JP6108044B2 - Steel plate for can lid and manufacturing method thereof - Google Patents

Description

  The present invention relates to a steel plate for can lids such as canned foods and canned beverages, and a method for producing the same.

  In food cans and beverage cans, the contents are heat sterilized at the manufacturing stage. At this time, a pressure difference is generated between the inside and outside of the can, and pressure acts on the can body. The can body is mainly composed of a can body and a can lid. Among these, the can body has a cylindrical shape that is easy to disperse stress, so that deformation is small even when pressure is applied. On the other hand, the can lid is often formed of a flat surface, and is easily deformed because it receives pressure on the flat surface. Excessive deformation of the can lid is undesirable, and there is a need to provide a can lid that is difficult to deform even under pressure.

  As a method for suppressing the deformation of the can lid with respect to the pressure, increasing the pressure resistance of the steel plate for can lid may be mentioned. As technologies related to steel plates for can lids with increased pressure resistance, there are technologies described in Patent Documents 1 to 3 below.

The technology described in Patent Document 1 secures workability by defining the product of the yield strength and the plate thickness, and the pressure strength by defining the product of the upper yield strength after aging and the square of the plate thickness. This relates to a steel plate for aerosol bottom cans. In Patent Document 1, C: 0.020% to 0.090%, Si: 0.01% to 0.05%, Mn: 0.05% to 0.60% by mass, P: 0.001% or more and 0.100% or less, S: 0.001% or more and 0.025% or less, N: 0.0010% or more and less than 0.0070%, Al: 0.010% or more {-4. 2 × N content (%) + 0.11}% or less, the balance is composed of Fe and inevitable impurities, the plate thickness is 0.350 mm or less, and the yield strength (N / mm ² ) The yield strength when the product of the plate thickness (mm) is 195 (N / mm) or less and the rolling pre-strain is performed at a rolling rate of 10% and then subjected to room temperature aging at 25 ° C. for 10 days. The product of (N / mm ² ) and the square of the plate thickness (mm) is 52.0 N or more, high pressure strength and processing A steel plate for an aerosol can bottom having excellent properties and a method for producing the same are disclosed.

The technique described in Patent Document 2 is a technique for increasing the pressure strength by positively adding 0.0075 to 0.013 mass% N for solid solution strengthening. In this patent document 2, by mass%, C: 0.025 to 0.065%, Mn: 0.10 to 0.28%, P: 0.005 to 0.03%, Al: 0.01 to A chemical composition containing 0.04%, N: 0.0075 to 0.013%, Si: 0.05% or less, S: 0.009% or less, the balance being Fe and inevitable impurities The yield strength YP in the rolling direction after the aging treatment is in the range of 460 to 540 MPa, the total elongation in the rolling direction after the aging treatment is 15% or more, and the yield point elongation EL _{YP in} the rolling direction after the aging treatment. Is the thickness t in mm, the yield strength TP in the rolling direction after aging in MPa, and the yield point elongation EL _{YP in} the rolling direction after aging in%. 130 ≦ t × meet _{YP × (1-EL YP /} 100), a steel sheet for an aerosol can lid Its production process and are disclosed.

In addition, the technique described in Patent Document 3 has a high strength at a relatively high elongation rate in Patent Document 1 and Patent Document 2, whereas 0.007-0. This is a technique in which 025% N is added and the pressure strength is increased by utilizing strain age hardening. In this Patent Document 3, in mass%, C: 0.02 to 0.10%, Si: 0.01 to 0.5%, P: 0.001 to 0.100%, S: 0.001 to 0.020%, N: 0.007 to 0.025%, Al: 0.01 to {-4.2 × N (%) + 0.11}%, Mnf = Mn−1.71 × S (However, when Mn content and S content in the formula are Mn content (mass%) and S content (mass%) in steel), Mnf: 0.10% or more and less than 0.30%, the balance Consists of Fe and inevitable impurities. And this steel plate has a plate thickness of 0.35 (mm) or less, and the product of the steel sheet's yield strength (N / mm ² ) and the plate thickness (mm) is 160 (N / mm) or less, The product of the upper yield strength (N / mm ² ) and the square of the plate thickness (mm) when the room temperature aging is performed at 25 ° C. for 10 days after 10% tensile pre-strain is 52.0 (N) or more. A steel plate for an aerosol can bottom having a high pressure strength and excellent workability and a method for producing the same are disclosed.

