Production method of thick low-yield-strength enamel steel

Abstract

The invention discloses a production method of thick low-yield-strength enamel steel. The thick low-yield-strength enamel steel TC2 comprises the following chemical components in percentage by mass: less than or equal to 0.07% of C; s is less than or equal to 0.03%; 0.30% or less of Mn; less than or equal to 0.020% of P; less than or equal to 0.015% of S; t is less than or equal to 0.040%; n is less than or equal to 0.0060%, and the balance is Fe and inevitable impurities. The invention further discloses a production process and related parameters. The mechanical properties of the produced thick-gauge low-yield-strength enamel steel meet the conditions that the yield strength is smaller than or equal to 310 MPa, the tensile strength is smaller than or equal to 420 MPa, the ductility is larger than or equal to 30.0%, the quality problem caused by fish scaling is not found in the using process, the performance is appropriate, and the thick-gauge low-yield-strength enamel steel can be widely applied and popularized.

Description

Technical Field

[0001] The invention belongs to the technical field of steel metallurgy and steelmaking technology, and in particular relates to a production method of thick-gauge low-yield strength enameled steel. Background Art

[0002] Enamel products are widely used in household appliances, kitchen utensils, architectural enamel and sanitary equipment. With the advancement of modern science and technology, new metal materials emerge in an endless stream, and new enamel materials also continue to appear, prompting enamel production to develop many new products, playing a special role in more fields. In recent years, domestic water heater brands have demanded enameled steels of different strength levels. Fully communicating with users and designing products that meet the strength requirements of users are the focus of product development. Baosteel uses new composition design and metallurgical process parameters to develop thick-gauge low-yield strength enameled steel TC2, and studies the influence of strengthening element content and each process on the performance indicators of the product. Summary of the invention

[0003] The purpose of the present invention is to provide a method for producing thick-gauge low-yield strength enameled steel, wherein the mechanical properties of the produced thick-gauge low-yield strength enameled steel meet the following requirements: yield strength ≤ 310 MPa, tensile strength ≤ 420 MPa, and elongation ≥ 30.0%.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The invention discloses a production method of thick-gauge low-yield strength enameled steel, comprising the following processes: steelmaking process-hot rolling process-cold rolling process-continuous annealing process; wherein: the steelmaking process comprises: converter top and bottom combined blowing smelting-LF refining-slab continuous casting; the hot rolling process comprises: billet heating-high-pressure water descaling-width-fixing press-E1 R1 roughing mill rolling-E2R2 roughing mill rolling-flying shear-high-pressure water descaling-F1-F7 finishing mill rolling-densified laminar cooling-coiling; the cold rolling process comprises: pickling uncoiling-welding-tension straightening-pickling-rinsing-drying-edge trimming-continuous rolling mill cold rolling-coiling; the continuous annealing process comprises: continuous annealing uncoiling-welding-cleaning-entry looper-annealing furnace-exit looper-leveling-loop looper inspection-edge trimming-surface inspection-oiling-coiling, wherein:

[0006] The tapping temperature of the converter is ≥1620℃ to ensure that the composition and temperature are coordinated. During the tapping process of the converter, aluminum-iron and manganese-iron alloys are added for deoxidation and alloying.

[0007] The LF furnace is desulfurized by slag making, and alloys such as aluminum iron, manganese iron, and titanium iron are added according to the composition of the molten steel to adjust the composition to the target value; after the LF treatment, calcium treatment is carried out to ensure that the soft blowing time is ≥ 8 minutes, and the reasonable argon flow rate is controlled to prevent the molten steel from being exposed;

[0008] When the casting machine is pouring, the tundish is purged with argon before pouring. During the pouring process, argon is continuously blown into the tundish while adding the covering agent. After the large ladle is poured, the slag detection equipment is used to avoid slag in the large ladle. During the casting process, the overheating range of the tundish is controlled at 20-40°C, and the production pulling speed is 1.0-1.8m / min.

[0009] The heating temperature of the ingot is 1180-1240°C, the heating time is 180-280min, the soaking temperature is 1180-1240°C, the soaking time is 30-60min, and the furnace discharge temperature is 1210°C;

[0010] The final rolling temperature of the finishing rolling is 840-900°C. The control of the coiling temperature has a certain influence on the precipitation of the second phase particles and the ferrite grains. The coiling temperature is 650-720°C.

[0011] The cooling method is a front dispersion cooling method;

[0012] In the continuous annealing process, the annealing heating temperature is 730-830°C, the annealing soaking temperature is 750-830°C, and the leveling machine elongation is 1.0-1.5%.

