JP6439666B2 - Steel plate for 3-piece can excellent in roll form workability and roundness after welding, manufacturing method thereof, and manufacturing method of 3-piece can - Google Patents

Description

  The present invention relates to a steel plate for cans suitable for a can container material used as a container material for beverages and foods, a method for producing the same, and a method for producing a three-piece can. Specifically, it is easy to form at the time of roll foam processing, and the roundness after welding (error from the roundness) is small and there is little deformation of the can body part, that is, excellent in roll form workability and roundness after welding. The present invention relates to a steel plate for a three-piece can and a method for producing the same, and a method for producing a three-piece can.

  In recent years, since the use of aluminum cans has been expanded, the steel plate for steel cans has been made thinner in order to reduce the cost of steel cans. However, as the thickness of the steel sheet is reduced, that is, as the thickness of the steel sheet is reduced, the deformation of the can body becomes large and the roundness increases during roll forming and welding, and there is a concern that the strength of the can may be reduced.

Many studies have been conducted to solve the above problems.
For example, Patent Document 1 discloses that a steel plate having a high N content, a yield strength of 440 MPa or more, and a total elongation of 12% or more can have a roundness of a can body of 0.34 mm or less after forming a three-piece can. A three-piece can body having a molded can body and a method of manufacturing the same are disclosed.

  Further, in Patent Document 2, when designing a metal material to be subjected to a cylindrical forming process by bending, the metal material is cylindrically formed under a condition that the bending radius r is 5 mm or more and the bending angle θ is 90 degrees or more and 180 degrees or less. The yield strength YP, Young's modulus E, and sheet thickness t of the metal material are calculated so that the springback angle Δθ when processed is a predetermined value, and the calculated yield strength YP and Young's modulus E are obtained. Thus, a method for designing a material for cylindrical forming, characterized by designing the metal material as described above, is disclosed.

International Publication 2013/183274 JP 2012-125780 A

  However, all of the above conventional techniques have problems.

  The steel sheet obtained by the technique of Patent Document 1 has high yield strength, but has a problem that roll form workability is inferior because Young's modulus is low.

  With the technique of Patent Document 2, the roll width of roll forming can be secured even if the yield strength (hereinafter sometimes referred to as YP) is low. However, there is a problem that the roundness after welding becomes large and the can strength is low.

  The present invention has been made in view of such circumstances, and solves the above-mentioned problems of the prior art. Even when the plate thickness is thin, it is excellent in roll form workability and excellent in roundness after welding. It aims at providing the manufacturing method of a steel plate, its manufacturing method, and a 3 piece can.

  The present inventors have intensively studied to solve the above problems. Since the can body of a three-piece can is a rectangular flat plate rolled into a cylindrical shape and joined at the end, roundness is an important form factor of the product after molding and has a great influence on can strength. . It is desirable that the roundness is as small as possible in order to maintain the can strength accompanying the reduction of the steel plate thickness. As YP becomes higher, deformation becomes harder and roundness becomes smaller. Therefore, increasing YP is an effective means for reducing roundness. On the other hand, when YP is too high, roll form processability deteriorates. The roll form processability can be improved by increasing the Young's modulus. However, when the Young's modulus is increased, the energy added to the can as an external force cannot be completely absorbed in the elastic region, causing plastic deformation and a problem of indentation. Therefore, the Young's modulus is conventionally set to 170 GPa or less.

  As a result of further studies based on these findings, it is possible to define the relationship between YP, Young's modulus and sheet thickness while prescribing YP and Young's modulus within a specified range. And it was found to be important from the point of roundness after welding. Optimized chemical composition, hot rolling, cold rolling and annealing conditions based on Ti-added low carbon steel to achieve high YP and high Young's modulus, and also satisfies the prescribed relationship with respect to YP, Young's modulus and sheet thickness Let As a result, even when the plate thickness is thin, it is possible to manufacture a steel plate excellent in roll form workability and roundness.

