 x 1014/m2and 1.0 x 1015/m2, the steel sheet has sufficient formability and strength even when the gauge is made thinner.
Description
STEEL SHEET, METHOD OF MANUFACTURING SAME, CROWN CAP,
AND DRAWING AND REDRAWING (DRD) CAN
BACKGROUND
[0001] This disclosure relates to a steel sheet, and in particular to a
high-strength thin steel sheet with excellent formability and a method for
manufacturing the same. Typical examples of such steel sheet include a thin
steel sheet serving as a material of a crown cap used as a stopper for a glass
bottle, as well as a DRD (Drawing and Redrawing) can formed by a
combination of drawing and redrawing. This disclosure also relates to a
crown cap and a DRD obtained by forming the steel sheet.
BACKGROUND
For example, metal caps called crown caps are often used in
containers for beverages such as soft drinks and liquors. Generally, the
crown cap is manufactured by press forming a thin steel sheet as a material,
and comprises a disk-like portion for closing the mouth of the bottle and a
corrugated portion provided around the periphery, and the corrugated portion
is fixed by caulking onto the mouth of the bottle to seal the bottle.
[0003] Bottles that use a crown cap are often filled with contents that
generate high internal pressure, such as beer or carbonated beverages. For
this reason, even when the internal pressure is increased due to a change in
temperature or the like, the crown cap needs to have high pressure resistance
in order to prevent the crown cap from deforming and leaking the content.
Furthermore, in the case where the internal pressure is increased due to a
change in temperature or the like, impact resistance is also important such that
the seal of the bottle is not broken by an external impact during transportation.
In addition, even if the strength of the material is sufficient, if the formability
is poor, the shape of the corrugated portion becomes uneven. Then,
sufficient sealing performance may not be obtained when a crown cap of such
a faulty shape is fixed by caulking onto the mouth of the bottle. Thus, it is
also necessary that the steel sheet be excellent in formability.
SR (Single Reduced) steel sheets are mainly used as thin steel sheets
to be used as materials for crown caps. SR steel sheets are manufactured by
PO180773-PCT-ZZ (1/29)
a process including thinning by cold rolling, annealing, and temper rolling.
The thickness of conventional steel sheets for crown caps is generally 0.22
mm or more, and sufficient pressure resistance, impact resistance, and
formability have been secured by applying SR material made of mild steel
used for food and beverage cans and the like.
In recent years, as with steel sheets for cans, there has been an
increasing demand for sheet metal thinning of steel sheets for crown caps for
the purpose of cost reduction. If the thickness of the steel sheet for crown
caps is less than 0.22 mm, particularly 0.20 mm or less, the pressure
resistance and impact resistance of the crown cap manufactured using the
conventional SR material are insufficient. In order to secure the pressure
resistance and impact resistance, a DR (Double Reduced) steel sheet is
applied, which can be subjected to secondary cold roling and hardened after
annealing to compensate for the decrease in strength due to sheet metal
thinning.
Crown caps are squeezed to some extent at the center at the beginning
of forming, and then the outer edge is formed into a corrugated shape. Here,
if the material of a crown cap is a steel sheet having low formability, a shape
defect as schematically illustrated in may occur, in which a fold forms
from the crown cap upper surface side deviating from the proper position.
Not only does such a crown cap with a shape defect look poor and reduce the
consumer's purchase intention, but even when plugged in a bottle, it does not
provide proper pressure resistance and impact resistance, and the contents
may leak.
[0007] On the other hand, DRD cans need to have high pressure resistance
such that the cans do not deform if the internal pressure increases or decreases.
Furthermore, impact resistance is also important because deformation of a
DRD can due to external impact during transportation may result in leakage of
the contents and loss of consumer confidence due to the loss of the appearance.
In addition, even when the strength of the steel sheet as the material of a DRD
can is sufficient, if the steel sheet is poor in formability, this will lead to a
shape defect in which wrinkles form in the flange during DRD can formation.
When wrinkles form in the flange portion, when the pressure inside the can
increases or decreases after the steel sheet is formed into a DRD can, stress
PO180773-PCT-ZZ (2/29)
tends to be concentrated in the vicinity of the wrinkle formation portion, and
sufficient pressure resistance may not be obtained. Therefore, the steel sheet
to be used as the material of a DRD can is also required to have excellent
formability.
[0008] Moreover, in recent years, in the same manner as the crown cap steel
sheet, the demand for sheet metal thinning of the steel sheet for DRD cans has
also been increased for the purpose of cost reduction. With this sheet metal
thinning, it has become more important to secure sufficient pressure resistance
and impact resistance and formability.
[0009] In view of the above, for a high strength thin steel sheet for crown
caps, for example, JP6057023B (PTL 1) proposes a steel sheet for crown caps
comprising a chemical composition containing, by mass%, C: 0.0010 % to
0.0060 %, Si: 0.005 % to 0.050 %, Mn: 0.10 % to 0.50 % Ti: 0 % to 0.100 %,
Nb: 0 % to 0.080 %, B: 0 % to 0.0080 %, P: 0 .040 % or less, S: 0.040 % or
less, Al: 0.1000 % or less, and N: 0.0100 % or less, with the balance being Fe
and impurities, wherein a minimum value of r values in a direction of 25° to
65° with respect to a rolling direction of the steel sheet is 1.80 or more, and an
average value of r values in a direction of 0° or more and less than 360° with
respect to the rolling direction is 1.70 or more, and wherein a yield strength is
570 MPa or more .
In addition, for example, JP4559918B (PTL 2) describes a steel sheet
for tin plates and TFS having excellent formability, comprising a chemical
composition containing, by mass%, C: 0.0030 % to 0.0060 %, Si: 0.04 % or
less, Mn: 0.60 % or less, P: 0.005 % or more and 0.03 % or less, S: 0.02 % or
less, Al: more than 0.005 %, 0.1% or less, and N: 0.005 % or less within a
range satisfying a a predetermined formula, with the balance being Fe and
inevitable impurities, wherein a sheet thickness is 0.2 mm or less, a hardness
level (HR30T) is 67 ±3 to 76 ±3, and an Δr value indicating in-plane
anisotropy is ±0.2 or less.
CITATION LIST
Patent Literature
PTL 1: JP6057023B
PO180773-PCT-ZZ (3/29)
PTL 2: JP4559918B
A steel sheet manufactured by the technique described in PTL 1 tends
to be insufficient in formability and strength particularly after sheet metal
thinning, and a crown cap formed using the steel sheet as a material has the
problem of having a lower impact resistance than that of a conventional crown
cap. This problem is the same as in the case of a material for DRD cans.
The steel sheet manufactured by the technique described in PTL 2
tends to be insufficient in formability and strength particularly after sheet
metal thinning, and a DRD can formed using the steel sheet as a material has
the problem of having a lower impact resistance than that of a conventional
DRD can. This problem is the same as in the case of a crown cap material.
It would thus be helpful to provide a steel sheet with sufficient
formability and strength even after sheet metal thinning, and a method of
manufacturing the same.
