Crack repairing process for zinc-aluminum-magnesium coating steel workpiece, workpiece and photovoltaic module

Abstract

The invention discloses a crack repairing process for a zinc-aluminum-magnesium coating steel workpiece, the workpiece and a photovoltaic module, and aims to solve the problems of repairing the zinc-aluminum-magnesium coating steel workpiece subjected to cold bending processing and eliminating cracks and stripping points generated in the processing process. The method comprises the following steps: under a protective atmosphere, quickly heating a machined and formed workpiece, and blowing by an air knife, so that a reactant generated by a coating reaction flows towards a crack position; an aluminum-rich phase, a zinc-rich phase, a zinc-magnesium binary eutectic and a zinc-aluminum-magnesium ternary eutectic are formed in the re-solidified coating again; after the workpiece is cooled to about 200 DEG C, under the protective atmosphere, the treated workpiece is cooled to about 100 DEG C and then air-cooled to the room temperature, crack repairing is completed, the optimal value of the ratio of the average value Dr of the maximum gap after workpiece repairing to the average value Dm of the maximum gap before repairing is smaller than 0.2, the corrosion medium blocking capacity of the zinc-aluminum-magnesium coating is recovered, the corrosion resistance of the zinc-aluminum-magnesium coating is guaranteed, and the service life of the zinc-aluminum-magnesium coating is prolonged. The service life is prolonged and the use stability of the photovoltaic module is enhanced.

Description

Technical Field

[0001] The present invention belongs to the field of photovoltaic module materials, in particular to a zinc-aluminum-magnesium coated steel workpiece crack repair process, the workpiece and a photovoltaic module. Background Art

[0002] Zinc-aluminum-magnesium (ZAMg)-coated steel is a further development of galvanized steel, offering superior corrosion resistance. Galvanized steel utilizes a more reactive metallic zinc coating on the steel surface, creating a galvanic reaction where zinc corrosion replaces steel / iron corrosion (a sacrificial anode), thereby extending the steel's service life. Steel coating (ZAMg) is often performed using a continuous hot-dip strip coating process. The process typically involves the following steps: First, the strip undergoes pre-treatment processes such as uncoiling, cutting, alkali cleaning, and pickling. Next, the strip is heated to a set temperature in a preheating furnace and immersed in a bath containing a specific Zn-Al-Mg ratio for one to several tens of seconds. The strip, coated with the ZAMg bath, is then pulled out of the bath and, after air knife purging and alloying, transformed into an alloyed ZAMg coating. Finally, the ZAMg-coated strip undergoes post-treatment processes such as cooling, skin-passing, and straightening to produce ZAMg-coated steel.

[0003] Different types of zinc-aluminum-magnesium coatings have similarities and differences. In general, the structure of zinc-aluminum-magnesium coatings is mainly composed of aluminum-rich phase, zinc-rich phase, zinc-magnesium binary eutectic and zinc-aluminum-magnesium ternary eutectic. Binary eutectic and ternary eutectic can be divided into Zn-Mg2Zn 11 or Zn-MgZn2 binary eutectic and Zn-Al-Mg2Zn 11 Or Zn-Al-MgZn2 ternary eutectic. Obviously, the types of magnesium zinc compounds are different (Mg2Zn 11 and / or MgZn2). The corrosion resistance of these two compounds is comparable, but the mechanical properties are significantly different. MgZn2 has a high hardness (about 5.0 GPa) and a low modulus (about 85.0 GPa), while Mg2Zn 11 The hardness is low (about 3.5GPa) and the modulus is high (about 110.0GPa).

[0004] The different alloy phases in the coating play different roles in corrosion protection. The zinc-rich phase and the Zn in the eutectic give the coating the corrosion protection function of a sacrificial anode. The binary and ternary eutectics of Mg and Al enable the zinc-aluminum-magnesium alloy to form dense, protective corrosion products after corrosion, thereby blocking contact between corrosive media (water vapor, oxygen, and corrosive gases) and steel / iron. The synergistic effect of these two corrosion protection mechanisms gives zinc-magnesium-aluminum-coated steel a longer service life than galvanized steel.

