Hot-dip galvanized steel plate for household appliances and preparation method thereof

Abstract

The invention discloses a hot-dip galvanized steel plate for household appliances and a preparation method thereof, and relates to the technical field of steel plate production. The hot-dip galvanized steel plate for the household appliances disclosed by the invention comprises the following chemical components in percentage by weight: 0.001 to 0.005 percent of C, 0.08 to 0.15 percent of Si, 0.60 to 1.2 percent of Mn, 0.040 to 0.090 percent of P, less than or equal to 0.015 percent of S, 0.020 to 0.060 percent of Als, 0.030 to 0.080 percent of Nb, 0.030 to 0.080 percent of Ti, 0.02 to 0.04 percent of Co and the balance of Fe and inevitable impurities. According to the embodiment of the invention, by controlling the mass percentage of each steel component in the hot-dip galvanized steel plate for the household appliances, the elongation and forming capacity of the hot-dip galvanized steel plate for the household appliances are improved on the basis of ensuring the strength of the hot-dip galvanized steel plate for the household appliances.

Description

Technical Field

[0001] The invention relates to the technical field of steel plate production, and in particular to a hot-dip galvanized steel plate for household appliances and a preparation method thereof. Background Art

[0002] As an important anti-corrosion material, hot-dip galvanized steel sheet is widely used in many industries, including construction, automobile manufacturing, home appliances, light industry, agriculture, animal husbandry and fishery, etc. Hot-dip galvanized steel sheet has excellent corrosion resistance, formability and coating performance, strong electrochemical protection performance, thick and dense coating, strong bonding with steel matrix, and service life of more than 30 years.

[0003] High-strength hot-dip galvanized steel sheets can improve the strength of parts, reduce their weight and reduce costs. With China's vigorous development of electricity, transportation, communications, energy and urban infrastructure, as well as the launch of the building steel structure market, high-strength hot-dip galvanized steel faces unprecedented opportunities and a huge market. In the field of home appliances, the demand for high-formability hot-dip galvanized steel sheets is even more urgent.

[0004] The elongation of hot-dip galvanized steel sheets for household appliances prepared by the existing methods is generally low and the forming performance is poor. Therefore, there is room for improvement in the existing technology. Summary of the invention

[0005] In view of this, the present invention provides a hot-dip galvanized steel sheet for household appliances and a preparation method thereof, which solves the problems of low elongation and poor forming performance of the existing hot-dip galvanized steel sheet for household appliances.

[0006] On the one hand, an embodiment of the present invention provides a hot-dip galvanized steel sheet for household appliances. The chemical composition of the hot-dip galvanized steel sheet includes, by weight percentage: C: 0.001-0.005%, Si: 0.08-0.15%, Mn: 0.60-1.2%, P: 0.040-0.090%, S: ≤0.015%, Als: 0.020-0.060%, Nb: 0.030-0.080%, Ti: 0.030-0.080%, Co: 0.02-0.04%, and the remainder is Fe and unavoidable impurities.

[0007] On the other hand, an embodiment of the present invention further provides a method for preparing a hot-dip galvanized steel sheet for household appliances, the method for preparing the hot-dip galvanized steel sheet comprising the following steps: The steel components are controlled according to the following weight percentages: C: 0.001-0.005%, Si: 0.08-0.15%, Mn: 0.60-1.2%, P: 0.040-0.090%, S: ≤0.015%, Als: 0.020-0.060%, Nb: 0.030-0.080%, Ti: 0.030-0.080%, Co: 0.02-0.04%, and the balance is Fe and unavoidable impurities, and the steel components are continuously cast into continuous casting billets; The continuous casting slab is subjected to rough rolling, finish rolling and coiling in sequence to obtain a hot rolled coil; cold rolling the hot rolled coil into a cold rolled coil; The cold rolled coil is annealed and hot dip galvanized to obtain a hot dip galvanized steel sheet.

[0008] In some embodiments, the continuous casting slab is subjected to rough rolling, finish rolling and coiling in sequence to obtain a hot rolled coil, comprising: The continuous casting slab is subjected to rough rolling, finish rolling and coiling in sequence to obtain a hot rolled coil.