SUMMARY OF THE INVENTION
The inventors made intensive studies on how to solve the above
problems, and found that by optimizing the alloy components and
manufacturing conditions and controlling the dislocation density at a depth
position of 1/2 of a sheet thickness from a surface, it may be possible to
provide a steel sheet having sufficient formability and strength. The present
disclosure was completed based on this finding, and the summary thereof is as
follows.
(1) A steel sheet comprising: a chemical composition containing
(consisting of), by mass , C: more than 0.006 and not more than 0.012 ,
Si: 0.02 or less, Mn: 0.10 or more and 0.60 or less, P: 0.020 or less,
S: 0.020 or less, Al: 0.01 or more and 0.07 or less, and N: 0.0080 or
more and 0.0200 or less, with the balance being Fe and inevitable
impurities, wherein a dislocation density at a depth position of 1 2 of a sheet
14 2
thickness from a surface of the steel sheet is 2.0 × 10 /m or more and 1.0 ×
2
/m or less when measured by X-ray diffraction.
(2) The steel sheet according to (1), having a thickness of 0.20
mm or less.
(3) A crown cap made of the steel sheet as recited in (1) or (2).
PO180773-PCT-ZZ (4/30)
(4) A DRD can made of the steel sheet as recited in (1) or (2).
(5) A method of manufacturing the steel sheet as recited in (1) or
(2), comprising: a hot rolling step of heating a steel raw material at 1200 C or
higher, finish rolling the steel raw material to obtain a hot rolled sheet, and
coiling the hot rolled sheet within a temperature range of 670 C or lower; a
pickling step of pickling the hot rolled sheet after the hot rolling step; a
primary cold rolling step of cold rolling the hot rolled sheet after the pickling
step to obtain a cold rolled sheet; an annealing step of annealing the cold
rolled sheet after the primary cold rolling step in a temperature range of 650
C to 750 C to obtain an annealed sheet; and a secondary cold rolling step of
cold rolling the annealed sheet after the annealing step, with a rolling
reduction of 10 or more and 30 or less and an average tension of 98 MPa
or more between cold rolling stands in a rolling apparatus having at least two
cold rolling stands.
According to the present disclosure, it is possible to provide a steel
sheet having sufficient strength and excellent formability even after sheet
metal thinning. In particular, when a crown cap or a DRD can is
manufactured using this steel sheet as a material, the impact resistance
performance can be maintained at a high level in a crown cap or a DRD can
even after sheet metal thinning.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings:
is a schematic view illustrating a crown cap having a poor shape;
illustrates a surface of a crown cap for observing a cross-sectional
shape profile;
FIGS. 3A and 3B illustrate a typical example of a cross-sectional profile of a
crown cap;
FIGS. 4A and 4B illustrate the procedure of an impact resistance test
performed on a DRD can; and
FIGS. 5A and 5B illustrate an evaluation target of an impact resistance test
performed on a DRD can.
PO180773-PCT-ZZ (5/30)
DETAILED DESCRIPTION
The steel sheet according to the present disclosure comprises: a
chemical composition containing, by mass , C: more than 0.006 and not
more than 0.012 , Si: 0.02 or less, Mn: 0.10 or more and 0.60 or less,
P: 0.020 or less, S: 0.020 or less, Al: 0.01 or more to 0.07 or less,
and N: 0.0080 or more and 0.0200 or less, with the balance being Fe and
inevitable impurities, wherein a dislocation density at a depth position of 1⁄2
14 2
of a sheet thickness from a surface of the steel sheet is 2.0 × 10 /m or more
2
and 1.0 × 10 /m or less.
First, the reasons for limitation of the content of each component in the
chemical composition of the steel sheet will be described in order. In the
following description, " " notation represents "mass " unless otherwise
specified.
[0024] C: more than 0.006 % and 0.012 % or less
C is an interstitial element, and a large amount of solid solution strengthening
can be obtained with a small amount of addition. As a result of improving
the frictional force of the base steel sheet by this solid solution strengthening,
the moving speed of dislocations during secondary cold rolling described later
decreases, and a large amount of dislocations are introduced into the material
even with a low rolling reduction, and the dislocation density improves.
That is, when the C content is 0.006 % or less, the dislocation density at a
depth of 1/2 of the sheet thickness from the surface of the steel sheet is less
14 2
than 2.0 × 10 /m , and for example, when the steel sheet is used for a crown
cap, the same impact resistance as that of a conventional crown cap can not be
obtained. Similarly, when the steel sheet is used as a DRD can, for example,
to form a thin DRD can, the same impact resistance as that of a conventional
DRD can may not be obtained. On the other hand, when the C content
exceeds 0.012 %, the dislocation density at a depth of 1/2 of the sheet
2
thickness from the surface of the steel sheet exceeds 1.0 × 10 /m , and the
formability of the steel sheet is lowered. For example, when the steel sheet
is used for a crown cap, a shape defect occurs in which a fold forms from the
crown cap upper surface during crown cap formation. Similarly, when the
steel sheet is used for a DRD can, for example, a shape defect occurs in which
PO180773-PCT-ZZ (6/29)
wrinkles form in the flange portion during DRD can formation. From the
above, the C content is more than 0.006 % and 0.012 % or less. Preferably, it
is 0.007 % or more and 0.01 % or less.
Si: 0.02 % or less
When the content of Si exceeds 0.02 %, the formability of the steel sheet is
reduced, and for example, a shape defect occurs in which a fold forms from
the crown cap upper surface during crown cap formation. Similarly, when
the steel sheet is used for a DRD can, for example, a shape defect occurs in
which wrinkles form in the flange portion during DRD can formation.
Furthermore, the surface treatment property of the steel sheet is deteriorated
and the corrosion resistance is lowered. From the above, the Si content is
0.02 % or less. Preferably, it is 0.01 % or less. Note that it is preferable to
set the Si content to 0.004 % or more, since reducing Si excessively causes
increase of steelmaking cost.
[0026] Mn: 0.10 % to 0.60 %
Mn is a interstitial element, and a large amount of solid solution strengthening
can be obtained with a small amount of addition. As a result of improving
the frictional force of the base steel sheet by this solid solution strengthening,
the moving speed of dislocations during secondary cold rolling described later
decreases, and a large amount of dislocations are introduced into the material
even with a low rolling reduction, and the dislocation density improves.
That is, when the Mn content is less than 0.10 %, the dislocation density at a
depth position of 1/2 of the sheet thickness from the surface of the steel sheet
14 2
is less than 2.0 × 10 /m , and for example, when the steel sheet is used for a
crown cap and after sheet metal thinning, the same impact resistance as a
conventional crown cap can not be obtained. Similarly, when the steel sheet
is used as a DRD can, for example, and after sheet metal thinning, the same
impact resistance as that of a conventional DRD can may not be obtained.
