JPS59129733A - Production of black plate for hard tinplate having no stretcher strain - Google Patents

Abstract

PURPOSE:To prevent the generation of stretcher strain in a black plate for a hard tin plate in the stage of producing a black plate for a hard tin plate by using an extra-low carbon Al killed steel and combining a continuous annealing treatment and temper rolling. CONSTITUTION:A continuously cast slab of an Al killed steel contg. <0.0030% C, <0.1% Si, <0.5% Mn, 0.010-0.080% Al, <0.0050% N, <0.030% S and <0.030% P, and having >=10 Mn/S or contg. further 1 kind of <0.10% Nb and <0.20% Ti in addition to the above-mentioned compsn. is worked to a plate material by ordinary hot rolling. The plate material is pickled to remove scale and is cold-rolled with a tandem rolling mill. The rolled sheet is subjected to >=10% temper rolling after recrystallization annealing on a continuous annealing furnace, whereby the black plate for a hard tin plate having no stretcher strain is stably produced.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a method for manufacturing a plated base plate for hard tin plate that does not generate stretcher strain.
Here, the plating original plate for hard tinplate includes the case where it is used for so-called tin 7 Lee steel.

According to JIS08308, regarding the heat quality of
Depending on the target Rockwell T hardness (HR80T), T-1 (HR30ff': 49±3) to T-6 (
HR30T: up to 70±8), there are several classifications.
40A NT-60A (HR30T:
61±8 to 70±3), the continuous baking method is prescribed.

This invention relates to the last-mentioned hard haze and tin-free steels of the above category.

(Prior art) Conventional plated base plates for tinplate of T-1 to 'I'-4 grades are C
: Low carbon aluminum killed steel with a weight coefficient of 0.01 to 0.10 C or less, the steel composition is also simply indicated by a coefficient], and also a T-
5. Regarding T-6, low carbon aluminum killed steel aiming at increasing hardness by adding P or N was mainly used.

The relationship between the annealing method applied to these plated original plates and the properties of tinplate is as follows.

Box annealing method: Recrystallization (after heating at 550-700°C, it is slowly cooled to near room temperature over several days, so most of the C in the steel precipitates as carbides. Also, the N in the steel is precipitated during heating. It precipitates as aluminum nitride.

In other words, 0 in steel. Since N does not exist as a solid solution, it is necessary to perform temper rolling and alloying treatment after tinting (23).
Hold at 0-250°C for several seconds. so-called reflow processing)
Even if applied, strain aging does not occur and yield point elongation does not occur 〇 Continuous annealing method: 600-730℃ at lO ~ 30℃/sec
After rapidly heating it and holding it for several tens of seconds to allow recrystallization,
5-b Since most of O and N exist in a solid solution state, 0
Therefore, dislocations are introduced into the steel by temper rolling, and then by the tin alloying treatment after tin tinting, the dislocations are brought into the solid solution state. N precipitates on dislocation lines and causes strain age hardening. Therefore, when this steel plate is processed into cans, etc., it will have streaks due to elongation at the yield point. (Stretcher strain) occurs, which significantly impairs the aesthetic appearance.

That is, conventionally manufactured by continuous furnace annealing method 7: T
In the case of hard tinplates having a quality of -4 to T-elJI, a considerable amount of stretcher strain occurred, causing problems.

By the way, by combining continuous annealing and temper rolling, T-4 to T
As a technique for manufacturing a hard tin plate with a heat treatment level of -6, Japanese Patent Publication No. 1987-11-196-S41S is known.

In the same publication, the material is 0:0.1 '1 piece (
Example 0.04%), si: 0.05% or less, In
: 0.05-0.44, acid soluble 10.01NO, 1
The material is aluminum guild steel containing %, N i O, 002 to 0.011, and the hot rolling finishing temperature is 700 to 900.
"C1 cold rolling reduction rate 75~93mm, surface hardening HR80T
It is disclosed that continuous annealing is carried out to a surface hardness of 43 to '58, followed by wet tempering to a surface hardness of 1.5 to 35, depending on the desired degree of tempering, ranging from 44 to 75.

