RU2382111C2 - Soft black sheet iron with hardness hr 30t, which is 51±3, for blanching and method for its manufacturing - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: there is molten steel, containing following components, wt %: carbon ≤ 0.005, manganese 0.20 - 0.30, aluminium 0.03 - 0.06, silicon ≤ 0.03, titanium 0.038 - 0.06, phosphorus ≤ 0.012, sulphur ≤ 0.015, nitrogen ≤ 0.003, oxygen ≤ 0.004, iron and unavoidable admixtures are the rest and it is implemented its pouring at yield temperature 1190 - 1250°C with receiving of slab. It is implemented hot rolling of slab into strip at final rolling temperature 880-920°C. It is unwinded strip into reel at temperature 560 - 620°C. It is implemented etching, cold rolling with reduction ratio at a level 82 - 92%, continuous annealing at temperature 730 - 760°C during 25-50 seconds and training with lengthening of strip for 1.2 - 2.2%.

EFFECT: there is provided required hardness of sheet iron.

10 cl, 9 tbl, 6 ex

Description

FIELD OF THE INVENTION

The present invention relates to soft tinplate for tinning and a method for its manufacture, in particular, it relates to soft tinplate for tinning having a hardness of HR30T (Super Rockwell hardness, measured using a diamond table), component 51 ± 3, and the method its manufacture. This soft tinplate for tinning is obtained by continuous annealing using titanium-containing steel free from interstitial atoms (IF-steel), which is mainly used in the manufacture of a bucket of flower baskets with expanding diameter, a can lid with complex deformation and cans produced by stamping deformation .

State of the art

The technology for producing soft black tin for tinning is known and is being improved. With the expansion of the use of soft black sheet for tinning, two main developing products are soft black sheet, which has good formability, and thin hard black sheet.

In accordance with Japanese industry standard JIS G 3303, Table 1 shows the HR30T hardness range of tin-plated steel sheets for various tempering classes, with tempering classes T-1 to T-3 designed for soft black tin for tinning, while grades from T-4 to T-6 are designed for solid gestures.

Table 1 Hardness range of different tinplate classes the class hardness range HR30T T-1 46 ~ 52 T-2 50 ~ 56 T-2.5 52 ~ 58 T-3 54 ~ 60 T-4 58 ~ 64 T-5 62 ~ 68 T-6 67 ~ 73

Currently, mild tinned steel sheet is produced mainly in two ways: using low-carbon aluminum-deoxidized steel or using IF-steel, including Nb. JP 8073943, issued to Japan Steel Pipe Co., Ltd on March 19, 1996, uses mild aluminum carbonized steel to prepare soft black sheet for tinning. The method according to the aforementioned patent not only requires re-heating for aging after rapid cooling, but also the resulting product has an obvious aging property, relatively high hardness and poor subsequent processability. Under conditions of deep stamping, large expanding diameter, large deformation, such as significant bending, defects such as cracking, slip line, cross hatching, curvature, and edging on the surface will easily appear. In addition, mild aluminum-mild steel is not suitable for the preparation of very soft tinplate for tinning.

With the development of IF-steel production technology, due to its inherent properties of good formability and aging resistance, tinned IF-steel products have demonstrated high competitiveness in the market. JP-719192 (of Japan Steel Pipe Co. Ltd), published on August 1, 1995, discloses soft black tin for tinning and a method for preparing it using IF steel comprising Nb. Mentioned soft black tin for tinning has the following composition:

C≤0.004%, Mn≤0.6%, A1: 0.03-0.10%, N≤0.004%, Nb: 0.021-0.050, and the ratio of the number of atoms Nb and C is more than 10. This patent uses a niobium-containing IF is steel and contains a special requirement for the content of Nb. Since niobium-containing IF steel is very sensitive to processing parameters, especially to hot rolling parameters, the product properties are not stable and not uniform. In addition, its recrystallization temperature is high, so it is required that its heating temperature during annealing is also high. The production of this product requires a greater number of transitional turns of the roll and a longer duration of the transition process. In particular, inside the continuous annealing furnace, curvature and even breakage of the strip easily occurs. As a result, the continuous strip discharge performance is poor. In addition, due to the large consumption of thermal energy and the high price of niobium as an alloying element, production costs are relatively higher. In addition, niobium-containing IF steel has poor ductility. Although its anisotropy is small, its general mechanical properties are worse than that of titanium-containing IF steel. Finally, during production and melting, Nb exhibits little radioactivity, so there is a debate as to whether or not tinned tin, including Nb, is harmful to the human body, mainly used in the food industry.

