JP6421773B2 - Steel plate for can and manufacturing method thereof - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a steel plate for cans used as a raw material for a three-piece can formed by high-process can body processing, a two-piece can that requires pressure strength, and a method for manufacturing the same.

  In recent years, in order to increase the demand for steel cans, measures have been taken to reduce can manufacturing costs and to introduce steel cans into new can types such as deformed cans.

  As a measure for reducing the can manufacturing cost, there is a cost reduction of the material. In addition to 2-piece cans formed by drawing, even 3-piece cans mainly made of simple cylindrical molding are being used to reduce the thickness of the steel sheets used.

  However, simply reducing the thickness of the steel sheet will reduce the strength of the can body. Therefore, it is not possible to use a thinned steel plate in a place where a high-strength material such as a redrawn can (DRD (draw-redraw) can) or a can body of a welded can is used. Therefore, a high strength and extremely thin steel plate for cans is desired.

  At present, ultra-thin and high-strength steel sheets for cans are manufactured by a double reduction method (hereinafter referred to as DR method) in which secondary cold rolling with a rolling reduction of 20% or more is performed after annealing. A steel plate produced by using the DR method (hereinafter also referred to as a DR material) has a high strength but is characterized by poor workability.

  In order to avoid such disadvantages of workability deterioration, various techniques for improving workability are disclosed in the following patent documents.

  Patent Document 1 discloses a technique for obtaining a steel plate for high-strength cans having excellent flange workability, characterized in that the average r value is greater than 1.0.

  According to Patent Document 2, a cold work having excellent bending workability characterized by a tensile strength TS of 390 MPa or more, a yield ratio of 80% or more, a plate thickness of 0.4 mm or more, and a plate thickness direction ultimate deformability of 1.3 or more. A rolled steel sheet is disclosed.

JP 2013-19027 A JP 2010-229545 A

  First, it is necessary to secure strength in order to reduce the gauge (thinner). On the other hand, when steel plates are used for can bodies formed by flange processing, can bodies formed by can body processing such as bead processing, and can bodies formed by can body processing such as can expansion processing, It is necessary to apply steel having excellent ductility, that is, workability. For example, it is necessary to use a material that does not cause cracks in a steel plate in can bottom processing and flange processing in three-piece can manufacturing, which is representative of bottom processing and can expansion processing in two-piece can manufacturing.

  Furthermore, considering the resistance to highly corrosive contents, it is necessary to use a steel sheet with good corrosion resistance.

  With respect to the above characteristics, the above-described conventional technology cannot produce a steel sheet that satisfies all of the requirements.

  In the method described in Patent Document 1, when a precipitation strengthening element such as Nb is added to obtain a high-strength material, the growth of recrystallized grains is suppressed, and the accumulation of (111) on the annealed plate is reduced. If the average r value decreases, the change in the plate thickness becomes larger than the change in the plate width, and the amount of reduction in the plate thickness increases.

  In Patent Document 2, the ultimate deformability in the plate width direction is not described, and in the process of expanding the diameter in the circumferential direction, such as flange processing, crack generation is suppressed because the deformability in the width direction is insufficient. I can't.

  This invention is made | formed in view of this situation, and it aims at providing the steel plate for cans which was high intensity | strength, and was excellent in workability and corrosion resistance, and its manufacturing method.

  The inventors of the present invention have intensively studied to solve the above problems. As a result, the following knowledge was obtained.

  Focusing on the combined combination of precipitation strengthening, solid solution strengthening, and process strengthening, the strength can be increased without inferior ductility (elongation) by changing the solid solution strengthening by N and the ferrite structure by the solid drag of solid solution Nb. .

  Further, by defining the local elongation at the fracture portion, the particle size of MnS observed on the fracture surface that is the starting point of fracture is 5 μm or less, and further the average particle size of Nb precipitates is 100 nm or less. Workability including flange molding can be improved.

