KR100240994B1 - The manufacturing method for tin plate steel sheet with excellent anti stretcher and strain property - Google Patents

Abstract

The present invention relates to a method of manufacturing a stone plate used as a material of the processing stone plate, which is used for the storage of shallow cans, ie sesame leaves, tuna, fish meat and meat products, and lowers the carbon and nitrogen content By adding Ti and Cr to form a steel and controlling its cold rolling rate, annealing conditions and temper rolling conditions, to provide a method for manufacturing a process stone master disk excellent in the plating plating adhesion and stretcher strain resistance. There is this.

In the present invention for achieving the above object is a method for producing a stone plate, in weight%, C: 0.007% or less, Mn: 0.05-0.2%, S: 0.015% or less, acid value Al: 0.02-0.05%, N: 0.004%, Ti: 0.015-0.035%, Cr: 0.02-0.5%, Remainder: Hot rolled aluminum-kilted steel ingots composed of Fe and other unavoidable impurities, followed by winding in a temperature range of 600-700 ° C. Workpieces with excellent strain resistance, including cold rolling in the range of -92% reduction rate, continuous annealing in the recrystallization temperature range up to 730 ° C, and temper rolling in the 0.4-0.8% elongation range. The manufacturing method of this is made into the summary.

Description

Manufacturing method of fine stone disc for excellent strain resistance

1 is a graph showing the recrystallization completion temperature behavior of the steel according to the Ti content changes.

FIG. 2 is a graph showing the aging index and the change in yield point yield after baking.

3 is a graph showing the change in workability according to the cold rolling rate change.

4 is a graph showing the change in yield strength of steel according to the change in temper rolling pressure.

The present invention relates to a method for manufacturing a stone can (for example, 'BP') used as a material for processing cans of shallow height, namely, a tin plated steel sheet used for storage of sesame leaf cans, tuna cans, fish meat and meat products. More particularly, the present invention relates to a method for producing a processing stone master disk excellent in stretcher strain resistance and adhesion of the plating plating.

Thin cans for processing can be used for the storage of sesame leaf, tuna, fish and meat products. The stone plate used for the above uses is mainly used by continuously annealing aluminum deoxidized steel containing carbon at a level of 0.04% to a Rockwell surface hardness of 57. However, this steel has a disadvantage in that a large amount of solid carbon is present in the steel, so that defects of streaks, ie, stretcher strains, are easily generated on the sides during forming into cans.

Since the strainer strain is a phenomenon caused by the formation of a fixed atmosphere with solid carbon and nitrogen in the steel, many proposals have been made to solve the defects caused by such strainer strains in stone discs, among which Japanese Patent Laid-Open 54-21432, Japanese Patent Laid-Open No. 61-14213 and 61-16323 are typical.

Japanese Patent Application Laid-Open No. 54-2143 is a method of increasing dislocation density through temper rolling under high pressure after annealing, and has a disadvantage in that the deformed structure remaining on the surface is not in good adhesion with the plated plating layer.

Japanese Patent Publications (SO) 61-15213 and (SO) 61-16323 disclose a method for producing a roughness T3 of roughness T3 having inferiority, but the aging phenomenon after long-term storage of materials and reflow treatment of tin. Because of the re-formation of the adhesion between the dislocation and the solid solution, there is a disadvantage that can not prevent the strainer strain during processing.

Accordingly, the present inventors have conducted research and experiments to solve the problems of the conventional methods, namely, the decrease in adhesion to the plated layer and the problems of the strainer strain, and the present invention has been proposed based on the results. A method of manufacturing a process stone disc for excellent processing of slag adhesion and stretch resistance by controlling the cold reduction rate, annealing condition, and temper rolling condition by reducing the carbon and nitrogen content and adding Ti and Cr. It is intended to provide a purpose.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

The present invention provides a method for producing a stone disc, in weight%, C: 0.007% or less, Mn: 0.05-0.2%, S: 0.015% or less, acid value Al: 0.02-0.05%, N: 0.004%, Ti: 0.015-0.035%, Cr: 0.02-0.5%, Remainder: Hot rolled aluminum-kilted steel ingot composed of Fe and other unavoidable impurities, and wound in a temperature range of 600-700 ° C, followed by a reduction ratio of 88-92%. The present invention relates to a process for producing an excellent strain-resistant stonework disc, comprising cold rolling to a recrystallization temperature of more than 730 ℃ continuous annealing, followed by temper rolling in a 0.4-0.9% elongation range.

Hereinafter, the present invention will be described in more detail.

