阅读说明：本技术 汽车用热轧酸洗钢制备方法 (Preparation method of hot-rolled pickled steel for automobiles ) 是由 王立新 陶文哲 杨腾飞 肖厚念 魏兵 尹云洋 徐锋 王靓 王世森 于 2021-08-18 设计创作，主要内容包括：本发明公开了一种汽车用热轧酸洗钢制备方法,在LF炉外精炼过程中对炉渣进行控制-RH炉真空处理、连铸、铸坯加热、热轧、冷却、卷取-平整-酸洗、漂洗、平整。利用冷轧酸轧联机生产线的富余产能生产汽车用热轧酸洗钢,既满足了汽车用热轧酸洗钢的高凸缘翻边性能要求,也具有高表面质量的特点,还创造了经济效益。2.2～5.5mm规格的热轧酸洗钢,抗拉强度为490～600MPa级,延伸率A-(50)≥35％,扩孔率Φ≥110％,塑性应变比R≥1.6,拉伸应变硬化指数N≥0.25。(The invention discloses a preparation method of hot-rolled pickled steel for automobiles, which is characterized in that furnace slag is controlled in an LF external refining process, namely, RH furnace vacuum treatment, continuous casting, casting blank heating, hot rolling, cooling, coiling, leveling, pickling, rinsing and leveling are carried out. The surplus capacity of the cold rolling and acid rolling on-line production line is utilized to produce the hot rolling acid-washing steel for the automobile, so that the requirement of high flange flanging performance of the hot rolling acid-washing steel for the automobile is met, the characteristic of high surface quality is achieved, and economic benefit is created. Hot-rolled pickled steel with the specification of 2.2-5.5 mm, the tensile strength of 490-600 MPa and the elongation A 50 More than or equal to 35 percent, the hole expansion ratio phi is more than or equal to 110 percent, the plastic strain ratio R is more than or equal to 1.6, and the tensile strain hardening index N is more than or equal to 0.25.)

1. A preparation method of hot-rolled pickled steel for automobiles is characterized by comprising the following steps: the hot-rolled pickled steel comprises the following chemical components in percentage by weight: 0.060 to 0.075%, Si: 0.100 to 0.150%, Mn: 1.000-1.150%, P is less than or equal to 0.015%, S is less than or equal to 0.006%, Nb: 0.015 to 0.022%, Als: 0.015-0.035%, Cu is less than or equal to 0.200%, Ni is less than or equal to 0.200%, and Cr is less than or equal to 0.200%; the balance of Fe and inevitable impurities;

the preparation method comprises the following steps:

1) smelting in a converter and then refining in an LF furnace and an RH furnace;

2) carrying out slab continuous casting production on molten steel: the thickness of the cast blank is 230-250 mm; heating the casting blank in a stepping heating furnace, wherein the heating temperature is controlled to be 1240-1280 ℃;

3) and (3) heating the casting blank, and performing sectional rolling: the finish temperature of rough rolling is controlled to be 1060-1100 ℃, and the finish rolling temperature of finish rolling is controlled to be 820-860 ℃;

4) cooling the rolled steel coil to 720-780 ℃ at the front section at the cooling speed of 40-80 ℃/s, and controlling the temperature of cooling water to be less than 35 ℃;

5) controlling the coiling temperature to be 580-620 ℃;

6) before pickling, the single machine is flattened, and the flattening force is set to be 150-250 t.

7) Pickling, leveling and oiling.