  In addition, by designing the components of the original plate with an element addition amount within a range that does not affect the corrosion resistance, the corrosion resistance is not impaired even for highly corrosive contents.

  Furthermore, in the manufacturing method, workability is lowered by appropriately adjusting the soaking time during slab heating in hot rolling, the time until the start of hot rolling, the rolling reduction of the final stand of finish rolling, etc. High strength can be achieved.

The present invention has been made based on the above findings, and the gist thereof is as follows.
[1] By mass%, C: 0.020% to 0.039%, Si: 0.04% or less, Mn: 0.10% to 0.60%, P: 0.100% or less, S : 0.020% or less, Al: 0.10% or less, N: 0.0120% to 0.0200% or less, Nb: 0.004% or more and 0.040% or less, the balance being Fe and inevitable It has a component composition consisting of impurities, the average grain size of Nb precipitates in the steel sheet is 100 nm or less, the upper yield strength is 460 MPa or more, JIS. Z. In the tensile test specified in 2241, the base metal plate thickness is t ₀ , the initial plate width of the tensile test piece is w ₀ , the fracture surface thickness of the tensile test piece after fracture is t, and the fracture surface length of the tensile test piece after fracture Is a steel plate for cans, wherein the following formula (1) is satisfied, and the particle size of MnS on the fracture surface is 5 μm or less.
− (Ln (t / t ₀ ) + ln (w / w ₀ )) ≧ 1.10 (1)
[2] The method for manufacturing a steel plate for cans according to [1] above, wherein the steel slab is heated to 1200 ° C. or higher, the soaking time is slab heated in 10 minutes or less, and after leaving the slab heating furnace. Hot rolling is started within 10 minutes, the hot rolling is performed at a finish rolling temperature of 820 ° C. or higher and 990 ° C. or lower, and a final rolling reduction ratio of 25% or lower, and a winding temperature of 400 ° C. or higher and 720 ° C. or lower. A primary rolling process in which the steel sheet is pickled and rolled at a reduction rate of 80% or more, and after the primary cold rolling process, the soaking temperature is 650 ° C. It is characterized by having an annealing step of continuous annealing at 800 ° C. or less and a soaking time of 55 s or less, and a secondary cold rolling step of rolling at a rolling reduction of 1% or more and 19% or less after the annealing step. Manufacturing method of steel plate for cans.
In addition, in this specification,% which shows the component of steel is mass% altogether.

  According to the present invention, a steel plate for cans having high strength and excellent workability and corrosion resistance can be obtained.

  Furthermore, according to the present invention, by increasing the strength of the steel sheet, it is possible to ensure high strength of the can even if the welded can is made thinner. In addition, because of excellent workability, it is possible to perform strong can body processing such as bead processing and can expansion processing used in flange processing and welded cans.

In equation (1), the base material plate thickness is t ₀ , the initial plate width of the tensile test piece is w ₀ , the fracture surface thickness of the tensile test piece after fracture is t, and the fracture surface length of the tensile test piece after fracture is It is a figure which shows the positional relationship of w.

  First, the component composition of the steel plate for cans of this invention is demonstrated.

  In the present invention, a steel plate for a can having a high yield strength of 460 MPa or more, excellent workability and corrosion resistance can be obtained by optimizing the component composition, precipitates and the like while containing the solid solution strengthening element.

  The steel plate for cans of the present invention is, by mass%, C: 0.020% or more and 0.039% or less, Si: 0.04% or less, Mn: 0.10% or more and 0.60% or less, P: 0.00. 100% or less, S: 0.020% or less, Al: 0.10% or less, N: 0.0120% to 0.0200% or less, Nb: 0.004% or more and 0.040% or less, the balance Has a component composition consisting of Fe and inevitable impurities.