[0005] Due to the excellent corrosion resistance of zinc-aluminum-magnesium-coated steel, many photovoltaic module manufacturers have begun using it instead of aluminum alloy to manufacture photovoltaic module frames. However, processing zinc-aluminum-magnesium-coated steel into photovoltaic module frames requires dozens of cold bending processes, ultimately forming steel profiles with complex cross-sectional shapes, including multiple 90-degree and 180-degree bends. In fact, due to the low ductility of the zinc-aluminum-magnesium coating, zinc-aluminum-magnesium-coated steel often breaks and even delaminates when cold-bent, especially during 180-degree and 90-degree bends. The appearance of these cracks and delamination points weakens the coating's ability to block corrosive media, deteriorating the corrosion resistance of the zinc-aluminum-magnesium-coated steel frame and affecting the lifespan and stability of the resulting photovoltaic module. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention discloses a crack repair process for a zinc-aluminum-magnesium coated steel workpiece after machining and forming, comprising the following steps:

[0007] S1. Rapidly heat the processed workpiece to 345℃~460℃ under a protective atmosphere;

[0008] S2. The workpiece after heating in S1 is purged with an air knife so that the reactants generated by the coating in step S1 flow toward the crack position;

[0009] S3. Cool the workpiece after purging in S2 to 330°C to 370°C and keep it at this temperature for 10s to 40s;

[0010] S4. Cooling the workpiece after S3 treatment to 180°C to 220°C;

[0011] S5. Cool the workpiece after S4 treatment to 80°C to 120°C under a protective atmosphere, and then cool it to room temperature.

[0012] By heating, holding and cooling the Zn-Al-Mg-coated steel profiles after processing, the cracks and peeling points of the Zn-Al-Mg-coated steel profiles that appear during processing can be repaired, thereby blocking the contact between corrosive media and steel / iron and improving the corrosion resistance of the Zn-Al-Mg-coated steel workpieces. In addition, by adjusting the temperature and time of holding, the different magnesium-zinc compounds (Mg2Zn 11 &MgZn2) ratio, thereby adjusting the mechanical properties (scratch resistance & ductility) of the coating. Through the combined effect of heat preservation and gradual cooling, aluminum-rich phase, zinc-rich phase, zinc-magnesium binary eutectic and zinc-aluminum-magnesium ternary eutectic are formed again in the re-solidified coating.

[0013] As a preferred embodiment, cooling the workpiece after the S3 treatment includes: cooling the workpiece after the S3 treatment to 180° C. to 200° C. in an alloying furnace.

[0014] As a preferred embodiment, S4 cools the workpiece after being processed in S3, including:

[0015] After the workpiece is cooled to about 200°C;

[0016] Cool the workpiece to about 100°C under a protective atmosphere;

[0017] The workpiece is cooled to room temperature by air cooling to complete the crack repair.

[0018] As a cooling step after repair, a gradual cooling method is used to make the repaired coating more uniform and reduce the generation of microcracks.

[0019] As a preferred method, cooling is performed gradually with a cooling rate of 20°C / s to 50°C / s. Reasonable control of the cooling rate makes it difficult for the repaired coating to crack.

[0020] Preferably, in S1, the heating rate is 50°C / s to 150°C / s. The zinc-aluminum-magnesium coating has certain fluidity and adhesion. This heating rate not only facilitates the repair of fractured areas of the zinc-aluminum-magnesium coating, but also prevents the zinc-aluminum-magnesium coating from peeling or falling off from the surface of the steel substrate.

[0021] As a preference, the protective atmosphere is an inert atmosphere and / or a reducing atmosphere; the inert atmosphere includes argon and / or nitrogen, and the reducing atmosphere includes hydrogen, methane and / or carbon monoxide.

[0022] Nitrogen and / or inert gas are generally selected to ensure that the workpiece will not undergo structural changes due to oxidation during the heating and cooling process, thereby affecting the coating performance.

[0023] As a preferred embodiment, in S2, the gas velocity of the air knife purge is calculated as shown in the formula:

[0024] T h -T i =υ×t 2 ×η(υ,T g )

[0025] Where Th is the temperature of the workpiece after heating;

[0026] Ti is the holding temperature of the workpiece;

[0027] t is the purge time;

[0028] υ is the gas flow rate at the outlet of the air knife;

[0029] η is the cooling coefficient, which is a function of flow rate and initial gas temperature. The cooling coefficients of different shielding gases are different.

