KR101302817B1 - High-strength steel plate for a can and method for manufacturing said high-strength steel plate - Google Patents

Abstract

The yield steel plate after coating and baking process has the strength of 500 Mpa or more, and provides the can steel plate and its manufacturing method. In mass%, C: more than 0.02%, 0.10% or less, Si: 0.10% or less, Mn: 1.5% or less, P: 0.20% or less, S: 0.20% or less, Al: 0.10% or less, N: 0.0120 to 0.0250% In addition, it contains 0.0100% or more as solid solution N in the N, and remainder consists of Fe and an unavoidable impurity. A high-strength material can be secured by securing an absolute amount of the solid-solution N amount by a certain amount or more and hardening by quenching aging and strain aging in a printing process, a film lamination process, a drying and a baking process performed before the can manufacturing process. Moreover, in manufacture, hot rolling which makes slab extraction temperature into 1200 degreeC or more and finish-rolling temperature into (Ar3 transformation point temperature -30) degreeC or more is performed, and it winds up at 650 degreeC or less.

Description

High-strength can steel sheet and its manufacturing method {HIGH-STRENGTH STEEL PLATE FOR A CAN AND METHOD FOR MANUFACTURING SAID HIGH-STRENGTH STEEL PLATE}

This invention relates to the steel plate for high strength cans suitable as a raw material for cans which reduces or enlarges a diameter shape after 3-piece processing, such as welding, and 2-piece processing, such as DI, and its manufacturing method.

In recent years, product development for reducing the thickness of the steel (steel plate) product which is a raw material for the purpose of reducing cost, and reducing the use material and environmental load is progressing.

Moreover, since the rigidity falls when the plate | board thickness of a product is thinned, in order to compensate for this rigidity fall, it is also necessary to aim at high strength of steel materials. However, when the strength of steel materials is increased, there is a problem that cracks are generated by flange processing or necking processing because they are hardened.

With respect to the above, various manufacturing methods are currently proposed.

For example, Patent Document 1 proposes a method of managing components in steel in a certain range, performing hot rolling at (Ar3 transformation point-30 ° C) or higher, and performing continuous annealing after cold rolling.

However, in the method of patent document 1, since P is made into 0.02 wt% or less, and the rolling reduction rate of secondary cold rolling is made into 15-30% so that flange workability, neck workability, and corrosion resistance may not deteriorate, a thin product is made efficient It is difficult to produce and difficult to produce, and there is a problem that appearance defects are likely to occur. Moreover, since it is difficult to manufacture stably, improvement is needed.

In addition, Patent Literature 2 manages the steel component and the solid solution N in a certain range, and then hot-rolls at (Ar3 transformation point-30 deg. C) or more, performs predetermined cooling, winds up the water, and cold-rolls. After performing the following, continuous annealing of a predetermined heat pattern is performed, and a manufacturing method of the steel plate for cans which has a yield stress of 550 Mpa or more after coating baking process is proposed.

However, in the method of patent document 2, it is a semi ultra low carbon | charcoal material, and also has a problem that it is difficult to strictly control a heat pattern by making high temperature of continuous annealing in order to ensure predetermined | prescribed solid solution N, and to strictly manage a heat pattern. . Moreover, only by securing solid solution N which is 80% or more of N in steel, it is difficult to manufacture a steel plate of predetermined strength stably because of the variation of N content in steel, and improvement is needed. Moreover, in the method of patent document 2, total elongation becomes small and workability deteriorates.

Moreover, the following method is proposed as a typical manufacturing method of a high strength can steel plate, and it selects suitably according to the kind of annealing, and is used (for example, nonpatent literature 1).

Hot rolling → pickling → cold rolling → box annealing (BAF) → second cold rolling (rolling ratio: 20-50%)

Hot rolling → pickling → cold rolling → continuous annealing (CAL) → cold rolling of the second time (rolling down rate: 20-50%)

However, in the said method, since the reduction ratio in 2nd cold rolling is high as 20 to 50%, and a rolling load is high, operation efficiency becomes low. Moreover, since various rolling oils with high viscosity are used for the purpose of improving the lubricity at the time of rolling, there exists a problem of the appearance defect after rolling by the density | concentration unevenness of a rolling oil, or partial oil adhesion. In addition, when the rolling reduction rate is high, the overall elongation decreases, the workability deteriorates, and the steel sheet is elongated by rolling, so that the difference in strength in the width direction and the longitudinal direction along the production direction and the processing direction of the raw material increases.