Furthermore, if the Mn content is less than 0.10 %, it becomes difficult to
avoid hot brittleness even if the S content is reduced, and problems such as
surface cracking occur during continuous casting. On the other hand, when
the Mn content exceeds 0.60 %, the formability of the steel sheet is reduced,
and for example, when the steel sheet is used for a crown cap, a shape defect
occurs in which a fold forms from the crown cap upper surface during crown
PO180773-PCT-ZZ (7/29)
cap formation. Similarly, when the steel sheet is used for a DRD can, for
example, a shape defect in which wrinkles form in the flange portion during
DRD can formation. From the above, the Mn content is 0.10 % or more and
0.60 % or less. Preferably, the Mn content is 0.15 % or more and 0.50 % or
less.
P: 0.020 % or less
When the P content exceeds 0.020 %, the formability of the steel sheet is
reduced, and for example, when the steel sheet is used for a crown cap, a
shape defect occurs in which a fold forms from the crown cap upper surface
during crown cap formation. Similarly, when the steel sheet is used for a
DRD can, for example, a shape defect occurs in which wrinkles form in the
flange portion during DRD can formation. Furthermore, the corrosion
resistance is reduced. From the above, the P content is 0.020 % or less.
Preferably, it is 0.015 % or less. Note that reducing the P content below
0.001 % requires excessive dephosphorization cost, the P content is preferably
0.001 % or more.
S: 0.020% or less
When the S content exceeds 0.020 %, inclusions are formed in the steel sheet
to cause a decrease in hot ductility and a deterioration in corrosion resistance
of the steel sheet, and further, a formability of the steel sheet is reduced.
When the steel sheet is used for a crown cap, a shape defect occurs in which a
fold forms from the crown cap upper surface during crown cap formation.
Similarly, when the steel sheet is used for a DRD can, for example, a shape
defect occurs in which wrinkles form in the flange portion during DRD
formation. Therefore, the S content is 0.020 % or less. Preferably, it is
0.015 % or less. In addition, reducing the S content below 0.005 % requires
excessive desulfurization cost, the S content is preferably 0.004 % or more.
Al: 0.01% or more and 0.07% or less
Al is an element necessary as a deoxidizer at the time of steel making, yet if
the Al content is less than 0.01 %, deoxidation becomes insufficient,
inclusions increase, and the formability of the steel sheet decreases , and for
example, when the steel sheet is used for a crown cap, a shape defect occurs in
which a fold forms from the crown cap upper surface during crown cap
formation. Similarly, when the steel sheet is used for a DRD can, for
PO180773-PCT-ZZ (8/29)
example, a shape defect occurs in which wrinkles form in the flange portion
during DRD can formation. On the other hand, when the Al exceeds 0.07 %,
a large amount of AlN is formed, and thus the amount of N in the steel
decreases and the effect of N described later can not be obtained. From the
above, the Al content is 0.01 % or more and 0.07 % or less. Preferably, it is
0.15 % or more and 0.55 % or less.
N: 0.0080 % or more to 0.0200 % or less
N is an interstitial element and, like C, a large amount of solid solution
strengthening can be obtained with a small amount of addition. As a result
of improving the frictional force of the base steel sheet by this solid solution
strengthening, the moving speed of dislocations during secondary cold rolling
described later decreases, and a large amount of dislocations are introduced
into the material even with a low rolling reduction, and the dislocation density
improves. That is, when the N content is less than 0.0080 %, the dislocation
density at a depth position of 1/2 of the sheet thickness from the surface of the
14 2
steel sheet is less than 2.0 × 10 /m , and for example, when the steel sheet is
used for a crown cap and after sheet metal thinning, the same impact
resistance as that of a conventional thick crown cap can not be obtained.
Similarly, for example, when the steel sheet is used for a DRD can and after
sheet metal thinning, the same impact resistance as that of a conventional
DRD can may not be obtained. On the other hand, when the N content
exceeds 0.0200 %, the dislocation density at a depth position of 1/2 of the
2
sheet thickness from the surface of the steel sheet exceeds 1.0 × 10 /m , the
formability of the steel sheet decreases, and for example, when the steel sheet
is used for a crown cap, a shape defect occurs in which a fold forms from the
crown cap upper surface during crown cap formation. Similarly, when the
steel sheet is used for a DRD can, for example, a shape defect occurs in which
wrinkles form in the flange portion during DRD can formation. From the
above, the N content is 0.0080 % or more and 0.0200 % or less. Preferably,
it is 0.0090 % or more and 0.019 % or less. The balance other than the above
components is Fe and inevitable impurities.
Furthermore, Cu, Ni, Cr, and Mo may be contained in the range which
does not impair the effect of the present disclosure. At that time, according
to ASTM A623M-11, it is preferable that Cu is 0.2 % or less, Ni is 0.15 % or
PO180773-PCT-ZZ (9/29)
less, Cr is 0.10 % or less, and Mo is 0.05 % or less. The contents of the other
elements are preferably 0.02 % or less.
Further, in the steel sheet disclosed herein, it is important that the
dislocation density at a depth position of 1/2 of the sheet thickness from the
14 2 15 2
surface of the steel sheet is 2.0 × 10 /m or more and 1.0 × 10 /m or less.
Our intensive studies revealed that the strength of the steel sheet can be
evaluated by, for example, the impact resistance of a crown cap when the steel
sheet is used for a crown cap, or the impact resistance of a DRD can when the
steel sheet is used for a DRD can, and that these impact resistances can be
improved by the increase of dislocation density. When the dislocation
density at a depth position of 1/2 of the sheet thickness from the surface of the
14 2
steel sheet is 2.0 × 10 /m or more, it is possible to obtain a impact resistance
equivalent to that of a conventional thick crown cap or DRD can, even after
sheet metal thinning. Although the reason for this is not clear, it is believed
that as dislocation density increases, deformation resistance increases due to
pinning of dislocations. Therefore, even when an external impact is applied
to a crown cap, for example, in a state where the internal pressure of the bottle
is high, the crown cap is less likely to come off. Alternatively, for example,
when an external impact is applied to a DRD can, the can becomes difficult to
deform. Therefore, the dislocation density at a depth position of 1/2 of the
14 2
sheet thickness from the surface of the steel sheet is set to 2.0 × 10 /m or
more.
On the other hand, when the dislocation density at a depth position of
1/2 of the sheet thickness from the surface of the steel sheet exceeds 1.0 ×
2
10 /m , the formability of the steel sheet is reduced, and for example, when
the steel sheet is used for a crown cap, a shape defect occurs in which a fold
forms from the crown cap upper surface during crown cap formation.
Similarly, when the steel sheet is used for a DRD can, for example, a shape
defect occurs in which wrinkles form in the flange portion during DRD can
formation. From the above, the dislocation density at a depth position of 1/2
14 2
of the sheet thickness from the surface of the steel sheet is set to 2.0 × 10 /m
2 14 2
or more and 1.0 × 10 /m or less. A more preferable range is 3.0 × 10 /m
14 2
or more and 9.0 × 10 /m or less. In order to set the dislocation density in
the above range, the steel slab with the above-described chemical composition
PO180773-PCT-ZZ (10/29)
may be subjected to the manufacturing process described later.
