Production method of 420MPa-grade zinc-aluminum-magnesium structural steel for low-cost photovoltaic bracket

Abstract

The invention discloses a production method of 420MPa-grade zinc-aluminum-magnesium structural steel for a low-cost photovoltaic bracket. The production method is characterized by comprising the following working procedures: a steelmaking working procedure, a hot rolling working procedure, a cold rolling working procedure and an annealing working procedure, wherein the casting blank comprises the following chemical components in percentage by mass: less than or equal to 0.22% of C; less than or equal to 0.10% of Si; mn < = 1.0%; less than or equal to 0.020% of P; s is less than or equal to 0.010%; alt is greater than or equal to 0.020%; ti is greater than or equal to 0.050%, N is less than or equal to 0.0080%, and the balance is Fe and inevitable impurities. According to the production method of the 420 MPa level zinc-aluminum-magnesium structural steel for the low-cost photovoltaic support, the cost is reduced, and meanwhile the mechanical properties meet the requirements that the yield strength is larger than or equal to 420 MPa, the tensile strength is larger than or equal to 480 MPa, the ductility is larger than or equal to 15.0%, and the yield ratio is smaller than 0.9.

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 420MPa grade zinc-aluminum-magnesium structural steel for low-cost photovoltaic brackets. Background Art

[0002] With the continuous improvement of the cold-rolled product series, customization for users according to market demand has become the mainstream of current design. Photovoltaic power generation has become a green, low-carbon and sustainable thermal power project. Through market research, it is found that there is a broad market demand for 420MPa grade zinc-aluminum-magnesium structural steel for low-cost photovoltaic brackets, which has requirements for strength and yield strength ratio. On the basis of meeting the user's use conditions, the purpose of this patent is to explore the feasibility of low-cost product development. Summary of the invention

[0003] The purpose of the present invention is to provide a method for producing 420MPa grade zinc-aluminum-magnesium structural steel for low-cost photovoltaic brackets, which reduces costs while meeting the following mechanical properties: yield strength ≥420MPa, tensile strength ≥480MPa, elongation ≥15.0%, and yield strength ratio <0.9.

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

[0005] The present invention provides a method for producing 420MPa grade zinc-aluminum-magnesium structural steel for low-cost photovoltaic brackets, comprising the following steps: steelmaking step - hot rolling step - cold rolling step - annealing step; wherein:

[0006] In the steelmaking process, a cast billet is obtained, and the chemical composition of the cast billet is calculated by mass percentage as follows: C≤0.22%; Si≤0.10%; Mn≤1.0%; P≤0.020%; S≤0.010%; Alt≥0.020%; Ti≥0.050%, N≤0.0080%, and the rest is Fe and unavoidable impurities;

[0007] The hot rolling process includes: heating of the ingot - high-pressure water descaling - fixed width press - E1R1 roughing mill rolling - E2R2 roughing mill rolling - insulation cover - flying shear - high-pressure water descaling - F1-F7 finishing mill rolling - encrypted laminar cooling - coiling; wherein:

[0008] In the heating of the ingot, the heating temperature is controlled to be 1210-1280°C, the heating time is 160-250min, the soaking temperature is 1230-1270°C, the soaking time is 25-60min, the furnace temperature is 1230-1270°C, the final rolling temperature of the finishing rolling is controlled to be 850-950°C, the coiling temperature is 550-650°C, and the cooling method is the front dispersion cooling method;

[0009] In the annealing process, the annealing heating temperature is controlled to be 700-730° C., the annealing soaking temperature is controlled to be 700-730° C., and the leveling machine elongation is controlled to be 0.5-1.0%.

[0010] Furthermore, the mechanical properties of the 420MPa grade zinc-aluminum-magnesium structural steel used for the photovoltaic bracket meet the following requirements: yield strength ≥420MPa, tensile strength ≥480MPa, elongation ≥15.0%, and yield strength ratio <0.9.

[0011] Furthermore, the steelmaking process includes: optimizing the converter top and bottom combined blowing smelting-LF-RH-slab continuous casting process to converter top and bottom combined blowing smelting-LF-slab continuous casting, thereby reducing the production cost by reducing the RH process; wherein:

[0012] The tapping temperature of the converter is ≥1600℃ to ensure that the composition and temperature are coordinated. During the tapping process of the converter, aluminum iron, silicon iron and manganese iron are added for deoxidation and alloying.