2. The method for producing a hot-rolled and pickled steel for automobiles according to claim 1, wherein: in the step 1), RH furnace vacuum treatment: the vacuum degree is less than or equal to 5.8KPa, the circulating pure degassing time is 12-20 min, and the vacuum time is 18-30 min; then calcium treatment is carried out, the weight of molten steel in each furnace is fed with 680-820 g/t of Si-Ca wires, the feeding rate is controlled to be 280-320 m/min, and the soft argon blowing time of the molten steel is ensured to be 8-158 min;

controlling the slag in the LF external refining process, wherein the slag comprises the following components in percentage by weight: 56% -58% of Al₂O₃：22％～24％、MgO：12％～14％、SiO₂: 10% -12%, TFe < 0.8%, and controlling the alkalinity R of the slag: 3.6 to 4.0; argon blowing and stirring are carried out in the whole process, and a ladle covering agent is added before the molten steel is discharged.

3. The method for producing a hot-rolled and pickled steel for automobiles according to claim 1, wherein: in the step 2), the tundish temperature is controlled at 1560 +/-30 ℃, the pulling speed is controlled at 1.45-1.95 m/min, wherein the slab continuous casting adopts a full-process protective casting process, and the crystallizer adopts an electromagnetic stirring technology;

controlling the heating of the casting blank: charging the cold blank into a furnace, wherein the temperature of a preheating section is 520-720 ℃, the preheating time is 30-45 min, the temperature of a first heating section is 740-1100 ℃, the temperature of a first heating section is 35-40 min, the temperature of a second heating section is 1120-1220 ℃, the temperature of a second heating section is 40-60 min, and the temperature of a soaking section is 1240-1280 ℃; soaking time is 40-50 min, total heating time is controlled to be 145-195 min, and the temperature difference between the same blanks is less than or equal to 30 ℃.

4. The method for producing a hot-rolled and pickled steel for automobiles according to claim 1, wherein: in the step 3), the rough rolling descaling is not less than five times, and the number of the descaling collecting pipes is not less than two before finish rolling.

5. The method for producing a hot-rolled and pickled steel for automobiles according to claim 1, wherein: in the step 7), the withdrawal and straightening elongation rate before pickling is set to be 1.2-1.8%; the production process of the acid-washed steel on the acid-washing online comprises acid washing and rinsing, wherein:

in pickling, the hot rolled steel strip is pickled through three pickling tanks: respectively as follows:

in the first pickling tank: the total acid concentration is 185-215 g/L, the Fe2+ concentration is 115-135 g/L, the free acid concentration is 25-45 g/L, and the temperature is 75-85 ℃;

in the second acid wash tank: the total acid concentration is 185-215 g/L, the Fe2+ concentration is 65-85 g/L, the free acid concentration is 95-115 g/L, and the temperature is 75-85 ℃;

in the third pickling tank: total acid concentration of 185-215 g/L, Fe²⁺The concentration is 30-50 g/L, the concentration of free acid is 150-170 g/L, and the temperature is 75-85 ℃;

in the pickling process, the total pickling time is about 26-30 seconds; adding a corrosion inhibitor into the pickling tank;

in the rinsing process, the steel band gets into the potcher, and the potcher is the cascade type cell body of level four, adopts the mode rinsing of spray rinsing against the current, through the pH value of water inflow and drainage volume adjustment rinsing section: 5.5-6.5, the conductivity is less than or equal to 40 mu s/cm; and adding a corrosion inhibitor into the rinsing tank.

6. The method for producing a hot-rolled and pickled steel for automobiles according to claim 1, wherein: in the step 7), in the leveling process, the elongation is set to be 1.0-1.4%, and the Ra of the leveling roller is 1.25-1.75 μm.

Technical Field

The invention belongs to the technical field of hot-rolled strip steel production, and particularly relates to a preparation method of hot-rolled pickled steel for an automobile.

Background

The steel industry is rapidly developed, the whole surplus of the productivity is continuously intensified, the quality requirement of downstream enterprises on steel products is higher and higher, and the control on the production cost is more and more precise. Therefore, the development and production of steel products are forced to follow the development direction of the downstream market, for example, with the ultra-high speed development of the automobile industry, the demand of automobile steel is larger and larger, the quality requirement is higher and higher, and the cost is more and more strictly controlled. In view of the characteristics and the forming condition requirements of the automobile steel, the hot-rolled pickled steel product for the automobile with high flange flanging performance is developed, and is an effective measure for solving the product development of steel mills and the development bottleneck of the downstream automobile industry.