The present invention has been made based on the above findings, and the gist thereof is as follows.
[1] Component composition is mass%, C: 0.010 to 0.080%, Si: 0.010 to 0.100%, Mn: 0.10 to 1.00%, P: 0.03% or less, N: 0.010% or less, S: 0.03% or less, Al: 0.02 to 0.10%, Ti: 0.010 to 0.150%, the balance is Fe and inevitable impurities, yield strength (YP) is 460MPa or more and 680MPa or less, rolling direction, at least one of 90 ° direction from rolling direction A steel plate for a three-piece can with excellent roll form workability and roundness after welding, characterized in that the Young's modulus (E) in this direction is 220 GPa or more and satisfies the following formula (1):
YP / (E ・ t) ≦ 18.0 (1)
Here, YP: yield strength (MPa), E: rolling direction, Young's modulus (GPa) in at least one direction 90 ° from the rolling direction, and t: plate thickness (mm).
[2] The steel sheet for a three-piece can according to [1], which further satisfies the following (2) and is excellent in roll form workability and roundness after welding.
4.5 ≦ YP / (E ・ t) ≦ 18.0 (2)
[3] A steel slab having the composition described in [1] above is hot-rolled at a finishing temperature of 850 ° C or higher, wound at a winding temperature of 550 ° C or higher, pickled, and reduced by 80% or higher. A method for producing a steel plate for a three-piece can excellent in roll form workability and roundness after welding, characterized in that the steel sheet is rolled at a rate and annealed at a temperature of 700 ° C to 900 ° C.
[4] A steel slab having the composition described in [1] above is hot-rolled at a finishing temperature of 850 ° C. or higher, wound at a winding temperature of 550 ° C. or higher, pickled, and reduced by 80% or higher. Rolling at a temperature of 700 ° C to 900 ° C, yield strength (YP) of 460MPa to 680MPa, and Young's modulus (E) of 220GPa or more. A method for producing a three-piece can with excellent roundness after welding.
In addition, in this specification,% which shows the component of steel is mass% altogether.

  According to the present invention, a steel plate for a three-piece can and a three-piece can excellent in roll form workability and roundness after welding can be obtained. Therefore, by using the steel plate for a three-piece can of the present invention as a container material for beverages and foods, it is possible to further reduce the thickness of the steel plate and achieve cost reduction.

FIG. 1 is a diagram showing a winding width at the time of roll forming.

Hereinafter, the present invention will be described in detail.
The steel plate for a 3-piece can of the present invention has a component composition of mass%, C: 0.010 to 0.080%, Si: 0.010 to 0.100%, Mn: 0.10 to 1.00%, P: 0.03% or less, N: 0.010% or less, S: 0.03% or less, Al: 0.02-0.10%, Ti: 0.010-0.150%, the balance is made of Fe and inevitable impurities, yield strength (YP) is 460MPa or more and 680MPa or less, rolling direction, rolling direction The Young's modulus (E) in at least one of the 90 ° directions is 220 GPa or more, which satisfies the following formula (1).
YP / (E ・ t) ≦ 18.0 (1)
Here, YP: yield strength (MPa), E: rolling direction, Young's modulus (GPa) in at least one direction 90 ° from the rolling direction, and t: plate thickness (mm).
Such a steel plate for a three-piece can is obtained by hot rolling steel having the above composition at a finishing temperature of 850 ° C. or higher, winding at a winding temperature of 550 ° C. or higher, pickling, and 80% or higher. It is possible to manufacture by performing cold rolling at a reduction ratio of and annealing at a temperature of 700 ° C to 900 ° C.
Further, by performing roll forming in a direction in which the yield strength (YP) is 460 MPa or more and 680 MPa or less and the Young's modulus (E) is 220 GPa or more, a three-piece can having excellent roundness after welding can be manufactured.
These are important requirements of the present invention.

  First, the component composition of the steel plate for 3 piece cans of this invention is demonstrated.

C :: 0.010 to 0.080%
C forms fine carbides and has the effect of increasing the strength of the steel sheet. In order to ensure the yield strength (YP) of 460 MPa or more, it is necessary to contain 0.010% or more. On the other hand, if it exceeds 0.080%, the yield strength increases excessively, exceeds the upper limit of yield strength of 680 MPa, and roll foam processability deteriorates. For this reason, C is limited to a range of 0.010 to 0.080%. Preferably, the C content is 0.040 to 0.060%.