The present invention adds Ti and Cr to the carbon-lowering ultra low carbon steel to precipitate and remove a part of the solid solution, while dispersing and dispersing fine Ti emulsion in hot rolled steel and using the solid solution strengthening effect by adding Cr. Through the method of securing the target hardness HR30T 56-58), it is characterized by preventing the strain strain during the aging phenomenon and securing the adhesion of the plating.

In order to achieve the above object of the present invention, first, it is preferable to form the steel as described above, for the following reason.

Carbon in steel acts as an invasive solid solution, develops a recrystallized texture that is detrimental to workability during annealing, gathers around dislocations, causes aging, and causes strain strain during processing. For this reason, nitrogen was also limited to 0.004% or less.

Since Mn exists as a substituted solid solution element and impairs workability, it is preferable to set it as 0.2% or less.

Since the steel of the present invention has a lower Ti content than the Ti-added ultra low carbon steel which is commonly used industrially, when N is contained in the upper limit, the precipitation of S is insufficient, so it is necessary to precipitate it by Mn, and Mn is at least 0.05% is required. Therefore, the minimum of Mn was made into 0.05%.

S content in the steel is less than 0.015%, especially in the present invention, S is combined with Mn and Ti in the steel to precipitate as an emulsion such as (Ti, Mn) S. However, since the Ti content is not sufficiently added (≥ 0.04%) as in the conventional method, if the S content exceeds 0.015, it is difficult to deposit and remove all nitrogen and a part of solid solution carbon in the steel, so it is limited to 0.015% or less. It was.

As the conventional steel, the lower limit is set to 0.02% or more having the effect of removing inclusions in molten steel for the purpose of deoxidation to remove oxygen in the steel, rather than to remove and remove nitrogen, which is a solid solution element in the steel, with AlN. As described above, nitrogen is preferentially removed by Ti, so if the aluminum in the present invention is too large, there is a problem of increase in manufacturing cost and deterioration of workability due to the increase in manufacturing cost and solid solution, and the upper limit is 0.05%.

Ti is different from processing steel manufactured by continuous continuous annealing because it requires a minimum amount (0.0137%) to precipitate solid solution nitrogen that has an addition range of 0.015% or more, and when added in excess of 0.035% There is no concern about grain boundary brittleness because there is no segregation of grain boundary carbon by depositing and removing carbon as well as S.

This causes brittle fracture during secondary processing and multi-stage processing of thin steel plates, while in shallow processing such as sesame leaves, very high plastic anisotropy is not required, and there is a problem of increase in manufacturing cost when a large amount is added. However, the biggest problem is that it is difficult to secure the flowability of the continuous annealing furnace as the recrystallization temperature rises. In particular, the thin steel plate like the stone plate has problems of wrinkle generation, plate bleeding, and plate breaking in the continuous annealing furnace at high temperature, so that the steel containing a large amount of Ti like the conventional Ti-added steel has not been applied. Accordingly, in the present invention, the recrystallization temperature change and the property change according to the Ti content were studied. As a result, the upper limit of the Ti content was limited to within 0.035%.

The reason for adding Cr is that it has the advantage of increasing the tensile strength without increasing the yield strength compared to the other substituted elements such as Mn and Al, and also because the plated steel is mainly used in food containers, It is due to the point that can be improved. The addition amount of Cr is sufficient in the range to obtain the target roughness (HR30T 54-60) and in the present invention aims at the hardness 57, the lower limit is 0.02 because the target hardness can be studied at 0.02% or more If the amount is too high, the upper limit is 0.05% because of too much workability and cost increase.

In the present invention, after manufacturing the aluminum-kilted steel to satisfy the alloying range as described above, it is preferable to produce the steel of the present invention by hot rolling and temper rolling, including hot rolling, intermediate annealing under the conditions described above. The reason for this is as follows.

After hot-rolling aluminum slab steel, it is preferable to wind it in a temperature range of 600-700 ° C., because winding in this temperature range provides sufficient workability and surface quality.

Then, cold rolling to a predetermined thickness in the rolling reduction range of 88-92% is preferable, because it minimizes the formation of an ear generated during the molding process of stone stones, thereby minimizing material loss and sufficient workability. To secure.

In addition, continuous annealing to secure the target hardness is preferably carried out in the temperature range from the recrystallization temperature to 730 ° C., because it is desirable to sufficiently secure the target quality. The reason is that if the annealing temperature is too high, it is difficult to secure hardness and in the continuous annealing furnace. In addition to problems such as plate scuffing, plate breakage and wrinkles during the mailing, there is a problem of rising production cost. If the annealing temperature is too low, the purpose of annealing cannot be sufficiently obtained.

As described above, the continuous annealed coil is subjected to temper rolling in a conventional manner, wherein the temper rolling elongation is preferably limited to 0.4-0.8%.