[0009] In some embodiments, the continuous casting slab is subjected to rough rolling, finish rolling and coiling in sequence to obtain a hot rolled coil, comprising: Rough rolling is performed on the continuous casting slab to obtain an intermediate slab; The intermediate slab is sequentially finish rolled and coiled to obtain a hot rolled coil.

[0010] In some embodiments, rough rolling is performed on the continuous casting slab to obtain an intermediate slab, comprising: Rough rolling the continuous casting slab at a first temperature to obtain an intermediate slab; The intermediate slab is sequentially subjected to finish rolling and coiling to obtain a hot rolled coil, including: Finish rolling the intermediate slab to obtain a finish rolled slab; The slab obtained after finish rolling is cooled to a second temperature, and the slab cooled to the second temperature is coiled to obtain a hot rolled coil, wherein the first temperature is greater than the finish rolling start temperature, greater than the finish rolling final temperature, and greater than the second temperature.

[0011] In some embodiments, cold rolling a hot rolled coil into a cold rolled coil comprises: The hot rolled coil is cold rolled into a cold rolled coil at a preset cold rolling reduction rate.

[0012] In some embodiments, cold rolling a hot rolled coil into a cold rolled coil at a preset cold rolling reduction rate comprises: The hot rolled coil is alkali washed, and the alkali washed hot rolled coil is cold rolled into a cold rolled coil at a preset cold rolling reduction rate.

[0013] In some embodiments, the cold rolled coil is annealed and hot-dip galvanized to obtain a hot-dip galvanized steel sheet, comprising: The cold rolled coil is sequentially subjected to annealing, hot dip galvanizing, tension leveling and skin pass to obtain a hot dip galvanized steel sheet.

[0014] In some embodiments, annealing the cold rolled coil comprises: The cold rolled coil is continuously annealed at a preset running speed, and the annealing soaking temperature and the slow cooling endpoint temperature are controlled during the continuous annealing process.

[0015] In some embodiments, the second temperature is in the range of 700°C to 720°C; Controlling the annealing soaking temperature includes controlling the annealing soaking temperature within the range of 790°C to 800°C; The cold rolled coils are sequentially annealed, hot dip galvanized, straightened and skin-passed, including: The cold rolled coil is sequentially subjected to annealing, hot dip galvanizing, tension straightening and skin pass, and the tension straightening elongation is controlled within the range of 0.2% to 0.5%, and the skin pass elongation is controlled within the range of 0.2% to 0.8%.

[0016] The present invention has at least the following beneficial effects: The present invention provides a hot-dip galvanized steel sheet for household appliances and a preparation method thereof. The household hot-dip galvanized steel sheet and a preparation method thereof provided by the present invention can improve the elongation and forming ability of the hot-dip galvanized steel sheet while ensuring the strength of the hot-dip galvanized steel sheet by controlling the mass percentage of each steel component in the hot-dip galvanized steel sheet. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A flow chart of a method for preparing a hot-dip galvanized steel sheet for household appliances provided in an embodiment of the present invention; Figure 2 A flow chart of a hot rolling method for a steel plate provided by an embodiment of the present invention; Figure 3 A flow chart of a hot-dip galvanizing method for a steel plate provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0020] It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are for distinguishing two non-identical entities with the same name or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. The subsequent embodiments will not explain this one by one.

[0021] In order to solve the problems of low elongation and poor forming performance of hot-dip galvanized steel sheets for household appliances in the related art, the present invention provides a hot-dip galvanized steel sheet for household appliances and a preparation method thereof.

[0022] The present invention is described in detail below in conjunction with embodiments and drawings.

[0023] A first aspect of an embodiment of the present invention provides a hot-dip galvanized steel sheet for household appliances, wherein the chemical composition of the hot-dip galvanized steel sheet includes, in terms of weight percentage: C: 0.001-0.005%, Si: 0.08-0.15%, Mn: 0.60-1.2%, P: 0.040-0.090%, S: ≤0.015%, Als: 0.020-0.060%, Nb: 0.030-0.080%, Ti: 0.030-0.080%, Co: 0.02-0.04%, and the remainder is Fe and unavoidable impurities.

