Production method of low-cost roller washing machine plate

Abstract

The invention discloses a production method of a low-cost roller washing machine plate. The production method comprises the following steps: a steelmaking process: molten steel comprises the following chemical components in percentage by mass: 0.010% < = C < = 0.020%, S < = 0.03%, 0.15% < = Mn < = 0.25%, 0.007% < = P < = 0.017%, S < = 0.010% and N < = 0.0040%; according to the hot rolling process, the heating temperature is 1180-1220 DEG C, the finish rolling temperature of finish rolling is larger than or equal to 880 DEG C, and the coiling temperature is 700-730 DEG C; acid rolling process; according to the galvanization process, the outlet temperature of a galvanization annealing and / or soaking section is 780-800 DEG C, the outlet temperature of a slow cooling section is 670-690 DEG C, the ductility of a temper mill is 1.2-1.50%, the ductility of a withdrawal and straightening machine is 0.20%, and the production line speed is 90-120 m / min. The low-cost production method of the special galvanized steel for the roller washing machine is designed by adopting the design of low carbon, phosphorus, silicon and manganese.

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 for a low-cost drum washing machine plate. Background Art

[0002] In order to reduce production costs, home appliance companies have proposed the need to develop a low-cost washing machine plate to replace the currently used HX180YD+Z (high-strength IF steel). In order to meet user requirements, we at Baosteel have carried out research on the metallurgical process route for low-cost washing machine steel.

[0003] The existing literature and patent research are as follows:

[0004] Retrieval document 1 "An aluminum killed steel hot-dip galvanized sheet and its production method" describes the development of aluminum killed steel hot-dip galvanized sheet, whose designed carbon content is 0.02-0.04%, Mn: 0.2-0.35%, and product elongation is 38.5-41.5%, which is significantly different from the present invention. Production according to this method cannot meet the requirements of users.

[0005] The searched patent "Production method of hot-dip galvanized steel sheet" mainly describes. The present invention belongs to the field of hot-dip galvanized steel sheet manufacturing, and the technical problem solved is to provide a production method of hot-dip galvanized steel sheet, specifically, the steel sheet is subjected to hot-dip galvanizing operation after pickling and annealing; during the hot-dip galvanizing operation, the temperature of the steel sheet itself entering the galvanizing bath is 475-485℃, the galvanizing bath temperature in the zinc pot is 450-460℃, the Fe content in the galvanizing bath is <0.03%, the Al content in the galvanizing bath is: 0.16-0.18%, the unit speed is: 100-110m / min, and the cooling rate of the steel sheet is 0%. The above process conditions make the atomic concentration A1 / Zn ratio of Al and Zn in the Fe-A1 intermediate transition layer between the steel plate substrate and the zinc coating greater than 0.9, no Γ phase is formed in the coating, the δ phase is relatively thin, the ε phase is very small, most of the coating is composed of several phases, and orientation-optimized Zn (002) grains are formed, so that the adhesion, scratch resistance and wear resistance of the coating are significantly improved. The main research is on the composition phase of the zinc layer, which does not belong to the same category as the present invention.

[0006] The present invention is a research and development of a low-cost special steel for drum washing machines. The design and development are carried out from the whole process of chemical composition, smelting, hot rolling, cold rolling, and hot-dip galvanizing, and the development process is explained in a relatively systematic and perfect manner. Not only is the production cost low, but it also meets the international ROSH and Reach environmental protection requirements. The yield strength is controlled at 180-240MPa, the tensile strength is controlled at 290-360MPa, and the elongation is ≥40%, which meets the stamping requirements of the outer plate of a certain brand of drum washing machines. Summary of the invention

[0007] The purpose of the present invention is to provide a low-cost production method for drum washing machine panels, which not only has low production costs, but also meets the international ROSH and Reach environmental protection requirements. The yield strength is controlled at 180-240MPa, the tensile strength is controlled at 290-360MPa, and the elongation is ≥40%, which meets the stamping requirements of a certain brand of drum washing machine outer panels.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0009] The present invention provides a method for producing a low-cost drum washing machine plate, comprising:

[0010] Steelmaking process: KR desulfurization → converter → RH refining → slab continuous casting; the chemical composition of the molten steel by mass percentage is: 0.010% ≤ C ≤ 0.020%, Si ≤ 0.03%, 0.15% ≤ Mn ≤ 0.25%, 0.007% ≤ P ≤ 0.017%, S ≤ 0.010%, N ≤ 0.0040%, the rest is Fe and unavoidable impurities;