JP 2013-147744 A International Publication No. 2012/077628 JP 2012-207305 A

  However, all of the techniques described in Patent Documents 1 to 3 relate to a steel plate used for an aerosol can. The bottom lid and bottom of this aerosol can have a dome shape that swells toward the inner surface of the can in order to achieve high pressure resistance, and in the techniques described in Patent Documents 1 to 3, the cans such as food cans described above The deformation due to the pressure difference between the inside and outside of the can, which is likely to occur in the flat plate-shaped can lid, was not considered.

  As described above, a technique for suppressing deformation due to a pressure difference between the inside and outside of the can, which is likely to occur in a flat can lid used for cans such as food cans, which has many flat portions, has not yet been established. Then, this invention was made | formed in view of this situation, and it aims at providing the steel plate for can lids which can suppress the deformation | transformation by the pressure difference inside and outside a can, and its manufacturing method.

  The present inventors examined the influence of the mechanical properties of the steel sheet on the pressure resistance characteristics of the can lid. As a result, it has been found that by properly controlling the yield strength YP and the yield point elongation YPEL, good pressure resistance characteristics can be obtained even in the case of a flat plate-shaped can lid having many flat portions. It was.

  In addition, the N content is increased, Al, Mn, and S are specified contents, and the slab heating temperature, the hot rolling coiling temperature, and the temper rolling elongation rate are within a predetermined range as manufacturing conditions. It has also been found that mechanical characteristics satisfying the above specific conditions can be obtained by adjustment.

  The present invention is based on such knowledge, and the gist thereof is as follows.

[1] By mass%
C: 0.020 to 0.060%,
Si: 0.01 to 0.05%,
Mn: 0.20 to 0.60%
P: 0.001 to 0.100%,
S: 0.008 to 0.020%,
N: 0.0130 to 0.0190%
Al: 0.005 to {-4.20 × N + 0.110}% (where N is the N content (mass%) in the steel),
Mnf = Mn-1.7 × S (where Mn and S are Mn content (mass%) and S content (mass%) in steel), Mnf: 0.30% or more and 0.00. 58% or less,
The balance consists of Fe and inevitable impurities,
After aging treatment at 210 ° C. × 10 minutes, the yield strength YP (N / mm ² ) and the yield point elongation YPEl (%) are YP ≧ 355, YPEl ≧ 2, and YPEl ≧ (60 / (YP-355). ) Steel plate for can lid satisfying +2 and YP ≦ 4.09 × YPEL + 476.
[2] A method for producing a steel plate for can lids according to [1],
Reheat the steel slab to a temperature of 1150 ° C or higher,
A steel slab reheated at a coiling temperature of 680 ° C. or lower is hot-rolled to produce a hot-rolled steel sheet,
Cold rolling the hot rolled steel sheet to produce a cold rolled steel sheet,
Recrystallizing the cold-rolled steel sheet,
A method for producing a steel plate for can lid, which is temper-rolled at an elongation of 3% or less.

  ADVANTAGE OF THE INVENTION According to this invention, the steel plate for can lids which can suppress the deformation | transformation by the pressure difference inside and outside a can can be obtained.

It is a figure which shows the external appearance of the can body which consists of a can body and a can lid. (A) is a top view which shows the shape of a can lid, (b) is AA sectional drawing in (a). It is a graph which shows the result of having evaluated the influence of the yield strength YP and the yield point elongation YPEl of the steel plate for can lids about the deformation | transformation by the pressure difference inside and outside of a can lid.

