JP3474647B2 - Manufacturing method of steel sheet for thin containers - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin container steel sheet which exhibits excellent neck workability and flange workability despite having a work structure. 2. Description of the Related Art An original plate for a container is DI (Drawing & Ironing).
It is used for two-piece cans represented by cans, three-piece cans such as welded cans and adhesive cans, and can lids. Recently, with the promotion of weight reduction of cans, thinner original plates have been promoted. However, as in the prior art, if the sheet is cold-rolled and then annealed to make a skin pass of about 1 to 8% to manufacture a container plate, the sheet thickness at the time of annealing becomes too thin. There is a problem that the plate property is poor and the sheet breaks or changes its shape on the way. For this reason, the sheet thickness at the time of annealing is kept relatively large, and rolling of 20% to 50% is performed after annealing.
Japanese Patent Publication No. 1-52451 discloses a method of manufacturing a container plate by the R (Double Reduce) method. [0003] However, this method is based on the premise that annealing is performed, so that a significant cost reduction cannot be achieved in terms of manufacturing cost. Therefore, as a method of manufacturing a more inexpensive original plate for a container, a technique in which annealing after cold rolling is omitted is disclosed in
No. 1244. At that time, the steel plate for containers was relatively thick, and the degree of work in forming the can was low, so the frequency of flange cracking was small. However, with the recent reduction in thickness of steel sheets, when a container is formed using a cold-rolled material, the frequency of occurrence of cracks at the flanged portion and wrinkling at the time of necking has been significantly increased. SUMMARY OF THE INVENTION The present invention relates to a steel sheet which can be used to form wrinkles at the time of necking when a cold-rolled material having low production cost is formed and to minimize the occurrence of cracks at the time of flange processing. The purpose is to provide. [0005] That is, the gist of the present invention is as follows. % By weight, C: 0.042% or more, 0.1% or less, N: 0.01% or less, Al: 0.005% or more, 0.5% or less, the balance being Fe and unavoidable impurities A for steel
Hot rolling is performed at the r ₃ transformation point or more, and the sheet thickness is 1.4 mm or less.
0.6 mm or more, and after normal pickling, 6
Cold rolling of 0% or more and 85% or less, with a sheet thickness of 0.22
A method for producing a steel sheet for a thin container, wherein the sheet thickness is not more than 0.1 mm and not more than 0.1 mm, and is not subjected to annealing thereafter. The present inventors cold rolled various hot rolled steel sheets by 50% or more, manufactured containers using the cold rolled material, and examined the occurrence of wrinkles during neck processing, flange workability, and the like. As a result, wrinkles occur during neck processing in the range of thin plate thickness,
It was found that the flange workability greatly depends on the cold rolling rate. The present invention is based on these findings, and the reasons for limiting the present invention will be described below. The reason why the upper limit of the C content is set to 0.1% is that if the C content is further increased, the work hardening during cold rolling increases, and it becomes difficult to suppress neck wrinkling during can making. To achieve the object of the present invention
The C content is preferably set to 0.042% or more. 0.0% of N
The reason for setting the content to 1% or less is that if the content is more than this, work hardening during cold rolling increases, and it becomes difficult to suppress neck wrinkles during can making. The lower limit of the amount of N added is not necessarily limited. The limitation on the amount of Al is that if the other deoxidizing element is not added at 0.005% or less, deoxidation becomes insufficient. If the deoxidizing element such as Ti is added, these expensive elements are used. This is because the element is used for deoxidation.
On the other hand, the upper limit is set to 0.5% because the addition of more than that is not preferable for workability and weldability. Next, the reasons for limiting the manufacturing process will be described. The most important limiting condition of the present invention is the cold rolling rate, under the precondition that the original sheet used for can forming is a cold-rolled material and its sheet thickness is extremely thin, a certain cold rolling rate or less. This is based on the fact that the generation of cracks and the generation of wrinkles during neck processing are significantly reduced in the flange processed part. Specifically, when the final rolling thickness of the steel sheet having a final thickness of 0.22 mm or less and 0.1 mm or more is 85% or less, both neck wrinkle resistance and flange workability are significantly improved. The lower limit of the cold rolling rate is 60%.
Because the final thickness is fixed, if the cold rolling reduction is low, it is necessary to reduce the thickness of the hot-rolled sheet, and excessive thinning of the hot-rolled sheet only causes a significant increase in production cost Not only that, there is also a problem with the passability. Therefore,
The lower limit of the thickness of the hot rolled sheet was 0.6 mm. The upper limit of the thickness of the hot-rolled sheet was set at 1.4 mm from the cold-rolling ratio and the final sheet thickness.
The reason why the final plate thickness is limited to 0.22 mm or less and 0.1 mm or more is that if the thickness is 0.22 mm or more, the contribution to weight reduction of the container is small. This is because the possibility of causing deterioration increases. EXAMPLES Table 1 shows the chemical composition of the steel of the present invention and the comparative steel.
These steels are continuous cast materials subjected to converter refining. Table 2 shows the manufacturing conditions when a container plate was manufactured using these steel types and the workability when cans were manufactured using the same. Hot rolling is performed by heating a 250 mm thick slab between 1100 ° C and 1250 ° C. The evaluation of workability in container manufacturing was organized based on neck workability of DI (Drawing & Ironing) cans and welded cans and subsequent flange workability. As a quantitative evaluation, 100 cans were manufactured using a laboratory canning machine, and the defective can occurrence rate at that time was indicated by%. The tin plating amount is 2.8 g per square meter for DI cans and 1 g per square meter for welded cans. The neck processing was performed using a spin necker. A spin flanger was used for the flange processing. [Table 1] [Table 2] Experiment Nos. 1, 2 and 2 within the scope of the present invention
5 , 8 , and 11 are good in both neck workability and flange workability. Here, the defective can rate of Experiment No. 11 is high, but this is because the plate thickness is thin. Compared with Experiment No. 12 which is a comparative example of the same plate thickness, the steel of the present invention has an excellent can It can be seen that it has moldability. On the other hand, in Experiment No. 3 in which the cold rolling ratio was 90%, which is out of the range of the present invention, the frequency of neck wrinkling and flange cracking was high probably because of the high workability. Finishing temperature was high occurrence frequency of a defect in Test No. 4 became less Ar ₃ transformation point. Experiment Nos. 9 and 1 using steels in which the amount of C added was greater than the range of the present invention.
Even at 0 and 12, defects occurred during can making. According to the present invention, the annealing step can be omitted in the production of the original plate for the container, and the can material can be made thinner, which leads to energy saving and resource saving, and has great industrial significance.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C21D 8/02-8/04 C21D 9/46-9/48

Claims (1)

(57) [Claims 1 In mass%, C: 0.042% or more, 0.1% or less, N: 0.01% or less, Al: 0.005% or more, 0 0.5% or less, with the balance being Fe and inevitable impurities
Hot rolling is performed at the r ₃ transformation point or more, and the sheet thickness is 1.4 mm or less.
0.6 mm or more, and after normal pickling, 6
Cold rolling of 0% or more and 85% or less, with a sheet thickness of 0.22
A method for producing a steel sheet for a thin container, wherein the sheet thickness is not more than 0.1 mm and not more than 0.1 mm, and is not subjected to annealing thereafter.