Moreover, the aforementioned patent discloses that the coiling of a hot-rolled strip is carried out at 600-800 ° C. This temperature of winding the strip into a roll, especially its upper limit (800 ° C), is too high for practical implementation. The temperature range of the strip winding declared in this patent is obviously unreasonable, because when the winding is performed at a temperature of about 800 ° C, the steel sheet is substantially oxidized. This not only affects the etching rate in subsequent operations, but also affects the surface quality of the final product. In addition, the aforementioned patent discloses that annealing is performed at a temperature of 670-800 ° C. However, since niobium-containing IF steel is used in the said patent for the production of soft black tin for tinning, while annealing is carried out at a temperature of about 670 ° C within the range of the heating temperature during annealing described in the said patent (for example, 670-740 ° C), it is difficult for steel sheet to achieve recrystallization at the usual speed of the production line. That is, it is impossible to produce an acceptable soft black sheet for tinning. Thus, the annealing heating temperature range claimed in the aforementioned patent is obviously unreasonable.

In addition, in recent years there has been a great demand for soft tinplate for tinning, which has a hardness of HR30T of 51 ± 3 and a thickness of 0.17 mm - 0.55 mm. Since the required thickness varies within the aforementioned wide range, it is very difficult to maintain the hardness of all these gestures within the range of 51 ± 3. For this reason, the present invention provides a method for manufacturing soft tinplate for tinning, which can stably maintain the hardness of an HR30T product within a range of 51 ± 3. Since the mentioned hardness is between the hardness of the T-1CA and T-2CA classes, it is called the T-1,5CA class.

Disclosure of invention

The objective of the present invention is to provide a method for producing soft black tin for tinning, carried out by continuous annealing using titanium-containing IF-steel. For the aforementioned purpose, the present invention provides soft black tinplate for tinning, which has a hardness of HR30T of 51 ± 3. Mentioned soft black tin for tinning has the following chemical composition,% by weight:

C ≤0.005%,

Mn: 0.20-0.30%,

Al: 0.030-0.060%,

Si ≤0.03%,

Ti: 0.03-0.06%,

P ≤ 0.012%,

S ≤0.015%,

N ≤0.003%,

About ≤0.004%,

the rest is iron and some inevitable impurity elements.

In order to ensure that the hardness of HR30T soft black sheet of the present invention falls within the range of 51 ± 3 (hereinafter referred to as T-1,5CA), two types of raw steel with different components are used in the preparation of products with different thicknesses. To prepare the product from thin soft black tinplate for tinning (with a thickness of less than or equal to 0.25 mm), raw steel contains the following components:

C≤0.002%,

Mn: 0.20-0.30%,

P≤0.012%,

S≤0.015%,

Al: 0.030-0.060%,

N≤0.003%,

Si≤0.03%,

Ti: 0.03-0.045%,

O≤0.004%,

To prepare the product from thick soft black tinplate for tinning (with a thickness of more than 0.25 mm), raw steel contains the following components:

C: 0.002-0.005%,

Mn: 0.20-0.30%,

P≤0.012%,

S≤0.015%,

Al: 0.030-0.060%,

N≤0.003%,

Si≤0.03%,

Ti: 0.04-0.06%,

O≤0.004%.

The functions and descriptions of the main elements of the present invention are given below.

Content C≤0.005%

C is one of the reinforcing elements. In order to stably maintain the hardness of HR30T at a level lower than 54 and provide an acceptable property of the product, the content of the present invention should be less than or equal to 0.005%. If the C content exceeds 0.005%, in order to provide resistance to aging of soft black sheet for tinning, a larger amount of Ti should be added. As a result, production costs increase. At the same time, the hardness of the product also increases, and the formability decreases. In this regard, it is difficult to prepare soft black sheet of class T-1,5CA for tinning. In addition, products with different thicknesses experience different effects on the base of the probe when testing the HR30T hardness. Thus, the thin product will experience a stronger effect of the base of the measuring tip, and the result obtained during the test is slightly higher. In this regard, for a product with a thickness of ≤0.25 mm, the content of C is maintained to be less than or equal to 0.002%, whereas for a product with a thickness of more than 0.25 mm, the content of C is maintained to be 0.002- 0.005%. Therefore, the actual hardness of the product is adjusted based on the C content, taking into account the compensation of the influence of the base of the measuring tip so as to achieve a stable maintenance of the hardness of the final product within 51 ± 3.