The steel plate for can lids of this invention is C: 0.020-0.060%, Si: 0.01-0.05%, Mn: 0.20-0.60%, P: 0.001-0. 100%, S: 0.008 to 0.020%, N: 0.0130 to 0.0190%, Al: 0.005 to {-4.20 × N + 0.110}% (where N is N content in steel (% by mass)), Mnf = Mn-1.7 × S (wherein Mn and S are Mn content in steel (% by mass), S content (% by mass) )), Mnf: not less than 0.30% and not more than 0.58%, the remainder has a component composition consisting of Fe and inevitable impurities, and after aging treatment at 210 ° C. for 10 minutes, the yield strength is lowered YP (N / mm ²⁾ and yield point elongation YPEl (%) is, YP ≧ 355, YPEl ≧ 2 , and YPEl ≧ (60 / (YP- 3 5)) + 2 and satisfy YP ≦ 4.09 × YPEl + 476. Below, the steel plate for can lids of this invention and its manufacturing method are demonstrated in detail.

  First, the component composition of the steel plate for can lids of this invention is demonstrated. All components are in weight percent.

C: 0.020 to 0.060%
The steel plate of the present invention is a steel plate manufactured through each process of hot rolling, cold rolling, recrystallization annealing, and temper rolling, and needs to have the above mechanical characteristics. In order to satisfy such characteristics, in the steel sheet of the present invention, it is important to contain C as a solid solution strengthening element, and the lower limit of the C content is 0.020%. If the C content is less than 0.020%, the mechanical properties defined in the present invention cannot be obtained. Preferably, the C content is 0.030% or more. On the other hand, when the content of C exceeds 0.060%, the contact surface pressure between the steel plate and the processing mold is increased during the lid processing due to being excessively hard, and the surface of the steel plate is coated. The organic film is damaged. Therefore, the upper limit of the C content is 0.060%. Preferably, the C content is 0.050% or less.

Si: 0.01-0.05%
Si provides an effective action for solid solution strengthening, but if contained in a large amount, the corrosion resistance of the steel sheet is deteriorated. Since Si is contained in a large amount in iron ore, which is a raw material for steel plates, the content is adjusted while removing it in the refining stage. In the case of the present invention, it is desirable to eliminate the influence of deteriorating the corrosion resistance rather than the contribution to the solid solution strengthening of Si. Therefore, the Si content is set to 0.05% or less where the influence of corrosion resistance is not apparent. Preferably, the Si content is 0.03% or less. From the viewpoint of corrosion resistance, it is desirable to reduce the Si content as much as possible. However, excessive reduction increases the work load in refining, so the lower limit is made 0.01%.

Mn: 0.20 to 0.60%
Mn is an element effective for adjusting the strength of the steel sheet, but if the Mn content is less than 0.20%, the effect cannot be obtained. On the other hand, if the Mn content exceeds 0.60%, the strength of the steel sheet becomes excessively high. Therefore, the Mn content is set to 0.20% or more and 0.60% or less. Regarding the Mn content, the lower limit side is preferably 0.25% or more. The upper limit is preferably 0.55% or less.

P: 0.001 to 0.100%
P is an element having a large solid solution strengthening ability, but if it exceeds 0.100%, corrosion resistance is significantly impaired. Therefore, the upper limit of the P content is 0.100%. Preferably, the P content is 0.020% or less. On the other hand, dephosphorization cost becomes excessive to make P less than 0.001%. Therefore, the lower limit of the P content is 0.001%.

S: 0.008 to 0.020%
S combines with Mn in steel to generate MnS. If the S content exceeds 0.020%, MnS precipitates at the grain boundaries at high temperatures, causing embrittlement. Therefore, the upper limit of the S content is 0.020%. On the other hand, desulfurization cost becomes excessive to make the S content less than 0.008%. Therefore, the lower limit for the S content is 0.008%.