[0013] LF refining process slag, deoxidation and desulfurization, adding aluminum, ferrosilicon, ferromanganese and ferrotitanium and other alloys to adjust the composition to the target range;

[0014] In the slab continuous casting, the superheat degree of the intermediate ladle is controlled within a range of 15 to 40° C. during the casting process of the casting machine, and the production casting speed is 1.0 to 1.8 m / min.

[0015] Furthermore, the cold rolling process includes: pickling uncoiling - welding - straightening - pickling - rinsing - drying - trimming - continuous rolling mill cold rolling - coiling;

[0016] The annealing process includes: uncoiling - welding - inlet looper - cleaning - annealing furnace - zinc-aluminum-magnesium pot - cooling after plating - water quenching - intermediate looper - skin pass machine - roller coater - dryer - outlet looper - trimming - surface inspection - oiling - sampling - coiling - weighing - packaging.

[0017] Furthermore, the thickness of the ingot is 230 mm, the thickness of the ingot after hot rolling is 3.2-5.0 mm, and the thickness of the ingot after cold rolling is 1.2-2.5 mm.

[0018] Furthermore, the chemical composition of the ingot is as follows by mass percentage: C 0.16%, Si 0.05%, Mn 0.72%, P 0.008%, S 0.002%, Alt 0.041%, Ti 0.056%, N 0.0053%, and the rest is Fe and unavoidable impurities.

[0019] Furthermore, the chemical composition of the ingot is as follows by mass percentage: C 0.17%; Si 0.05%; Mn 0.76%; P 0.018%; S 0.007%; Alt 0.036%; Ti 0.060%, N 0.0049%, and the rest is Fe and unavoidable impurities.

[0020] Furthermore, the chemical composition of the ingot is as follows by mass percentage: C 0.17%; Si 0.06%; Mn 0.76%; P 0.014%; S 0.005%; Alt 0.030%; Ti 0.056%, N 0.0030%, and the rest is Fe and unavoidable impurities.

[0021] Furthermore, the chemical composition of the ingot is as follows by mass percentage: C 0.16%; Si 0.06%; Mn 0.75%; P 0.011%; S 0.006%; Alt 0.036%; Ti 0.063%, N 0.0028%, and the rest is Fe and unavoidable impurities.

[0022] Furthermore, the chemical composition of the ingot is as follows by mass percentage: C 0.18%, Si 0.07%, Mn 0.73%, P 0.016%, S 0.002%, Alt 0.035%, Ti 0.054%, N 0.0037%, and the rest is Fe and unavoidable impurities.

[0023] Compared with the prior art, the beneficial technical effects of the present invention are:

[0024] The preparation method of the present invention adopts a new component design and controls process parameters such as a steelmaking process, a hot rolling process, a cold rolling process, and an annealing process (characterized in that the product adopts a strengthening design mainly adding titanium elements, optimizes and reduces RH processes, and reduces production costs), thereby obtaining a product that meets user needs and has a certain strength supporting capacity, and is proven by actual use to have suitable performance, and its mechanical properties meet the following requirements: yield strength ≥420MPa, tensile strength ≥480MPa, elongation ≥15.0%, and yield strength ratio <0.9. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below in conjunction with the accompanying drawings.

[0026] Figure 1 The yield strength test results distribution range of 420MPa grade zinc-aluminum-magnesium structural steel obtained according to the method of the present invention.

[0027] Figure 2 The distribution range of the tensile strength test results of 420MPa grade zinc-aluminum-magnesium structural steel obtained according to the method of the present invention.

[0028] Figure 3 The distribution range of the elongation test results of 420MPa grade zinc-aluminum-magnesium structural steel obtained according to the method of the present invention.

[0029] Figure 4 The distribution range of the yield strength ratio test results of 420MPa grade zinc-aluminum-magnesium structural steel obtained according to the method of the present invention. DETAILED DESCRIPTION

[0030] In response to users' demand for 420MPa zinc-aluminum-magnesium structural steel, the present invention provides a method for preparing 420MPa zinc-aluminum-magnesium structural steel for photovoltaic brackets at low cost that meets users' needs by adopting new component design and optimizing metallurgical process parameters (adopting a strengthening design that mainly adds titanium elements, optimizing and reducing RH processes, and reducing production costs).