In this method, the fact that the desired degree of tempering can be achieved by temper rolling can be easily inferred by considering work hardening in temper rolling.

However, this optical disclosure does not mention any measures to prevent stretcher strain that occurs during processing, even if the material properties required for tinplate, such as hardness, can be satisfied. In other words, when continuous annealing is performed using a material with the above components, as mentioned above, a large amount of C remains in the steel in a solid solution state, so strain is introduced in the subsequent temper rolling process, resulting in strain aging. It becomes a situation where it is easy to occur. That is, after applying tinting to a temper-rolled matting original plate, 230 ~
Strain aging occurs due to heating during alloying treatment at 300℃ for a few seconds or chromium plating to dry out tin-free steel, causing significant stretcher strain during processing such as can manufacturing. The disadvantages of this were still unresolved.

(Motivation for the Invention) The inventors developed a method of temper rolling and subsequent rolling. ! +
7) When we investigated a method for manufacturing hard tinplate that does not generate stretcher strain in the t't' plating alloying process, we found that 0:0.0 (extremely low carbon aluminum guild steel of 184 or less) was used as the material. It has been found that the objective of the present invention can be advantageously achieved by combining continuous annealing and temper rolling. S1
0.1% or less, Mn: 0.5% or less, l
: 0.010~o, oao staff, N: 0.005
04T or less, the ratio with the above In i is 10 or more, and o, oao is limited to 4 or less.
Contains P and other unavoidable impurities below oao z, or additionally above 0.101 lJb, 0.20%
If the composition contains at least one type of Ti below μ, rl,
It is particularly advantageous to heat a cold-rolled steel sheet that has been hot-rolled and cold-rolled according to a conventional method, heat it to a temperature higher than the recrystallization temperature by continuous annealing, then cool it, and then perform temper rolling of 10% or more. It has been found that hard tin or tin-free steel with a heat treatment level of T-4 to T-6 can be obtained without the risk of stretcher strain. The behavior of C is important.

As already mentioned, conventionally the C content was o, oi ~ 0
．． As the C content is as high as 10%, a large amount of solid solution C exists in the steel due to rapid cooling during continuous annealing, and this solid solution C is removed by temper rolling and post-plating alloying treatment. Precipitates on lines and causes stretcher strain. Therefore, it is preferable that the amount of O present in solid solution in the side after continuous annealing be as small as possible. The most effective way to reduce the amount of zero in solid solution is to reduce the amount of C contained in the carbon.

Therefore, in order to investigate the relationship between stretcher strain after zero-load plating alloying treatment, vacuum melted steels with different amounts of C were melted in the laboratory and the following basic experiments were conducted.

(Basic experiment) The composition of the material was changed from C to 0.0008% to 0.040%, and the other components were Si, 70.01% to 0.02%,
In: 0.2B:...person, P: 0.01
1NO, 012%, S: 0.007-0.0
Section 09, A/: 0.028 ~ 0.080
%, N: Almost common between 0.001 and 0.0025.

This steel is forged into a 80mm 4 sheet bar, then hot rolled by heating the sheet bar to 1150°C, making a 2.6mm hot rolled steel plate at a finishing temperature of 860''C, and then immediately rolling it to 560°C. The coil was placed in a furnace and slowly cooled for 30 minutes to a coil winding temperature of 560°C.

After the steel plate was acid-dried, it was cold-rolled to a thickness of Q of 32 mm using a small rolling mill, and further recrystallized annealed using a continuous annealing cycle.

In other words, a cold-rolled steel plate is heated at 15℃/
It was rapidly heated to 710℃ in seconds, held at that temperature for 30 seconds, and then rapidly cooled to room temperature at 10℃/second. After that, it was subjected to temper rolling of 12 steps, and then plated and alloyed after plating. In order to reproduce this in a laboratory setting, the sample was kept in an oil bath at 250°C for 8 seconds and then cooled with water.