This is because the yield point elongation is removed when the temper rolling elongation is 0.4% or more, and when it exceeds 0.8%, the shape freeze is impaired during processing due to the increase in yield strength due to work hardening.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

Steel having a composition as shown in Table 1 was prepared by vacuum induction melting.

In Table 1, steel grades (1, 2) satisfy the composition of the present invention, and steel grades (3-6) are ultra low carbon steel or Ti-added ultra low carbon steel, and the component range of Ti or Cr does not satisfy the composition of the present invention. . In addition, the steel grade 7 is a steel that satisfies the composition of the conventionally proposed (Japanese Patent Laid-Open Publication No. 5421432, Japanese Patent Laid-Open Publication No. 61-14213 and (Small) 61-16323) corresponding to the roughness T3. It is prepared to compare the characteristics of the.

TABLE 1

Recrystallization behavior was observed according to the Ti content of the steel composition as shown in Table 1 and the results are shown in FIG. At this time, the recrystallization behavior was hot rolled the steels listed in Table 1 in a conventional manner, hot-rolled at 650 ℃, cold-rolled at a rolling rate of 88%, followed by continuous annealing for 30 seconds at each temperature, then hardness ( Rockwell 30T) and histological examination showed the temperature at which complete recrystallization was made.

As can be seen in FIG. 1, it can be seen that the recrystallization temperature mainly depends on the Ti content in the ultra low carbon steel, and the recrystallization completion temperature continuously increases with increasing Ti content. The steel grade 3 containing no Ti exhibited a recrystallization temperature of about 610 ° C, while the steel grade 6 containing 0.035% of Ti reached 725 ° C. On the other hand, the recrystallization temperature of the steel grade (1, 2), the invention steel, shows the same recrystallization temperature as steel with similar Ti addition amount, which does not change the recrystallization temperature even if Cr is added up to 0.05%, and is absolutely dependent on the Ti addition amount. Able to know. If the Ti content exceeds 0.035%, it can be seen that the recrystallization temperature exceeds 730 ° C. If the recrystallization temperature is high in this way, the continuous annealing temperature must be increased, so there is a problem of plate breaking, flakes, and wrinkles. Therefore, it can be seen that the appropriate Ti content is preferably within 0.035%.

In addition, the samples prepared in the same manner as in FIG. 1 were temper-rolled to have a temper reduction rate of 0.5%, and then the aging index and the post-baking yield point elongation change according to their Ti content were observed. It is shown in the figure.

In this case, the aging index was obtained by calculating the difference between the strength before aging and the yield strength after aging after artificial aging for 1 hour at 100 ° C after 7.5% of tensile strength. Obtained and shown.

Normally, the aging guarantee guarantees that no strainer strain has occurred during processing, and a three-month aging guarantee is possible when the aging index is 3 or less. However, seokdo steel pipe is processed after performing the reflow treatment for about 5 seconds at 250 ℃ after plating, which unlike the cold rolled steel sheet, the strainer strain due to the aging of tin-plated steel easily occurs regardless of time Suggests.

In the present invention, as a result of this test, as can be seen in Figure 2, when the aging index is not more than 1.5 revealed that the stretcher defects do not occur on the surface of the stone steel sheet even during the processing such as tension, In the case of yield point extension of more than 1%, fine stretcher strain defects were observed in the weak processed part within 4%.

Accordingly, it can be seen that the Ti content is required to be 0.015% or more in order to obtain the stretcher strain resistance. In addition, the comparative steel (3), which is not shown in the second, but does not contain Ti at all, had an aging index of 3.2 kgf / mm2 and a yield point elongation of 7.6% after quench hardening, and the comparative carbon (7), which was low carbon steel, was 4.7 9.8 was very high. Therefore, even if these steels are manufactured to have a roughness T3 by applying annealing temperature, it can be seen that the occurrence of stretcher strain defects during processing is inevitable.

In addition, in order to confirm the change in workability of the material according to the cold rolling rate change, the heat treatment and other manufacturing conditions for the inventive steels (1, 2) were the same as in the case of FIG. The change was -92% and the change in machinability was evaluated accordingly, and the result is shown in FIG.

In processing containers such as sesame leaves, etc., if the ear generated during the drawing process is large, the loss of material to be cut is large and processing defects due to non-uniformity of residual flanges are likely to occur. Therefore, it is necessary to minimize ear formation. In general, when the value of planar anisotropy is close to 0, ear formation is minimal, and when the value is 0.2 or more, 4 ears are formed at 0 ° and 90 ° elements in the rolling direction, and 4 are formed at 45 ° elements and height when the value is negative. Is also high.