Mn Content: 0.20-0.30%

Mn is the main solid-soluble reinforcing element in the present invention and has a stronger effect on the mechanical property of the final product. The higher its content, the higher the hardness of the product. Accordingly, in the present invention, the Mn content is maintained so as to be lower than 0.30%. If the content of the Mn element exceeds 0.30%, then production costs will increase, and the hardness of the product will also increase, easily exceeding the upper hardness limit of class T-1.5CA. On the other hand, if the Mn content is less than 0.20%, then the hardness of the product will easily drop below the lower hardness limit of class T-1.5CA. Accordingly, in the present invention, the Mn content is maintained at 0.20-0.30%.

Ti content: 0.03-0.06%

Ti is a carbide forming element mainly used to bind free C in steel to form TiC, and Ti can significantly increase the aging resistance of soft black sheet, especially its stampability. In addition, Ti also to a certain extent performs the function of dispersion hardening, thereby leading to an increase in the strength and hardness of the material. The price of Ti, however, is high (even though it is much lower than that of Nb). Increasing Ti will result in higher costs. For this reason, its content should be strictly controlled. In the present invention, the Ti content is maintained at a level lower than 0.06%. But when its content is too low, it is impossible to bind all solid soluble atoms, such as C in steel. For this reason, the Ti content should be higher than 0.03%. In addition, the specific amount of Ti used can be adjusted based on the C content of the steel. In the case of a C content of ≤0.002%, the Ti content is maintained so that it is 0.03-0.045%, in the case of a C content of 0.002-0.005%, the Ti content is maintained so that it is 0.04-0.06 %

Al content: 0.03-0.06%

Al is a deoxidizing element, also a strong nitride forming element, used mainly to bind the N atom, which is favorable for increasing the resistance of the material to aging. In addition, it affects erosion resistance and mechanical property. In this invention, the Al content is strictly limited within the range of 0.03% -0.06%. If its content is lower than 0.03%, then binding of the N atom cannot be achieved, and the aging resistance deteriorates. If this content is higher than 0.06%, then not only will costs increase, but grain growth will also be suppressed during recrystallization during annealing. For this reason, the Al content should be lower than 0.060%.

Si content: ≤0.03%

Although Si has a certain reinforcing function, it also reduces erosion resistance in parallel, so that the lower the silicon content, the better the effect of the present invention. Therefore, the Si content should be below 0.03%. When the Si content exceeds 0.03%, erosion resistance is significantly deteriorated.

The content of other elements: P≤0.012%, S≤0.015%, N≤0.003%, O≤0.004%.

The elements P, C, N, and O are harmful impurity elements and must be strictly controlled. The lower the content of these elements, the better the product of the present invention. Otherwise, the mechanical properties and erosion resistance of soft tinplate for tinning will be affected. The O content reflects the amount of impurity in the material. Since soft tin of grade T-1,5CA for tinning is mainly used for the preparation of the can body formed by stamping, the O content should be strictly controlled so as to control oxide impurities and to ensure that thin steel sheet does not crack after stamping.

Soft tin grade T-1,5CA of the present invention is produced using a process comprising the following steps: melting → continuous casting → hot rolling → etching and cold rolling → continuous annealing → training → tinning. Another process may also be used, comprising the steps of: melting → continuous casting → hot rolling → pickling → continuous cold rolling → continuous annealing → training → tinning; or a process comprising the steps of: melting → continuous casting → hot rolling, pickling → multiple reverse cold rolling → continuous annealing → training → tinning.

The key points of the main operations are described below.