[0013] Furthermore, the thickness of the ingot is 230 mm, and the hot-rolled thickness is 5.0-6.0 mm.

[0014] Furthermore, the cold-rolled thickness is 1.8-2.0 mm.

[0015] Furthermore, the chemical composition of the enameled steel is as follows by mass percentage: C≤0.07%; Si≤0.03%; Mn≤0.30%; P≤0.020%; S≤0.015%; Ti≤0.040%; N≤0.0060%, and the rest is Fe and unavoidable impurities.

[0016] Furthermore, the mechanical properties of the enameled steel meet the following requirements: yield strength ≤ 310 MPa, tensile strength ≤ 420 MPa, and elongation ≥ 30.0%.

[0017] Compared with the prior art, the beneficial technical effects of the present invention are:

[0018] A thick gauge low yield strength enameled steel provided based on the above technical solution is a moderate strength cold-rolled product, and it has been proved by actual use that the product adopts new component design and metallurgical process parameters, has suitable performance, and its mechanical properties meet the following requirements: yield strength ≤310MPa, tensile strength ≤420MPa, and elongation ≥30.0%. The production method provided provides a production method for cold-rolled thick gauge low yield strength enameled steel strip that meets the actual needs of users by adopting new component design and metallurgical process parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below in conjunction with the accompanying drawings.

[0020] Figure 1 The yield strength mechanical property range of steel strip TC2 obtained for the example;

[0021] Figure 2 The tensile strength mechanical property range of steel strip TC2 obtained for the example;

[0022] Figure 3 The elongation range of the steel strip TC2 obtained for the example. DETAILED DESCRIPTION

[0023] Aiming at the personalized demand for domestic water heater enameled steel, the present invention provides a production method for cold-rolled thick-gauge low-yield strength enameled steel strip that meets the needs of users by adopting new component design and metallurgical process parameters.

[0024] The production method specifically includes the following steps: steelmaking step - hot rolling step - cold rolling step - continuous annealing step; wherein:

[0025] The steelmaking process includes: converter top and bottom combined blowing smelting - LF refining - slab continuous casting;

[0026] The converter tapping temperature is ≥1620°C to ensure that the composition and temperature are coordinated for tapping. During the converter tapping process, aluminum iron, manganese iron and other alloys are added for deoxidation and alloying.

[0027] The LF furnace is slag-forming and desulfurized, and alloys such as aluminum iron, manganese iron, and titanium iron are added according to the composition of the molten steel to adjust the composition to the target value. After the LF treatment, calcium treatment is carried out to ensure that the soft blowing time is ≥ 8 minutes, and the reasonable argon flow rate is controlled to prevent the molten steel from being exposed;

[0028] In the slab continuous casting, the tundish is purged with argon before pouring by the casting machine. During the pouring process, argon is continuously blown into the tundish while adding a covering agent. After the pouring of the large ladle is completed, a slag detection device is used to avoid slag from the large ladle. During the casting process of the casting machine, the overheating range of the tundish is controlled at 20 to 40° C., and the production pulling speed is 1.0 to 1.8 m / min.

[0029] The thickness of the above-mentioned ingot is 230mm, and the hot-rolled thickness is: 5.0-6.0mm;

[0030] The hot rolling process includes: heating of the ingot - high-pressure water descaling - fixed width press - E1R1 roughing mill rolling - E2R2 roughing mill rolling - flying shear - high-pressure water descaling - F1-F7 finishing mill rolling - dense laminar cooling - coiling; this process uses a walking beam heating furnace to heat the ingot (heating process see Table 1), rough rolling uses double-frame R1 and R2 reciprocating rolling, finishing rolling uses F1-F7 continuous rolling process, and the cooling method is front dispersed cooling method. The specific hot rolling process is shown in Table 2.

[0031] Table 1: Billet heating system

[0032]

[0033] Table 2: Rolling process

[0034]

[0035]

[0036] The cold rolling process includes: pickling uncoiling - welding - straightening - pickling - rinsing - drying - trimming - continuous rolling mill cold rolling - coiling;

[0037] The continuous annealing process includes: continuous annealing uncoiling - welding - cleaning - entrance looper - annealing furnace - exit looper - leveling - looper inspection - edge trimming - surface inspection - oiling - coiling;

[0038] The specific process system of the continuous annealing process is shown in Table 3.

[0039] Table 3: Annealing process

[0040]

[0041] The present invention is described in detail below through specific examples. The examples are only intended to help understand the present invention but are not intended to limit the present invention.