C: 0.020% or more and 0.039% or less In the steel plate for cans of the present invention, it is necessary to achieve an upper yield strength of 460 MPa or more. For that purpose, it is important to use precipitation strengthening by Nb precipitates (NbC) produced by containing Nb. In order to utilize precipitation strengthening by Nb precipitates, the C content of the steel plate for cans is important. Specifically, it is necessary to set the lower limit of the C content to 0.020%. On the other hand, if the C content exceeds 0.039%, the amount of iron carbide produced increases and the workability deteriorates. For this reason, the upper limit of the C content is 0.039%.

Si: 0.04% or less Si is an element that increases the strength of a steel sheet by solid solution strengthening. However, if the Si content exceeds 0.04%, the corrosion resistance is significantly impaired. Therefore, the Si content is set to 0.04% or less. In the present invention, since it is possible to increase the upper yield strength by adjusting elements other than Si and manufacturing conditions, the high strength, which is one of the objects of the present invention, without using the solid solution strengthening by Si is Can be achieved. For this reason, in this invention, it is not necessary to contain Si.

Mn: 0.10% or more and 0.60% or less Mn increases the strength of the steel sheet by solid solution strengthening. In order to ensure the target upper yield strength, the Mn content must be 0.10% or more. Therefore, the lower limit of the Mn content is 0.10%. On the other hand, if the Mn content exceeds 0.60%, the corrosion resistance and surface characteristics are inferior. Therefore, the upper limit of the Mn content is set to 0.60%.

P: 0.100% or less P is an element having a large solid solution strengthening ability. In order to acquire such an effect, it is preferable to contain 0.007% or more. Moreover, in order to make P content less than 0.007%, dephosphorization time rises significantly. For this reason, the P content is preferably 0.007% or more. On the other hand, if the P content exceeds 0.100%, the corrosion resistance is poor. For this reason, the P content is 0.100% or less.

S: 0.020% or less Since the steel plate for cans of the present invention has a high N content and contains Nb that forms precipitates that cause slab cracking, the slab edge tends to crack in the straightening zone during continuous casting. . In view of preventing slab cracking, the S content is set to 0.020% or less. Preferably, the S content is 0.015% or less. More preferably, the S content is 0.005% or less.

Al: 0.10% or less Since an increase in the Al content causes an increase in the recrystallization temperature, it is necessary to set the annealing temperature higher by the increase in the Al content. In the present invention, the recrystallization temperature rises due to the influence of other elements added to increase the upper yield strength, and the annealing temperature must be set high. Therefore, it is necessary to avoid the increase in the recrystallization temperature due to Al as much as possible. Therefore, the Al content is set to 0.10% or less. On the other hand, Al is preferably added as a deoxidizer, and in order to obtain this effect, the Al content is preferably 0.001% or more.

N: 0.0120% to 0.0200% or less N is an element necessary for increasing solid solution strengthening. In order to exert the effect of solid solution strengthening, the N content needs to be over 0.0120%. On the other hand, when there is too much N content, it will become easy to produce a slab crack in the lower correction zone where the temperature at the time of continuous casting falls. Therefore, the N content is 0.0200% or less.

Nb: 0.004% or more and 0.040% or less Nb is an element having a high carbide generating ability and precipitates fine carbides. As a result, the upper yield strength increases. In the present invention, the upper yield strength can be adjusted by the Nb content. Since this effect occurs when the Nb content is 0.004% or more, the lower limit of the Nb content is limited to 0.004%. On the other hand, Nb increases the recrystallization temperature. Therefore, when the Nb content exceeds 0.040%, a large amount of non-recrystallized structure is caused by continuous annealing at an annealing temperature of 650 to 800 ° C. and a soaking time of 55 s or less. Remain. For this reason, the upper limit of Nb content is limited to 0.040%.

  The balance other than the above is Fe and inevitable impurities.

  Next, the steel plate for cans of the present invention will be described.