Si: 0.010 to 0.100%
Si is an element that has the effect of increasing the hardness of a steel sheet by solid solution strengthening. In order to ensure the yield strength (YP) stably, Si needs to be contained by 0.010% or more. On the other hand, since Si is an element harmful to corrosion resistance for cans, the upper limit is made 0.100%.

Mn: 0.10 to 1.00%
Mn is an element that has the effect of increasing the hardness of the steel sheet by solid solution strengthening. In order to stably secure the yield strength (YP), Mn needs to be contained in an amount of 0.10% or more. On the other hand, as the amount of Mn increases, the cost of the raw material increases, so the upper limit of Mn is set to 1.00%. However, since the upper limit of Mn of the tin plate used for food containers is defined as 0.60% or less, it is preferably 0.60% or less when used as food containers.

P: 0.03% or less
P segregates at the grain boundaries and lowers the ductility and toughness of the steel sheet. It is also a harmful element that reduces corrosion resistance. From the above points, the upper limit is set to 0.03%. In addition, Preferably it is 0.02% or less. On the other hand, since P is an element having an effect of increasing the hardness of the steel sheet by solid solution strengthening, it is preferably 0.01% or more.

N: 0.010% or less
When N is contained in a large amount, excess nitride is generated, and the ductility and toughness of the steel sheet are lowered. Moreover, workability is deteriorated. Therefore, the upper limit is made 0.010%.

S: 0.03% or less
In the present invention containing Mn and Ti, S combines with Ti to form TiS and Mn to form MnS. Since these sulfides deteriorate the surface properties and reduce the ductility in hot rolling, the upper limit is set to 0.03%. Preferably it is 0.01% or less.

Al: 0.02-0.10%
Al is a useful element that acts as a deoxidizer, and in order to obtain the effect, it is necessary to contain 0.02% or more. On the other hand, if it exceeds 0.10%, surface defects of the steel sheet are induced, so the upper limit is made 0.10%.

Ti: 0.010 to 0.150%
Ti is an important element in the present invention, and is combined with C to form fine carbide TiC, thereby contributing to high strength of the steel sheet. In addition, a part of the solute carbon existing in the steel is fixed, the texture of the steel plate is developed, and the Young's modulus is improved. In order to obtain these effects, the Ti content needs to be 0.010% or more. On the other hand, if it exceeds 0.150%, the yield strength (YP) exceeds 680 MPa, the strength becomes too high, and the roll foam processability is deteriorated. Moreover, since the rolling load is increased, it is difficult to produce a stable steel sheet. For these reasons, Ti is limited to the range of 0.010 to 0.150%.

  The balance is Fe and inevitable impurities.

Next, the material characteristics of the present invention will be described.
The steel plate for a three-piece can of the present invention has a yield strength (YP) of 460 MPa or more and 680 MPa or less, a Young's modulus (E) in at least one direction of 90 ° from the rolling direction and the rolling direction of 220 GPa or more. Satisfy (1).
YP / (E ・ t) ≦ 18.0 (1)
Here, YP: yield strength (MPa), E: rolling direction, Young's modulus (GPa) in at least one direction 90 ° from the rolling direction, and t: plate thickness (mm).

  In order to obtain the effects of the present invention, it is not sufficient to adjust the component composition to the above range, and it is important to control the yield strength and Young's modulus to a range satisfying specific conditions.

Yield strength (YP): 460 MPa or more and 680 MPa or less In the steel plate for a three-piece can of the present invention, the yield strength (YP) is 460 MPa or more and 680 MPa or less. By setting the YP to 460 MPa or more, the can body is difficult to deform, the roundness is reduced, and the can strength can be maintained. On the other hand, when YP exceeds 680 MPa, roll form workability deteriorates as the plate thickness decreases. Here, the yield strength (YP) can be measured by cutting a JIS No. 5 tensile test piece according to the rolling direction and by a tensile test specified in JIS Z 2241. Moreover, the yield strength (YP) is C: 0.010 to 0.080%, Si: 0.010 to 0.100%, Mn: 0.10 to 1.00%, Ti: 0.010 to 0.150% as the component composition. It can be set to 460 MPa or more and 680 MPa or less by 80% or more.