On the other hand, the method of restraining the reduction ratio in the cold rolling of a 2nd time can be considered. However, when the reduction ratio is made low, it is difficult to obtain the required strength.

Japanese Patent Publication No. 3108615 Japanese Laid-Open Patent Publication 2001-107187

 "Technical History of Surface-treated Steel Sheets for Cans in Japan" Nippon Steel Association October 30, 1998 issuance p.188

Thus, when it is desired to obtain a steel sheet for cans with a thin plate thickness of the product, there is no manufacturing method that can achieve both strength and productivity.

This invention is made | formed in view of such a situation, and an object of this invention is to provide the steel plate for cans whose yield stress (YP) after a coating and baking process is 500 Mpa or more, and its manufacturing method.

The present invention is as follows.

[1] In mass%, C: more than 0.02% and 0.10% or less, Si: 0.10% or less, Mn: 1.5% or less, P: 0.20% or less, S: 0.20% or less, Al: 0.10% or less, N: 0.0120 to A steel sheet for high strength cans containing 0.0250%, containing 0.0100% or more as solid solution N in the N, and the balance being made of Fe and unavoidable impurities.

[2] The steel sheet for high strength can according to [1], which has a plating layer on its surface.

[3] In mass%, C: more than 0.02% and 0.10% or less, Si: 0.10% or less, Mn: 1.5% or less, P: 0.20% or less, S: 0.20% or less, Al: 0.10% or less, N: 0.0120 to A steel slab containing 0.0250%, the remainder of which is composed of Fe and unavoidable impurities, is subjected to hot rolling with a slab extraction temperature of 1200 ° C or higher and a finish rolling temperature of (Ar3 transformation point temperature-30) ° C or higher, After winding and pickling at 650 degrees C or less, it cold-rolls and performs continuous annealing, The manufacturing method of the steel plate for high strength cans characterized by the above-mentioned.

[4] A method for producing the steel sheet for high strength can according to [3], wherein the second cold rolling is performed with the reduction ratio of 10% or more and less than 20% after the continuous annealing.

[5] The method for producing a steel sheet for high strength can according to [3] or [4], wherein the crack temperature of the continuous annealing is equal to or higher than the Ar1 transformation point temperature.

[6] The method for producing a high strength can steel sheet according to any one of [3] to [5], wherein the plating treatment is performed after the continuous annealing or the second cold rolling.

In the present specification, the percentages representing the steel components are all% by mass. In addition, in this invention, a "steel plate for high strength cans" is a steel sheet for cans which has the strength whose yield stress (YP) after coating and baking process is 500 Mpa or more.

Moreover, the steel plate for high strength cans of this invention makes a raw material for cans an object. In addition, with or without surface treatment, tin plating, nickel tin plating, chromium plating (so-called tin-free plating) or additional organic coatings can be applied to a very wide range of applications.

Moreover, although it does not specifically limit about the thickness of a steel plate, In the point which exhibits an effect by demonstrating this invention to the maximum, 0.3 mm or less of plate | board thickness is preferable, and 0.2 mm or less is more preferable. Especially preferred is 0.170 mm or less.

Carrying out the invention  Best form for

The present inventors earnestly researched in order to solve the said subject. As a result, the following findings were obtained.

As a component composition, it is made of a low carbon material, secures the absolute amount of solid solution N quantity more than a certain amount, and hardens by hardening aging and strain aging in the printing process, film lamination process, drying and baking process performed before can manufacturing process, etc. I found out that I can secure it.

As mentioned above, in this invention, the high strength can steel plate was completed by managing a component based on the said knowledge.

Hereinafter, the present invention will be described in detail.

The steel plate for high strength cans of this invention is a steel plate for cans whose strength of yield stress (YP) after a coating and baking process is 500 Mpa or more.