Steel melting

During melting in the converter, proper purging with purge gas and pauses in this purge to control the concentration of C and free oxygen in the ladle are key to ensuring the Rurshtal-Gereus deoxidation effect. During cleaning, vacuum degassing is performed with the Rurshtal-Gereus process. The key is to control the concentration of C. The time for introducing Al depends on the content of free oxygen in the molten steel in order to avoid the formation of excess Al ₂ O ₃ . In addition, impurity control is also important during melting. In this regard, the content of O should be strictly controlled.

Hot rolling

At the stage of hot rolling, the temperature of the release of molten metal is 1190-1250 ° C, preferably 1200-1240 ° C. The final temperature of hot rolling is maintained at the level of 880-920 ° С. In theory and industrial practice, it is proved that when the final temperature is higher than 920 ° C, the surface of the steel strip is substantially oxidized, which leads to poor surface quality. On the other hand, if it is lower than 880 ° C., the hot-rolled steel strip tends to form a double granular structure within the strip, and this leads to an inhomogeneous structural characteristic of the final product. For the soft black sheet of the present invention, prepared by continuous annealing, the final hot rolling temperature is maintained at 880-920 ° C, as a result of which the surface oxidation of the steel strip is reduced, the efficiency of subsequent etching is improved, and the surface quality of the product is improved. In addition, a double grain structure does not occur in the steel strip, which leads to a uniform characteristic of the structure of the final product. Preferably, the final hot rolling temperature is maintained at 885-915 ° C.

The cooling temperature of the hot rolling of the present invention is maintained at 560-620 ° C. An increase in the temperature of winding the strip into a roll can reduce the hardness of the final product and increase the formability of the final product. However, when the temperature of winding the strip into a roll is more than 620 ° C, the scale from oxidation on the surface of the steel strip tends to thicken easily, which leads to difficulties at the etching stage and affects the surface quality of the product. When the strip winding temperature is lower than 560 ° C, the crystalline grains of the hot rolling intermediate are too small, which affects the structure and property of the final product. This also leads to a final product with fine crystalline grains with increased hardness and poor ductility. So for soft tin grade T-1,5SA according to the present invention, produced by continuous annealing, if the temperature of coiling the strip of hot rolling is maintained at 560-620 ° C, the hardness of the final product can be maintained within the range of 51 ± 3, and the amount the scale on the surface of the steel strip after the reeling operation is small, which allows etching to be performed more easily, and the surface quality of the final product is good. Preferably, the temperature of the coiling of the strip of hot rolling was maintained at a level of 570-610 ° C.

Pickling and cold rolling

A combined pickling and cold rolling production line may be used, or pickling is performed first, and then continuous cold rolling or multiple reverse cold rolling is performed. It is preferable to use a combined pickling and cold rolling production line in order to increase production efficiency. During the etching operation, the speed of the production line must be adjusted in accordance with the etching performance in the production line to ensure a good etching result. When cold rolling is performed continuously, five stands are used. The full degree of compression during cold rolling is 82-92%. The degree of compression during cold rolling will affect the mechanical properties of the strip material. In addition, the proper degree of compression during cold rolling is favorable to ensure the exact size of the solid material and control the profile of the cross section of the strip. Too small a reduction leads to a poor property of formability of the strip material, while too large a reduction leads to an increase in costs during the cold rolling operation and an unsatisfactory cross-sectional profile of the strip of solid material, affecting the stability of the continuous movement of the strip at high speed during subsequent continuous annealing operations. In the present invention, soft black sheet of class T-1,5CA for tinning of various specifications is obtained by continuous annealing. The cold rolling reduction ratio is appropriately increased based on the rolling standard of conventional low carbon aluminum deoxidized tinplate, and the rolling force in each stand during cold rolling is also suitably increased so as to ensure stable rolling of IF steel.