[0031] The preparation method specifically includes the following steps: steelmaking step - hot rolling step - cold rolling step - annealing step; wherein:

[0032] The steelmaking process includes: converter top and bottom combined blowing smelting - LF - slab continuous casting;

[0033] The tapping temperature of the converter is 1600 ≥ ℃ to ensure that the composition and temperature are coordinated. During the tapping process of the converter, aluminum iron, silicon iron and manganese iron are added to perform deoxidation and alloying.

[0034] The LF refining process includes slagging, deoxidation and desulfurization, and the addition of alloys such as ferroaluminum, ferrosilicon, ferromanganese and ferrotitanium to adjust the composition to the target range;

[0035] In the slab continuous casting, the superheat degree of the intermediate ladle is controlled within the range of 15 to 40° C. during the casting process of the casting machine, and the production casting speed is 1.0 to 1.8 m / min.

[0036] The thickness of the above-mentioned ingot is 230mm, and the hot-rolled thickness is: 3.2-5.0mm;

[0037] 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.

[0038] Table 1: Billet heating system

[0039]

[0040] Table 2: Hot rolling process

[0041]

[0042] The cold rolling process includes: pickling uncoiling - welding - straightening - pickling - rinsing - drying - trimming - continuous rolling mill cold rolling - coiling;

[0043] Annealing process includes: uncoiling - welding - entrance looper - cleaning - annealing furnace - zinc-aluminum-magnesium pot - cooling after plating - water quenching - intermediate looper - skin pass machine - roller coater - dryer - exit looper - trimming - surface inspection - oiling - sampling - coiling - weighing - packaging;

[0044] The specific process system of the annealing process is shown in Table 3.

[0045] Table 3: Annealing process

[0046]

[0047] 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.

[0048] Example

[0049] 1. According to the above steelmaking process requirements, the actual slab chemical composition (mass percentage) is shown in Table 4 below.

[0050] Table 4: Chemical composition (%)

[0051]

[0052] 2. According to the above hot rolling process requirements, the hot rolling thickness is 3.2-5.0mm, and the actual process is shown in Table 5.

[0053] Table 5: Rolling process

[0054]

[0055] 3. According to the above annealing process requirements, the finished product thickness is 1.2-2.5mm, and the actual process is shown in Table 6.

[0056] Table 6: Annealing process

[0057]

[0058] 4. The mechanical properties of representative steel strip products obtained through the above process are shown in Table 7. The test method refers to GB / T 228.1. Figure 1-4As shown, the distribution range of the mechanical properties (yield strength, tensile strength, elongation and yield strength ratio) of the steel strip S420GD+ZAM obtained according to the method of the present invention is shown. It can be seen that the mechanical properties produced by the above process meet the user requirements: yield strength ≥420MPa, tensile strength ≥480MPa, elongation ≥15.0%, and yield strength ratio <0.9.

[0059] Table 7: Mechanical properties

[0060]

[0061] The steel strip products obtained by the above process have been used by users and have suitable strength and can be widely promoted and used.

[0062] 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 420MPa grade zinc-aluminum-magnesium structural steel for low-cost photovoltaic brackets, characterized by: The process includes the following steps: steelmaking process - hot rolling process - cold rolling process - annealing process; wherein: In the steelmaking process, a cast billet is obtained, and the chemical composition of the cast billet is as follows by mass percentage: C≤0.22%; Si≤0.10%; Mn≤1.0%; P≤0.020%; S≤0.010%; Alt≥0.020%; Ti≥0.050%, N≤0.0080%, and the rest is Fe and unavoidable impurities; The hot rolling process includes: heating of the ingot - high-pressure water descaling - fixed width press - E1R1 roughing mill rolling - E2R2 roughing mill rolling - insulation cover - flying shear - high-pressure water descaling - F1-F7 finishing mill rolling - encrypted laminar cooling - coiling; wherein: In the heating of the ingot, the heating temperature is controlled to be 1210-1280°C, the heating time is 160-250min, the soaking temperature is 1230-1270°C, the soaking time is 25-60min, the furnace temperature is 1230-1270°C, the final rolling temperature of the finishing rolling is controlled to be 850-950°C, the coiling temperature is 550-650°C, and the cooling method is the front dispersion cooling method; In the annealing process, the annealing heating temperature is controlled to be 700-730° C., the annealing soaking temperature is controlled to be 700-730° C., and the leveling machine elongation is controlled to be 0.5-1.0%.