In the present invention, the low carbonaceous material is used, the absolute amount of the solid solution N content is secured by a fixed value or more, and the secondary cold rolling is not carried out by aging hardening after the coating baking process, or by performing the secondary cold rolling with a low reduction ratio. Higher productivity can be achieved by increasing the productivity of the steel sheet for cans. In addition, in the steel plate for cans obtained by not performing secondary cold rolling, ie, temper rolling about 1% after continuous annealing, the total elongation (E1) after coating and baking process is 20% or more. Moreover, in the steel plate for cans which secondary cold rolling is carried out by the reduction ratio of 10% or more and less than 15%, the total elongation (E1) after coating and baking process exceeds 10%.

The component composition of the steel plate for containers of this invention is demonstrated.

C: 0.02% or more and 0.10% or less

C is an effective element that increases the strength of the steel by solid solution strengthening, but on the other hand, carbides are formed to reduce the ductility of the steel sheet and thus the workability. When there are many C components, the steel plate after secondary cold rolling will be hardened, and can manufacturability and neck workability will deteriorate. Moreover, it becomes an element which generate | occur | produces a HAZ crack at the time of flange processing by remarkable hardening of a weld part. When C exceeds 0.10%, since these effects become remarkable, C shall be 0.10% or less. On the other hand, when C component becomes extremely low, since there exists a problem that intensity | strength cannot be secured unless the rolling reduction rate of secondary cold rolling is made into 20% or more of down pressure, C shall be more than 0.02%. It is preferable to make C 0.03% or more and 0.05% or less.

Si: 0.10% or less

Although Si is an element which increases the strength of steel by solid solution strengthening, Si is limited to 0.10% or less because it causes problems such as deterioration of surface treatment properties and corrosion resistance. In addition, when especially excellent corrosion resistance is calculated | required, it is preferable to make Si into 0.02% or less.

Mn: 1.5% or less

Mn is an element effective for preventing the hot crack by S. And an effect which prevents a crack is acquired by adding according to S amount suitably. In order to exhibit these effects, it is preferable to add Mn 0.20% or more. Moreover, it has the effect | miniaturization of crystal grains. On the other hand, when a large amount is added, the corrosion resistance tends to deteriorate, and the steel sheet is hardened more than necessary to deteriorate flange workability and neck workability, so the upper limit is 1.5%. It is preferable to make Mn into 0.20% or more and 0.30% or less.

P: not more than 0.20%

P significantly hardens the steel, which deteriorates the flange workability and the neck workability, and the corrosion resistance significantly. For this reason, in this invention, P is limited to 0.20% or less. It is preferable to set P to 0.001% or more and 0.018% or less.

S: 0.20% or less

S is an element present in the steel as inclusions to reduce the ductility of the steel sheet and deteriorate the corrosion resistance. Therefore, you may be 0.20% or less. It is preferable to make S into 0.001% or more and 0.018% or less.

Al: 0.10% or less

Al combines with solid solution N to form AlN, and has the effect of reducing the amount of solid solution N. In addition, an increase in Al content causes an increase in the recrystallization temperature, and it is necessary to make the annealing temperature high. At high temperature annealing, the amount of solid solution N is reduced for the formation of AlN, and the amount of aging hardening is reduced, thus causing a decrease in the strength of the steel sheet. In the case of a low carbon material, such a phenomenon becomes remarkable when Al content exceeds 0.10%. In this regard, Al was limited to 0.10% or less. Moreover, it is preferable to make Al into 0.020% or more from a viewpoint of the stable operation in the steel solvent process. It is preferable to make Al 0.020% or more and 0.060% or less.

N: 0.0120% to 0.0250%

N is an element which increases aging hardenability and is actively contained in the present invention. A significant increase in aging hardenability is found in the case of containing at least 0.0120% of low carbon materials. On the other hand, when it contains exceeding 0.0250%, the risk of causing a crack defect in a rolled material (slab) will remarkably increase. Therefore, N is limited to 0.0120% or more and 0.0250% or less.

Solid solution N of can steel sheet (cold rolled steel sheet): 0.0100% or more

In order to ensure the large age hardening property which is a characteristic of this invention, it is necessary to make the solid solution N amount in the steel plate for steels (cold rolled steel plate) into 0.0100% or more. This is the most important requirement in the present invention.