N: 0.0130 to 0.0190%
N is an element that contributes to solid solution strengthening and securing the yield point elongation YPEL described later. In order to express these effects, it is necessary to contain 0.0130% or more of N. On the other hand, if N is contained in an amount exceeding 0.0190%, the effect on strain age hardening is saturated and not effective, and hot ductility is deteriorated. Therefore, the upper limit of the N content is 0.0190%. For the N content, the lower limit is preferably 0.0135% or more. The upper limit is preferably 0.0175% or less.

Al: 0.005 to {-4.20 × N + 0.110}% (where N is the N content (mass%) in the steel)
Al acts as a deoxidizer and is an element necessary for increasing the cleanliness of the steel sheet. In the present invention, solid solution N is used to ensure mechanical properties. On the other hand, Al combines with N in steel to form AlN. From the above, it is necessary to suppress excessive precipitation of AlN, and it is necessary to define the upper limit of the Al amount. When the Al content exceeds {−4.20 × N content (%) + 0.110}%, there is a problem that the precipitation of AlN becomes excessive and the amount of dissolved N is insufficient. On the other hand, in steel with an Al content of less than 0.005%, deoxidation is insufficient and the cleanliness of the steel sheet deteriorates, so the lower limit is made 0.005%. In the present invention, Al is acid-soluble Al.

Mnf = Mn-1.7 × S (where Mn and S are Mn content (mass%) and S content (mass%) in steel), Mnf: 0.30% or more and 0.00. Mn of 58% or less increases the strength of the steel sheet by solid solution strengthening and crystal grain refinement. However, since Mn combines with S to form MnS, the amount of Mn contributing to solid solution strengthening is considered to be the amount obtained by subtracting the amount of Mn capable of forming MnS from the Mn content. Considering the atomic weight ratio of Mn and S, the amount of Mn contributing to solid solution strengthening can be expressed as Mnf = Mn−1.7 × S. When Mnf is more than 0.58%, the effect of reducing the crystal grain size is remarkably produced, and it is hardened excessively. Therefore, Mnf is 0.58% or less. Preferably, Mnf is 0.53% or less. On the other hand, when Mnf is less than 0.30%, it softens and the required pressure strength cannot be obtained. Therefore, Mnf is set to 0.30% or more. Preferably, Mnf is 0.33% or more.

  The balance is Fe and inevitable impurities.

The steel sheet of the present invention preferably has a structure that does not contain a pearlite structure. The pearlite structure is a structure in which a ferrite phase and a cementite phase are deposited in a layered manner. If a coarse pearlite structure is present, cracks may be generated from stress concentration during deformation. When the can lid is attached to the can body by tightening, there is a possibility that cracking of the tightening portion will occur if there is such a crack starting point, so the steel sheet of the present invention does not include a pearlite structure. It is desirable. This structure not including the pearlite structure can be obtained by setting the rolling rate during cold rolling to 80% or more, and by setting the annealing temperature in recrystallization annealing after cold rolling to less than the Ac ₁ transformation point. .

  Next, the mechanical properties that the steel sheet of the present invention should have will be described. The present inventors examined the influence of the mechanical characteristics of the steel sheet on the pressure resistance characteristics of the can lid. As a result, by properly controlling the yield strength YP and the yield point elongation YPEL, a can lid having good pressure resistance characteristics can be obtained even with a flat lid having many flat parts. I found.

Specifically, in the steel sheet of the present invention, after aging treatment at 210 ° C. × 10 minutes, the yield strength YP (N / mm ² ) and the yield point elongation YPEl (%) are YP ≧ 355, YPEl ≧ 2, And YPEl ≧ 60 / (YP-355) +2 and YP ≦ 4.09 × YPEL + 476 are satisfied.

  Generally, in order to suppress deformation of the can lid with respect to pressure, it is effective to increase the rigidity of the can lid by improving the rigidity of the steel plate itself. In contrast, the present invention focuses on the residual stress of the can lid.