The thickness of the hot-rolled pickled steel for the automobile is generally less than 6mm, and the hot-rolled pickled steel is generally processed in a stamping forming mode in the production process of automobile parts, and relates to main stamping forming processes such as blanking, drawing, punching, flanging and shaping, so that the steel material for the automobile is required to have good flange flanging performance and good high surface quality so as to meet the strict standard requirements of the automobile industry on steel materials. The hot-rolled pickled steel for the automobile has the following characteristics: compared with a hot-rolled plain plate, the hot-rolled pickled steel for the automobile has the following advantages: firstly, the surface quality is high, because the iron scale on the surface of the strip steel is removed, the surface quality of the strip steel is improved, the welding performance and the coating performance of the material are improved, the appearance effect of the strip steel is obviously improved, and the material is an ideal automobile material; and secondly, the formability and the high dimensional precision are easy, after the hot-rolled pickled steel for the automobile is subjected to a flattening process, the residual internal stress is optimized, the anisotropy of the material is small, the forming processing of the material is facilitated, and the defect of poor flatness of the strip steel is reduced.

Some large iron and steel enterprises at home and abroad have professional continuous hot-rolled pickled steel production lines, some iron and steel enterprises only have push-pull hot-rolled pickled steel production lines, and even others have no hot-rolled pickled steel production line and only can produce hot-rolled pickled steel by an outsourcing earth method. The quality of the hot-rolled pickled steel for the automobile produced by the continuous hot-rolled pickled steel production line is guaranteed, but the equipment investment cost is too high; although the cost of the push-pull hot-rolled pickled steel production line and the production of hot-rolled pickled steel by the outsourcing earth method are reduced, the quality cannot be guaranteed, and particularly, the hot-rolled pickled steel products for automobiles are produced, the requirements on the surface quality of the materials are high, and the flange flanging performance is also high. Therefore, such production methods have production difficulties that cannot be overcome.

Disclosure of Invention

The invention aims to provide a preparation method of hot-rolled pickled steel for automobiles, which has high flange flanging performance and good material surface quality, aiming at the defects of the technology.

In order to achieve the purpose, the invention provides a preparation method of hot-rolled pickled steel for automobiles, which is characterized by comprising the following steps: the hot-rolled pickled steel comprises the following chemical components in percentage by weight: 0.060 to 0.075%, Si: 0.100 to 0.150%, Mn: 1.000-1.150%, P is less than or equal to 0.015%, S is less than or equal to 0.006%, Nb: 0.015 to 0.022%, Als: 0.015-0.035%, Cu is less than or equal to 0.200%, Ni is less than or equal to 0.200%, and Cr is less than or equal to 0.200%; the balance of Fe and inevitable impurities;

the preparation method comprises the following steps:

1) smelting in a converter and then refining in an LF furnace and an RH furnace;

2) carrying out slab continuous casting production on molten steel: the thickness of the cast blank is 230-250 mm; heating the casting blank in a stepping heating furnace, wherein the heating temperature is controlled to be 1240-1280 ℃;

3) and (3) heating the casting blank, and performing sectional rolling: the finish temperature of rough rolling is controlled to be 1060-1100 ℃, and the finish rolling temperature of finish rolling is controlled to be 820-860 ℃;

4) performing front-stage ultra-fast cooling on the rolled steel coil at a cooling speed of 40-80 ℃/s to 720-780 ℃, and controlling the temperature of cooling water to be less than 35 ℃;

and a front-section ultra-fast cooling mode is adopted, the cooling speed is 40-80 ℃/s, and the temperature of cooling water is controlled to be less than 35 ℃. Increasing the cooling rate can make Ar₃Decrease, increase of phase transformation nucleus, and inhibit the growth of crystal grain after phase transformation, so that F crystal grain can be refined, and the material can be strengthened by fine crystal grain

5) Controlling the coiling temperature to be 580-620 ℃; therefore, the loose iron scale mainly with an FeO structure is formed on the surface of the material, and the iron oxide scale layer on the surface of the material is conveniently removed by acid washing in the subsequent processing process, so that the processed material with good surface quality is obtained.