2. The method for producing 420MPa grade zinc-aluminum-magnesium structural steel for low-cost photovoltaic bracket according to claim 1, characterized in that: The mechanical properties of the 420MPa grade zinc-aluminum-magnesium structural steel for the photovoltaic bracket meet the following requirements: yield strength ≥420MPa, tensile strength ≥480MPa, elongation ≥15.0%, and yield strength ratio <0.

9.

3. The method for producing 420MPa grade zinc-aluminum-magnesium structural steel for low-cost photovoltaic support according to claim 1, characterized in that: The steelmaking process includes: optimizing the converter top and bottom combined blowing smelting-LF-RH-slab continuous casting process to converter top and bottom combined blowing smelting-LF-slab continuous casting, thereby reducing the production cost by reducing the RH process; wherein: The tapping temperature of the converter is ≥1600℃ to ensure that the composition and temperature are coordinated. During the tapping process of the converter, aluminum iron, silicon iron and manganese iron are added for deoxidation and alloying. LF refining process slag, deoxidation and desulfurization, adding aluminum, ferrosilicon, ferromanganese and ferrotitanium and other alloys to adjust the composition to the target range; In the slab continuous casting, the superheat degree of the intermediate ladle is controlled within a range of 15 to 40° C. during the casting process of the casting machine, and the production casting speed is 1.0 to 1.8 m / min.

4. The method for producing 420MPa grade zinc-aluminum-magnesium structural steel for low-cost photovoltaic bracket according to claim 1, characterized in that: The cold rolling process includes: pickling uncoiling - welding - straightening - pickling - rinsing - drying - trimming - continuous rolling mill cold rolling - coiling; The annealing process includes: uncoiling - welding - inlet looper - cleaning - annealing furnace - zinc-aluminum-magnesium pot - cooling after plating - water quenching - intermediate looper - skin pass machine - roller coater - dryer - outlet looper - trimming - surface inspection - oiling - sampling - coiling - weighing - packaging.

5. The preparation method according to claim 4, characterized in that: The thickness of the ingot is 230 mm, the thickness of the ingot after hot rolling is 3.2-5.0 mm, and the thickness of the ingot after cold rolling is 1.2-2.5 mm.

6. The method for producing 420MPa grade zinc-aluminum-magnesium structural steel for low-cost photovoltaic support according to claim 1, characterized in that: The chemical composition of the ingot is calculated by mass percentage as follows: C 0.16%, Si 0.05%, Mn 0.72%, P 0.008%, S 0.002%, Alt 0.041%, Ti 0.056%, N 0.0053%, and the rest is Fe and unavoidable impurities.

7. The method for producing 420MPa grade zinc-aluminum-magnesium structural steel for low-cost photovoltaic support according to claim 1, characterized in that: The chemical composition of the ingot is calculated by mass percentage as follows: C 0.17%; Si 0.05%; Mn 0.76%; P 0.018%; S 0.007%; Alt 0.036%; Ti 0.060%, N 0.0049%, and the rest are Fe and unavoidable impurities.

8. The method for producing 420MPa grade zinc-aluminum-magnesium structural steel for low-cost photovoltaic support according to claim 1, characterized in that: The chemical composition of the ingot is calculated by mass percentage as follows: C 0.17%, Si 0.06%, Mn 0.76%, P 0.014%, S 0.005%, Alt 0.030%, Ti 0.056%, N 0.0030%, and the rest is Fe and unavoidable impurities.

9. The method for producing 420MPa grade zinc-aluminum-magnesium structural steel for low-cost photovoltaic support according to claim 1, characterized in that: The chemical composition of the ingot is calculated by mass percentage as follows: C 0.16%, Si 0.06%, Mn 0.75%, P 0.011%, S 0.006%, Alt 0.036%, Ti 0.063%, N 0.0028%, and the rest is Fe and unavoidable impurities.

10. The method for producing 420MPa grade zinc-aluminum-magnesium structural steel for low-cost photovoltaic support according to claim 1, characterized in that: The chemical composition of the ingot is calculated by mass percentage as follows: C 0.18%, Si 0.07%, Mn 0.73%, P 0.016%, S 0.002%, Alt 0.035%, Ti 0.054%, N 0.0037%, and the rest is Fe and unavoidable impurities.

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