[0024] The C content in hot-dip galvanized steel sheet directly affects its microstructure, and then affects the elongation of hot-dip galvanized steel sheet. Low carbon content helps to refine the pearlite structure, thereby improving the plasticity and elongation of the material.

[0025] In the present invention, the C content is controlled within the range of 0.001 to 0.005%, which can improve the purity of steel and effectively improve the elongation and forming ability of the hot-dip galvanized steel sheet. When the hot-dip galvanized steel sheet is used for parts processing, it can be beneficial to the stamping of parts and reduce cracking and springback, and is particularly suitable for deep drawing in the field of home appliances.

[0026] Si, as a ferrite solid solution strengthening element, can significantly improve the strength of the steel sheet. For example, adding Si to high-strength steel can promote the formation of ferrite, thereby improving the yield strength and tensile strength of the material. However, in hot-dip galvanized steel sheets, Si is one of the elements that promotes the most intense iron-zinc reaction, which can significantly affect the structure of the coating and the appearance and performance of the galvanized product. During the hot-dip galvanizing process, excessive Si content will lead to oxidation enrichment on the surface of the steel sheet, thereby deteriorating the quality of galvanizing. Therefore, in the present invention, the Si content is controlled within the range of 0.08 to 0.15%, thereby providing the strength of the steel sheet.

[0027] In hot-dip galvanized steel sheets, the content of Mn has a significant effect on the elongation and formability of the hot-dip galvanized steel sheets. In the present invention, the Mn content needs to be controlled within the range of 0.60 to 1.2%, which can effectively improve the elongation and plasticity of the hot-dip galvanized steel sheets. When processing parts, it can be beneficial to the stamping of parts, reduce cracking and rebound, and is particularly suitable for use in the field of home appliances.

[0028] P is a solid solution strengthening element that can improve the mechanical strength of steel. However, too high a P content will increase the brittleness of the steel and segregate at the grain boundaries, affecting the plasticity and weldability of the steel. Therefore, in the present invention, the P content needs to be controlled within the range of 0.040 to 0.090%, thereby improving the plasticity and strength of the steel plate.

[0029] In hot-dip galvanized steel sheets, the tensile strength of the steel sheets can be significantly improved by adding 0.60-1.2% Mn and 0.040-0.090% P.

[0030] S is a harmful element in steel. S will form FeS in steel, which affects the quality of hot-dip galvanized steel sheets. Therefore, in the present invention, the S content is controlled below 0.015% to reduce the impact of S on the quality of the steel sheet.

[0031] Aluminum Als is mainly used as a deoxidizer in the hot-dip galvanizing process to improve the purity of steel and improve the steel quality. However, too high an Als content will affect the welding performance of the steel and the control of inclusions in the ingot. Therefore, in the present invention, the Als content is controlled at 0.020-0.060%, thereby improving the quality of the hot-dip galvanized steel sheet.

[0032] Nb is a grain refining element. By combining with C to form fine carbides (such as NbC), ferrite grains can be significantly refined, thereby improving the strength and toughness of the steel sheet. During the hot-dip galvanizing process, undissolved NbC particles can pin the ferrite grain boundaries and further refine the grains. The addition of Nb can improve the yield strength and tensile strength of the steel sheet through precipitation strengthening and grain refinement strengthening. Therefore, in the present invention, the Nb content is controlled within the range of 0.030 to 0.080%, thereby improving the strength and toughness of the hot-dip galvanized steel sheet, thereby improving the formability of the hot-dip galvanized steel sheet.

[0033] Ti can form titanium carbide compounds with C in steel, improve the strength of the steel sheet and refine the ferrite grains. In the present invention, the Ti content is controlled within the range of 0.030-0.080%, which can improve the strength and toughness of the hot-dip galvanized steel sheet, thereby improving the formability of the hot-dip galvanized steel sheet.

[0034] Co is a carbide-forming element that can improve the performance of steel, delay grain coarsening, inhibit martensite recovery and recrystallization, and thus improve the strength and toughness of steel. In the present invention, the Co content is controlled within the range of 0.02-0.04%, which can improve the strength and toughness of the hot-dip galvanized steel sheet.

