JPS6043431A - Manufacture of soft steel sheet for surface treatment with superior fluting resistance by continuous annealing - Google Patents

Abstract

PURPOSE:To improve the fluting resistance by heat treating and rolling a steel billet contg. prescribed percentages of C, Mn, N and Al under prescribed conditions. CONSTITUTION:A steel billet consisting of, by weight, 0.04-0.1% C, 0.05-0.6% Mn, >=0.03% acid-sol. Al, <=0.01% N and the balance Fe is continuously cast or cogged. The cast or cogged steel billet is cooled to the Ar1 transformation point or below, heated to <=1,150 deg.C, hot rolled, and coiled at 620-700 deg.C. It is descaled, cold rolled, and continuously annealed by heating to the Ac1 transformation point or above. The resulting steel sheet is rapidly cooled to a temp. in the overaging temp. range, and it is overaged at 300-500 deg.C for >=10sec and subjected to temper rolling.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is applicable to a method for producing soft surface treated copper plates with a surface treatment such as tin plating or chromic acid treatment, such as soft tinplate plates, which have a tensile strength of 3 or less. The present invention relates to a method of manufacturing a copper plate for soft surface treatment with excellent fluting resistance by continuous annealing.

(Prior art) As a guideline for selecting a tin plate decorated with a young Japanese pine tree depending on the quality of the material required for various uses, tJ'A is used as a guideline.
The quality (denno nichiichi) is specified. In other words, Denba is Rockwell surface hardness (HIL30T or Q and Ll)
几151'), from soft to hard
T-146-52 T-250-56 T-354-60 T-458-64 'f'-562-68 T-6, 67-73.

These tinplates are generally manufactured by hot-rolling a hot-rolled coil made from a low-carbon steel billet to a predetermined thickness, annealing it, and applying tin plating to a temper-rolled tin plate. ing. Among these manufacturing processes, two are used: patch annealing method and continuous annealing method, but T-
1 to T-3 tin plates are conventionally annealed by the patch annealing method, and are also classified by T5-JIS.

Continuous annealing is an annealing cycle consisting of rapid heating, short-time soaking, and rapid cooling, so it has conventionally been applied to the production of hard tinplates of T-4 or higher. However, continuous annealing can efficiently produce VC copper plates.1 Also, the steel plates manufactured have a long I9i with small material variations, so continuous annealing has recently been applied to produce soft VC copper plates of 1"-3 or less. Various tests have been conducted regarding the manufacture of tin plate blanks.

By the way, in order to manufacture a soft tin plate blank by continuous annealing, it is necessary to prevent grain refinement, reduce supersaturated solid solution C, solid solution N, and reduce aging properties. . First, in order to prevent the crystal grains from becoming finer,
In hot rolling, low-temperature finishing is performed at a finishing temperature near or below the kAr3 point, and a method in which the positioning temperature is set at a high temperature or adjustment of the copper component is carried out. In order to reduce the supersaturated solid solution C1 in (2), an overaging treatment is performed in the cooling process following short-time soaking during continuous annealing.

In addition, in order to reduce supersaturated solid solution N, methods such as adding K to υ18°Nb are known (4).As a result, continuous annealing has recently been applied to produce soft tinplates of T-3 or less. is being manufactured in some parts.

However, in recent years, the required standards for the cup quality of soft tinplate have become increasingly strict, and in addition to guaranteeing stable tempering once, customers are also required to ensure that paint baking does not cause processing defects such as buckling during post-treatment processing. There is a growing tendency to demand that

Waist bending is a phenomenon in which tinplate is bent into a broken line during bending, and is called fluting. Up until now, fluting has been closely related to aging properties, and it is sufficient to keep the elongation at yield point to about 4% or less. It is said that.

However, since the tinplate is heated to about 210 DEG C. during the paint baking process, an unpleasant aging phenomenon occurs and yield point elongation is unavoidable, for example, yield point elongation of 6 to 12%. For these reasons, the problem of fluting has not yet been solved satisfactorily.