Container in which roll foam is applied so that the Young's modulus (E) in at least one of the rolling direction and the 90 ° direction from the rolling direction is 220 GPa or more and the rolling direction or the 90 ° direction from the rolling direction is the circumferential direction of the can body In order to increase the rigidity of the can body, the Young's modulus in at least one of the rolling direction and the 90 ° direction from the rolling direction is set to 220 GPa or more. By setting it to 220 GPa or more, it is possible to prevent buckling deformation of the can body due to increase or decrease in pressure outside the can in the heat sterilization treatment of the contents accompanying the thinning of the steel plate. Either the rolling direction only, the 90 ° direction from the rolling direction, or both the rolling direction and the 90 ° direction from the rolling direction may be 220 GPa or more, but the direction with the highest Young's modulus is the circumference of the can body part. It is preferable to apply the roll form so that it is in the direction.
The Young's modulus in the rolling direction and / or 90 ° direction from the rolling direction can be measured by a transverse vibration type resonance frequency measuring device. In addition, Young's modulus (E) is obtained by fixing a part of solute carbon in steel at Ti: 0.010 to 0.150% as a component composition, and by setting a reduction rate of 80% or more in cold rolling as a manufacturing condition. The texture of the steel sheet can be developed to 220 GPa or higher.
Furthermore, in the present invention, the yield strength (YP), Young's modulus (E), and plate thickness (t) shall satisfy the following formula.
YP / (E ・ t) ≦ 18.0
Where, YP: yield strength (MPa), E: Young's modulus (GPa) in the rolling direction and / or 90 ° direction from the rolling direction, t: plate thickness (mm)
By increasing YP, the can body is less likely to deform, the roundness is reduced, and the can strength can be maintained. On the other hand, the roll foam processability deteriorates due to the high YP as the steel plate thickness decreases. In order to prevent this, it is necessary to increase the Young's modulus. As a result of considering all of these, in the present invention, YP / (E · t) ≦ 18.0. Preferably 4.5 ≦ YP / (E · t) ≦ 18.0. By setting YP / (Et) to 18.0 or less, even when the plate thickness is extremely thin, roll form workability is good and roundness after welding is excellent, that is, roll form workability and post-weld A steel plate for a three-piece can capable of achieving both roundness of the same is obtained.

Plate thickness is 0.17mm or less (preferred conditions)
The steel plate for a three-piece can of the present invention has a remarkable roll effect and excellent roundness after welding when the plate thickness is thin, so that the plate thickness is 0.17 mm or less. It is preferable to do.

Next, the manufacturing method of the steel plate for 3 piece cans of this invention is demonstrated.
The steel plate for a three-piece can of the present invention is obtained by hot-rolling a steel having the above composition at a finishing temperature of 850 ° C. or higher, winding at a winding temperature of 550 ° C. or higher, pickling, and rolling reduction of 80% or higher. It is manufactured by performing cold rolling at a temperature of 700 ° C. or higher and 900 ° C. or lower.
In the present invention, as described above, a 3-piece can steel plate having good roll form workability and excellent roundness after welding can be produced without performing rolling twice. When trying to manufacture a steel plate for a three-piece can by one rolling according to the prior art, it is necessary to increase the rolling load of the cold rolling mill and increase the reduction rate in order to increase the strength. Moreover, when it is going to make plate | board thickness thin, it is necessary to take a rolling load large. Therefore, there has been a problem that the deformation resistance is increased and the breaking rate of the steel sheet is increased. However, in the present invention, C: 0.010 to 0.080%, Si: 0.010 to 0.100%, Mn: 0.10 to 1.00%, Ti: 0.010 to 0.150% are added, and cold rolling with a rolling reduction of 80% or more is performed. Therefore, the above problem does not occur.

Slab reheating temperature: 1150-1300 ° C (preferred conditions)
If the slab reheating temperature before hot rolling is too high, problems such as product surface defects and increased energy costs occur. On the other hand, if it is too low, it will be difficult to ensure the final finish rolling temperature. Therefore, the slab reheating temperature is preferably 1150 to 1300 ° C.

Hot rolling finishing temperature: 850 ° C. or more When the finishing temperature is lower than 850 ° C., crystal grains stretched in the rolling direction tend to be generated, and the development of the texture of the cold-rolled steel sheet is lowered. Moreover, when manufacturing a steel plate for a three-piece can with a thin plate thickness, the temperature on the edge side of the coil tends to decrease, so the finishing temperature is set to 850 ° C. or higher.