[0030] Tg is the gas temperature.

[0031] The purge time and cooling rate can be accurately determined by calculation, and no secondary damage will be caused by the air knife purge step.

[0032] As a preference, in step S2, the gas temperature Tg of the air knife is 80-100°C; and / or the blowing direction is perpendicular to or obliquely upwards to the workpiece repair surface; the air knife blowing gas is nitrogen, inert gas or compressed air.

[0033] For the heated workpiece, especially the large-angle bending area of ​​the workpiece, the air knife is used for blowing, and the blowing pressure is within the range of 0.02-0.05MPa; Figure 1 The blowing direction shown is vertical or oblique to the repaired surface of the workpiece. Tests have shown that the broken coating can be rejoined better.

[0034] As a preferred embodiment, in S3, the workpiece is cooled to 330°C to 350°C in the holding furnace.

[0035] For example, the "medium aluminum" coating in Example 1 still has high fluidity when the holding temperature is 370°C, and the repair effect is worse than when the holding temperature is 330°C to 350°C. In other words, the problem of uneven distribution can be avoided to a large extent by the appropriate holding temperature.

[0036] The present invention also provides a workpiece having a zinc-aluminum-magnesium coating, which is repaired by any of the above-mentioned zinc-aluminum-magnesium coated steel workpiece crack repair processes.

[0037] The maximum gap of the crack is the width of the widest position of the crack. The average value of the maximum gap of the crack after the workpiece is repaired is D r The average value of the maximum gap between the crack before repair D m The ratio is less than 0.6, the average value of the maximum gap of the crack refers to the average value of the maximum gap of the crack in n sample areas selected from the surface of the workpiece, n ≥ 2; and / or, the Mg2Zn in the reaction product generated after the zinc-aluminum-magnesium coating of the workpiece is heated 11 The mass ratio of MgZn2 is 20 <Mg2Zn 11 / (MgZn2+Mg2Zn 11 )<100.

[0038] This value can be rated as good in the repair rating, which can ensure normal use.

[0039] As a preferred method, the average value of the maximum gap of the crack after the workpiece is repaired is D r The average value of the maximum gap between the crack before repair D m The ratio is less than 0.4, and / or 40 <Mg2Zn 11 / (MgZn2+Mg2Zn 11 )<100.

[0040] This value can be rated as excellent in the repair rating, which is better than the good grade repair effect. The repair conditions are relatively simple and it is more recommended. The highest hardness can reach level III, which is a relatively ideal repair effect.

[0041] As a preferred method, the average value of the maximum gap of the crack after the workpiece is repaired is D r The average value of the maximum gap between the crack before repair D m The ratio is less than 0.2, and / or 20 <Mg2Zn 11 / (MgZn2+Mg2Zn 11 )≤40.

[0042] This value can be rated as excellent in the repair rating, although Mg2Zn 11 The content is not high, but the hardness can reach level IV, which is the best repair method.

[0043] The present invention provides a crack repair process for zinc-aluminum-magnesium coated steel workpiece after forming, which repairs the zinc-aluminum-magnesium coated steel workpiece after cold bending, eliminates cracks and peeling points generated during the processing, and the average value of the maximum gap of the crack after the workpiece is repaired is D r The average value of the maximum gap between the crack before repair D m The optimal value of the ratio is less than 0.2, the repair rating is excellent, and the hardness can be guaranteed. It can restore the ability of the zinc-aluminum-magnesium coating to block corrosive media, ensure the corrosion resistance of the zinc-aluminum-magnesium coating, extend the service life, and enhance the stability of the use of photovoltaic modules.

[0044] As a preference, the workpiece is a steel frame, a steel angle bracket and / or a steel purlin.

[0045] A photovoltaic assembly includes any of the above-mentioned workpieces. Compared with the prior art, the photovoltaic assembly provided by this application has the same beneficial effects as the above-mentioned repaired workpiece, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The drawings described herein are used to provide further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0047] Figure 1 Schematic diagram of air knife blowing for crack repair;

[0048] Figure 2 This is a schematic diagram of the cross section of the cold-bent zinc-aluminum-magnesium coated steel frame; DETAILED DESCRIPTION

[0049] The present invention will be described in detail below by way of examples. The present invention is not limited to the following examples.