The average particle size of Nb precipitates in the steel sheet is 100 nm or less. There are two types of Nb precipitates, one is a single precipitate and the other is a compound that precipitates in a complex manner using MnS as a nucleus. The type in which MnS is used as a core to precipitate together promotes the generation of voids in the vicinity of MnS, thus degrading the formability. When the average particle diameter exceeds 100 nm, since MnS is used as the core and the compound is precipitated, the average particle diameter of Nb precipitates in the steel sheet is set to 100 nm or less.

The average grain size of Nb precipitates in the steel sheet is 50,000 times the field of view of 2.79 μm ² at the center of the plate thickness by electropolishing the cross section of the steel sheet and using a transmission electron microscope (TEM). The average particle size was calculated by averaging the particle sizes of all the observed Nb precipitates. Moreover, the average particle diameter of the Nb precipitate in a steel plate can be made into 100 nm or less by controlling soaking temperature of 800 degreeC or less of annealing conditions, and soaking time to 55 seconds or less.

The upper yield strength is 460 MPa or more in order to ensure the dent strength of the welded can and the pressure resistance of the two-piece can. While adopting the above component composition, for example, by employing the manufacturing conditions described later, the upper yield strength of the steel plate for cans can be controlled to 460 MPa or more.

JIS. Z. In the tensile test specified in 2241, the base metal plate thickness is t ₀ , the initial plate width of the tensile test piece is w ₀ , the fracture surface thickness of the tensile test piece after fracture is t, and the fracture surface length of the tensile test piece after fracture The following expression (1) is satisfied, where is w. FIG. 1 illustrates these positional relationships.
− (Ln (t / t ₀ ) + ln (w / w ₀ )) ≧ 1.10 (1)
When − (ln (t / t ₀ ) + ln (w / w ₀ )) ≧ 1.10, the local elongation until the fracture at the time of molding is good.

When a tensile test is performed with an extremely thin material such as a steel plate for cans, deformation does not progress uniformly between the marks on the tensile test piece, and the elongation between the marks and the local elongation near the fractured part. A different phenomenon occurs. In the evaluation of workability (formability), it is important whether cracks are generated after processing. The evaluation up to the occurrence of this crack cannot be performed correctly with the elongation between the gauge points of the conventional tensile test, and represents a local elongation-(ln (t / t ₀ ) + ln (w / w ₀ ). ) Can be used for evaluation. In this formula, the strain in the plate thickness direction at break can be expressed as ln (t / t ₀ ), and the strain in the plate width direction at break can be expressed as ln (w / w ₀ ). This formula indicates local elongation at the fracture portion, and the occurrence of cracks in can molding can be evaluated. That is, the local elongation corresponding to the above formula is evaluated, and when it is 1.10 or more, workability is improved.

The particle size of MnS on the fracture surface is 5 μm or less. MnS is often observed on the surface of the fractured portion, and is observed in a dent called a dimple on the ductile fracture surface. Since voids are generated in the vicinity of MnS and breakage occurs, voids increase as the particle size of MnS increases, and fracture occurs when the degree of processing is small. When the particle size (maximum particle size) of MnS observed on the fracture surface exceeds 5 μm, the inclusions become the starting point of the fracture. Therefore, the particle size (maximum particle size) of MnS on the fracture surface is 5 μm or less.
The MnS grain size of the fracture surface is observed with a scanning electron microscope (SEM) at 500 times the full width of the thickness of the fracture surface after measuring the upper yield strength. Visually select the 10 largest particles and measure the maximum particle size, and set the largest MnS particle size to the maximum particle size. Also control the soaking time during slab heating and the hot rolling start time. Accordingly, − (ln (t / t ₀ ) + ln (w / w ₀ )) ≧ 1.10 and the particle diameter of MnS can be set to 5 μm or less.

Plate thickness is 0.4mm or less (preferred condition)
Currently, steel sheets are being made thinner in order to reduce can manufacturing costs. However, there is a concern that the strength of the can may be reduced as the thickness of the steel plate is reduced, that is, as the steel plate thickness is reduced. On the other hand, the steel plate for cans of the present invention does not reduce the strength of the can even when the plate thickness is thin. When the plate thickness is thin, the effects of the present invention, such as high ductility and high strength, are significant. From this point, the plate thickness is preferably 0.4 mm or less. More preferably, it is 0.3 mm or less, More preferably, it is 0.2 mm or less.