[0011] Hot rolling process: heating furnace → rough rolling high-pressure water descaling machine → fixed width press → E1R1 rough rolling mill → E2R2 rough rolling mill → insulation cover → flying shear → finishing high-pressure water descaling machine → F1-F7 finishing mill → encrypted laminar cooling → coiler; slab heating temperature is 1180-1220℃, finishing rolling temperature is ≥880℃, coiling temperature is 700-730℃;

[0012] Pickling process: Pickling uncoiling → welding → straightening → pickling → rinsing → drying → trimming → rolling → coiler → pickling reduction rate ≥ 70%;

[0013] Galvanizing process: hot-dip galvanizing uncoiling → welding → entrance looper → cleaning → annealing furnace → zinc pot → cooling after plating → water quenching → intermediate looper → skin pass machine → straightening machine → roller coater → dryer → air cooling device → exit looper → trimming → surface inspection → oiling → sampling → coiling; galvanizing annealing heating / soaking section outlet temperature 780-800℃, slow cooling section outlet temperature 670-690℃, skin pass machine elongation 1.2-1.50%, straightening machine elongation 0.20%, production line speed 90-120m / min.

[0014] Furthermore, the molten iron is subjected to KR desulfurization treatment, and the sulfur content of the molten iron entering the converter is required to be less than 0.015%, and the slag removal area of ​​the molten iron is required to be greater than 90%.

[0015] Furthermore, the converter endpoint control requirements are: the tapping temperature is ≥1660°C, the tapping temperature drop is required to be less than 70°C when using a normal turnover ladle for tapping. Add top slag modifier according to the oxygen content of the molten steel and the amount of slag.

[0016] Furthermore, the casting machine adopts constant pulling speed control, and the pulling speed range is 1.0-1.8m / min.

[0017] Furthermore, the chemical composition of the washing machine plate by mass percentage is: C 0.018%, Si 0.002%, Mn 0.22%, P 0.010%, S 0.007%, N 0.0020%, and the rest is Fe and unavoidable impurities.

[0018] Furthermore, the chemical composition of the washing machine plate by mass percentage is: C 0.016%, Si 0.008%, Mn 0.23%, P 0.013%, S 0.005%, N 0.0012%, and the rest is Fe and unavoidable impurities.

[0019] Furthermore, the chemical composition of the washing machine plate in terms of mass percentage is: C 0.015%, Si 0.007%, Mn 0.24%, P 0.011%, S 0.006%, N 0.0011%, and the rest is Fe and unavoidable impurities.

[0020] Compared with the prior art, the beneficial technical effects of the present invention are:

[0021] A material that meets user requirements has been developed. Using the design concept of low carbon + phosphorus + silicon + manganese, a low-cost production method for galvanized special steel for drum washing machines has been designed.

[0022] By strictly controlling the contents of C, Si, Mn, P and N and formulating reasonable processes, we can ensure that the washing machine plate has a certain plasticity and strength (formability and anti-clamping deformation ability), and achieve a finished product yield strength of 180-240MPa, a tensile strength of 290-360MPa, and an elongation of ≥40%. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below in conjunction with the accompanying drawings.

[0024] Figure 1 The metallographic structure of the low-cost drum washing machine plate of the present invention;

[0025] Figure 2 The following are photos of the actual washing machine panels and their components that have been processed by the user according to the product manufactured according to the present invention. DETAILED DESCRIPTION

[0026] A method for producing a low-cost drum washing machine plate, comprising:

[0027] Smelting process:

[0028] KR desulfurization process: The molten iron needs to be treated with KR desulfurization, and the sulfur content of the molten iron entering the converter is required to be less than 0.015%, and the slag cleaning area of ​​the molten iron is required to be greater than 90%.

[0029] Converter smelting process: converter endpoint control requirements: tapping temperature ≥ 1660℃, use normal turnover ladle to tap steel, tapping temperature drop requirement is less than 70℃. Add top slag modifier according to the oxygen content of molten steel and the amount of slag.

[0030] RH process: Decarburization is carried out according to the composition and temperature of the RH molten steel supplied by the converter. After decarburization, aluminum particles are added for deoxidation according to the oxygen setting conditions. After deoxidation, alloys such as ferromanganese are added to adjust the composition of the molten steel to the target value.

[0031] Continuous casting process: The casting machine adopts constant casting speed control, and the casting speed range is 1.0-1.8m / min.

[0032] Hot rolling process:

[0033] The ingot was heated in a walking beam heating furnace (the heating process is shown in Table 1), the rough rolling adopted the 3+3 mode, the finishing rolling adopted F1-F7 continuous rolling, the cooling method was post-dispersion, and the specific hot rolling process was shown in Table 2.