[0050] The crack repair process of the zinc-aluminum-magnesium coated steel workpiece after processing and forming includes the following steps:

[0051] S1. Under a protective atmosphere, rapidly heat the workpiece formed from zinc-aluminum-magnesium steel strip to 345°C to 460°C at a normal heating rate for steel processing (50°C / s to 150°C / s). At this point, the coating has a certain degree of fluidity and adhesion, which not only facilitates the repair of broken areas of the coating, but also prevents the coating from peeling off / falling off from the steel substrate.

[0052] S2, the heated workpiece, especially the large-angle bending area of ​​the workpiece, is purged with an air knife, and the purging pressure is within the range of 0.02 to 0.05 MPa; Figure 1 The purge direction shown is vertical or obliquely upward, so that the reactants generated by the coating reaction in step S1 flow toward the crack position, and the reactants cover the crack to reduce the width of the crack or reconnect the broken coating; the purge is to cool the hot coated steel.

[0053] The working principle of air knife purging is that compressed air enters the air knife's high-pressure chamber through the air inlet. After passing through a narrow, thin nozzle, the airflow forms a balanced airflow sheet along the length of the air knife. Because the chamber's compression ratio for the high-pressure airflow is 40:1, the airflow velocity loss is minimized while the pressure is maximized, resulting in an airflow sheet with strong impact and minimal shear force. The air knife purging gas temperature is adjustable, ranging from 80 to 100°C. The purge determines the cooling rate. The cooling rate of the coated steel after air knife purging is 3°C / s to 30°C / s. Air knife purging can be performed with nitrogen, inert gas, and compressed air.

[0054] The calculation method of air knife blowing is as follows:

[0055] T h -T i =υ×t 2 ×η(υ,T g )

[0056] Where Th is the temperature of the workpiece after heating;

[0057] Ti is the holding temperature of the workpiece;

[0058] t is the purge time;

[0059] υ is the gas flow rate at the outlet of the air knife;

[0060] η is the cooling coefficient, which is a function of flow rate and initial gas temperature. The cooling coefficients of different shielding gases are different.

[0061] Tg is the gas temperature

[0062] S3, transfer the purged workpiece to a holding furnace, cool it to 330℃~370℃, and hold it there for a period of time (10s~40s). The fluidity of the coating with the same composition depends on the holding temperature. For example, the "Medium Aluminum" coating in Example 1 still has high fluidity when the holding temperature is 370℃, and the repair effect is worse than when the temperature is 330℃-350℃. In other words, the appropriate holding temperature can largely avoid the problem of uneven distribution.

[0063] At this time, the coating re-solidifies to form magnesium-zinc compounds (Mg2Zn 11 By adjusting the holding temperature and holding time of the workpiece, the two magnesium-zinc compounds (Mg2Zn 11 and MgZn2) ratio, thereby adjusting the ductility and hardness of the coating;

[0064] S4, the workpiece that has completed the holding process is transferred to an alloying furnace and gradually cooled to 180°C to 220°C (cooling rate 20°C / s to 50°C / s), preferably to 200°C in this step. Through the combined action of the holding furnace and the alloying furnace, the re-solidified coating re-forms an aluminum-rich phase, a zinc-rich phase, a zinc-magnesium binary eutectic, and a zinc-aluminum-magnesium ternary eutectic;

[0065] S5, under a protective atmosphere, rapidly cooling the workpiece to 80°C to 120°C, and then air-cooling to room temperature to complete the crack repair. Preferably, cooling to 100°C is performed in this step.

[0066] In the above embodiments, the protective atmosphere may include an inert atmosphere and / or a reducing atmosphere. The inert atmosphere may include argon and / or nitrogen. The reducing atmosphere may include hydrogen, methane, and / or carbon monoxide. Specifically, the protective atmosphere may be a mixture of one or more of hydrogen, methane, and / or carbon monoxide with argon or nitrogen.