Hot rolling coiling temperature: 550 ° C or more If the coiling temperature falls below 550 ° C, the steel plate becomes hard due to the generation of hard low-temperature transformation phase such as bainite and martensite, and the load during subsequent cold rolling also increases. This makes it difficult to operate. Therefore, the coiling temperature is 550 ° C or higher. On the other hand, when the coiling temperature exceeds 700 ° C., the ferrite grains in the hot-rolled sheet stage become coarse, and the hardness decreases. Therefore, it is preferably 700 ° C. or lower.

Rolling ratio in cold rolling: 80% or more In order to achieve the yield strength specified by the present invention, it is made 80% or more. If the rolling reduction in cold rolling is less than 80%, the texture that improves the Young's modulus will not develop. Further, the crystal grains are coarsened and the material is softened. Therefore, the rolling reduction in cold rolling is 80% or more.

Annealing temperature: 700 ° C. or higher and 900 ° C. or lower If the annealing temperature is lower than 700 ° C., ferrite grains stretched in the rolling direction remain and the ductility is greatly reduced. Therefore, the annealing temperature needs to be 700 ° C. or higher. Preferably it is 750 degreeC or more. On the other hand, if the annealing temperature exceeds 900 ° C., the crystal grains become coarse and the hardness decreases. The annealing temperature is 900 ° C or less. Preferably it is 850 degrees C or less.
The holding time at the annealing temperature is not particularly limited, but is preferably 15 to 40 seconds. If the holding time is not less than 15 seconds, the ferrite crystal grain size tends to be non-uniform, and a dent may remain in the can body after roll forming. Moreover, when holding time exceeds 40 second, a carbide | carbonized_material melt | dissolves and yield strength may fall. Therefore, the holding time of the annealing temperature is preferably 15 to 40 seconds.

  By the above, the steel plate for 3 piece cans of this invention is obtained. In addition, temper rolling with a rolling reduction of 1 to 6% can be further performed as necessary.

  Further, the three-piece can is manufactured by subjecting the obtained steel plate for a three-piece can to roll forming in a direction having a Young's modulus (E) of 220 GPa or more. That is, a steel slab having the above composition is hot-rolled at a finishing temperature of 850 ° C. or higher, wound at a winding temperature of 550 ° C. or higher, pickled, rolled at a rolling reduction of 80% or higher, and 700 ° C. By performing annealing at a temperature of 900 ° C or less, yield strength (YP) of 460 MPa to 680 MPa, and Young's modulus (E) of 220 GPa or more, excellent roundness after welding is achieved. 3 piece cans are produced.

Hot rolling was performed under the conditions shown in Table 2 on a steel slab containing the component composition shown in Table 1 and the balance being Fe and inevitable impurities. Next, after pickling, cold rolling, annealing, and temper rolling with a reduction rate of 3% were performed under the conditions shown in Table 2, and temper rolled steel sheets with sheet thicknesses of 0.17 mm and 0.35 mm (steel sheets for 3-piece cans) ) Was manufactured. In addition, pickling was performed by hydrochloric acid or the like in a usual manner, and annealing was performed in a continuous annealing furnace with a holding time of 30 seconds.
Each performance was measured and investigated by the method shown below with respect to the steel plate for 3 piece cans obtained above. Each test method and measurement method are as follows.