In this case, the dislocation density at a depth position of 1/2 of the
thickness from the surface of the steel sheet was determined by performing
X-ray diffraction using a Co radiation source on a surface exposed by
chemical polishing the surface of the steel sheet to the depth position of 1/2 of
the sheet thickness to measure peak positions and half-value widths of 4
planes of Fe(110), (200), (211), and (220). Each of the measured half-value
widths was corrected with a half-value width of an unstrained Si single crystal,
a local strain ε was determined by the Williamson Hall method, and the
dislocation density ρ was calculated using the following Equation (1):
where Burgers vector b was 0.25 nm.
The structure of the steel sheet disclosed herein is preferably a
recrystallized structure. The reason is that if there is non-recrystallization
after annealing, the material uniformity decreases, and for example, a fold
forms from the crown cap upper surface during crown cap formation.
Alternatively, for example, a shape defect occurs in which wrinkles form in
the flange portion during DRD can formation. However, if the area ratio of
non-recrystallized microstructures is 5 % or less, it does not substantially
affect the shape defect in which a fold forms from the crown cap upper surface
during crown cap formation, nor the shape defect in which wrinkles form in
the flange portion during DRD can formation. Therefore, an area ratio of
non-recrystallized microstructures of 5 % or less is acceptable. The
recrystallized microstructure is preferably a ferrite phase, and the phases
other than the ferrite phase are preferably less than 1.0 %.
Next, the manufacturing method disclosed herein will be described.
The manufacturing method includes a hot rolling step, a pickling step, a
primary cold rolling step, an annealing step, and a secondary cold rolling step.
In the following description, the temperature is defined as the surface
temperature of a steel sheet (blank sheet).
First, a steel adjusted to the above-described chemical composition is
PO180773-PCT-ZZ (11/29)
melted in a converter or the like to obtain a steel raw material such as a slab.
The steel material used is preferably manufactured by continuous casting to
prevent macrosegregation of the components, yet may be manufactured by
ingot casting or thin slab casting. In addition, after manufactured, the steel
raw material may be cooled to room temperature and heated again according
to a conventional method, or alternatively to a heat energy saving process
such as direct feed rolling and direct rolling in which the steel sheet is
charged into the furnace as a hot piece without being cooled to room
temperature, or is alternatively subjected to slight soaking, immediately
followed by rolling, without problems. The obtained steel material is
subjected to hot rolling. This hot rolling step is a step of heating a steel
material having the above-mentioned chemical composition at 1200 °C or
higher, finish rolling the steel raw material to obtain a hot rolled sheet, and
coiling the hot rolled sheet within a temperature range of 670 °C or lower.
[0038] [Steel raw material heating temperature: 1200 °C or higher]
When reheating the steel material, if the steel material reheating temperature
is lower than 1200 °C, AlN can not be sufficiently dissolved, and formation of
solute N can not be secured at the time of the secondary cold rolling step.
Thus, the dislocation density improving effect can not be obtained, and the
14 2
dislocation density becomes less than 2.0 × 10 /m at a depth position of 1/2
of the sheet thickness from the surface of the steel sheet, and for example,
when the steel sheet is used as a crown cap and after sheet metal thinning, an
impact resistance equivalent to that of a conventional thick crown cap can not
be obtained. Alternatively, for example, when the steel sheet is used as a
DRD can and after sheet metal thinning, an impact resistance equivalent to
that of a conventional DRD can may not be obtained. It is desirable that the
slab heating temperature be 1300 °C or lower in view of the increase in scale
loss due to the increase in the oxidation weight. Note that it is also possible
to use what is called a sheet bar heater which heats a sheet bar from the
viewpoint of preventing hot rolling problems even if the slab heating
temperature is lowered.
[Finish rolling]
The finish rolling temperature in the hot rolling step is preferably 850 °C or
higher from the viewpoint of the stability of the rolling load. On the other
PO180773-PCT-ZZ (12/29)
hand, raising the finish rolling temperature more than necessary may make it
difficult to manufacture thin steel sheets. Specifically, the finish rolling
temperature is preferably in a temperature range of 850 °C to 960 °C.
[Coiling temperature: 670 °C or lower]
If the coiling temperature exceeds 670 °C, the amount of AlN precipitated in
the steel after coiling increases, solute N can not be sufficiently secured
during the secondary cold rolling step, and thus the dislocation density
improving effect can not be obtained. The dislocation density at a depth
position of 1/2 of the sheet thickness from the surface in the sheet thickness
14 2
direction is less than 2.0 × 10 /m . Therefore, the coiling temperature is
670 °C or lower. Preferably, the temperature is 640 °C or lower. On the
other hand, the lower limit of the coiling temperature is not particularly
limited, yet if the coiling temperature is excessively lowered, the strength of
the hot rolled steel sheet obtained in the hot rolling step increases, the rolling
load in the primary cold rolling step increases, and it is difficult to control
rolling. Therefore, the coiling temperature is preferably 500 °C or higher.
In the hot rolling disclosed herein, in order to reduce the rolling load
at the time of hot rolling, part or all of finish rolling may be lubricated rolling.
Lubricated rolling is also effective from the viewpoint of making the shape of
the steel sheet uniform and making the material uniform. The coefficient of
friction in lubrication rolling is preferably in a range of 0.25 to 0.10.
Moreover, it is preferable to set it as a continuous rolling process which joins
preceding and following sheet bars, and carries out finish rolling continuously.
Applying a continuous rolling process is also desirable from the viewpoint of
the hot rolling operation stability.
[Pickling process]
Then, pickling is performed. The pickling step is a step of removing oxide
scales on the surface of the hot rolled steel sheet obtained in the hot rolling
step by pickling. The pickling conditions are not particularly limited, and
may be set as appropriate.
[Primary cold rolling process]
After the pickling, primary cold rolling is performed. The primary cold
rolling step is a step of subjecting the pickled sheet after the pickling step to
cold rolling. The cold rolling conditions are not particularly limited, and for
PO180773-PCT-ZZ (13/29)
example, the conditions such as the rolling reduction may be determined from
the viewpoint of the desired sheet thickness and the like. In order to make
the thickness of the steel sheet after secondary cold rolling be 0.20 mm or less,
the rolling reduction is preferably 85 % to 94 %.
[0044] [Annealing process]
Next, annealing is performed on the primary cold rolled sheet. The
annealing step is a step of annealing the cold rolled steel sheet obtained in the
primary cold rolling step in a temperature range of 650 °C to 750 °C. If the
annealing temperature is lower than 650 °C, AlN precipitates during annealing,
and solute N can not be secured during the subsequent secondary cold rolling
process. Thus, the dislocation density improving effect can not be obtained,
and the dislocation density at a depth position of 1/2 of the sheet thickness
14 2
from the surface of the steel sheet is less than 2.0 × 10 /m . Furthermore, if
the annealing temperature is lower than 650 °C, the area ratio of the
non-recrystallized microstructures exceeds 5 %, and the formability
deteriorates.