This sample was processed into a JI No. 85 tensile test piece, a tensile test was conducted, and the hardness of some of the samples was also measured. FIG. 1 shows the effect of zero amount on yield point elongation and hardness in a tensile test.

By the way, the maximum value of elongation at yield point that does not cause stretcher strain during processing is approximately 1.04, so the results shown in Figure 1 are as follows: If a: o,,ooao is 4 or less, the elongation at yield point is 11 or less, which means that acid stress It can be assumed that Letcher strain does not occur. Next, regarding Si + In, S and P, which are the ingredients in the steel of this invention, if large amounts of these elements are added, grain growth during continuous annealing is suppressed and hardness is achieved. oxidation, which not only causes an increase in the rolling load during later temper rolling, but also impairs the corrosion resistance of tinplate, so the less the better.
: 0.1 eg or less, Mn: 0.5 or less, s:
o, oao% or less, P: 0.080% or less.

However, Mn replaces S, which causes embrittlement during hot rolling.
Since it is necessary to fix it as S, Mrv'S > 10
is necessary.

ht is necessary to fix N as aluminum nitride, and must be at least 0.010%. Adding too much will increase costs, so the upper limit is set at 0.080%.
Similar to C, if it exists in a solid solution state after continuous furnace annealing, it will cause stretcher strain during processing into the product, so the smaller the better, but the upper limit should be set to 0.0050'1 to achieve fixation by the above At. I can do it.

In addition to the above, Nb and Ti are each 0
．． 104 or less, solid solution m7) O at 0.201 or less
The role of fixing as NbO and Tie is again the first
In the figure, ☆ and ★ indicate Q in the above experiment, respectively:
When the ratio is 0.0028, Nb = O,,01, and 0
= 0.0 (Ti = 0.028 at 126%) The results were obtained under the same conditions except that the yield point elongation was 0 for all steels, and the stretcher strain This problem does not occur at all, that is, Nb and Ti are equally effective in preventing stretcher strain, which is the purpose of this invention.The upper limit of these contents is determined by taking into consideration the cost increase due to addition.
Nb: 0.10%, Ti: 0.20%. In order to particularly expect the effect of Nb and Ti, Nb: 0.005 忤, Ti: 0.0
It is useful from Section 1.0 The molten steel whose composition has been adjusted as described above is hot-rolled into slabs that have been subjected to blooming and rolling by an agglomeration method, or more preferably to slabs that have been continuously cast. Although rolling and cold rolling are carried out, there is no need to limit the hot rolling conditions and cold rolling conditions to <K, and conventional methods may be followed.

Regarding the continuous furnace annealing conditions after this cold rolling, in order to obtain uniform material properties in the longitudinal and width directions of the strip, especially in the continuous furnace annealing method, which is different from the face annealing method. Although the object of the present invention is met, the conditions for continuous furnace annealing do not need to be particularly limited as long as the annealing temperature is equal to or higher than the recrystallization temperature.

Also, there are no particular limitations on the cooling rate to near room temperature.

On the other hand, temper rolling is the most important constituent factor in determining the hardness of tinplate.This invention uses ultra-low carbon aluminum killed material with a content of less than a:o, ooao% as a material. , after continuous furnace annealing and temper rolling for 10 or more times, through tinting and tinting alloying treatment or corresponding treatment in tin-free steel, where stretcher strain caused by yield point elongation does not occur. This is a new proposal to manufacture hard tinplate or tin-free steam with a tempering degree of T-4 to 1-6, which has specific properties. is extremely low carbon A
! Because it is killed cutting, it is very soft and can be easily reduced by more than 10 degrees in a skin pass rolling mill.◇ That is, the following experiment was conducted to confirm the effect of the rolling reduction rate of this skin pass rolling.

(Confirmation experiment) Materials are O = 0.00184, Si = 0.01%,
Mn = 0.23%, l = 0. ．． 031 Section, N =
0.0 (+28 coefficient, P = 0.011%, S = 0.
Steel containing 007 was produced in the laboratory by vacuum melting, and the steps up to continuous furnace annealing were the same as those described in the basic experiment.