(1) Measurement of Young's modulus Young's modulus is evaluated by cutting out a 10 x 35 mm test piece with the rolling direction and 90 ° direction from the rolling direction as the longitudinal direction, respectively, and using a transverse vibration type resonance frequency measuring device. The Young's modulus (GPa) was measured according to the criteria of for Testing Materials (C1259).
(2) Measurement of yield strength JIS No. 5 tensile test piece (JIS Z 2201) with the tensile direction parallel to the rolling direction was collected from the obtained steel plate for 3-piece cans, and stipulated in JIS Z 2241 A compliant tensile test was performed to measure the yield strength.
(3) Measurement of roll foam processability In order to evaluate the roll foam processability, a three-piece can roll foam process was performed on the steel sheet. Specifically, the steel plate plated with tin on the surface of the steel plate was sheared into a rectangular flat plate blank (length: 160 mm, width: 140 mm). As shown in FIG. 1, the roll former was adjusted using a plate of steel symbol B, with the rolling direction as the bending direction, and the roll width was adjusted to 5 to 10 mm. Using the processing conditions of the roll former using the plate of steel symbol B as it is, roll forming was performed on steel sheets of all levels, and the winding width was measured. The case where the winding width was 5 mm or more and 10 mm or less was determined to be acceptable (◯), and the case where the winding width was less than 5 mm or exceeding 10 mm was determined to be unacceptable (x).
(4) Measurement of roundness The cylindrical ends formed with a winding width of 5 to 10 mm as described above are joined by seam welding of electric resistance welding, and the roundness measurement device defined in “JIS B 7451” is used. The roundness of the central part in the can height direction was measured. As shown in “JIS B 0621”, the roundness of the can in the present invention is such that when the circular shape is sandwiched between two concentric geometric circles, the interval between two parallel circles is the minimum. It is expressed by the difference between the radii of the two circles. A roundness of less than 0.020mm is considered to be even better (◎), a roundness of 0.021mm to less than 0.030mm is passed (○), and a roundness of 0.030mm or more is rejected (×). It was.

  The results obtained as described above are shown in Table 3.

  From Table 3, in the example of this invention, the steel plate for 3 piece cans excellent in roll-form workability and the roundness after welding is obtained. In manufacture which performs roll foam processing using the steel plate for 3 piece cans of the present invention, roundness was small and can strength could be maintained, without a can body part changing.

Claims (4)

Component composition is mass%, C: 0.010-0.080%, Si: 0.010-0.100%, Mn: 0.10-1.00%, P: 0.03% or less, N: 0.010% or less, S: 0.03% or less, Al: 0.02 ~ 0.10%, Ti: 0.010 ~ 0.150% containing, the balance consists of Fe and inevitable impurities,
Yield strength (YP) is 460 MPa or more and 680 MPa or less,
Roll form workability and roundness after welding characterized by Young's modulus (E) in at least one of the rolling direction and 90 ° direction from the rolling direction being 220 GPa or more and satisfying the following formula (1): Excellent steel plate for 3-piece cans.
YP / (E ・ t) ≦ 18.0 (1)
Here, YP: yield strength (MPa), E: rolling direction, Young's modulus (GPa) in at least one direction 90 ° from the rolling direction, and t: plate thickness (mm). Furthermore, the steel plate for 3 piece cans of Claim 1 excellent in roll foam workability characterized by satisfy | filling following (2) and the roundness after welding.
4.5 ≦ YP / (E ・ t) ≦ 18.0 (2) A steel slab having the component composition according to claim 1 is hot-rolled at a finishing temperature of 850 ° C or higher, wound at a winding temperature of 550 ° C or higher, pickled, and rolled at a reduction rate of 80% or higher. The yield strength (YP) is 460 MPa or more and 680 MPa or less, the Young's modulus (E) in at least one of the rolling direction and 90 ° direction from the rolling direction, characterized by annealing at a temperature of 700 ° C. to 900 ° C. Is a method for producing a steel plate for a three-piece can having a roll form workability and a roundness after welding satisfying the following formula (1) :
YP / (E ・ t) ≦ 18.0 (1)
Here, YP: yield strength (MPa), E: rolling direction, Young's modulus (GPa) in at least one direction 90 ° from the rolling direction, and t: plate thickness (mm). A steel slab having the component composition according to claim 1 is hot-rolled at a finishing temperature of 850 ° C or higher, wound at a winding temperature of 550 ° C or higher, pickled, and rolled at a reduction rate of 80% or higher. The Young's modulus (E) for a steel plate for a three-piece can that is annealed at a temperature of 700 ° C to 900 ° C and has a yield strength (YP) of 460 MPa to 680 MPa and satisfies the following formula (1 ) Is a method for producing a three-piece can with excellent roundness after welding, characterized in that roll forming is performed in a direction of 220 GPa or more.
YP / (E ・ t) ≦ 18.0 (1)
Here, YP: yield strength (MPa), E: rolling direction, Young's modulus (GPa) in at least one direction 90 ° from the rolling direction, and t: plate thickness (mm).

Images