(Objective of the Invention) An object of the present invention is to provide a method for manufacturing a soft surface-treated steel sheet that performs continuous annealing and has excellent flute properties.

(Counts and effects of the invention) The inventors of the present application have developed a method for manufacturing steel sheets including copper components in order to manufacture them by applying continuous annealing of a steel sheet for searing treatment that is soft below T-3 and has no flutes. The entire process was thoroughly considered. As a result, H-killed steel was used as a total material, and the heat temperature of the cutting edge before hot rolling of sumpu, which had been cooled to below the Arl transformation point, was heated at a low temperature of 1150°C or less, and the winding temperature during hot rolling was 620 to 700°C. 1 as °C. To promote the precipitation of l'JN and C, and in continuous annealing after cold rolling, soaking is performed at a temperature range of 7CA-cl transformation point or higher, which has been generally avoided, and then heated to the overaging treatment temperature, e.g. 30°C. /second or more, preferably 100℃/second or more, and overaging treatment at a temperature of 300 to 500℃ to reduce the solid solution to 0, solid f8N overall width, and the carbide precipitation density in the grains. increases and acts as a dislocation source,
For example, as shown in Figure 1, copper plates manufactured by the M-adic method, which includes these steps, will suffer from paint burning due to the aging phenomenon during processing [, t = even if the bending point elongation occurs by several percent or more. We found that no routing occurs.

In addition, the test material e in FIG. 1, O: 0.045 to 0,
070%, fun: 0.20-0.30%, acid soluble H: 0, 040-0.060%, N: 0.00 a
o~0. ．． 0060%, and the six conditions such as hot rolling, continuous annealing, and paint baking treatment are as shown in Table 1.O is a 'fc coated steel plate manufactured by the method of the present invention, is a surface-treated steel manufactured according to a comparative example (slab heating temperature and continuous annealing temperature are outside the range of the method of the present invention).

The present invention has been made based on the above findings, and
The gist of the present invention is heavy liquid %, c: o, 04~0.10%, Mn: 0.05~
0.6 ON, acid soluble AA: 0.03'X or more, N
: 0.010 Y;
The material is heated to the following temperature, hot rolled and rolled at a temperature of 620 to 700℃, then de-schooled, cold rolled, then continuously annealed to a temperature above the ACl transformation point, and overaged. Rapid cooling to a temperature range of 300-500 °C for 10 minutes.

This is a method for manufacturing a steel sheet for soft surface treatment with excellent fluting resistance by continuous annealing, which is characterized by performing an over-aging treatment for more than a second, followed by temper rolling.

The present invention will be explained in detail below.

The present invention is made of killed copper, and the copper component will be described first.

The lower limit of C is set at 0.0491, since solid solution C tends to remain in continuous dulling when the amount of C contained is small.

- If the amount of blade metal is too large, it will become hard, so it should be 0.10X or less.

Mn completely prevents hot brittleness and allows smooth hot rolling.
．． Contain 05cX or more. If its content increases, it becomes hard, so the content should be 0.60% or less.

M is N as acid-soluble M (hereinafter referred to as SoA An)
In order to fix the u, o a 9(,) or more.

Although it is not necessary to specify the upper limit, 0.15X is the upper limit from the viewpoint of cost reduction.

N makes steel hard and also contributes to aging properties, so o,
0.010% or less.

The basic ingredients are as above, but if necessary, if deoxidized with Si before application, the content may be 0.1 to 0.2%. In addition, one or more of the following elements (B, Ti, Nb, Zr, V) for promotion of grain growth and reduction of solid solution N (IB, Ti, Nb, Zr, V) is added in a total of 0.000%.
You may add 3-0.02N.

Steel made of the above-mentioned components is made into a bath in a converter, electric furnace, etc., and then made into a slab by continuous casting or ingot-forming and blooming. The slab is once cooled below the ArI transformation point in order to completely precipitate AAN.