6) Before pickling, the single machine is flattened, the flattening force is set to be 150-250 t, the plastic deformation range of the material can be expanded, the yield platform of the material is eliminated, and a slip line is prevented from being generated during cold forming. Meanwhile, the elongation of the material in the rolling direction is ensured to be uniform, the plate shape and the surface quality of the material are adjusted, and the forming performance of the material is improved. The single machine leveling is the technical key point for ensuring the high surface quality of the hot-rolled pickled steel for the automobile. The flattening process is used for adjusting the tissue structure of the hot-rolled raw material, eliminating the yield platform of the material and improving the mechanical property of the material, and is used for improving the plate shape quality of the material and improving the prerequisite condition for obtaining good pickling quality.

7) Pickling, leveling and oiling.

The adoption of electrostatic oiling ensures the surface quality of the pickled steel, prevents the pickled steel from generating corrosion defects in the subsequent transportation process and the storage process of users, and the proper and uniform oiling quality can not only prevent the surface of the strip steel from being corroded, but also improve the service performance of the material and play a role in lubricating in the stamping forming process of the material. The electrostatic oiling mode is adopted for oiling, and oiling can be carried out according to user requirements and requirements

Further, in the step 1), the RH furnace vacuum treatment: the vacuum degree is less than or equal to 5.8KPa, the circulating pure degassing time is 12-20 min, and the vacuum time is 18-30 min; and then calcium treatment is carried out, the molten steel in each furnace is fed with 680-820 g/t of Si-Ca wires according to weight, the feeding speed is controlled at 280-320 m/min, the soft argon blowing time of the molten steel is ensured to be 8-158 min, impurities in the steel further float upwards and enter slag, the purity of the molten steel is improved, aluminum balls are added in the later treatment stage to adjust the content of Als in the molten steel, and then the alloy is homogenized.

Controlling the slag in the LF external refining process, wherein the slag comprises the following components in percentage by weight: 56% -58% of Al₂O₃：22％～24％、MgO：12％～14％、SiO₂: 10% -12%, TFe < 0.8%, and controlling the alkalinity R of the slag: 3.6 to 4.0; argon blowing and stirring are carried out in the whole process, and a ladle covering agent is added before the molten steel is discharged out of the station so as to protect the molten steel.

Further, in the step 2), crack-resistant slab casting powder is used, a continuous casting secondary cooling system adopts a weak cooling mode to prevent cracks from being generated during slab casting, the temperature of a tundish is controlled at 1560 +/-30 ℃, the pulling speed is controlled at 1.45-1.95M/min, wherein the slab continuous casting adopts a whole-process protective casting process, and a crystallizer adopts an electromagnetic stirring (M-EMS) technology; the superheat degree of the molten steel is greatly reduced, the solidification time is shortened, so that a wide and thin equiaxed crystal area is generated, forced convection is carried out at the solidification front, dendritic crystals at the solidification front are broken, fragments of the dendritic crystals are remelted, the temperature of the molten steel is reduced, an equiaxed crystal core is increased, the development of the front of a columnar crystal is blocked, and the wide equiaxed crystal area is formed. The stirring of the molten steel reduces the temperature gradient of the liquid core from outside to inside, and the surrounding crystallization develops uniformly, thereby improving the equiaxed crystal rate on the section of the casting blank, enabling the segregation elements to be distributed uniformly, avoiding the aggregation of solute elements and finally improving the segregation of the casting blank.