[0035] The embodiment of the present invention can improve the elongation and formability of the hot-dip galvanized steel sheet while ensuring the strength of the hot-dip galvanized steel sheet by controlling the mass percentage of each steel component in the hot-dip galvanized steel sheet.

[0036] On the other hand, an embodiment of the present invention further provides a method for preparing a hot-dip galvanized steel sheet for household appliances.

[0037] like Figure 1 As shown, the method for preparing a hot-dip galvanized steel sheet provided in an embodiment of the present invention comprises the following steps: S1. Continuously casting each steel component into a continuous casting billet.

[0038] Among them, the weight percentage of each steel component is: C: 0.001~0.005%, Si: 0.08~0.15%, Mn: 0.60~1.2%, P: 0.040~0.090%, S: ≤0.015%, Als: 0.020~0.060%, Nb: 0.030~0.080%, Ti: 0.030~0.080%, Co: 0.02~0.04%, and the balance is Fe and unavoidable impurities.

[0039] S2. Rough rolling, finish rolling and coiling are performed on the continuous casting billet in sequence to obtain a hot rolled coil.

[0040] The heated continuous casting billet is initially compressed and stretched by rough rolling to form a thinner steel plate. The rough rolled steel plate is further reduced in thickness by finish rolling, thereby improving the surface quality and dimensional accuracy of the steel. The finish rolled steel plate is coiled to obtain a hot rolled coil.

[0041] S3, cold rolling the hot rolled coil into a cold rolled coil.

[0042] In order to improve the strength, surface quality and smoothness of the steel plate, the hot rolled coil is cold rolled into a cold rolled coil.

[0043] S4. Annealing and hot-dip galvanizing the cold-rolled coil to obtain a hot-dip galvanized steel sheet.

[0044] The cold rolled coil is continuously annealed, and the sheet after continuous annealing is directly hot-dip galvanized to obtain a hot-dip galvanized steel sheet.

[0045] According to the embodiment of the present invention, by controlling the mass percentage of each steel component in the hot-dip galvanized steel sheet, the formability of the hot-dip galvanized steel sheet can be improved while ensuring the strength of the hot-dip galvanized steel sheet.

[0046] In some embodiments, the present invention Figure 1 The step S2 shown, sequentially rough rolling, finish rolling and coiling the continuous casting billet to obtain a hot rolled coil, may include: rough rolling the continuous casting billet to obtain an intermediate slab; sequentially finish rolling and coiling the intermediate slab to obtain a hot rolled coil.

[0047] In some embodiments, the present invention Figure 1 Step S2 shown in the figure is to sequentially perform rough rolling, finish rolling and coiling on the continuous casting billet to obtain a hot rolled coil, and may also include the following steps: Figure 2 Steps S21 to S24 are shown.

[0048] S21. Rough rolling the continuous casting billet at a first temperature to obtain an intermediate slab.

[0049] In a specific implementation, the continuous casting billet is heated to a first temperature, and rough rolled during a furnace time of 200 to 260 minutes to obtain an intermediate billet.

[0050] The first temperature can be controlled within the range of 1220°C to 1250°C, the rough rolling can be performed in multiple passes, for example, 5 passes, and the whole length of the rough rolling is fully dephosphorized. The thickness of the intermediate slab can be controlled within the range of 35mm to 38mm.

[0051] S22, finishing rolling the intermediate slab to obtain a finish-rolled slab.

[0052] S23, cooling the slab obtained after finish rolling to a second temperature, and coiling the slab cooled to the second temperature to obtain a hot-rolled coil.

[0053] Among them, the first temperature is greater than the finishing rolling start temperature, greater than the finishing rolling final temperature, and greater than the second temperature.

[0054] In a specific implementation, the finishing rolling start temperature can be controlled within the range of 1150°C to 1190°C.

[0055] In a specific implementation, the finishing rolling temperature can be controlled within the range of 890°C to 950°C.

[0056] In a specific implementation, the steel plate obtained after finish rolling is cooled, cooled to a second temperature and then coiled to obtain a hot-rolled coil of a certain thickness.

