JPH06248338A - Production of starting sheet for vessel - Google Patents

Abstract

PURPOSE:To separately produce starting sheets for vessel of a wide range of grades by the use of a single steel while obviating the necessity of additional stages such as 2CR by subjecting a highly purified ultralow C steel of specific composition to cold rolling and then to annealing at specific temp. CONSTITUTION:A steel having a composition containing, by weight, <=0.003% C, <=0.1% Si, <=0.4% Mn, <=0.015% S, <=0.02% P, 0.01-0.1% Al, and <=0.005% N is hot-rolled, pickled, cold-rolled, and annealed at a temp. between 400 deg.C and the recrystallization temp. By this method, workability necessary for can forming can be secured even if perfect recrystallization is not performed at the time of annealing, and, by changing annealing conditions, sheets of a wide range of grades can stably be produced. Accordingly, the plating starting sheets for vessel, free from stretcher strain, can be economically obtained. Moreover, one or more kinds among <=0.05% each of Ti, Nb, and Zr and <=0.005% B can be further incorporated into the above steel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an economical method for producing a plating base plate for a container in which stretcher strain does not occur.

[0002]

2. Description of the Related Art Container original plates are graded according to hardness, and as a technique for making them roughly, a method of adding an alloy and a method of utilizing 2CR are known.
Regarding the former, there is a problem in production efficiency because it is necessary to melt steel with different components for each grade. In order to avoid this drawback, it is disclosed as a technology for consolidating steel types and making them differently in cold rolling / annealing process.
% Or less steel with a reduction rate of 2CR, which is disclosed in Japanese Patent Publication No. 56-3413, and C: 0.0030%.
There is Japanese Patent Publication No. 01-52451 which discloses a technique for making the following steels with a reduction rate of 2CR. However,
These methods require cold rolling twice, and are not efficient.

[0003]

The present invention is an uneconomical grade-specific steel grade composition or an additional process, 2CR.
It is an object of the present invention to provide a manufacturing method in which a predetermined grade is separately produced by omitting.

[0004]

The gist of the present invention is as follows. That is, the weight ratio of C: 0.
003% or less, Si: 0.1% or less, Mn:
0.4% or less, S: 0.015% or less,
P: 0.02% or less, Al: 0.005%
~ 0.1%, N: 0.005% or less, depending on the case,
Furthermore, Ti: 0.05% or less, Nb: 0.0
5% or less, Zr: 0.05% or less, B:
Steel containing at least one of 0.005% or less, the balance of which is Fe and unavoidable impurities, is hot-rolled, pickled and cold-rolled, and then annealed at 400 ° C or more and at a recrystallization temperature or less to prepare. It is a method for manufacturing a steel sheet for containers, which is characterized in that different grades of quality are produced.

The present invention will be described in detail below. As a result of repeated studies on the influence of components and manufacturing conditions on the workability of the material for containers, the present inventor has found that high-purification of steel does not necessarily require complete recrystallization during annealing after steel sheet cold rolling. It was clarified that the workability required for the above can be secured.
It was also found that the grades can be made differently and stably by changing the annealing conditions by limiting the component system to a high purity region and setting the annealing temperature to a temperature range of 400 ° C. or more below the recrystallization temperature region. In the present invention, the temperature at which the recrystallization rate is 10% is the recrystallization temperature.

Next, the limiting conditions of the present invention will be described in consideration of the above findings. First, the limiting conditions of the components will be described. C
The amount is set to 0.003% or less because stretcher strain occurs when C is added more than this.
If N remains in the steel in the form of a solid solution, it will cause stretcher strain to occur, so normally it is in the form of precipitates such as AlN and TiN, but if the amount of precipitates increases, the workability deteriorates. , N were limited to 0.005% or less. The amount of Al is necessary to fix N as aluminum nitride, and is required to be at least 0.01%. However, when other nitride forming elements such as Ti, Nb, Zr, and B are added, it is necessary to add 0.005% or more in view of sufficiently performing Al deoxidation. Further, addition of a large amount not only increases the cost but also deteriorates workability, so the upper limit of the addition amount is 0.1%.

The amounts of Si, Mn, S and P added are Si: 0.
1% or less, Mn: 0.4% or less, S: 0.015% or less, and P: 0.02% or less are limited, and if these alloys are further added, they will not only be a factor that impairs corrosion resistance. This is because softening due to annealing, which will be described later, becomes small, and stable material production over a wide range cannot be performed. In particular, reducing C, S, and N causes remarkable softening due to recovery during annealing. Therefore, C <0.002%, S <0.01%, N
<0.002% is preferable. In addition, Ti, Nb, Zr,
The addition of B improves the workability by forming carbonitrides and eliminating the solid solutions C and N. However, addition of a large amount not only increases the cost, but conversely deteriorates the workability. The upper limit of the addition amount is Ti: 0.05% or less, Nb: 0.05
% Or less, Zr: 0.05% or less, and B: 0.005% or less.