The cold rolled steel sheet of the present invention is preferably produced by pickling a hot rolled sheet, followed by cold rolling, continuous annealing and, if necessary, second cold rolling, wherein AlN is precipitated in this continuous annealing process. Since there exists a tendency, it becomes important to manage the process in which the solid-solution N amount in a steel plate for steels (cold rolled steel sheet) does not become less than 0.0100%. In addition, in this invention, the amount of N which becomes AlN is calculated | required by extraction analysis after the dissolution process by bromine ester normally performed (hereinafter called N as AlN), and the value obtained by subtracting N as AlN from the total amount of N is dissolved. N amount is used.

Moreover, it is preferable to make said solid solution N amount and solid solution C amount into 0.0150% or more in total. The solid solution C amount may be determined by measurement by internal friction or by subtracting the amount of C in the precipitate extracted from the steel sheet from the total amount of C.

Remainder shall be Fe and an unavoidable impurity.

Remainder other than the above-mentioned component is Fe and an unavoidable impurity. As unavoidable impurities, for example, Sn: 0.01% or less can be allowed.

Next, the manufacturing method of the steel plate for high strength cans of this invention is demonstrated.

The steel plate for high strength cans of this invention is obtained by the following method. First, molten steel which consists of said composition is melted by the conventionally well-known solvent method using a converter, etc., and is made into a rolled material (slab) by the conventionally well-known casting method, such as a continuous casting method. Next, a hot rolled sheet is made by hot rolling using these rolled materials. At this time, slab extraction temperature shall be 1200 degreeC or more, and finish rolling temperature shall be (Ar3 transformation point temperature-30) or more (preferably Ar3 transformation point temperature or more). Next, after winding up and pickling at 650 degreeC or less, it cold-rolls and performs continuous annealing. Moreover, as needed, the 2nd cold rolling which makes a reduction ratio 10% or more and less than 20% (preferably 10% or more and less than 15%) is performed. Moreover, plating process can also be performed.

This will be described in detail below.

Slab extraction temperature: above 1200 ℃

In order to make solid solution N amount of the steel plate for cans into 0.0100% or more, the slab is inserted into a heating furnace and heated, and the temperature extracted from the heating furnace is made into 1200 degreeC or more. This is for accelerating decomposition of AlN to secure a predetermined amount of solid solution N. It is preferable to insert and heat in the heating furnace maintained at this temperature.

Finish rolling temperature: (Ar3 transformation point-30 ℃) or more

In the present invention, in order to effectively suppress the precipitation of AlN and not to deteriorate anisotropy and workability, the finish rolling temperature in hot rolling is set to (Ar3 transformation point-30 ° C) or more. When the finish rolling temperature is lower than (Ar3 transformation point-30 ° C), precipitation of AlN becomes remarkable, solute N is reduced, and anisotropy and workability deteriorate. Moreover, it is preferably more than Ar3 transformation point.

Moreover, it is preferable to force-cool by water cooling after finish rolling. Thereby, precipitation of AlN can be suppressed.

Winding temperature: below 650 ℃

The coiling temperature is set at 650 ° C or lower in order to suppress the fixation of N by Al. When the coiling temperature exceeds 650 ° C., the amount of AlN precipitates is significantly increased and the solid solution N decreases. As a result, the target age hardenability cannot be obtained. Moreover, in order to acquire high age hardenability stably, it is more preferable to make winding temperature into 600 degrees C or less.

Moreover, in this invention, it is preferable to air-cool or water-cool in a coil state after a bristling. In the case of water cooling, productivity can be made high, but it is preferable to air-cool for uniformity of the material of the plate width direction and the longitudinal direction of a steel plate.

Pickling, cold rolling

Pickling and cold rolling are performed to the hot rolled sheet manufactured as described above to obtain a cold rolled sheet. Pickling may be carried out by removing the surface scale with an acid such as hydrochloric acid or sulfuric acid according to a conventional method. Cold rolling reduction also follows a conventional method, the thinner the plate thickness, the higher.