[0057] The second temperature can be controlled within the range of 700℃~720℃. The coiling temperature has an important influence on the structure and performance of steel. In the hot-dip galvanizing process, the coiling temperature is controlled within the range of 700℃~720℃. A higher coiling temperature can promote the phase transformation of the steel plate, improve the grain heterogeneity, and improve the formability and plasticity of the steel plate.

[0058] In some embodiments, the present invention Figure 1 The step S3 shown, cold rolling the hot rolled coil into the cold rolled coil, may include: cold rolling the hot rolled coil into the cold rolled coil at a preset cold rolling reduction rate.

[0059] In a specific implementation, the cold rolling reduction ratio is set in the range of 70% to 80%, so that the hot rolled coil is cold rolled into a cold rolled coil at the cold rolling reduction ratio.

[0060] In some embodiments, cold rolling the hot rolled coil into the cold rolled coil at a preset cold rolling reduction rate may include: alkali washing the hot rolled coil, and cold rolling the alkali washed hot rolled coil into the cold rolled coil at the preset cold rolling reduction rate.

[0061] In a specific implementation, after the hot rolled coil is cleaned by alkali washing, the cleaned hot rolled coil is cold rolled into a cold rolled coil at a preset cold rolling reduction rate.

[0062] In some embodiments, the present invention Figure 1 The step S4 shown, annealing and hot-dip galvanizing the cold-rolled coil to obtain the hot-dip galvanized steel sheet, may include: sequentially annealing, hot-dip galvanizing, straightening and skin-passing the cold-rolled coil to obtain the hot-dip galvanized steel sheet.

[0063] In the hot-dip galvanizing process, the cold-rolled coil is annealed through preheating, heating, soaking and cooling. The strip is heated to the recrystallization temperature to restore the material's processing and forming properties, and improve the cleanliness of the strip surface so that it can be sealed into the zinc pot for hot-dip galvanizing. After that, the hot-dip galvanized steel sheet is straightened and skin-passed. Straightening ensures the flatness and mechanical properties of the hot-dip galvanized steel sheet. Skin-passing ensures the strip shape and surface quality.

[0064] In some embodiments, the present invention Figure 1 Step S4 shown in the figure, annealing and hot-dip galvanizing the cold-rolled coil to obtain a hot-dip galvanized steel sheet, may also include the following steps: Figure 3 S31 and S32 shown.

[0065] S31, continuously annealing the cold-rolled coil at a preset running speed, and controlling the annealing soaking temperature and the slow cooling endpoint temperature during the continuous annealing process.

[0066] The running speed of the cold rolled coil can ensure the uniformity of heating of the steel plate during the annealing process, thereby enhancing the adhesion and toughness of the zinc layer.

[0067] The soaking temperature directly affects the recrystallization annealing effect of the strip. The soaking treatment can keep the strip at the specified annealing temperature for a period of time to ensure the recrystallization of the strip. If the soaking temperature is too low, the strip may not be fully recrystallized, affecting the quality of the subsequent coating; while too high a temperature may cause oxidation on the strip surface, increase iron loss, and thus affect the uniformity and adhesion of the coating.

[0068] In a specific implementation, the annealing soaking temperature is controlled within the range of 790°C to 800°C, which can effectively improve the strength of the steel plate and the coating quality, make the steel plate have good forming performance, and can also save energy and improve the production efficiency of the steel plate.

[0069] Reasonable control of hot-dip galvanized strip speed and annealing temperature. For example, when annealing at 810℃, controlling the hot-dip galvanized strip speed at 75~95 m / min can obtain good forming performance and mechanical properties.

[0070] The selection of slow cooling temperature has an important influence on the microstructure and properties of the coating. During the hot-dip galvanizing process, appropriate slow cooling temperature can promote the uniform growth of the Fe-Zn alloy layer in the coating, avoid the increase of iron loss and zinc slag formation caused by excessive temperature, thereby improving the adhesion and corrosion resistance of the coating and improving the overall quality of the coating.