Continuous annealing

In the present invention, continuous annealing with a heating temperature during annealing of 730-760 ° C and a holding time of 25-50 seconds is used for the production of T-1.5CA soft black sheet for tinning. Although soft tinplate for tinning can also be obtained using annealing in a bell furnace, the mechanical properties of soft tinplate are heterogeneous, and the cross-sectional profile of the strip and the surface quality of the product is much worse than that of soft tinplate for tinning obtained by continuous annealing. The soft black sheet of class T-1,5CA of the present invention is obtained by continuous annealing using titanium-containing IF steel, the mechanical properties of the product thus obtained are uniform, and the surface quality is good. The product meets the requirements of the user, so it has a high market competitiveness. When the heating temperature during annealing is higher than 760 ° C, the steel strip tends to bend and even break in the annealing furnace if the steel strip is wide and thin, which is caused by the softness of the strip steel. At the same time, energy consumption is also increasing. Thus, in the present invention, the heating temperature during annealing is maintained below 760 ° C. When the heating temperature during annealing is lower than 730 ° C, under conditions of normal speed of the continuous annealing production line, it is difficult to complete the recrystallization of the steel strip under the condition of a high speed of the production line, and the hardness of the product increases and the formability of the product deteriorates. For this reason, in the present invention, the heating temperature during annealing is maintained above 730 ° C, preferably 735-755 ° C. The holding time and the heating temperature during annealing affect each other. An increase in the heating temperature during annealing shortens the holding time. But the aging time cannot be less than 25 seconds, otherwise the grain growth during recrystallization is insufficient, and the result is a material of too high hardness. At the same time, if the speed of the production line is slightly higher, the steel strip tends to go off the guide. On the other hand, the aging time cannot last too long. If it is longer than 50 seconds, then the production efficiency decreases due to the too low speed of the continuous annealing production line, and the crystalline grains grow too large, resulting in a soft material. In addition, the steel strip tends to bend and even break in the annealing furnace. According to the present invention, T-1.5CA soft black sheet for tinning is prepared by continuously annealing titanium-containing IF steel at an annealing temperature lower than continuous annealing of niobium-containing IF steel (usually above 750 ° C). Therefore, when organizing production, the amount of transition roll used can be reduced, and the time for raising and lowering the temperature can be reduced, so as to increase production efficiency and reduce production costs. In addition, the likelihood of bending and breaking of the steel strip in the annealing furnace is significantly reduced due to lower temperatures.

Training

After annealing with two stands, training is performed. The elongation during training is maintained at 1.2-2.2%. If the elongation during training is less than 1.2%, it is difficult to maintain the surface quality of the product, especially the surface roughness and sheet profile of the thick product. In addition, the product is too soft. On the other hand, if the elongation during training is more than 2.2%, then the hardness will increase significantly and the property of formability and weldability (welding quality) will deteriorate. In addition, training costs increase. Preferably, the elongation during training was 1.4-2.0%.

Tinning

Since soft T-1.5CA grade tin made from titanium-containing IF steel has a low yield strength, low hardness and high elongation, n value (i.e., hardenability index) and r value (i.e., the ratio of ductility to force), and does not have an elongation corresponding to the yield strength (that is, YpE1 = 0), then, due to this, the soft tin of the T-1.5CA class of the present invention has a soft nature and excellent aging resistance. It can provide not only an excellent formability and resistance to aging, but also uniform characteristics and an excellent shape of the final product. At the same time, soft black tinplate containing chemical components according to the present invention, which is obtained from titanium-containing IF steel, according to the present invention, is not sensitive to the parameters of the hot rolling process, its recrystallization temperature is low, it has excellent various mechanical properties . In addition, since the heating temperature during annealing is lower for titanium-containing IF steel than for niobium-containing IF steel, the operation of continuous annealing is safer, consumes less heat, uses fewer transition turns. In addition, Ti is cheaper than Nb. Thus, the cost of preparing soft black sheet for tinning of the present invention is reduced.

Examples

Below are given an example of a description of soft black sheet (class T-1,5CA) for tinning produced according to the present invention.

Examples 1-6

Soft tin of grade T-1.5 CA for tinning, having a thickness exceeding 0.25 mm, is obtained using titanium-containing IF steel. The molten steel is subjected to purification by the Rurshtal-Gereus process and vacuum degassing, taking various measures to control impurities. Finally, a continuous casting slab is prepared according to conventional continuous casting technology. The chemical composition of molten steel is given in table 2. Other inevitable impurity elements are also present in this steel, the rest is Fe.