Crack temperature of continuous annealing: above 600 ℃ (suitable conditions)

In a continuous annealing process, it is preferable to crack in the temperature range 600 degreeC or more. When the cracking temperature is set to 600 ° C or higher, the progress of recrystallization is fast, and work deformation introduced by cold rolling does not remain, and ductility is high, which is suitable for press working. In addition, cracking at an Ar1 transformation point or more is preferable because the strength can be further improved. If the crack is above the Ar1 transformation point, it is inferred that the pearlite structure partially contributes to the strength.

Moreover, if it is in this temperature range, it does not need to maintain especially constant temperature. Due to the stability of the operation, it is sufficient to have a time equivalent to a crack of 10 s or more.

After continuous annealing, it is preferable to perform rough rolling about 1% and to adjust surface roughness and hardness.

The cold rolled steel sheet obtained through the above process becomes 20% or more of the total elongation (E1) after coating and baking process, and becomes a steel plate for cans which is very excellent in workability.

After continuous annealing, you may further perform the cold rolling of the 2nd time of a reduction ratio: 10% or more and less than 20%. In this second cold rolling, further high strength is mainly aimed at. By setting it as 10% or more, further high strength can be achieved. By setting it as less than 20%, elongation is ensured (total elongation (E1) after coating and baking process is 8% or more and 15% or less), and the effect of the said high strength is acquired, without degrading workability. In particular, by setting the reduction ratio of the second cold rolling to 10% or more and less than 15%, the total elongation (El) after coating and baking treatment: 10% or more can be ensured.

By setting it as less than 20%, the effect of the said high strength is acquired, without extending | stretching and degrading workability. Rolling ratio: The cold-rolled steel sheet subjected to the second cold rolling of 10% or more and less than 20% has a total elongation (E1) of 8% or more and 15% or less after coating and baking treatment, and has excellent workability while being very high strength for cans. It becomes steel plate. As for the reduction ratio, 10% or more and less than 15% are preferable, and the cold rolled steel plate whose total elongation (El) after coating and baking process is 10% or more is obtained.

The cold rolled steel sheet is obtained through the above process. And when it is made into a hard material by the coating and baking process before can manufacturing process (before press process), and is applied to the ultra-thin steel plate whose plate | board thickness is 0.3 mm or less, the superiority is exhibited more effectively. Moreover, the cold rolled sheet steel manufactured by the above-mentioned process becomes a steel plate for high strength cans whose solid-solution N amount has 0.0100% or more, and has yield stress (YP): 500 Mpa or more after coating and baking process. Moreover, since the steel sheet for cans of this invention can obtain a big elongation, it is excellent in workability.

The steel plate for cans of this invention has obtained the big age hardenability by the solid solution N. Therefore, it has yield stress (YP): 500 Mpa or more after coating and baking process, and it can advance thinning of a steel plate predominantly. In addition, the cold rolled steel sheet of the present invention effectively increases the strength even after the reflow treatment after plating, and a significant age hardening phenomenon occurs during the coating and baking process after press molding, by effectively utilizing the action of solid solution N. May cause an increase.

In this invention, a plating layer (at least one side) can be formed in the surface of the cold rolled sheet steel obtained by the above, and it can be set as a plated steel sheet. The plated layer formed on the surface can be applied to anything applied to the steel sheet for cans. Examples of the plating layer include tin plating, chromium plating, nickel plating, and nickel chromium plating. Moreover, it is also no problem to stick a coating, an organic resin film, or the like after these plating treatments.

Example 1

The steel which consists of components shown in Table 1 was melted in the converter, and it was set as the slab by the continuous casting method. Subsequently, these slabs were hot-rolled on the conditions shown in Table 2, and it was set as the hot rolled sheet of plate | board thickness: 2.0 mm. Subsequently, the descaling process by pickling is given to the hot-rolled sheet obtained by the above, cold rolling is performed further, and continuous annealing and some secondary rolling are performed on the conditions shown in Table 2, and the final finishing plate thickness : It was set as the cold rolled sheet steel of 0.17 mm.

The thus obtained cold rolled steel sheet was subjected to a tensile test before and after the measurement of the solid solution N content and the baking curing test.