Next, the limitation of manufacturing conditions will be described. Regarding the hot rolling conditions, the heating temperature, finishing temperature, winding temperature, etc. were changed in a wide range to manufacture the hot rolled sheet, but the effect on grade production is not remarkable, and there is no particular need to limit it. The cold rolling conditions such as the cold rolling ratio do not have a large effect under normal conditions, and thus do not need to be particularly limited. On the contrary, the annealing condition is the most important process constituent factor in the present invention. Here, the lower limit of the annealing temperature is set to 400 ° C. because the softening does not proceed sufficiently at the annealing temperature lower than this and grades cannot be made separately. On the other hand, the reason why the upper limit is set to the recrystallization temperature is that recrystallization can achieve remarkable softening, but in the region immediately above the recrystallization temperature, a partially non-uniform recrystallization structure occurs, which causes problems in molding. . When the recrystallization rate is substantially 10% or less, the poor molding due to the inhomogeneity of the structure does not become apparent. In this temperature range, as shown in FIG. 1, the hardness greatly changes with respect to the annealing temperature, so that it is possible to separately prepare the temper grade. Here, the annealing method is not particularly limited and may be continuous annealing or box annealing.

As described above, the basic constitution of the present invention clarifies the component system which can secure the workability necessary for can forming even in the non-recrystallized structure and can increase the softening degree by the recovery during annealing, and recrystallize the composition. It is based on an unprecedented idea of making different materials for non-aged steel sheets by adjusting the annealing temperature below the temperature.

[0010]

EXAMPLES Table 1 shows the chemical composition of the steel of the present invention and the comparative steel.
Fig. 1 shows that a hot-rolled sheet of steel type A is cold-rolled by 88% to have a sheet thickness of 0.24 mm at about 10 ° C / sec. The following shows the relationship between the hardness and the annealing temperature, and the recrystallization rate and the annealing temperature of a material that has been heated at 1, various annealing temperatures, air-cooled, and then subjected to 1% skin pass rolling. As shown in this figure, the hardness change remarkably occurs at a temperature of 400 ° C. or higher. From the structure observation, the recrystallization temperature in this experiment was about 630 ° C. As described above, in the steel of the present invention, grades of T4 to T6 can be produced separately in the annealing temperature range of 400 ° C. or lower under the recrystallization temperature.

Table 2 shows the results of examining whether or not the stretcher strain was generated and whether or not the workability was good, using the materials of Table 1. There is a method to judge the occurrence of stretcher strain by observation, but since it is easy to be subjectivity, a tensile test is performed after aging treatment at 250 ° C for 3 seconds.
The yield point elongation was measured. Generally, it is considered that the stretcher strain is not generated when the yield point elongation is 0.3% or less. In addition, the workability was evaluated by the elongation (herein referred to as local elongation) measured with a R-shaped test piece having a gauge length of 6 mm, and if the value was 10% or less, it was normally used for can forming during flanging. The frequency of cracking increases. The test piece was obtained by cold rolling a 2 mm thick hot-rolled sheet.
24 mm and then about 10 ° C./sec. Heated at 450
After being kept at 60 ° C. for 60 seconds, air-cooled, 1% skin pass rolled, and then aged at 250 ° C. for 3 seconds. In addition, the results of the samples in which the 1-part annealing temperature is changed are also shown. As shown in this table, it is understood that the steel of the present invention has no stretcher strain and has excellent workability.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

INDUSTRIAL APPLICABILITY As described above, the present invention not only makes it possible to separately produce a wide range of grades of container original plates with a single steel type, but also has a low annealing temperature and an additional addition like the 2CR method. Since no additional steps are required, it has great industrial significance as an economical new method for producing a container original plate.

[Brief description of drawings]

FIG. 1 shows an example of the relationship between hardness and annealing temperature and recrystallization rate and annealing temperature of the steel of the present invention.

Claims (2)

[Claims] 1. A weight ratio of C: 0.003% or less, Si: 0.1% or less, Mn: 0.4% or less, S: 0.015% or less, P: 0.02% or less, Al: Steel containing 0.01% to 0.1% and N: 0.005% or less, the balance of which is Fe and unavoidable impurities is hot-rolled, pickled and cold-rolled, and then recrystallized at 400 ° C. or higher. A method for producing a steel sheet for containers, which comprises annealing at a temperature or lower to separately prepare a refining grade. 2. By weight ratio, C: 0.003% or less, Si: 0.1% or less, Mn: 0.4% or less, S: 0.015% or less, P: 0.02% or less, Al: 0.005% to 0.1%, N: 0.005% or less, and Ti: 0.05% or less, Nb: 0.05% or less, Zr: 0.05% or less, B: 0. Steel containing at least one of 005% or less and the balance being Fe and unavoidable impurities is hot-rolled, pickled and cold-rolled, and then annealed at a temperature of 400 ° C. or higher and a recrystallization temperature or lower to obtain a tempered grade. A method for manufacturing a steel plate for a container, characterized in that