[0067] Mg2Zn in the workpiece coating after crack repair 11 Relative content evaluation method:

[0068] First, a high-resolution XRD pattern of the crystalline phase of the repaired coating is obtained by X-ray diffractometer.

[0069] X-ray diffraction measurement conditions: the light source is a copper target (Cu, Kα1, λ = 0.154056 nm), the measurement voltage is 20 kV to 40 kV, the current is 100 mA, the measurement range (2Theta) is 5-70°, the step scan is 0.02° / step, and the dwell time is 1 s or 2 s per step.

[0070] Secondly, perform a phase analysis on the obtained spectrum, determine the crystal structure spectrum, and import it into the structure refinement software.

[0071] Finally, perform fitting and calculation to determine the mass percentage content of each phase. Among them, the content of Mg2Zn 11 is a, and the content of MgZn2 is b. Then, the relative proportion x of Mg2Zn 11 / (MgZn2 + Mg2Zn 11 ) is x = a / (a + b) × 100%.

[0072] When 0 < x ≤ 20, the content of Mg2Zn 11 is defined as --;

[0073] When 20 < x ≤ 40, the content of Mg2Zn 11 is defined as -;

[0074] When 40 < x ≤ 60, the content of Mg2Zn <00,00038>is defined as +;

[0075] When 60 < x ≤ 80, the content of Mg2Zn 11 is defined as ++;

[0076] When 80 < x < 100, the content of Mg2Zn 11 is defined as +++.

[0077] Hardness evaluation method for the workpiece after crack repair:

[0078] Use a micro-Vickers hardness tester to measure the surface hardness (H min , H max , H c ) of pure zinc, pure MgZn2 alloy, and the coating of the workpiece after crack repair, respectively. The test force range is 20 g to 100 g, and the load time is 10 s. <00002,,,The hardness ratio y = (H c - H min ) / (H max 4]] - H <C min ) × 100%.

[0080] When y ≤ 10, the surface hardness is defined as grade I;

[0081] When 10 < y ≤ 20, the surface hardness is defined as grade II;

[0082] When 20 < y ≤ 30, the surface hardness is defined as grade III;

[0083] When 30 < y ≤ 40, the surface hardness is defined as grade IV;

[0084] When y > 40, the surface hardness is defined as grade V.

[0085] Microcrack Repair Rating:

[0086] The maximum gap of the crack is the width of the widest position of the crack. The average value of the maximum gap of the crack after the workpiece is repaired is D r The average value of the maximum gap between the crack before repair D m The optimal value of the ratio is less than 0.6. The average value of the maximum gap of the crack refers to the average value of the maximum gap of the cracks in n sample areas selected from the surface of the workpiece, n ≥ 2. Specifically, n sample areas are selected in the large-angle bending area of ​​the workpiece, magnified to about 200 times for observation under a scanning electron microscope, and the maximum gaps of the cracks in the n sample areas are measured. After calculating the sum of the maximum gaps of the cracks in the n sample areas, the average value is calculated, which is the average value of the maximum gap of the cracks, n ≥ 2, preferably n ≥ 5. When there are multiple cracks in a sample area, the maximum gap of the cracks in the sample area can be the maximum gap of the widest crack in the sample area.

[0087] Specifically, the average value of the maximum gap of the crack before repair is D m Before repair, n sample areas are selected on the workpiece surface, and the maximum gap of the crack in the n sample areas is measured, and the average value is D m ; The average value of the maximum gap of the crack after the workpiece is repaired D r After repair, select n sample areas on the workpiece surface and measure the maximum gap of the crack in the n sample areas. The average value is D r The n sample areas selected before repair and the n sample areas selected after repair can be the same to facilitate comparison of repair effects. Microcrack repair ratings are as follows:

[0088] When D r :D m When <0.2, the rating is excellent;

[0089] When 0.2≤D r :D m When <0.4, the rating is excellent-;

[0090] When 0.4≤D r :D m When <0.6, the rating is good;

[0091] When 0.6≤D r :D m When <0.8, the rating is medium;

[0092] When 0.8≤D r :D m When <1.0, the rating is poor.