Next, the manufacturing method of the steel plate for cans of this invention is demonstrated.
The manufacturing method of the steel plate for cans of this invention heats the steel slab which consists of the said component composition to 1200 degreeC or more, slab heats in 10 minutes or less, and within 10 minutes after leaving a slab heating furnace. Heat that starts hot rolling, is hot-rolled at a finish rolling temperature of 820 ° C. or higher and 990 ° C. or lower, a final rolling reduction ratio of 25% or lower, and wound at a winding temperature of 400 ° C. or higher and 720 ° C. or lower. After the cold rolling process and the hot rolling process, pickling and rolling at a reduction rate of 80% or more, and after the primary cold rolling process, the soaking temperature is 650 ° C. or higher and 800 ° C. or lower, It has the annealing process which continuously anneals with a heat time of 55 s or less, and the secondary cold rolling process rolled at a rolling reduction of 1% or more and 19% or less after the annealing process.

  The steel used as a rolling material will be described. Steel is obtained by melting molten steel adjusted to the above-described component composition by a known melting method using a converter or the like, and then forming a rolled material by a commonly used casting method such as a continuous casting method. It is done.

Hot rolling process At the start of hot rolling, the temperature of the steel is set to 1200 ° C or higher. In addition, the soaking temperature is desirably 1250 ° C. or lower in order to reduce the heating cost of the steel and to maintain the durability of the heating furnace.
The soaking time during slab heating is an important condition for obtaining the workability important in the present invention. When the soaking time exceeds 10 minutes, the particle size of MnS increases and the workability decreases. For this reason, the soaking time at the time of slab heating shall be 10 minutes or less.
In addition, when 10 minutes or more elapses from the exit of the slab heating furnace to the start of hot rolling, the particle size of MnS increases and the workability deteriorates. For this reason, hot rolling is started within 10 minutes after the slab leaves the heating furnace.

  The finish rolling temperature in the hot rolling is 820 ° C. or higher and 990 ° C. or lower. The finish rolling temperature in hot rolling is an important factor in securing the upper yield strength. When the finishing temperature is less than 820 ° C., grains grow by two-phase region hot rolling of austenite + ferrite (γ + α), and the crystal grains after cold rolling and annealing become coarse. As a result, the upper yield strength decreases. Therefore, the finish rolling temperature in the hot rolling is set to 820 ° C. or higher. On the other hand, the upper limit is set to 990 ° C. for the purpose of suppressing the generation of scale.

  The coiling temperature in the hot rolling process is 400 ° C. or more and 720 ° C. or less. When the coiling temperature is less than 400 ° C., the temperature distribution in the width direction becomes non-uniform because the runout table is excessively cooled. This causes a shape defect in the width direction, and a shape defect called middle elongation or ear wave occurs after cold rolling. For this reason, the minimum of coiling temperature shall be 400 degreeC. The upper limit of the winding temperature is set to 720 ° C. for the purpose of suppressing the generation of scale.

Primary cold rolling process Pickling is performed to remove scale before the primary cold rolling process. The pickling method is not particularly limited. What is necessary is just to be able to remove the surface layer scale of the steel sheet, and pickling can be performed by a usual method. Moreover, you may remove a scale by methods other than pickling.

The reduction ratio in the primary cold rolling is 80% or more. If the rolling reduction is less than 80%, it is difficult to produce a steel plate having an upper yield strength of 460 MPa or more. Furthermore, when the reduction rate in this step is less than 80%, in order to obtain a plate thickness (about 0.17 mm) comparable to that of a conventional DR material in which the reduction rate of secondary cold rolling is 20% or more, At least the thickness of the hot-rolled sheet needs to be 0.9 mm or less. However, in operation, it is difficult to set the thickness of the hot rolled sheet to 0.9 mm or less. Therefore, the rolling reduction in this step is 80% or more.
In addition, another process may be appropriately included after the hot rolling process and before the primary cold rolling process. Moreover, you may perform a primary cold rolling process, without performing pickling immediately after a hot rolling process.

