High-strength steel sheet for cans and method for manufacturing the same
Inactive Publication Date: 2011-03-31
JFE STEEL CORP
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- Abstract
- Description
- Claims
- Application Information
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Benefits of technology
[0034]In the present invention, by using a low carbon material, maintaining the absolute quantity of dissolved N at a certain value or more, and performing age hardening after coating and baking, a high-strength steel sheet for cans can be efficiently produced without second cold rolling or by second cold rolling at a low draft. A steel sheet for cans manufactured without second cold rolling, that is, manufactured by temper rolling of about 1% after continuous annealing has a total elongation E1 of at least 20% after coating and baking. A steel sheet for cans subjected to second cold rolling at a draft of 10% or more but less than 15% has a total elongation E1 above 10% after coating and baking.
[0064]A steel sheet for cans according to the present invention has undergone substantial age hardening because of dissolved N. Thus, a steel sheet for cans according to the present invention has a yield stress YP of at least 500 MPa after coating and baking, and the reduction in the thickness of the steel sheet can be achieved advantageously. A cold-rolled steel sheet according to the present invention, effectively utilizing the effects of dissolved N, has an increased strength after reflowing after plating, and a substantial age hardening phenomenon may occur during a coating and baking process after press forming, thus resulting in a tremendous increase in the strength of cans.
Problems solved by technology
However, since higher-strength steel is hard, cracking may occur during a flanging or necking process.
However, in the method according to Patent Document 1, in which P is 0.02% by weight or less to prevent deterioration in flanging and necking formability and corrosion resistance, and the draft in second cold rolling ranges from 15% to 30%, it is difficult to efficiently treat and manufacture thin products, and defective appearance tends to occur.
Furthermore, stable manufacturing is difficult to achieve, and therefore some improvements are needed.
However, in the method according to Patent Document 2, semi-very low carbon material is used, the continuous annealing temperature is increased to secure predetermined dissolved N, and the heating pattern is difficult to control precisely.
These make the manufacture difficult.
Furthermore, only by securing dissolved N in an amount of at least 80% of N in steel, it is difficult to stably manufacture a steel sheet having a specified strength, because the N content in steel varies.
Furthermore, the method according to Patent Document 2 provides small total elongation, resulting in poor processibility.
However, in these methods, since the draft in the second cold rolling is as high as 20% to 50%, the high rolling load results in low operational efficiency.
Furthermore, since various viscous rolling oils are used to improve lubricity in rolling, inconsistencies in concentration of the rolling oil and partial oil deposition cause defective appearance after rolling.
A high draft results in small total elongation and low processibility.
However, at a low draft, it is difficult to achieve a desired proof stress.Patent Document 1: Japanese Patent No. 3108615Patent Document 2: Japanese Unexamined Patent Application Publication No. 2001-107187Non-patent Document 1: “Wagakuniniokeru kanyohyomensyorikohan no gijutushi (Technography of surface-treated steel sheets for cans in Japan)”, The Iron and Steel Institute of Japan, Oct. 30, 1998, p.
Thus, there is presently no method for manufacturing a thin steel sheet for cans that satisfies both strength and productivity, and such a method is desired.
Method used
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Experimental program
Comparison scheme
Effect test
example 1
[0066]A steel composed of the components shown in Table 1 was melted in a converter and was formed into a slab by a continuous casting method. The slab was then hot-rolled under the conditions shown in Table 2 to form a hot-rolled sheet having a thickness of 2.0 mm. The hot-rolled sheet thus formed was then descaled by pickling, was cold-rolled, and was continuously annealed under the conditions shown in Table 2. Part of the sheets were subjected to second rolling. Thus, a cold-rolled steel sheet having a final thickness of 0.17 mm was manufactured.
TABLE 1Chemical components (% by mass)Steel No.CSiMnPSAlNA0.0440.010.250.0170.0100.0350.0148B0.0150.020.300.0120.0170.0090.0160
TABLE 2Hot rollingSecondAr3SlabColdAr1Continuous annealingcoldSteeltransformationextractionFinish rollingCoilingrollingtransformationAnnealingSoakingrollingsheetSteelpointtemperaturetemperaturetemperatureDraftpointtemperaturetimeDraftNo.No.° C.° C.° C.° C.%° C.° C.s%1*A860121089059091.472368014—2*A860115089059091....
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Abstract
A steel sheet for cans that has a yield stress of at least 500 Mpa after coating and baking and a method for manufacturing the steel sheet for cans are provided. The steel sheet for cans contains, on the basis of mass percent, C: more than 0.02% but 0.10% or less, Si: 0.10% or less, Mn: 1.5% or less, P: 0.20% or less, S: 0.20% or less, Al: 0.10% or less, N: 0.0120% to 0.0250%, dissolved N being 0.0100% or more, and a remainder of Fe and incidental impurities. A high-strength material can be obtained by maintaining the absolute quantity of dissolved N at a certain value or more and performing hardening by quench aging and strain aging, for example, in a printing process, a film lamination process, or a drying and baking process performed before can manufacturing. In the manufacture, hot rolling is performed at a slab extraction temperature of 1200° C. or more and a finish rolling temperature of (Ar3 transformation temperature—30)° C. or more, and coiling is performed at 650° C. or less.
Description
TECHNICAL FIELD[0001]The present invention relates to a high-strength steel sheet for cans, which is suitable as a material for cans in which the diameter shape is reduced or increased after three-piece processing, such as welding, or two-piece processing, such as drawing and ironing, and to a method for manufacturing the high-strength steel sheet for cans.BACKGROUND ART[0002]In recent years, for the purpose of reducing costs and for the purpose of reducing materials to be used and environmental lead, product development has been performed to decrease the thickness of a product formed of a steel material (steel sheet).[0003]Since a reduction in the thickness of a product sheet results in lower rigidity, the strength Of steel must be increased to compensate for the reduction in rigidity. However, since higher-strength steel is hard, cracking may occur during a flanging or necking process. To address this problem, various manufacturing methods have been proposed.[0004]For example, Pat...
Claims
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Patent Timeline
Login to View More IPC IPC(8): C22C38/60B21B27/06C22C38/06C22C38/04C22C38/00C21D8/02
CPCC21D8/0473C21D2211/004C22C38/001C22C38/02C22C38/04C21D8/0263C21D8/0426C21D8/0436C21D8/0442B21B1/26C22C38/06C22C38/60
InventorARATANI, MAKOTOKATO, TOSHIKATSUKAWAMURA, KATSUHITOTANAKA, TAKUMIKOJIMA, KATSUMISATO, KAKUSUJITA, SHIGEKOKOIZUMI, MASAKI
OwnerJFE STEEL CORP