[0071] S32. The cold-rolled coil is subjected to annealing, hot-dip galvanizing, straightening and skin-passing in sequence, and during the straightening process, the straightening elongation is controlled within the range of 0.2% to 0.5%, and during the skin-passing process, the skin-passing elongation is controlled within the range of 0.2% to 0.8%.

[0072] In a specific implementation, the flatness and mechanical properties of hot-dip galvanized steel sheets are improved by controlling the elongation of straightening within the range of 0.2% to 0.5%. The shape and surface quality of the strip are improved by controlling the elongation of skin-finishing within the range of 0.2% to 0.8%.

[0073] The following is a specific example of the embodiment of the present invention. Figure 1 Unless otherwise specified, the raw materials, equipment, consumables, etc. used in the following examples can be obtained by conventional commercial means.

[0074] For the parts involving numerical ranges, those skilled in the art can select any value within the numerical range defined by the present invention according to actual needs, and are not limited to the numerical values ​​listed in the specific embodiments.

[0075] Examples 1 to 3 and Comparative Examples 1 and 2: S1. Continuously casting each steel component into a continuous casting billet.

[0076] The various steel components in the continuous casting billet are shown in Table 1.

[0077] Table 1 Chemical composition (wt.%)

[0078] S2. Rough rolling, finish rolling and coiling are performed on the continuous casting billet in sequence to obtain a hot rolled coil.

[0079] Specifically, the continuous casting billet is subjected to rough rolling and finish rolling in sequence according to the hot rolling process parameters shown in Table 2, and after the finish rolling, the steel is cooled to the coiling temperature and coiled to obtain a hot rolled coil with a thickness of 3.5 mm.

[0080] Table 2 Hot rolling process parameters

[0081] S3, cold rolling the hot rolled coil into a cold rolled coil.

[0082] The cold rolling reduction ratio of the hot rolled coil to the cold rolled coil is 80%.

[0083] S4. Annealing and hot-dip galvanizing the cold-rolled coil to obtain a hot-dip galvanized steel sheet.

[0084] Specifically, the cold-rolled coil is continuously annealed, and the soaking temperature and the slow cooling end temperature during the continuous annealing process are controlled according to the soaking temperature and the slow cooling end temperature in Table 3. The slowly cooled steel sheet is placed in a zinc pot, wherein the zinc pot temperature is controlled according to the zinc pot temperature in Table 3. The steel sheet coming out of the zinc pot is sequentially tension-corrected and skin-passed according to the tension-corrected elongation and skin-passed elongation in Table 3, and the mechanical parameters of the obtained hot-dip galvanized steel sheet are shown in Table 4.

[0085] Table 3 Continuous annealing process parameters

[0086] Table 4 Mechanical properties of cold rolled steel sheets

[0087] In Table 4, n 90 and r 90 The value is an important indicator to measure its forming performance. 90 The value represents the strain hardening exponent of the material during the tensile process, while r 90 The value indicates the material's ability to rebound during bending.

[0088] From the mechanical property analysis of the above embodiments and comparative examples, it can be seen that compared with comparative examples 1-2, embodiments 1-3 improve the elongation of the hot-dip galvanized steel sheet.

[0089] The higher the elongation of the steel plate, the better the forming ability. The hot-dip galvanized steel plates suitable for the home appliance field obtained by Examples 1 to 3 of the present invention have good elongation and forming ability, which can not only meet the strength requirements of the home appliance field for the parts, but also significantly improve the forming ability of the parts. Comparative Examples 1 and 2, although the tensile strength and yield strength are slightly higher than those of Examples 1 to 3, their elongation is lower, and the forming ability of the parts manufactured by the hot-dip galvanized steel plates is lower.

[0090] Through the above embodiments, the method of the present invention can be used to obtain a high-formability hot-dip galvanized steel sheet for household appliances, and the finished mechanical properties of the hot-dip galvanized steel sheet meet the following requirements: yield strength of 280-340 MPa, tensile strength of 400-460 MPa, elongation ≥36.0%, n 90 ≥0.20, r 90 ≥1.7.

[0091] The high-formability hot-dip galvanized steel sheet for household appliances in the embodiment of the present invention can improve the formability of parts and reduce weight, meet the user's demand for lightweight structure while ensuring the user's performance, and plays an important role in improving the structure of cold-rolled galvanized products.