Table 2. The chemical composition of the gestures according to examples 1-6 (weight%) Examples Thickness (mm) FROM Si Mn P S Al N O Ti one 0.26 0.0050 0.007 0.26 0.010 0.0065 0,045 0.0026 0.0027 0,060 2 0.28 0.0040 0.015 0.28 0.012 0.0055 0,053 0.0030 0.0040 0,045 3 0.32 0.0032 0.012 0.30 0.006 0.0150 0,030 0.0018 0.0030 0,055 four 0.55 0.0020 0,030 0.20 0.008 0.0065 0,060 0.0025 0.0023 0,040 5 0.30 0.0027 0.008 0.27 0.009 0.010 0,035 0.0021 0.0035 0,043 6 0.35 0.0035 0,023 0.23 0.007 0.012 0,055 0.0023 0.0021 0,046

Before hot rolling, the continuous casting slab is heated to the temperature of the rolling start. It undergoes rough rolling, finishing rolling and cooling in a laminar flow, and this is followed by coiling the strip. After cooling at room temperature for 2-3 days, it is subjected to pickling and continuous cold rolling using a combined production line consisting of a CDCM production line (for pickling) and a continuous cold rolling production line for preparing cold rolled sheet. Specific processing parameters are given in table 3.

Table 3. The main parameters of the processing process according to examples 1-6 Examples The temperature of the release of molten metal (° C) End temperature of hot rolling The temperature of the winding strip of hot rolling in a roll (° C) The degree of compression during cold rolling,% one 1250 920 625 89 2 1220 910 605 88 3 1215 905 587 87 four 1190 880 560 82 5 1200 885 570 89 6 1240 915 610 87

The cold-rolled steel strip undergoes continuous annealing at the CAPL production line (continuous annealing and rolling processing line) (for continuous annealing) and training at the tempering production line, followed by traditional tinning, thereby obtaining tinned tin. The parameters of the annealing process and the hardness of soft black tin for tinning are given in Table 4.

Table 4. Annealing parameters and hardness according to examples 1-6 Examples Annealing Duration (seconds) Annealing heating temperature (° C) Elongation during training (%) Hardness of soft tinplate HR30T one 25 760 2.2 52.7 2 32 755 1,5 51.1 3 38 745 1,2 51,2 four fifty 730 1.4 50.3 5 40 750 2.0 51.7 6 27 735 1.8 52.0

The mechanical properties of the final product before aging are essentially the same as the mechanical properties after aging, and the mechanical properties after aging are given in table 5.

Table 5. Mechanical properties and surface quality according to examples 1-6 Examples Elongation stress 0.2% σ _0.2 (MPa) Tensile Strength (MPa) Uniform elongation (%) Elongation corresponding to yield strength YpE1 (%) Elongation at break (%) Hardness of the final product HR30T Surface quality one 255 362 24 0 39 52.7 excellent 2 259 358 25 0 40 51.1 very excellent 3 252 350 25 0 40 51.3 very excellent four 246 359 26 0 42 50.3 excellent 5 253 352 25 0 40 51.7 very excellent 6 251 350 26 0 41 52.0 excellent

Examples 7-12

Soft tinplate for tinning, having a thickness equal to or less than 0.25 mm, is prepared using titanium-containing IF steel. The molten steel is subjected to purification by the Rurshtal-Gereus process and vacuum degassing, taking various measures to control impurities. Finally, a continuous casting slab is prepared according to conventional continuous casting technology. The chemical composition of the molten steel is given in table 6. Other inevitable impurity elements are also present in this steel, the rest is Fe.

Table 6. The chemical composition of the gestures according to examples 7-12 Examples Thickness (mm) FROM Si Mn P S Al N O Ti 7 0.23 0.0015 0,025 0.23 0.009 0.0150 0,060 0.0023 0.0040 0,045 8 0.25 0.0020 0.006 0.28 0.012 0,0100 0,030 0.0020 0.0021 0,042 9 0.17 0.0012 0.015 0.30 0.007 0.0060 0,045 0.0030 0.0018 0,035 10 0.20 0.0018 0.008 0.21 0.010 0.0080 0,050 0.0018 0.0027 0,030 eleven 0.21 0.0017 0,030 0.27 0.009 0.0120 0,040 0.0027 0,029 0,038 12 0.19 0.0019 0.018 0.20 0.011 0.0110 0,055 0.0023 0,035 0,039

Before hot rolling, the continuous casting slab is heated to a temperature to start rolling. It undergoes rough rolling, finishing rolling and cooling in a laminar flow, and this is followed by coiling the strip. After cooling at room temperature for 2-3 days, it is subjected to pickling and continuous cold rolling using a combined production line consisting of a CDCM production line (for pickling) and a continuous cold rolling production line for preparing cold rolled sheet. The specific processing parameters are given in table 7.