Controlling the heating of the casting blank: charging the cold blank into a furnace, wherein the temperature of a preheating section is 520-720 ℃, the preheating time is 30-45 min, the temperature of a first heating section is 740-1100 ℃, the temperature of a first heating section is 35-40 min, the temperature of a second heating section is 1120-1220 ℃, the temperature of a second heating section is 40-60 min, and the temperature of a soaking section is 1240-1280 ℃; soaking time is 40-50 min, total heating time is controlled to be 145-195 min, the temperature difference between the same slabs is less than or equal to 30 ℃, the temperature of the slabs is uniform, elements are fully dissolved in solution, the thickness and the number of furnace-produced iron oxide scales are effectively controlled, and the product material with good surface quality is obtained.

Further, in the step 3), the rough rolling descaling is not less than five times, and the number of the opened descaling collecting pipes before finish rolling is not less than two. The descaling device after F1 is also started to ensure descaling effect, and the rolling mode leads the scale structure which is easy to remove by acid pickling and mainly contains FeO to be changed into Fe which is difficult to remove by acid pickling₃O₄The transformation of the main iron scale is blocked, the thickness of the iron scale is reduced, the phosphorus removal mode can also ensure the phosphorus removal effect, the surface quality of the steel plate is ensured, and the product material with high surface quality can be finally obtained.

Further, in the step 7), the withdrawal and straightening elongation before pickling is set to be 1.2-1.8%; the process of the acid-washing steel in the acid-washing on-line production comprises the processes of uncoiling, straightening, head and tail cutting, welding, straightening, acid-washing, rinsing, drying and the like, wherein:

straightening: the steel plate is bent or stretched in a considerable direction, so that the bent part of the steel is subjected to certain elastic-plastic deformation, after the external force is removed, the steel is elastically restored and then is straightened, and simultaneously, due to different plasticity of iron scales on the surface of the steel plate, the steel plate falls off in the repeated straightening deformation process of straightening, so that the dephosphorization effect is achieved.

A withdrawal and straightening procedure: firstly, the strip shape is improved, and after the strip steel is stretched and bent and straightened, the strip steel can partially eliminate the defects of strip shapes such as edge waves, middle waves and the like, C-shaped bending, L-shaped bending and the like, thereby improving the flatness of the strip steel. And secondly, the processing performance is improved, and the yield platform is reduced or no longer exists when the strip steel is deformed subsequently through the stretching and bending action, so that uniform deformation is generated, and the processing performance is improved. And similarly, under the action of straightening and withdrawal, the iron oxide scales on the surface of the strip steel are further loosened or peeled off, so that the effect of removing phosphorus is further achieved, and a good condition is created for the pickling process. )

In pickling, the hot rolled steel strip is pickled through three pickling tanks: respectively as follows:

in the first pickling tank: the total acid concentration is 185-215 g/L, the Fe2+ concentration is 115-135 g/L, the free acid concentration is 25-45 g/L, and the temperature is 75-85 ℃;

in the second acid wash tank: the total acid concentration is 185-215 g/L, the Fe2+ concentration is 65-85 g/L, the free acid concentration is 95-115 g/L, and the temperature is 75-85 ℃;

in the third pickling tank: total acid concentration of 185-215 g/L, Fe²⁺The concentration is 30-50 g/L, the concentration of free acid is 150-170 g/L, and the temperature is 75-85 ℃;

in the pickling process, the total pickling time is 26-30 seconds; and the corrosion inhibitor is added into the pickling tank, and the corrosion inhibitor added into the pickling tank is used for preventing over-pickling when the strip steel stops in the pickling tank.

In the rinsing process, the steel band gets into the potcher, and the potcher is the cascade type cell body of level four, adopts the mode rinsing of spray rinsing against the current, through the pH value of water inflow and drainage volume adjustment rinsing section: 5.5-6.5, the conductivity is less than or equal to 40 mu s/cm; the corrosion inhibitor is added into the rinsing tank, and the corrosion inhibitor added into the rinsing tank is used for preventing acid spots from being generated when the strip steel stops in the rinsing tank.