On the other hand, if the annealing temperature exceeds 750 °C, C
segregates at the grain boundaries and aggregates to form carbides, and thus
sufficient solute C can not be secured during the secondary cold rolling step.
Accordingly, the dislocation density improving effect can not be obtained, and
the dislocation density at a depth position of 1/2 of the sheet thickness from
14 2
the surface in the sheet thickness direction is less than 2.0 × 10 /m . From
the above, the annealing temperature is 650 °C or higher and 750 °C or lower.
Preferably, it is 660 °C or higher and 740 °C or lower. The holding time in
the temperature range of 650 °C to 750 °C is not particularly limited, yet if the
holding time is shorter than 5 seconds, non-recrystallized microstructures may
exceed 5 %, and if it exceeds 120 seconds, C segregates at grain boundaries
and aggregates to form carbides, solute C may not be sufficiently secured in
the secondary cold rolling step, and the cost is increased. Therefore, the
holding time is preferably 5 seconds or more and 120 seconds or less.
[Secondary cold rolling process]
Secondary cold rolling is performed on the annealed sheet after the annealing.
The secondary cold rolling step is a step of cold rolling the annealed sheet
obtained in the annealing step, with a rolling reduction of 10 % or more to
PO180773-PCT-ZZ (14/29)
% or less and an average tension of 98 MPa or more between cold rolling
stands in a rolling apparatus having at least two cold rolling stands.
When the average tension between the cold rolling stands is less than 98 MPa,
the dislocation density at a depth position of 1/2 of the sheet thickness from
14 2
the surface of the steel sheet is less than 2.0 × 10 /m . The average tension
between the cold rolling stands is preferably 127.4 MPa or more. On the
other hand, the upper limit of the average tension between the cold rolling
stands is not particularly limited, and may be determined from the viewpoint
of operability. For example, the tension may be adjusted so as not to cause
fracture of the steel sheet. Specifically, 392 MPa or less is preferable.
When the rolling reduction of secondary cold rolling is less than 10 %, the
dislocation density at a depth position of 1/2 of the sheet thickness from the
14 2
surface of the steel sheet is less than 2.0 × 10 /m . On the other hand, when
the rolling reduction of secondary cold rolling exceeds 30 %, the dislocation
density at a depth position of 1/2 of the sheet thickness from the surface of the
2
steel sheet exceeds 1.0 × 10 /m , and the formability of the steel sheet
decreases. In view of the above, the rolling reduction of secondary cold
rolling is 10 % or more and 30 % or less. The rolling reduction of secondary
cold rolling is preferably 12 % or more and 28 % or less.
[0047] It suffices for the number of rolling stands for secondary cold rolling
be plural. However, if it is five or more, the apparatus cost is increased.
Therefore, two to four cold rolling stands are preferred.
Optionally, the cold rolled steel sheet thus obtained may then be
subjected to plating treatment using electroplating, such as tin plating,
chromium plating, or nickel plating, to form a plating layer on the surface of
the steel sheet, and may be used as a plating steel sheet. In addition, since
the thickness of the layer subjected to surface treatment such as plating is
sufficiently smaller than the sheet thickness, the influence on the mechanical
properties of the steel sheet is negligible.
[0049] As described above, the steel sheet disclosed herein may have
sufficient formability and strength even after subjected to sheet metal thinning.
Therefore, the steel sheet disclosed herein is particularly suitable as a material
for a crown cap or a DRD can.
The crown cap is mainly composed of a disk-like portion for closing the
PO180773-PCT-ZZ (15/29)
mouth of the bottle and a corrugated portion provided around the periphery,
and can be formed by punching the steel sheet disclosed herein into a circular
blank and press forming the circular blank. A crown cap made of the steel
sheet disclosed herein has an excellent forming shape as a crown cap and
excellent impact resistance, and has an effect of reducing the amount of waste
discharged with use.
In addition, the DRD can may be formed by punching the
above-described steel sheet into a circular blank and then drawing and
redrawing the circular blank. The DRD can made of the steel sheet disclosed
herein is excellent in impact resistance, uniform in shape, and does not
deviate from the product specification. Therefore, the yield in the DRD can
manufacturing process is improved, and the effect of reducing the amount of
waste discharged from DRD can manufacturing is also achieved.
EXAMPLES
Steel Slabs having the chemical compositions listed in Table 1 with
the balance being Fe and inevitable impurities were prepared by steelmaking
in a converter and subjected to continuous casting to obtain steel slabs. The
steel slabs thus obtained were heated to 1220 C, subjected to finish rolling at
890 C to obtain hot rolled sheet, and coiled at coiling temperatures listed in
Table 2. After the hot rolling, pickling was performed. Then, primary cold
rolling was performed with a rolling reduction of 90 %, annealing was
performed under the annealing temperatures listed in Table 2, and secondary
cold rolling was subsequently performed with the rolling reductions listed in
Table 2 to obtain steel sheets having a sheet thickness of 0.17 mm. Each of
the obtained steel sheets was continuously subjected to electrolytic chromic
acid treatment to obtain a tin-free steel.
PO180773-PCT-ZZ (16/29)
PO180773-PCT-ZZ (17/29)
Table 1
(mass%)
Steel C Si Mn P S sol. Al N
A 0.0064 0.01 0.31 0.006 0.005 0.032 0.0130 Example
B 0.0075 0.01 0.46 0.002 0.004 0.056 0.0152 Example
C 0.0092 0.02 0.22 0.012 0.001 0.021 0.0112 Example
D 0.0111 0.01 0.21 0.018 0.006 0.035 0.0094 Example
E 0.0081 0.01 0.16 0.005 0.011 0.033 0.0193 Example
F 0.0078 0.01 0.32 0.010 0.008 0.015 0.0085 Example
G 0.0036 0.02 0.18 0.008 0.006 0.045 0.0143 Comparative example
H 0.0142 0.01 0.55 0.007 0.007 0.051 0.0124 Comparative example
I 0.0088 0.02 0.22 0.012 0.013 0.036 0.0074 Comparative example
J 0.0081 0.01 0.19 0.003 0.009 0.020 0.0215 Comparative example
K 0.0072 0.03 0.21 0.009 0.008 0.041 0.0132 Comparative example
L 0.0095 0.01 0.62 0.003 0.009 0.020 0.0132 Comparative example
M 0.0096 0.01 0.35 0.022 0.007 0.025 0.0122 Comparative example
N 0.0101 0.01 0.15 0.011 0.008 0.072 0.0163 Comparative example
O 0.0075 0.01 0.20 0.009 0.006 0.004 0.0142 Comparative example
P 0.0060 0.01 0.25 0.009 0.006 0.044 0.0125 Comparative example
Q 0.0079 0.01 0.21 0.010 0.007 0.069 0.0119 Example
R 0.0078 0.01 0.08 0.008 0.005 0.059 0.0111 Comparative example
S 0.0094 0.02 0.35 0.013 0.021 0.049 0.0099 Comparative example
* Underlined if outside of the scope of the disclosure.