In the present invention, as can be seen in Figure 3, the invention steel (1, 2) was drawn directly (drawing 2.1, cup diameter 50mm Φ) and the rolling reduction rate at which six ears of the cup were examined is shown in the range of 88-92%. The plastic anisotropy, which is the workability evaluation index, did not change much as the rolling reduction rate increased.

In addition, in order to confirm the change in yield strength of the steel according to the temper rolling reduction rate, the heat treatment and other manufacturing conditions for the inventive steels (1, 2) were the same as in the case of FIG. Only the reduction ratio was observed and the change in yield strength was observed. The results are shown in FIG.

As can be seen in Figure 4, in the case of the inventive steel (1,2) yield yield elongation in the annealing plate is less than 2%, showing a much lower yield point elongation than conventional steel. Accordingly, if the temper rolling elongation is 0.4% or more, the yield point elongation can be completely removed, and there is no stretcher strain even after the tin adhesion treatment. According to the solubility formulas of various researchers, the solid solution carbon of the present invention steel (1,2) is Ti carbohydrate, which is partially precipitated and removed. Only the solid solution carbon within 15 ppm exists and is segregated at the grain boundary. There is little characteristic of reproducing yield point elongation following aging and deterioration.

Example 2

The inventive steel (1, 2) and the comparative steel (3-7) having the chemical composition as shown in Table 1 was hot-rolled and cold rolled under the conditions as shown in Table 2 to prepare a stone plate for processing.

The mechanical properties of the prepared raw stone disc thus prepared were measured and the results are shown in Table 2 below.

TABLE 2

CR: cold reduction rate (%)

AT: Continuous Annealing Temperature (℃)

SP: Temper Rolling Elongation (%)

YS: Yield strength (kgf / mm2)

TS: Tensile Strength (kgf / ㎡)

El: Elongation (%)

r: plastic anisotropy

Δr: in-plane anisotropy

Hardness: Crowell Hardness (HR 30%)

AI: Aging Index (kgf / ㎡)

As can be seen in Table 2, the invention steel (1,2) satisfying the steel component system of the present invention is a stone original plate manufactured by satisfying the manufacturing conditions of the present invention 700 ° C It has excellent workability and aging resistance with r value of 1.7 or more, elongation of 38% or more, aging index of 0.8kgf / mm2 or less, and aging index of 1.5kgf / mm2 or less, with excellent strain resistance and hardness of 56-58. The crudeness can stably produce T3.

On the other hand, in Comparative Examples (5, 6) manufactured the invention steel (1, 2) outside the cold rolling reduction range of the present invention, the Δr value becomes 0.4 or more, and there is a problem in that the amount of ear formation during processing increases.

In the case of Comparative Example (7), in which both Ti and Cr contents were not added, the hardness value was 54 level and the lower limit of T3 (54-60), the R value was low as 1.5 level, and the AI was 3 or more. As a result, poor machining and stretcher strain are inevitable.

In addition, in the case of Comparative Example (8-10) in which only Ti is added, workability is sufficiently secured by addition of Ti, and the aging index satisfies the characteristics required by the present invention, but the hardness decreases with increasing Ti content. As a result, quality T3 cannot be secured.

Comparative Example (11) is a steel grade proposed in the existing patent, but it is easy to secure the quality T3, but the r value is very low at 1.1 level, so the machining is extremely poor and the aging index is 4.7. .

As described above, the present invention can produce a processing stone master disc excellent in stretcher strain resistance by appropriately controlling the composition of steel, cold rolling rate, continuous annealing temperature and rolling rate during temper rolling. Stones suitable for thin cans for processing that have excellent workability compared to the stone master disks, and do not have streaking defects due to processing on the side of the can, and the surface is completely recrystallized. A disc can be manufactured. In addition, the present invention can secure the T3 quality by adding Ti and Cr appropriately, while having the same quality as before, the workability has a deep processing characteristic of r value of 1.7 or more, and very small amount of carbon can be segregated at grain boundaries. Because it prevents secondary processing brittleness and hardly deteriorates due to aging, it is suitable for long-term inventory of materials and tin welding after tin plating.

Claims (1)

In the method for producing a stone disc, in weight%, C: 0.007% or less, Mn: 0.05-0.2%, S: 0.015% or less, acid value Al: 0.02-0.05%, N: 0.004%, Ti: 0.015-0.035 %, Cr: 0.02-0.5%, Remainder: Hot rolled aluminum-kilted steel ingots composed of Fe and other unavoidable impurities, wound in a temperature range of 600-700 ° C, cold rolled to a rolling reduction range of 88-92%. And a continuous annealing in the temperature range from the recrystallization temperature to 730 ° C., followed by temper rolling in the 0.4-0.8% elongation range.