Table 7. The main parameters of the processing process according to examples 7-12 Examples The temperature of the release of molten metal (° C) The temperature of the end of hot rolling (° C) The temperature of the winding strip of hot rolling in a roll (° C) The degree of compression during cold rolling (%) 7 1245 918 600 89 8 1250 920 620 88 9 1200 885 570 92 10 1225 912 590 90 eleven 1240 915 610 90 12 1190 880 560 91

The cold-rolled steel strip is subjected to continuous annealing at the CAPL production line (continuous annealing and rolling mill line for continuous annealing) and tempering at the tempering production line, followed by traditional tinning, thereby obtaining tinned tin. The annealing process parameters are given in table 8.

Table 8. Annealing parameters and hardness according to examples 7-12 Examples Annealing heating temperature (° C) Annealing Duration (seconds) Elongation during training (%) Hardness HR30T soft tinplate for tinning 7 735 29th 1.9 52.9 8 730 fifty 2.2 51.7 9 745 27 1,5 50.7 10 760 25 1.4 51.6 eleven 740 35 2.0 51.3 12 750 26 1,2 51.9

The mechanical properties of the final product before aging are essentially the same as the mechanical properties after aging, and the mechanical properties after aging are given in table 9.

Table 9.
Mechanical properties and surface quality according to examples 7-12 Examples Conditional stress 0.2% σ _0.2 (MPa) Tensile Strength (MPa) Uniform elongation (%) Elongation corresponding to yield strength YpE1 (%) Elongation at break (%) Hardness of the final product HR30T Surface quality 7 265 363 25 0 39 52.8 excellent 8 250 350 24 0 41 51.7 excellent 9 249 351 24 0 37 50.8 very excellent 10 252 352 25 0 40 51.6 very excellent eleven 251 350 24 0 40 51.3 very excellent 12 256 357 24 0 38 51.9 excellent

Claims (10)

1. Soft black tin for tinning, having a hardness of HR30T 51 ± 3, containing the following components, wt.%:
FROM ≤0.005 Mn 0.20-0.30 Al 0.03-0.06 Si ≤0.03 Ti 0,038-0,06 P ≤0.012 S ≤0.015 N ≤0.003 O ≤0.004
Fe and unavoidable impurities - the rest obtained by a single cold rolling. 2. The soft black tin for tinning according to claim 1, in which the C content is not more than 0.002%, the Ti content is 0.038-0.045% with a product thickness of not more than 0.25 mm. 3. The soft tinplate for tinning according to claim 1, wherein the C content is 0.002% -0.005% and the Ti content is 0.04-0.06% with a product thickness greater than 0.25 mm. 4. The method of producing soft black sheet for tinning according to claim 1, including steelmaking, casting molten slab, hot rolling of the slab into a strip at a slab discharge temperature of 1190-1250 ° C and at a final rolling temperature of 880-920 ° C, winding of the strip into roll at a temperature of 560-620 ° C, etching, cold rolling with a compression ratio of 82-92%, continuous annealing at a temperature of 730-760 ° C for 25-50 s and training with a strip elongation of 1.2-2, 2% 5. The method according to claim 4, in which the etching and cold rolling is performed on a combined production line. 6. The method according to claim 4, in which cold rolling is performed in the form of continuous cold rolling or in the form of reverse cold rolling. 7. The method according to claim 4, in which the hot rolling of the slab at a discharge temperature of the slab 1200-1240 ° C is carried out at a final rolling temperature of 885-915 ° C, and the temperature of the strip winding into a roll is maintained at 570-610 ° C. 8. The method according to claim 4, in which annealing is carried out at a temperature of 735-755 ° C. 9. The method according to claim 4, in which training is performed using a single training camp or paired training mills. 10. The method according to claim 4, in which training is performed with an elongation of the strip by 1.4-2.0%.