Table 2
Hot rolling step Annealing step Secondary cold rolling step
Holding Average
Slab time in tensile
Coiling Annealing Number Rolling
No. Steel heating temp. range strength Remarks
temp. temp. of reduction
temp. of 650 C between
( C) ( C) stands ( )
( C) to 750 C stands
(s) (MPa)
1 A 1250 640 670 20 2 205.8 15 Example
2 A 1230 600 700 30 3 245.0 25 Example
3 A 1180 600 720 40 2 147.0 20 Comparative example
4 B 1280 600 730 50 3 225.4 25 Example
B 1200 600 690 30 2 196.0 25 Example
6 B 1250 650 730 70 2 156.8 25 Example
7 B 1230 600 730 60 2 313.6 40 Comparative example
8 B 1230 700 730 90 2 137.2 25 Comparative example
9 C 1250 600 660 100 3 117.6 15 Example
C 1250 600 680 10 2 186.2 25 Example
11 C 1220 640 700 25 2 147.0 25 Example
12 C 1250 600 700 40 2 78.4 15 Comparative example
13 C 1250 600 600 20 3 254.8 25 Comparative example
14 D 1250 550 680 60 3 254.8 25 Example
D 1210 640 700 60 4 303.8 20 Example
16 D 1210 640 700 130 4 303.8 20 Example
17 D 1270 550 780 70 2 254.8 25 Comparative example
18 E 1220 620 700 30 3 196.0 20 Example
19 E 1220 640 700 50 2 215.6 20 Example
E 1220 630 700 60 3 284.2 5 Comparative example
21 F 1240 660 730 40 3 294.0 25 Example
22 F 1240 640 730 40 2 333.2 20 Example
23 F 1240 620 730 40 2 205.8 15 Example
24 G 1250 600 700 30 2 225.4 20 Comparative example
H 1250 600 700 30 2 225.4 20 Comparative example
26 I 1250 600 700 30 2 225.4 20 Comparative example
27 J 1250 600 700 30 2 225.4 20 Comparative example
28 K 1250 600 700 30 2 225.4 20 Comparative example
29 L 1250 600 700 30 2 225.4 20 Comparative example
M 1250 600 700 30 2 225.4 20 Comparative example
31 N 1250 600 700 30 2 225.4 20 Comparative example
32 O 1250 600 700 30 2 225.4 20 Comparative example
33 P 1250 600 700 30 2 225.4 20 Comparative example
34 Q 1210 580 740 25 2 245.0 15 Example
R 1210 580 740 25 2 245.0 15 Comparative example
36 S 1210 580 740 25 2 245.0 15 Comparative example
* Underlined if outside of the scope of the disclosure.
PO180773-PCT-ZZ (18/29)
For each of the steel sheets thus obtained, the dislocation density at a
depth position of 1/2 of the thickness from the surface of the steel sheet was
determined by performing X-ray diffraction using a Co radiation source on a
surface exposed by chemical polishing the surface of the steel sheet to the
depth position of 1/2 of the sheet thickness to measure peak positions and
half-value widths of 4 planes of Fe(110), (200), (211), and (220). Each of
the measured half-value widths was corrected with a half-value width of an
unstrained Si single crystal, a local strain ε was determined by the Williamson
Hall method, and the dislocation density ρ was calculated using the following
Equation (1):
where Burgers vector b was 0.25 nm.
Each of the steel sheets thus obtained was subjected to heat treatment
corresponding to coating and baking at 210 °C for 15 minutes, and then
formed into a crown cap, and crown cap formability was evaluated. A
circular blank with a diameter of 37 mm was used and formed into the
dimensions of three types of crown caps prescribed in "JIS S9017" (1957)
(outer diameter: 32.1 mm, height: 6.5 mm, number of folds; 21) by press
forming.
[0056] Each of the crown caps thus obtained was evaluated for formability by
measuring the 3D shape from the top using a 3D shape measuring machine
VR-3000 manufactured by Keyence. The evaluation of the formability of
each crown cap was based on the presence or absence of a shape defect in
which a fold formed from the crown cap upper surface. The cross sectional
shape profile was observed in a cross sectional shape profile observation
plane as typically illustrated in FIGS. 3A and 3B. Specifically, as illustratd
in FIGS. 3A and 3B as a typical example of a cross sectional shape profile, it
is assumed that the starting point of a fold ridge is located at the inflection
point of the portion where the fold ridge starts, and the vertical distance H
between the inflection point of a shoulder portion of the crown cap and at the
starting point of the fold ridge. As illustrated in , if the vertical
distance H is not 0, this means the formation of a normal fold, and as
PO180773-PCT-ZZ (19/29)
illustrated in , if a fold forms from the crown cap upper surface, the
crown cap shoulder coincides with the starting point of the fold ridge, the
vertical distance H is 0, and it is determined that a defective fold has formed.
The fold starting point depth H was measured for all 21 folds, and samples
with a shape defect in which a fold formed from the crown cap upper surface
were judged as "Poor", and samples with no such defects as "Good". The
evaluation results are liset in Table 3.
The impact resistance of crown caps was evaluated by a drop impact
test using the formed crown caps. That is, a commercial beer was poured
into a commercial bottle, then the bottle was plugged with a formed crown cap
and stirred for 1 minute, inclined by 20°, then a ball of 500 g of hard
polyvinyl chloride was freely dropped from a height of 1 m above to the
crown cap, and leakage of beer was checked. Drop impact test was
performed on five bottles plugged with five crown caps formed from
respective steel sheets. This test was conducted for each steel sheet, and the
impact resistance was judged "Excellent" for crown caps with zero beer leaks
as being particularly excellent, "Good" for crown caps with one beer leak as
being equivalent to that of the conventional crown cap, or "Poor" for crown
caps with two or more beer leaks as being inferior to that of the conventional
crown cap. The evaluation results are listed in Table 3. In addition, the
conventional crown cap used as a reference was a crown cap formed using a
mild steel having a thick of 0.22 mm.
In addition, each of the obtained steel sheets was subjected to heat
treatment corresponding coating and baking at 210 C for 15 minutes, then
formed into a DRD can, and the DRD can formability was evaluated. That is,
a circular blank with a diameter of 158 mm was subjected to drawing and
redrawing to form a DRD can having an inner diameter of 82.8 mm and a
flange diameter of 102 mm, and the DRD can formability was evaluated. In
the evaluation, samples were judged as "Poor" if the number of fine wrinkles
visually observed in the flange portion was three or more, or "Good" if the
number of such fine wrinkles was two or less. The results are listed in Table
Furthermore, the impact resistance of DRD cans was evaluated.