The slab is heated prior to hot rolling to a temperature of Ic1150° C. or lower to prevent AAH from redissolving.

In hot rolling, finish rolling is carried out at a normal finishing temperature,
It is rolled up in a temperature range of 620-700°C.

The reason why the lower limit is set to 620°C is to promote the precipitation of slag. On the other hand, if the ground failure temperature becomes high, the pickling properties deteriorate, so the upper limit is set at 700°C.

Next, it is descaled and cold rolled, and the rolling reduction rate is arbitrary so as to obtain a predetermined product thickness.

After cold rolling, continuous annealing is performed, and the soaking temperature is set to be equal to or higher than the ACl transformation point. Until now, the soaking temperature fi in general tin plate annealing was about 630 to 700°C, which was below the ACl transformation point, but in the present invention, the solid solution C was increased by combining with the subsequent rapid cooling and overaging treatment. In order to significantly reduce the amount of A, c (the temperature is set to be above the transformation point. At the conventional soaking temperature, on the contrary, li!) molten C increases.

The soaking time t in the IC$-method of the present invention does not need to be particularly specified, but is approximately 10 seconds to 5 minutes.

Then, it is rapidly cooled to an overaging treatment temperature range at a cooling rate of, for example, 30° C./second or more, preferably 100° C./second or more, and 3
Overaging treatment is performed in a temperature range of 00 to 500°C. Rapidly cooling V not only reduces solid solution O2 through the subsequent overaging treatment VC, but also increases the precipitation of carbides within the grains.
This is to prevent fluting from occurring due to dislocation sources.

The lower limit of the overaging treatment temperature is set at 300° C., since at low temperatures, solid solution O continues to precipitate for a long time. On the other hand, when the temperature is high @V, it is solid I! ! ! Since there is a large amount of carbon used, the upper limit is set at 500°C. The time required for overaging treatment is 10 seconds or more. SotL i, J: This is because at the above-mentioned overaging temperature of 300 to 500°C, the solid solution C is reduced in 10 seconds or more.

After this continuous annealing, temper rolling is performed to adjust the tensile strength.

Next, examples will be shown.

Examples 1 to 8 of the present invention and comparative examples 9 to 1 shown in Table 2
Each of the sample steels of No. 3 was subjected to 61 hot rollings and continuous knot β-ton conditions shown in the same table.

Then, the hardness t (B30T) after temper rolling and the fluting after paint baking treatment were measured. Comparison of Table 2 In the example, sample number 9 has a continuous annealing temperature outside the range of the method of the present invention, sample number 10 has a C amount, sulfur heating temperature, winding temperature, and continuous annealing temperature, and sample number 11 has an acid temperature. Bath A7 [71, continuous annealing temperature is sample number 12, bath ηf1 thermal temperature, winding continuous annealing temperature is sample number 13
The slab-7trl heating temperature, winding temperature, and overaging treatment temperature are outside the range of the method of the present invention. As is clear from the Fruity Ig values in this field, the copper plate produced by the method of the present invention has superior Fruity Ig resistance compared to the comparative example copper plate.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between yield point elongation and fruching property after paint baking treatment. (・11 people Patent attorney Masaaki Akizawa 2 people 4 parties H mouth

Claims (1)

[Claims] (1) Weighted % (j: 0.04-0.10%, Mn: o, o5
~0.60%, acid soluble A, #: 0.03% or more, N: 0.010% or less, after continuous casting or blooming rolling of a copper piece with the balance consisting of iron and impure impurities After cooling to below the hrl transformation point, N
Heating to 1150℃ or less and hot rolling to 620~70℃
It is rolled up at 0°C, then descaled, cold rolled, and then continuously annealed to the Ac1 transformation point or higher.
A method for producing a copper plate for soft surface treatment with excellent fluting resistance by continuous annealing, which is characterized by performing continuous annealing, followed by temper rolling.