The air temperature is controlled to be 120 +/-10 ℃, edge blowing equipment is used for blowing and brushing residual liquid stored on two sides of the steel strip to the outer side of the steel strip by utilizing compressed air, and the edge of the steel strip is easy to dry; and hot air drying equipment for heating and continuously drying the moisture attached to the surface of the steel strip.

Further, in the step 7), in the leveling process, the elongation of a fifth frame of the five frames is set to be 1.0-1.4%, and the Ra of the leveling roll is 1.25-1.75 μm.

Compared with the prior art, the invention has the following beneficial effects: the preparation method of the hot-rolled pickled steel for the automobile has high flange flanging performance and good surface quality of the material, and completely meets the requirements of the stamping forming process and the high surface quality of the steel for the automobile; hot-rolled pickled steel with the specification of 2.2-5.5 mm, the tensile strength of 490-600 MPa and the elongation A₅₀More than or equal to 35 percent, the hole expansion ratio phi is more than or equal to 110 percent, the plastic strain ratio R is more than or equal to 1.6, and the tensile strain hardening index N is more than or equal to 0.25;

the invention overcomes the defects in the background technology, and produces the hot-rolled pickled steel for the automobile by utilizing the surplus capacity of the cold-rolling and acid-rolling online production line, thereby not only meeting the requirement of high flange flanging performance of the hot-rolled pickled steel for the automobile, but also having the characteristic of high surface quality, and creating economic benefit.

Detailed Description

The present invention will be described in further detail with reference to specific examples and comparative examples to facilitate a clearer understanding of the present invention, but the present invention is not limited thereto.

The present invention is described in detail below:

table 1 chemical composition list of each example of the invention

Table 2 list of main process parameters of various embodiments of the present invention

TABLE 3 Pickling, rinsing, drying, and leveling Process parameter List for the examples of the present invention

Table 4 shows the main process parameters of finish rolling in sequence 1

The method comprises the following steps:

1) controlling the slag in the LF external refining process, wherein the weight percentage of the components in the slag is CaO: 56-58%, Al2O 3: 22-24%, MgO: 12-14%, SiO 2: 10-12%, TFe < 0.8%, and controlling the alkalinity R of the slag: 3.6 to 4.0; fine adjustment of molten steel components is carried out after slagging; argon blowing and stirring are carried out in the whole process, and a ladle covering agent is added before the molten steel is discharged out of the station so as to protect the molten steel.

2) And (3) RH furnace vacuum treatment: the vacuum degree is less than or equal to 5.8KPa, the circulating pure degassing time is 12-20 minutes, and the vacuum time is 18-30 min. And then calcium treatment is carried out, the molten steel in each furnace is fed with 680-820 g/t of Si-Ca wires according to weight, the feeding speed is controlled at 280-320 m/min, the soft argon blowing time of the molten steel is guaranteed to be more than or equal to 8min, impurities in the steel further float upwards and enter slag, the purity of the molten steel is improved, aluminum balls are added in the later treatment stage to adjust the content of Als in the molten steel, and then the alloy is homogenized.

3) Slab continuous casting: using anti-crack slab covering slag, and adopting a weak cooling mode in a continuous casting secondary cooling system to prevent cracks from being generated during slab casting; the tundish temperature is controlled at 1560 +/-30 ℃, the pulling speed is controlled at 1.45-1.95M/min, the slab continuous casting adopts the whole-process protective casting process, and the crystallizer adopts the electromagnetic stirring (M-EMS) technology.