From the bottom of each DRD can, a circular steel sheet of 45 mm in diameter
PO180773-PCT-ZZ (20/29)
was cut out and subjected to an impact resistance test. The striking die had a
diameter of 12.7 mm and a flat bottom, and the base and the sheet holder were
provided with circular holes having a diameter of 13.5 mm. The positional
relationship between the striking die, the base, the sheet holder, and the
circular steel sheet, as illustrated in is such that the holes of the
striking die and the base, the hole of the sheet holder, and the center of the
circular steel sheet are aligned, and the bottom of the striking die can be
pushed downward by 0.5 mm. In a state where the circular steel sheet was
unmovably fixed by a sheet holder, a weight of 500 g was dropped onto the
striking die from a height of 50 cm, and the circular steel sheet was deformed
upon impact. The 3D shape of the deformed portion was measured using a
3D shape measuring machine VR-3000 made by Keyence, and as illustrated in
the average value of recess depths at four cross sections of the
deformed portion was evaluated as the recess depth of the steel sheet. The
impact resistance was judged "Excellent" as being particularly excellent when
the recess depth was less than 650 m, "Good" when the recess amount was
650 m or more and less than 700 m as being equivalent to that of the
conventional DRD can, or "Poor" when the recess amount was 700 m or
more as being inferior to that of the conventional DRD can. The evaluation
results are listed in Table 3. The conventional DRD can used as a reference
was a DRD can formed using a mild steel having a thickness of 0.22 mm.
PO180773-PCT-ZZ (21/29)
Table 3
Steel sheet microstructure Crown cap DRD can
Dislocation density
at a depth positon of
No. Steel Impact Impact Remakrs
1/2 of the sheet thickness
Formability Formability
resistance resistance
from the surface
14 2
( 10 /m )
1 A 2.3 Good Good Good Good Example
2 A 2.9 Good Good Good Good Example
3 A 1.1 Good Poor Good Poor Comparative example
4 B 6.9 Good Excellent Good Excellent Example
B 6.2 Good Excellent Good Excellent Example
6 B 2.9 Good Good Good Good Example
7 B 12.2 Poor Good Poor Good Comparative example
8 B 1.3 Good Poor Good Poor Comparative example
9 C 2.6 Good Good Good Good Example
C 8.3 Good Excellent Good Excellent Example
11 C 7.9 Good Excellent Good Excellent Example
12 C 1.4 Good Poor Good Poor Comparative example
13 C 1.3 Poor Poor Poor Poor Comparative example
14 D 9.2 Good Excellent Good Excellent Example
D 7.1 Good Excellent Good Excellent Example
16 D 2.7 Good Good Good Good Example
17 D 1.8 Good Poor Good Poor Comparative example
18 E 6.9 Good Excellent Good Excellent Example
19 E 6.6 Good Excellent Good Excellent Example
E 1.6 Good Poor Good Poor Comparative example
21 F 2.9 Good Good Good Good Example
22 F 2.8 Good Good Good Good Example
23 F 2.6 Good Good Good Good Example
24 G 1.3 Good Poor Good Poor Comparative example
H 11.3 Poor Good Poor Good Comparative example
26 I 1.4 Good Poor Good Poor Comparative example
27 J 10.7 Poor Good Poor Good Comparative example
28 K 6.3 Poor Good Poor Good Comparative example
29 L 8.1 Poor Good Poor Good Comparative example
M 7.2 Poor Good Poor Good Comparative example
31 N 1.8 Good Poor Good Poor Comparative example
32 O 5.3 Poor Good Poor Good Comparative example
33 P 1.9 Good Poor Good Poor Comparative example
34 Q 2.8 Good Good Good Good Example
R 1.7 Good Poor Good Poor Comparative example
36 S 2.7 Poor Good Poor Good Comparative example
* Underlined if outside of the scope of the disclosure.
PO180773-PCT-ZZ (22/29)
From Table 3, each of the steel sheets of our examples had a
14 2 15 2
dislocation density of 2.0 × 10 /m or more and 1.0 × 10 /m or less at a
depth position of 1/2 of the sheet thickness from the surface in the sheet
thickness direction. The crown cap formed by using the steel sheet disclosed
herein did not have a shape defect in which a fold forms from the crown cap
upper surface, and the beer leakage results in the drop impact test were
comparable to or better than that of the conventional crown cap. In addition,
the DRD cans formed using the steel sheet disclosed herein did not suffer
from shape defects in which wrinkles form in the flange portion, and the
recess amount in the impact resistance test was comparable to or better than
conventional DRD cans, and excellent formability and impact resistance were
obtained.
On the other hand, in the steel sheets of comparative examples which
fall outside the disclosed range, the dislocation density at a depth position of
1/2 of the sheet thickness from the surface in the sheet thickness direction was
14 2 15 2
less than 2.0 × 10 /m or greater than 1.0 × 10 /m , and the crown caps and
DRD cans formed using the sheet sheets of the comparative examples were
inferior in either formability or impact resistance.
For No. 3, the slab heating temperature in the hot rolling step was less
than 1200 °C out of the disclosed range, and the dislocation density at a depth
position of 1/2 of the sheet thickness from the surface in the thickness
14 2
direction was less than 2.0 × 10 /m out of the disclosed range, and the
impact resistance was inferior to that of the conventional crown cap and DRD
can.
[0064] For No. 7, the rolling reduction in the secondary cold rolling step was
over 40 % outside the disclosed range, and the dislocation density at a depth
position of 1/2 of the sheet thickness from the surface in the sheet thickness
2
direction was more than 1.0 × 10 /m out of the disclosed range, and a shape
defect occured in which a fold formed from the crown cap upper surface
during crown cap formation, a shape defect occurred in which wrinkles
formed in the flange portion during DRD can formation, and the formability
was inferior to that of the conventional crown cap and DRD can.
For No. 8, the coiling temperature in the hot rolling step exceeded
670 °C out of the disclosed range, and the dislocation density at a depth
PO180773-PCT-ZZ (23/29)
position of 1/2 of the sheet thickness from the surface in the thickness
14 2
direction was less than 2.0 × 10 /m out of the disclosed range, and the
impact resistance was inferior to that of the conventional crown cap and DRD
can. For No. 12, the average tension between cold rolling stands in the
secondary cold rolling step was less than 98 MPa out of the disclosed range,
and the dislocation density at a depth position of 1/2 of the thickness from the
14 2
surface in the thickness direction was less than 2.0 × 10 /m out of the
disclosed range, and the impact resistance was inferior to that of the
conventional crown cap and DRD can.
[0066] For No. 13, the annealing temperature in the annealing step was lower
than 650 °C, the dislocation density at a depth position of 1/2 of the sheet
thickness from the surface in the thickness direction was less than 2.0 ×
14 2
/m out of the disclosed range, non-recrystallized microstructures
exceeded 5 %, a shape defect occurred in which a fold formed from the crown
cap upper surface during crown cap formation, a shape defect occurred in
which wrinkles formed in the flange portion during DRD can formation, and
the impact resistance was inferior to that of the conventional crown cap and
DRD can.
For No. 17, the annealing temperature in the annealing step was over
750 °C, the dislocation density at a depth position of 1/2 of the sheet thickness
14 2
from the surface in the thickness direction was less than 2.0 × 10 /m out of
the disclosed range, and the impact resistance was inferior to that of the
conventional crown cap and DRD can.