[0034] Table 1 Billet heating system

[0035]

[0036] Table 2 Rolling process

[0037]

[0038]

[0039] Galvanizing process

[0040] The outlet temperature control conditions of each section of the galvanizing annealing furnace are shown in Table 3, and the elongation settings of the leveler and straightening machine are shown in Table 4.

[0041] Table 3 Annealing process

[0042]

[0043] Table 4 Leveling machine and tension leveling machine process

[0044]

[0045] Example Analysis

[0046] Steelmaking ingredients:

[0047] According to the above steelmaking process requirements, the actual slab chemical composition (mass percentage) is shown in Table 5.

[0048] Table 5 Chemical composition of examples wt.%

[0049]

[0050] Finished product performance: The room temperature tensile mechanical properties of the finished product are shown in Table 6. The yield and tensile strength of the product are stable, meeting the user's requirements. The product manufactured according to the present invention has a small fluctuation range, and the metallographic structure is ferrite + a small amount of pearlite. The organizational morphology is shown in Table 6. Figure 1 .

[0051] Table 6 Tensile mechanical properties of finished products

[0052]

[0053] Usage:

[0054] The products manufactured according to the present invention are processed by the user into washing machine panels and their parts such as Figure 2 As shown, the stamping condition is good and meets the user's requirements.

[0055] In summary, the performance indicators and formability of this product meet the user's requirements and have been supplied in batches.

[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 low-cost drum washing machine plates, characterized in that: include: Steelmaking process: KR desulfurization → converter → RH refining → slab continuous casting; the chemical composition of the molten steel by mass percentage is: 0.010% ≤ C ≤ 0.020%, Si ≤ 0.03%, 0.15% ≤ Mn ≤ 0.25%, 0.007% ≤ P ≤ 0.017%, S ≤ 0.010%, N ≤ 0.0040%, the rest is Fe and unavoidable impurities; Hot rolling process: heating furnace → rough rolling high-pressure water descaling machine → fixed width press → E1R1 rough rolling mill → E2R2 rough rolling mill → insulation cover → flying shear → finishing high-pressure water descaling machine → F1-F7 finishing mill → encrypted laminar cooling → coiler; slab heating temperature is 1180-1220℃, finishing rolling temperature is ≥880℃, coiling temperature is 700-730℃; Pickling process: Pickling uncoiling → welding → straightening → pickling → rinsing → drying → trimming → rolling → coiler → pickling reduction rate ≥ 70%; Galvanizing process: hot-dip galvanizing uncoiling → welding → entrance looper → cleaning → annealing furnace → zinc pot → cooling after plating → water quenching → intermediate looper → skin pass machine → straightening machine → roller coater → dryer → air cooling device → exit looper → trimming → surface inspection → oiling → sampling → coiling; galvanizing annealing heating / soaking section outlet temperature 780-800℃, slow cooling section outlet temperature 670-690℃, skin pass machine elongation 1.2-1.50%, straightening machine elongation 0.20%, production line speed 90-120m / min.

2. The method for producing a low-cost drum washing machine plate according to claim 1, characterized in that: After KR desulfurization treatment, the sulfur content of the molten iron entering the converter is required to be less than 0.015%, and the slag removal area of ​​the molten iron is required to be greater than 90%.

3. The method for producing a low-cost drum washing machine plate according to claim 1, characterized in that: The control requirements of converter endpoint are: the tapping temperature is ≥1660℃, and the tapping temperature drop is required to be less than 70℃ when using a normal turnover ladle for tapping. Add top slag modifier according to the oxygen content of molten steel and the amount of slag.

4. The method for producing a low-cost drum washing machine plate according to claim 1, characterized in that: The casting machine adopts constant pulling speed control, and the pulling speed range is 1.0-1.8m / min.

5. The method for producing a low-cost drum washing machine plate according to claim 1, characterized in that: The chemical composition of the washing machine plate by mass percentage is: C 0.018%, Si 0.002%, Mn 0.22%, P 0.010%, S 0.007%, N 0.0020%, and the rest is Fe and unavoidable impurities.

6. The method for producing a low-cost drum washing machine plate according to claim 1, characterized in that: The chemical composition of the washing machine plate by mass percentage is: C 0.016%, Si 0.008%, Mn 0.23%, P 0.013%, S 0.005%, N 0.0012%, and the rest is Fe and unavoidable impurities.

7. The method for producing low-cost drum washing machine plates according to claim 1, characterized in that: The chemical composition of the washing machine plate by mass percentage is: C 0.015%, Si 0.007%, Mn 0.24%, P 0.011%, S 0.006%, N 0.0011%, and the rest is Fe and unavoidable impurities.

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