[0092] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0093] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A hot-dip galvanized steel sheet for household appliances, characterized in that: According to weight percentage, the chemical composition of the hot-dip galvanized steel sheet includes: C: 0.001-0.005%, Si: 0.08-0.15%, Mn: 0.60-1.2%, P: 0.040-0.090%, S: ≤0.015%, Als: 0.020-0.060%, Nb: 0.030-0.080%, Ti: 0.030-0.080%, Co: 0.02-0.04%, and the balance is Fe and unavoidable impurities.

2. A method for preparing a hot-dip galvanized steel sheet for household appliances, characterized in that: The method comprises the following steps: The steel components are controlled according to the following weight percentages: C: 0.001-0.005%, Si: 0.08-0.15%, Mn: 0.60-1.2%, P: 0.040-0.090%, S: ≤0.015%, Als: 0.020-0.060%, Nb: 0.030-0.080%, Ti: 0.030-0.080%, Co: 0.02-0.04%, and the balance is Fe and unavoidable impurities, and the steel components are continuously cast into continuous casting billets; The continuous casting slab is subjected to rough rolling, finish rolling and coiling in sequence to obtain a hot rolled coil; Cold rolling the hot rolled coil into the cold rolled coil; The cold rolled coil is annealed and hot dip galvanized to obtain a hot dip galvanized steel sheet.

3. The method according to claim 2, characterized in that The step of sequentially rough rolling, finish rolling and coiling the continuously cast slab to obtain a hot rolled coil comprises: Rough rolling the continuous casting slab to obtain an intermediate slab; The intermediate slab is sequentially finish-rolled and coiled to obtain a hot-rolled coil.

4. The method according to claim 3, characterized in that The step of rough rolling the continuous casting billet to obtain an intermediate slab comprises: Rough rolling the continuous casting slab at a first temperature to obtain an intermediate slab; The method of sequentially finishing rolling and coiling the intermediate slab to obtain a hot rolled coil comprises: Finish rolling the intermediate slab to obtain a finish rolled slab; The slab after finish rolling is cooled to a second temperature, and the slab cooled to the second temperature is coiled to obtain a hot rolled coil, wherein the first temperature is greater than the finish rolling start temperature, greater than the finish rolling final temperature, and greater than the second temperature.

5. The method according to claim 4, characterized in that The second temperature is in the range of 700°C to 720°C.

6. The method according to claim 2, characterized in that The step of cold-rolling the hot-rolled coil into the cold-rolled coil comprises: The hot rolled coil is cold rolled into a cold rolled coil at a preset cold rolling reduction rate.

7. The method according to claim 6, characterized in that The step of cold rolling the hot rolled coil into a cold rolled coil at a preset cold rolling reduction rate comprises: The hot rolled coil is alkali washed, and the alkali washed hot rolled coil is cold rolled into a cold rolled coil at the preset cold rolling reduction rate.

8. The method according to claim 2, characterized in that: The step of annealing and hot-dip galvanizing the cold-rolled coil to obtain a hot-dip galvanized steel sheet comprises: The cold rolled coil is subjected to annealing, hot dip galvanizing, tension straightening and skin pass in sequence, thereby obtaining a hot dip galvanized steel sheet.

9. The method according to claim 8, characterized in that The step of annealing the cold rolled coil comprises: The cold rolled coil is continuously annealed at a preset running speed, and the annealing soaking temperature and the slow cooling endpoint temperature are controlled during the continuous annealing process.

10. The method according to claim 9, characterized in that The controlling of the annealing soaking temperature includes controlling the annealing soaking temperature within a range of 790° C. to 800° C.; The cold-rolled coil is sequentially subjected to annealing, hot-dip galvanizing, tension straightening and skin pass, including: The cold rolled coil is sequentially subjected to annealing, hot-dip galvanizing, tension straightening and skin pass, and during the tension straightening process, the tension straightening elongation is controlled within the range of 0.2% to 0.5%, and during the skin pass process, the skin pass elongation is controlled within the range of 0.2% to 0.8%.

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