[0042] Example

[0043] 1. According to the above steelmaking process requirements, the actual slab chemical composition (mass percentage) is shown in Table 4 below.

[0044] Table 4: Chemical composition (%)

[0045]

[0046] 2. According to the above hot rolling process requirements, the hot rolling thickness is 5.0-6.0mm, and the actual process is shown in Table 5.

[0047] Table 5: Rolling process

[0048]

[0049] 3. According to the above annealing process requirements, the cold rolling thickness is 1.8-2.0mm, and the actual process is shown in Table 6.

[0050] Table 6: Annealing process

[0051]

[0052] 4. The mechanical properties of the steel strip products obtained through the above process are shown in Table 7. The test method refers to GB / T228.1. Figures 1 to 3 As shown, the mechanical properties range of the steel strip TC2 obtained is shown. Figure 1 It can be seen from the curve that the mechanical properties produced by the above process meet the user's requirements.

[0053] Table 7: Mechanical properties

[0054]

[0055] In summary, the steel strip products obtained by the process have been used by users and no unsuitability due to insufficient strength or excessive strength has been found. The performance is suitable and can be promoted and used on a large scale.

[0056] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for producing thick gauge low yield strength enameled steel, comprising the following steps: Steelmaking process - hot rolling process - cold rolling process - continuous annealing process; among which: The steelmaking process includes: converter top and bottom combined blowing smelting - LF refining - slab continuous casting; the hot rolling process includes: billet heating - high-pressure water descaling - fixed width press - E1R1 roughing mill rolling - E2R2 roughing mill rolling - flying shear - high-pressure water descaling - F1-F7 finishing mill rolling - dense laminar cooling - coiling; the cold rolling process includes: pickling uncoiling - welding - straightening - pickling - rinsing - drying - trimming - continuous rolling mill cold rolling - coiling; the continuous annealing process includes: continuous annealing uncoiling - welding - cleaning - inlet looper - annealing furnace - outlet looper - leveling - looper inspection - trimming - surface inspection - oiling - coiling, which is characterized in that: the converter tapping temperature is ≥1620℃ to ensure that the composition and temperature are coordinated for tapping, and aluminum-iron and manganese-iron alloys are added during the converter tapping process for deoxidation and alloying; The LF furnace is desulfurized by slag making, and alloys such as aluminum iron, manganese iron, and titanium iron are added according to the composition of the molten steel to adjust the composition to the target value; after the LF treatment, calcium treatment is carried out to ensure that the soft blowing time is ≥ 8 minutes, and the reasonable argon flow rate is controlled to prevent the molten steel from being exposed; When the casting machine is pouring, the tundish is purged with argon before pouring. During the pouring process, argon is continuously blown into the tundish while adding the covering agent. After the large ladle is poured, the slag detection equipment is used to avoid slag in the large ladle. During the casting process, the overheating range of the tundish is controlled at 20-40°C, and the production pulling speed is 1.0-1.8m / min. The heating temperature of the ingot is 1180-1240°C, the heating time is 180-280min, the soaking temperature is 1180-1240°C, the soaking time is 30-60min, and the furnace discharge temperature is 1210°C; The final rolling temperature of the finishing rolling is 840-900°C. The control of the coiling temperature has a certain influence on the precipitation of the second phase particles and the ferrite grains. The coiling temperature is 650-720°C. The cooling method is a front dispersion cooling method; In the continuous annealing process, the annealing heating temperature is 730-830°C, the annealing soaking temperature is 750-830°C, and the leveling machine elongation is 1.0-1.5%.

2. The method for producing thick gauge low yield strength enameled steel according to claim 1, characterized in that: The thickness of the ingot is 230mm, and the hot-rolled thickness is 5.0-6.0mm.

3. The method for producing thick gauge low yield strength enameled steel according to claim 1 or 2, characterized in that: The cold rolled thickness is 1.8-2.0mm.

4. The method for producing thick gauge low yield strength enameled steel according to claim 1, characterized in that: The chemical composition of the enameled steel is as follows by mass percentage: C≤0.07%; Si≤0.03%; Mn≤0.30%; P≤0.020％； S≤0.015%; Ti≤0.040%; N≤0.0060%, and the rest are Fe and unavoidable impurities.

5. The method for producing thick gauge low yield strength enameled steel according to claim 4, characterized in that: The mechanical properties of the enameled steel meet the following requirements: yield strength ≤310MPa, tensile strength ≤420MPa, and elongation ≥30.0%.

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