For No. 20, the rolling reduction in the secondary cold rolling step
was less than 10 %, the dislocation density at a depth position of 1/2 of the
sheet thickness from the surface in the sheet thickness direction was less than
14 2
2.0 × 10 /m out of the disclosed range, and the impact resistance was
inferior to that of the conventional crown cap and DRD can.
For No. 24, the C content was 0.006 % or less, the dislocation density
at a depth position of 1/2 of the sheet thickness from the surface in the
14 2
thickness direction was less than 2.0 × 10 /m out of the disclosed range, and
the impact resistance was inferior to that of the conventional crown cap and
DRD can.
For No. 25, the C content was more than 0.012 %, the dislocation
PO180773-PCT-ZZ (24/29)
density at a depth position of 1/2 of the thickness from the surface in the
2
thickness direction exceeded 1.0 × 10 /m out of the disclosed range, a shape
defect occurred in which a fold formed from the crown cap upper surface
during crown cap formation, a shape defect occurred in which wrinkles
formed in the flange portion during DRD can formation, and the formability
was inferior to that of the conventional crown cap and DRD can.
For No. 26, the N content was less than 0.0080 %, the dislocation
density at a depth position of 1/2 of the sheet thickness from the surface in the
14 2
thickness direction was less than 2.0 × 10 /m out of the disclosed range, and
the impact resistance was inferior to that of the conventional crown cap and
DRD can.
For No. 27, the N content was more than 0.0200 %,
the dislocation density at a depth position of 1/2 of the sheet thickness from
2
the surface in the thickness direction exceeded 1.0 × 10 /m out of the
disclosed range, a shape defect occurred in which a fold formed from the
crown cap upper surface during crown cap formation, a shape defect occurred
in which wrinkles formed in the flange portion during DRD can formation,
and the formability is inferior to that of the conventional crown cap and DRD
can.
[0073] For No. 28, the Si content was more than 0.02 %, the formability of
the steel sheet was reduced, a shape defect occurred in which a fold formed
from the crown cap upper surface during crown cap formation, a shape defect
occurred in which wrinkles formed in the flange portion during DRD can
formation, and the formability was inferior to that of the conventional crown
cap and DRD can.
For No. 29, the Mn content was more than 0.60 %, the formability of
the steel sheet was reduced, a shape defect occurred in which a fold formed
from the crown cap upper surface during crown cap formation, a shape defect
occurred in which wrinkles formed in the flange portion during DRD can
formation, and the formability was inferior to that of the conventional crown
cap and DRD can.
For No. 30, the P content was more than 0.020 %, the formability of
the steel sheet was reduced, a shape defect occurred in which a fold formed
from the crown cap upper surface during crown cap formation, a shape defect
PO180773-PCT-ZZ (25/29)
occurred in which wrinkles formed in the flange portion during DRD can
formation, and the formability was inferior to that of the conventional crown
cap and DRD can.
For No. 31, the Al content was more than 0.07 %, the dislocation
density at a depth position of 1/2 of the sheet thickness from the surface in the
14 2
thickness direction was less than 2.0 × 10 /m out of the disclosed range, and
the impact resistance was inferior to that of the conventional crown cap and
DRD can.
For No. 32, the Al content was less than 0.01 %, the formability of the
steel sheet was reduced, a shape defect occurred in which a fold formed from
the crown cap upper surface during crown cap formation, a shape defect
occurred in which wrinkles formed in the flange portion during DRD can
formation, and the formability was inferior to that of the conventional crown
cap and DRD can.
[0078] For No. 33, the C content was 0.0060 or less, the dislocation density at
a depth position of 1/2 of the sheet thickness from the surface in the thickness
14 2
direction was less than 2.0 × 10 /m out of the disclosed range, and the
impact resistance was inferior to that of the conventional crown cap and DRD
can.
[0079] For No. 35, the Mn content was less than 0.10 %, the dislocation
density at a depth position of 1/2 of the sheet thickness from the surface in the
14 2
thickness direction was less than 2.0 × 10 /m out of the disclosed range, and
the impact resistance was inferior to that of the conventional crown cap and
DRD can.
[0080] For No. 36, the S content was more than 0.20 %, the formability of the
steel sheet was reduced, a shape defect occurred in which a fold formed from
the crown cap upper surface during crown cap formation, a shape defect
occurred in which wrinkles formed in the flange portion during DRD can
formation, and the formability was inferior to that of the conventional crown
cap and DRD can.
The reference in this specification to any prior publication (or
information derived from it), or to any matter which is known, is not, and
should not be taken as an acknowledgment or admission or any form of
suggestion that that prior publication (or information derived from it) or
PO180773-PCT-ZZ (26/30)
known matter forms part of the common general knowledge in the field of
endeavour to which this specification relates.
Throughout this specification and the claims which follow, unless the
context requires otherwise, the word "comprise", and variations such as
"comprises" and "comprising", will be understood to imply the inclusion of a
stated integer or step or group of integers or steps but not the exclusion of any
other integer or step or group of integers or steps.
PO180773-PCT-ZZ (27/30)
Claims (5)
1. A steel sheet comprising: a chemical composition containing, by mass , 5 C: more than 0.006 and not more than 0.012 , Si: 0.02 or less, Mn: 0.10 or more and 0.60 or less, P: 0.020 or less, S: 0.020 or less, 10 Al: 0.01 or more and 0.07 or less, and N: 0.0080 or more and 0.0200 or less, with the balance being Fe and inevitable impurities; wherein a dislocation density at a depth position of 1 2 of a sheet thickness 14 2 15 2 from a surface of the steel sheet is 2.0 × 10 /m or more and 1.0 × 10 /m or 15 less when measured by X-ray diffraction.
2. The steel sheet according to claim 1, having a thickness of
0.20 mm or less. 20 3. A crown cap made of the steel sheet as recited in claim 1 or 2.
4. A DRD can made of the steel sheet as recited in claim 1 or 2.
5. A method of manufacturing the steel sheet as recited in claim 1 25 or 2, comprising: a hot rolling step of heating a steel raw material at 1200 C or higher, finish rolling the steel raw material to obtain a hot rolled sheet, and then coiling the hot rolled sheet within a temperature range of 670 C or lower; a pickling step of pickling the hot rolled sheet after the hot rolling 30 step; a primary cold rolling step of cold rolling the hot rolled sheet after the pickling step to obtain a cold rolled sheet; an annealing step of annealing the cold rolled sheet after the primary cold rolling step in a temperature range of 650 C to 750 C to obtain an PO180773-PCT-ZZ (
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2017-071544 | 2017-03-31 | ||
JP2017071544 | 2017-03-31 | ||
PCT/JP2018/012697 WO2018181449A1 (en) | 2017-03-31 | 2018-03-28 | Steel sheet, production method therefor, bottle cap, and drd can |
Publications (2)
Publication Number | Publication Date |
---|---|
NZ756845A NZ756845A (en) | 2021-01-29 |
NZ756845B2 true NZ756845B2 (en) | 2021-04-30 |
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