  FIG. 1 is a view showing an appearance of a can body 10 having a can lid in which the steel plate of the present invention is used. As shown in FIG. 1, the can body 10 is mainly composed of a can body 1 and a can lid 2. 2A is a plan view showing the shape of the can lid 2, and FIG. 2B is a cross-sectional view taken along line AA in FIG. As shown in FIG. 2, the can lid 2 for food canned foods, beverage canned foods, and the like, which is an object of the present invention, includes an expanding ring in the vicinity of the outer peripheral portion (see reference numeral x in FIG. 2B). Residual stress can be generated inside the can lid 2 by generating a spring back by processing in the expanding ring.

  In order to increase the springback, it is effective to increase the yield strength YP of the steel sheet. On the other hand, as shown in FIG. 2, the can lid 2 for food cans and beverage cans targeted by the present invention has a generally flat region at the center. In order to generate a residual stress in this portion, it is effective to improve the yield point elongation YPEL. In other words, discontinuous deformation occurs in the flat portion of the can lid 2 by improving the yield point elongation YPEL, and residual stress is generated in the can lid 2 by mixing the deformed portion and the undeformed portion. Can be made.

  In order to generate such residual stress, it is necessary to appropriately adjust the yield strength YP and the yield point elongation YPEL. FIG. 3 is a graph showing the results of evaluating the influence of the lower yield strength YP and the yield point elongation YPEL of the steel plate for can lids on the deformation due to the pressure difference between the inside and outside of the can lid. In the evaluation shown in FIG. 3, a can lid having a plate thickness of 0.251 mm to 0.277 mm and a nominal diameter of 603 (diameters of about 6 inches and 3/16 inches) was formed, and the lid of the lid due to a pressure difference between the inside and outside of the can lid was formed. The deformation was examined using a pressure strength tester. Specifically, after the molded can lid is wound around the can body at atmospheric pressure, the pressure difference between the inside and outside of the can is set to 50 kPa by injecting pressurized air into the inside of the can. The difference in height of the tightening portion apex was measured. About the result, the value was 4 mm or less, the thing over 4 mm was made unsuccessful, the acceptance was indicated by ○, and the failure was indicated by ×.

  In order to generate residual stress in the can lid, it is considered that the lower the yield strength YP and the yield point elongation YPEl, the more advantageous, and the lid deformation passes in the region where YPEl ≧ 60 / (YP-355) +2. . On the other hand, when the falling yield strength YP is too high, the lid deformation is rejected, and it is necessary that YP ≦ 4.09 × YPEL + 476. Although this mechanism is not clear at present, the reason is that if the yield strength YP is too high, the spring back becomes large, the shape of the expanding ring becomes non-uniform, and the shape of the lid becomes unstable.

  The tensile test of the present invention can be performed according to JIS Z 2241 “Metal material tensile test method” using No. 5 test piece defined in JIS Z 2201 “Metal material tensile test piece”.

  As the yield point elongation YPEL, an elongation based on a gauge length of 50 mm is adopted. The tensile direction in the tensile test is the rolling direction of the steel sheet. In general, the lower yield strength YP of the steel sheet is the lowest in the rolling direction, and when the can lid is deformed by pressure, the deformation starts from the rolling direction with the lowest lower yield strength YP, and the pressure resistance behavior of the can lid is taken into consideration. In this case, considering the direction in which the lower yield strength YP is the lowest gives the lower limit value of the pressure strength, the rolling direction of the steel sheet is taken as the tensile direction.

  The yield strength YP can be adjusted by controlling the components and production conditions within an appropriate range. In particular, it is important to control the Mn content and S content and the temper rolling rate. Further, the yield point elongation YPEL can be adjusted by controlling the components and production conditions within an appropriate range. In particular, the control of the Al content and the N content, the slab heating temperature, the hot rolling coil The control of the temperature is important.

In the present invention, the specifications of the lower yield strength YP (N / mm ² ) and the yield point elongation YPEL (%) are determined from the experimental results on the can lid having a nominal diameter of 603. Since the smaller the deformation of the can lid, the smaller the deformation of the can lid, the above evaluation index can be applied to a can lid having a diameter smaller than that of a can lid having a nominal diameter of 603.