After continuous furnace annealing, the steel plate VC8~501i was subjected to temper rolling, then held in an oil bath for 25o"c for a second, processed into JI No. 85 test pieces, subjected to a tensile test, and yielded. Point elongation and hardness were measured.The results are shown in FIG.

At any temper rolling reduction ratio, the elongation at yield point is less than 0.5, and there is no problem with stretcher strain. In addition, when the temper rolling reduction is less than 10 to 20 degrees, the degree of temper is approximately T-4, and when it is 20 to 8 degrees, the degree of temper is T-5, and further, it is 40 to 50 degrees.
%, it can be seen that each hard tin plate with a T-6 tempering degree can be obtained.

As mentioned above, this invention has an extremely low carbon content of A: o, ooao or lower! The material is kill tone, and this is tM? : Based on the completely new idea of combining temper rolling, we have established an advantageous manufacturing method for hard tin or tin-free steel that does not generate stretcher strain. The mill is not limited to the conventionally commonly used 01 series or two-stand temper rolling mill, but may be any type of rolling mill capable of rolling 10 or more rolls.

(Example) Steel having the components shown in Table 1 was melted in a converter and made into a slab by continuous casting. The slab was finished into a 2.8 fin under the hot rolling conditions shown in Table 1.

After pickling, the material was cold-rolled to a hardness of 0.8 in a Kundem rolling mill and then continuously annealed in a heat cycle shown in FIG. 8 in an 8th continuous annealing furnace. 15.2 with this steel plate VC temper rolling mill
After performing temper rolling of 5.454, No. 25 tin plating was performed on an electroplating line, and then plating alloying treatment was performed.

These steel plates were processed into JI No. 85 test pieces, and the yield point elongation and hardness (HH30T) when a tensile test was conducted are shown in Table 2.
Shown below.

Table 2 The test materials (illustrated) according to the present invention have a yield point elongation of 1 or less, and the temper rolling shown in Table 2 results in T, 4 to 4.
Hardness of T-6 tempering degree can be obtained.

As described above, the present invention makes it possible to obtain hard tinplate or similar products that do not generate stretcher strain caused by the elongation at yield point that occurs during processing of tinplate or similar products. Needless to say, no bending defects occur during processing.

[Brief explanation of the drawing]

Figures 1 and 2 show yield point elongation 6 and hardness H)j
80 T ) is a graph showing the effects of C content, skin pass rolling and rolling reduction ratio, respectively. FIG. 8 shows the heat cycle of the continuous annealing furnace used in the examples. Figure 1 C amount (% series)

Claims (1)

[Claims] 1.0: 0.0080 weight coefficient or less, si
: o, i weight ratio or less, In: 0.5 weight ratio or less, 1: 0.010 to o, oso weight ratio, N: 0
．． 0050 weight or less, and the ratio to the above In ant is 1
0 or more and o, oa. A cold-rolled steel sheet that has undergone hot and cold rolling according to a conventional method is continuously sintered to have a composition containing S, O, O, oao, and other opaque impurities with a vc limit of vc or less and other opaque impurities. A method for producing a rough-grained hard tin plate that does not generate stretcher strain because it is heated to a temperature above the recrystallization temperature by annealing, then cooled, and then subjected to temper rolling at a speed of 10 or more.O a c: o, ooao below the weight ratio, Si
: 0.1 weight or less, Mn: 0.5 weight φ or less, AI: 0.010 to 0.080 heavy weight, N:
Contains less than 0.00 FlO gravity, and further vcO, 10
Contains at least one piece of Nb below 0.20%, and has a ratio of 10 or more to the above Mnit and 0.03011
In addition to the S limited below, the composition contains P below 0.030% by weight and other OT@ impurities.
A cold-rolled steel plate that has undergone hot and cold rolling according to conventional methods is heated to a temperature higher than the recrystallization temperature by continuous annealing, then cooled, and then subjected to temper rolling of 101 or more, so that stretcher strain does not occur. *How to use plated base plate for hard tinplate 0