(i) analysis of employment N quantities

The amount of N in the cold rolled steel sheet was analyzed by chemical analysis, and the amount of N present as AlN was determined by extraction analysis after the dissolution treatment with bromine ester. As the solid solution N content in the cold rolled steel sheet, a value of {(N amount in the cold rolled steel sheet)-(N amount present as AlN)} was used.

(Ii) Tensile test

A JIS 13-B tensile test piece was taken from the center part of the width direction of these cold-rolled steel sheets in the rolling direction, the tensile test was performed at a strain rate crosshead speed of 10 mm / s, and the yield stress (YP) and the total elongation ( E1) was measured. In addition, the tensile test was performed within 1 day after commercialization. The tensile test piece was used as a JIS 13-B test piece in order to reduce as much as possible the phenomenon of breaking outside the mark.

(Iii) Baking Curability Test

JIS 13 No.-B tensile test piece was taken from the width direction center part of these cold-rolled steel sheets in the rolling direction, and after adding 2% tensile predeformation, it was once unloaded and the coating baking process of 210 degreeC * 20min was carried out. The heat treatment corresponding to was performed. Before and after this test, the tensile test shown in (ii) was performed. These results are shown in Table 3.

From Table 3, No. 1, 4, 5, and 6 which are examples of this invention have sufficient yield stress (YP) and total elongation (E1) after coating and baking process, For example, the strength and workability required for three-piece process Is achieving enough.

Moreover, in the example of this invention of No. 6 which performed the secondary cold rolling at 10% of reduction ratio, although the secondary cold rolling was performed, the total elongation (E1) after coating and baking process is more than 10% by 12%. It can be seen that it is secured.

On the other hand, No. 2 and 3 of the comparative example lack the yield stress (YP), respectively, and do not have the strength and workability required for three-piece processing, and therefore, the predetermined processing cannot be performed.

As mentioned above, according to this invention, the steel plate for high strength cans whose yield stress (YP) after coating and baking process has the strength of 500 Mpa or more is obtained.

Moreover, in this invention, it is set as low carbon material, and it contains predetermined N amount as (1) component,

(2) The slab extraction temperature is set to 1200 ° C or higher to decompose AlN generated during slab casting;

(3) By suppressing the precipitation of AlN by winding the hot rolled coil at 650 ° C. or lower, the absolute amount of the solid solution N content of the cold rolled steel sheet is secured to a certain level or more, and secondary cold rolling is not performed by aging hardening after the coating baking process. Alternatively, by performing secondary cold rolling at a low reduction ratio, the productivity can be increased to increase the strength of the steel sheet for cans.

And in the steel plate for high strength cans obtained by carrying out the secondary cold rolling of this invention, ie, temper rolling about 1% after continuous annealing, the total elongation (E1) after coating and baking process is 20% or more. Moreover, in the steel plate for high strength cans which performs a secondary cold rolling, the total elongation (E1) after coating and baking process can be more than 10% by making secondary cold rolling reduction ratio into 10% or more and less than 15% which is a preferable range. .

Industrial availability

The steel sheet for cans of the present invention greatly contributes to the thinning of the steel sheet because the yield stress greatly increases due to the coating baking treatment after molding, and the winding strength greatly increases accordingly.

Claims (7)

delete delete delete In mass%, C: more than 0.02% and 0.10% or less, Si: more than 0% and more than 0.10%, Mn: more than 0% and more than 1.5% or less, P: more than 0% and more than 0.20%, S: more than 0% and 0.20% or less, Al : Slab extraction temperature is set to 1200 degreeC or more for the steel slab which contains more than 0% and 0.10% or less and N: 0.020-200.0% and remainder consists of Fe and an unavoidable impurity, and finish-rolling temperature (Ar3 transformation point temperature- 30) hot rolling to above 0 ° C., winding up at 650 ° C. or below to pickling, followed by cold rolling, followed by continuous annealing,
After the said continuous annealing, the 2nd cold rolling which makes a reduction ratio 10% or more and less than 20% is performed, The manufacturing method of the steel plate for high strength cans characterized by the above-mentioned. delete delete delete