  Next, an example of the manufacturing method of the steel plate for can lids of this invention is demonstrated.

  The steel sheet of the present invention is manufactured through each step of hot rolling, cold rolling, recrystallization annealing, temper rolling, and surface treatment as necessary. Details will be described below.

  First, a steel slab having the component composition described above can be melted and obtained by continuous casting. In continuous casting, it is preferable that a slab is produced by a vertical bending type or a curved type continuous casting machine, and the surface temperature of the corner in a region where bending or unbending deformation is applied to the slab is 800 ° C. or lower or 900 ° C. or higher. . Thereby, the crack in the corner | angular part of the long side and short side in a slab cross section can be avoided.

  And steel slab is reheated at 1150 degreeC or more. By reheating the slab at a temperature of 1150 ° C. or higher, the AlN deposited during the slab cooling process can be dissolved. On the other hand, in order to prevent excessive oxidation accompanying heating, the slab heating temperature is preferably 1300 ° C. or lower. In the present invention, the slab temperature is the surface temperature of the slab.

The slab is then hot rolled. At this time, it is desirable that the finishing temperature in the hot rolling is a temperature of Ar ₃ points or more. The coiling temperature is 680 ° C. or less, preferably less than 680 ° C., more preferably 600 ° C. or less. When the coiling temperature after finish rolling exceeds 680 ° C., AlN precipitates, and the effect of N in the present invention cannot be obtained. In order to avoid excessive hardening of the steel sheet, the winding temperature is preferably 540 ° C. or higher. The winding temperature is the steel sheet surface temperature.

  After hot rolling, it is preferable to remove the scale from the cooled hot-rolled steel sheet (hot-rolled steel strip). Various methods can be applied to the scale removal method, and various methods such as chemical removal such as pickling and physical removal can be applied. In the case of pickling, it can be carried out according to conventional methods such as sulfuric acid method and hydrochloric acid method.

  Next, cold rolling is performed. Cold rolling is preferably performed at a rolling rate of 80% or more. By setting the rolling rate during cold rolling to 80% or more, the pearlite structure produced after hot rolling can be crushed. If the rolling rate during cold rolling is less than 80%, a pearlite structure may remain. On the other hand, the upper limit of the rolling rate during cold rolling is preferably 95% in order to avoid an increase in the load on the rolling mill due to an excessive rolling rate and the occurrence of rolling defects accompanying it.

Next, after cold rolling, recrystallization annealing is performed. The recrystallization annealing is preferably continuous annealing. In box annealing, solid solution N may precipitate as AlN, and room temperature strain age hardening may not be obtained. The annealing temperature is preferably less than the Ac ₁ transformation point. When the annealing temperature is set to the Ac ₁ transformation point or higher, an austenite phase is generated during annealing, and a pearlite structure that can be a starting point of cracking during the processing of the can lid may be formed. In the present invention, the Ac ₁ transformation point (° C.) can be determined by differential thermal analysis. The annealing temperature is the steel sheet surface temperature.

  After annealing, temper rolling is performed to make the steel sheet have predetermined mechanical properties and surface roughness. The higher the elongation during temper rolling, the higher the yield strength YP, while the yield point elongation YPEL decreases. In order to obtain the yield strength and yield point elongation balance required in the present invention, the elongation rate is 3% or less. On the other hand, in order to obtain a predetermined surface roughness, the elongation rate is desirably 0.8% or more.

  Thus, the steel plate for can lid of the present invention is manufactured.