The soaking temperature in the annealing process is 650 ° C. or higher and 800 ° C. or lower. In order to make the structure of the steel sheet more uniform, the soaking temperature is set to 650 ° C. or higher. On the other hand, in order to perform continuous annealing under conditions where the soaking temperature exceeds 800 ° C., it is necessary to reduce the conveying speed as much as possible in order to prevent the steel sheet from being broken, and productivity is lowered. Preferably, it is 660 degreeC or more and 760 degreeC or less.
The soaking time is 55 s or less. Since productivity cannot be secured at a speed at which the soaking time exceeds 55 s, the soaking time is set to 55 s or less. On the other hand, in order to shorten the soaking time, it is necessary to increase the conveyance speed, and it is difficult to stably convey without meandering.

A rapid cooling treatment can be performed after the soaking. For example, by carrying out at an average cooling rate from the soaking temperature to the cooling stop temperature: 250 to 400 ° C .: 30 ° C./s or more and less than 150 ° C./s, it becomes possible to further achieve both high ductility and high strength. .
In addition, a continuous annealing apparatus is used for annealing. Moreover, another process may be appropriately included before the annealing process after the primary cold rolling process, or the annealing process may be performed immediately after the primary cold rolling process.

Secondary cold rolling step The rolling reduction is 1 to 19%. If the reduction ratio in the secondary cold rolling after annealing is the same as the normal DR material production conditions (20% or more), the strain introduced during processing increases, so − (ln (t / t ₀ ) + ln ( w / w ₀ )) decreases. Since it is necessary to ensure − (ln (t / t ₀ ) + ln (w / w ₀ )) ≧ 1.10, the reduction ratio in the secondary cold rolling is set to 19% or less. In addition, secondary cold rolling has a role of imparting surface roughness of the steel sheet, and in order to uniformly impart the surface roughness to the steel sheet, the reduction ratio of secondary cold rolling needs to be 1% or more. Preferably, it is 8 to 19%.
In addition, another process may be appropriately included before the secondary cold rolling process after the annealing process, or the secondary cold rolling process may be performed immediately after the annealing process.

  By the above, the steel plate for cans of this invention is obtained. In the present invention, various processes can be further performed after the secondary cold rolling. For example, with respect to the steel plate for cans of this invention, you may have a plating layer further on the steel plate surface. Examples of the plating layer include a Sn plating layer, a tin plating layer such as a tin plating layer, a Ni plating layer, and a Sn—Ni plating layer. Moreover, you may perform processes, such as a coating baking process and a film lamination.

Steel containing the composition shown in Table 1 and the balance being Fe and inevitable impurities was melted in an actual converter to obtain a steel slab. The obtained steel slab was reheated at 1200 ° C., and then hot rolled and wound up. Then, after pickling by a normal method, primary cold rolling was performed to produce a thin steel plate. The obtained thin steel sheet was heated at a heating rate of 15 ° C./sec for continuous annealing. Next, after cooling, secondary cold rolling was performed, and normal Sn plating was continuously performed to obtain a Sn-plated steel sheet (cover) with a single-side adhesion amount of 11.2 g / m ² . Detailed production conditions are shown in Table 2. “Base material plate thickness t ₀ ” in Table 2 is a thickness not including the Sn plating layer.

  The Sn-plated steel sheet (cover) obtained as described above was subjected to a heat treatment corresponding to a coating baking process at 210 ° C. for 20 minutes, and then a tensile test was performed to measure the upper yield strength. In addition, pressure strength and formability were investigated. The measurement method and survey method are as follows.