[0093] The commercially available "Zhonglu" zinc-aluminum-magnesium coated steel sheet (thickness 0.8mm, zinc-aluminum-magnesium coating weight on both sides is about 150g / m 2 ) is used as the material and processed into a frame sample (workpiece) by cold bending. The cross-sectional configuration of the sample is similar to the commonly used aluminum frame of photovoltaic modules, such as Figure 2 shown.

[0094] Example 1

[0095] S1, under a protective atmosphere (nitrogen or argon), rapidly heating the frame sample (workpiece) to 460°C;

[0096] S2, the heated workpiece, especially the large-angle bending area of ​​the workpiece, is purged with an air knife. The purging pressure is within the range of 0.02-0.05 MPa and the purging temperature is 80°C. Figure 1 The blowing direction shown is perpendicular to the surface of the repaired workpiece or obliquely upward. The calculation formula for air knife blowing is as follows:

[0097] T h -T i =υ×t 2 ×η(υ,T g )

[0098] Where Th is 460°C, Ti is 330°C, the gas flow rate υ is 1.023 m / s, and η is 1.63 K / (m·s). The purge time is calculated based on this. After the cooling rate is calculated, the air knife purge is performed to make the reactants generated by the reaction in step S1 flow to the crack position. The reactants cover the crack to reduce the crack width or reconnect the broken coating.

[0099] S3, cooling the purged workpiece to 330°C, transferring it to a holding furnace, and keeping it warm for 10 seconds;

[0100] S4, transferring the workpiece after the holding process to an alloying furnace and gradually cooling it to about 200°C (cooling rate 20°C / s to 50°C / s);

[0101] S5: Under a protective atmosphere, the workpiece is rapidly cooled to about 100°C, and then air-cooled to room temperature to complete the crack repair.

[0102] The repair results are detailed in Table 1.

[0103] Example 2

[0104] The workpiece is repaired according to the repair process of Example 1, with the only difference being that the temperature is lowered to 350° C. in S3 .

[0105] Example 3

[0106] The workpiece is repaired according to the repair process of Example 2, except that the temperature is kept at room temperature for 40 seconds in S3.

[0107] Example 4

[0108] The workpiece is repaired according to the repair process of Example 1, with the only difference being that the temperature is lowered to 370° C. in S3 .

[0109] Example 5

[0110] The workpiece is repaired according to the repair process of Example 4, except that in S3, the temperature is kept at room temperature for 25 seconds.

[0111] Example 6

[0112] The workpiece is repaired according to the repair process of Example 4, with the only difference being that in S3, the temperature is kept at room temperature for 40 seconds.

[0113] Example 7

[0114] The workpiece is repaired according to the repair process of Example 1, with the only difference being that in S1 , the workpiece is heated to 440° C.

[0115] Comparative Example 1

[0116] The workpiece is repaired according to the repair process of Example 1, except that the workpiece is heated to 345° C. in S1 .

[0117] Comparative Example 2

[0118] The workpiece is repaired according to the repair process of Example 1, except that in S1 , the workpiece is heated to 380° C.

[0119] Comparative Example 3

[0120] The workpiece is repaired according to the repair process of Example 4, with the only difference being that in S1 , the workpiece is heated to 380° C.

[0121] Comparative Example 4

[0122] The workpiece is repaired according to the repair process of Example 1, except that in S1 , the workpiece is heated to 420° C.

[0123] Comparative Example 5

[0124] The workpiece is repaired according to the repair process of Example 5, with the only difference being that in S1 , the workpiece is heated to 420° C.

[0125] Table 1

[0126] serial number <![CDATA[Mg2Zn 11 Content]]> Hardness evaluation Repair Rating Example 1 - Level IV excellent Example 2 + Level III excellent- Example 3 +++ Level I excellent- Example 4 ++ Level II good Example 5 +++ Level I good Example 6 +++ Level I good Example 7 - Level IV good Comparative Example 1 -- V-level Difference Comparative Example 2 -- V-level Difference Comparative Example 3 - Level IV Difference Comparative Example 4 -- V-level middle Comparative Example 5 + Level III Difference

[0127] It can be found from the examples and comparative examples that adjusting the heating temperature, holding temperature and holding time can change the surface mechanical properties of the zinc-aluminum-magnesium coated steel workpiece, making it more scratch-resistant or easier to process.