4) Controlling the heating of the casting blank: charging the cold blank into a furnace, wherein the temperature of a preheating section is 520-720 ℃, the preheating time is 30-45 min, the temperature of a first heating section is 740-1100 ℃, the temperature of a first heating section is 35-40 min, the temperature of a second heating section is 1120-1220 ℃, the temperature of a second heating section is 40-60 min, and the temperature of a soaking section is 1240-1290 ℃; the soaking time is 40-50 min, the total heating time is controlled to be 145-195 min, the temperature difference between the same slabs is less than or equal to 30 ℃, and the temperature of the slabs is uniform.

5) Hot rolling: the rough rolling finishing temperature is controlled to be 1060-1100 ℃, the finish rolling finishing temperature is controlled to be 820-860 ℃, the rough rolling descaling is not less than five times, the number of descaling headers before finish rolling is not less than two, and the descaling device is also started after F1 to ensure the descaling effect.

6) Laminar cooling adopts the mode of front-section ultra-fast cooling, the cooling speed is 40-80 ℃/s, and the temperature of cooling water is controlled to be less than 30 ℃.

7) Coiling temperature: the coiling temperature is controlled to be 580-620 ℃.

8) Single machine leveling before pickling: the leveling force is set to 150 to 250t

9) Acid washing process:

the withdrawal and straightening elongation percentage before the pickling process is set to be 1.2-1.8%;

acid picklingSetting process parameters in a first pickling tank: total acid concentration of 185-215 g/L, Fe²⁺The concentration is 115-135 g/L, the concentration of free acid is 25-45 g/L, and the temperature is 75-85 ℃; in the second acid wash tank: total acid concentration of 185-215 g/L, Fe²⁺The concentration is 65-85 g/L, the concentration of free acid is 95-115 g/L, and the temperature is 75-85 ℃; in the third pickling tank: total acid concentration of 185-215 g/L, Fe²⁺The concentration is 30-50 g/L, the concentration of free acid is 150-170 g/L, and the temperature is 75-85 ℃;

during the pickling process, the total pickling time was about 26 seconds.

Rinsing after acid washing: the potcher is the cascade formula cell body of level four, adopts the mode rinsing of spray rinsing against the current, through the pH value of water inflow and drainage volume adjustment rinsing section: 5.5-6.5, and the conductivity is less than or equal to 40 mu s/cm.

Drying after rinsing: the hot air drying temperature is controlled to be 120 +/-10 ℃.

10) Leveling after pickling: the elongation of the fifth frame of the five frames is set to be 1.0-1.4%, and the Ra of the leveling roller is 1.25-1.75 mu m.

11) Oiling: and the electrostatic oiling is adopted, so that the quantitative oiling required by customers can be realized.

TABLE 1 chemical composition List for each example

Composition (I)	C	Mn	Si	P	S	Nb	Cu	Ni	Cr	Als
											1	0.063	1.070	0.105	0.010	0.0043	0.019	0.008	0.006	0.018	0.021
2	0.061	1.094	0.104	0.013	0.0041	0.020	0.010	0.007	0.020	0.024
											3	0.064	1.094	0.103	0.008	0.0044	0.017	0.021	0.011	0.018	0.028
4	0.066	1.096	0.108	0.014	0.0042	0.018	0.013	0.013	0.013	0.025
											5	0.065	1.109	0.110	0.015	0.0038	0.019	0.016	0.010	0.021	0.026
6	0.062	1.056	0.112	0.012	0.0040	0.016	0.009	0.019	0.016	0.024
											Comparative example 1	0.086	1.123	0.151	0.030	0.0141	0.043	0.012	0.011	0.015	0.048
Comparative example 2	0.082	1.124	0.162	0.029	0.0124	0.046	0.011	0.014	0.018	0.050
											Comparison 3	0.089	1.126	0.160	0.031	0.0113	0.044	0.013	0.012	0.016	0.051

TABLE 2 List of the main process parameters for the examples

TABLE 3 list of pickling, rinsing, drying and leveling process parameters for each example

TABLE 4 tabulation of mechanical properties of the products of each example