  The steel plate manufactured by the above is used as an original plate for a surface-treated steel plate. Since the effect of the present invention is not affected by the type of surface treatment, the type of surface treatment is not limited. Typical examples of surface treatment for cans are coating treatments for metals such as tin plating (blink) and chrome plating (tin-free steel), metal oxides, metal hydroxides, inorganic salts, and the like. The upper layer is coated with an organic resin film, for example, a laminate process. In these surface treatments, the steel sheet may be subjected to heat treatment, and the steel sheet is subjected to aging. Also, when the steel sheet is stored before being processed into a can lid, it is subjected to aging according to the storage temperature and the storage period. Furthermore, it is also subjected to aging when painting on steel sheets. However, it has been confirmed that aging in these original plate states does not affect the effect of the present invention.

Examples of the present invention will be described below. First, steel having the composition shown in Table 1 was melted, slab heated at the slab heating temperatures shown in Tables 2 to 4, hot rolled at the coiling temperatures shown in Tables 2 to 4, and cold rolled. Thereafter, recrystallization annealing was performed, and temper rolling was performed at the elongation shown in Tables 2 to 4.
In Table 1, steel K is a missing number. In Tables 2 to 4, numbers 34 to 37 are missing numbers.

  Thereafter, an artificial aging treatment was performed at 210 ° C. for 10 minutes. The steel sheet obtained as described above was subjected to a tensile test in accordance with JIS Z 2241 “Metal material tensile test method” using a No. 5 test piece defined in JIS Z 2201 “Metal material tensile test piece”. (YP), yield point elongation (YPEl) was measured. With respect to those results, pass / fail was determined under the following determination conditions 1 and 2. In this example, a case that matches the determination condition is indicated by ◯, and a case that does not match the determination condition is indicated by ×.

  Furthermore, after the obtained steel plate was formed into a 603 diameter lid, it was wound around the can body, the pressure inside the can was increased to 50 kPa, and the height of the central portion of the can lid with respect to the wound portion was measured. If this measured value was 4 mm or less, it was judged as acceptable (◯), and the pressure resistance characteristics were evaluated.

  As shown in Tables 2 to 4, if the present invention example, that is, the determination condition 1 and the determination condition 2 pass, the pressure resistance characteristics also passed. Thus, in the example of this invention, the steel plate for can lids which can suppress the deformation | transformation with respect to a pressure was able to be obtained.

Judgment condition 1
After artificial aging treatment at 210 ° C. × 10 minutes, the yield strength YP (N / mm ² ) and the yield point elongation YPEl (%) are YP ≧ 355, YPEl ≧ 2, and YPEl ≧ (60 / (YP-355). )) + 2 is satisfied.

Judgment condition 2
After the artificial aging treatment at 210 ° C. × 10 minutes, the yield strength YP (N / mm ² ) and the yield point elongation YPEl (%) satisfy YP ≦ 4.09 × YPEL + 476.

1 Can body 2 Can lid 10 Can body

Claims (2)

% By mass
C: 0.020 to 0.060%,
Si: 0.01 to 0.05%,
Mn: 0.20 to 0.60%,
P: 0.001 to 0.100%,
S: 0.008 to 0.020%,
N: 0.0130 to 0.0190%
Al: 0.005 to {-4.20 × N + 0.110}% (where N is the N content (mass%) in the steel),
Mnf = Mn-1.7 × S (where Mn and S are Mn content (mass%) and S content (mass%) in steel), Mnf: 0.30% or more and 0.00. 58% or less,
The balance consists of Fe and inevitable impurities,
After aging treatment at 210 ° C. × 10 minutes, the yield strength YP (N / mm ² ) and the yield point elongation YPEl (%) are YP ≧ 355, YPEl ≧ 2, and YPEl ≧ (60 / (YP-355). ) +2, and YP ≦ 4.09 × YPEL + 476. It is a manufacturing method of the steel plate for can lids of Claim 1,
Reheat the steel slab to a temperature of 1150 ° C or higher,
A steel slab reheated at a coiling temperature of 680 ° C. or lower is hot-rolled to produce a hot-rolled steel sheet,
Cold rolling the hot rolled steel sheet to produce a cold rolled steel sheet,
Recrystallizing the cold-rolled steel sheet,
A method for producing a steel plate for can lid, which is temper-rolled at an elongation of 3% or less.

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