Tensile test JIS No. 5 tensile test piece (JIS Z 2201) with the direction parallel to the rolling direction as the tensile direction is collected, subjected to paint baking equivalent treatment at 210 ° C for 10 minutes, and then stipulated in JIS Z 2241 A compliant tensile test was performed at a tensile speed of 10 mm / min, and an upper yield point (U-YP) was measured.

Roll forming is performed so that the winding width is 5 mm with the pressure-resistant strength rolling direction as the bending direction, both ends of the cylindrical shape are seam welded by electric resistance welding, neck forming and flange forming are performed, and then the lid is wound and empty A can sample was made. The obtained empty can sample was put into a chamber, pressurized with compressed air, and the pressure at which the sample buckled after pressurization was measured. When the buckling pressure is 0.20 MPa or more, the pass (合格), less than 0.20 MPa, 0.13 MPa or more is passed (◯), and less than 0.13 MPa is rejected (x).

Formability Roll-form processing so that the rolling direction is the bending direction and the winding width is 5 mm, both ends of the cylindrical shape are seam welded by electric resistance welding, neck forming is performed, then flange forming is performed, and the crack is visually observed Observed. The case where there was no crack at all was acceptable (◯), and the case where one or more fine cracks were observed visually was regarded as unacceptable (x).

The sample after corrosion-resistant annealing was subjected to Sn plating with an adhesion amount of 11.2 g / m ² on one side, and the number of sites where the Sn plating was thinned and observed as holes was measured. Observation was carried out at a measurement area of 2.7 mm ² with an optical microscope of 50 ×. The case where the number was 20 or less was marked as ◯, and the case where the number was 21 or more was marked as x.

  From Table 2, in the present invention examples, steel plates for cans having good corrosion resistance, high strength and excellent workability were obtained.

  According to the present invention, a steel plate for cans having high strength, excellent workability, and good corrosion resistance can be obtained. The present invention is most suitable as a steel plate for cans centering on a three-piece can with a high degree of can body processing and a two-piece can whose bottom portion is processed by several percent.

Claims (2)

In mass%, C: 0.020% to 0.039%, Si: 0.04% or less, Mn: 0.10% to 0.60%, P: 0.100% or less, S: 0.00. 020% or less, Al: 0.10% or less, N: 0.0120% to 0.0200% or less, Nb: 0.004% or more and 0.040% or less, with the balance being Fe and inevitable impurities Having an ingredient composition;
The average particle size of Nb precipitates in the steel sheet is 100 nm or less,
The upper yield strength is 460 MPa or more,
JIS. Z. In the tensile test specified in 2241, the base metal plate thickness is t ₀ , the initial plate width of the tensile test piece is w ₀ , the fracture surface thickness of the tensile test piece after fracture is t, and the fracture surface length of the tensile test piece after fracture Is a steel plate for cans, wherein the following formula (1) is satisfied, and the particle size of MnS on the fracture surface is 5 μm or less.
− (Ln (t / t ₀ ) + ln (w / w ₀ )) ≧ 1.10 (1) It is a manufacturing method of the steel plate for cans according to claim 1,
Steel slab is heated to 1200 ° C or higher, soaking time is slab heated for 10 minutes or less, hot rolling is started within 10 minutes after leaving the slab heating furnace, and finish rolling temperature is 820 ° C to 990 ° C. Hereinafter, a hot rolling step of rolling at a rolling reduction of 400 ° C. or more and 720 ° C. or less with a rolling reduction at a final stand of finish rolling of 25% or less,
After the hot rolling step, pickling and primary cold rolling step of rolling at a reduction rate of 80% or more,
After the primary cold rolling step, an annealing step in which the soaking temperature is 650 ° C. or more and 800 ° C. or less, and the soaking time is 55 s or less, and continuous annealing,
A secondary cold rolling step of rolling at a rolling reduction of 1% or more and 19% or less after the annealing step.

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