[0128] After the cold bending process is completed, the present invention is heated, purged, and heat-insulated again to repair the cracks and peeling points of the zinc-aluminum-magnesium coating during the processing, thereby blocking the contact between the corrosive medium and the steel / iron and improving the corrosion resistance of the zinc-aluminum-magnesium coated steel workpiece. After the air knife purging, the heat is first kept for a period of time, and then gradually cooled to form the zinc-aluminum-magnesium coated steel. The addition of the heat-insulating process can simultaneously contain Mg2Zn 11 The ratio of the two magnesium-zinc compounds can be adjusted by different holding times. Therefore, the surface mechanical properties of the zinc-aluminum-magnesium coated steel workpiece can be adjusted.

[0129] The present invention also provides a workpiece with a zinc-aluminum-magnesium coating, which is repaired by the zinc-aluminum-magnesium coated steel workpiece crack repair process of any of the above embodiments. The double-sided coating amount of the zinc-aluminum-magnesium coating on the surface of the workpiece is 130g / m 2 -170 g / m 2 , preferably 150g / m 2 .

[0130] Specifically, the steel workpiece may be a steel frame, a steel angle bracket and / or a steel purlin. Of course, the workpiece may also be any other steel workpiece.

[0131] The present invention further provides a photovoltaic assembly comprising the workpiece provided by any of the aforementioned embodiments. Specifically, the photovoltaic assembly may include a steel frame, steel angle brackets, and / or steel purlins that have been treated with the aforementioned crack repair process. Compared to the prior art, the photovoltaic assembly provided by this application has the same beneficial effects as those of the aforementioned workpieces and will not be further elaborated here.

[0132] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0133] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A zinc-aluminum-magnesium coated steel workpiece crack repair process, characterized in that: The following steps are involved: S1. Heat the processed workpiece to 345℃~460℃ under protective atmosphere; S2. The workpiece after heating in S1 is purged with an air knife so that the reactants generated by the coating in step S1 flow toward the crack position; S3. Cool the workpiece after purging in S2 to 330°C to 370°C and keep it at this temperature for 10s to 40s; S4. Cooling the workpiece after S3 treatment to 180°C to 220°C; S5. Cool the workpiece after S4 treatment to 80°C to 120°C under a protective atmosphere, and then cool it to room temperature.

2. The repair process according to claim 1, characterized in that: The step of cooling the workpiece after the S3 treatment comprises cooling the workpiece after the S3 treatment to 180° C. to 200° C. in an alloying furnace.

3. The repair process according to claim 1 or 2, characterized in that: In S4, the cooling rate is 20°C / s to 50°C / s; and / or, in S1, the processed workpiece is heated to 440°C to 460°C; and / or, in S1, the heating rate is 50°C / s to 150°C / s; and / or, in S3, the workpiece after purging is cooled to 330°C to 350°C.

4. The repair process according to claim 1, characterized in that: The protective atmosphere is an inert atmosphere and / or a reducing atmosphere; The inert atmosphere includes argon and / or nitrogen, and the reducing atmosphere includes hydrogen, methane and / or carbon monoxide.

5. The repair process according to claim 1, characterized in that: In S2, the gas velocity of the air knife purge is calculated as shown in the formula: T h -T i =v×t 2 ×η(υ,T g ) Where Th is the temperature of the workpiece after heating; Ti is the holding temperature of the workpiece; t is the purge time; υ is the gas flow rate at the outlet of the air knife; η is the cooling coefficient; Tg is the gas temperature.

6. The repair process according to claim 5, characterized in that: In step S2, the gas temperature Tg of the air knife is 80-100°C; and / or the blowing direction is perpendicular to or obliquely upward the workpiece repair surface; and / or the air knife blowing gas is inert gas or compressed air.

7. A workpiece having a zinc-aluminum-magnesium coating, characterized in that: The workpiece is repaired by the zinc-aluminum-magnesium coated steel workpiece crack repair process according to any one of claims 1-6.

8. The workpiece according to claim 7, characterized in that The maximum gap of the crack is the width of the widest position of the crack. The average value of the maximum gap of the crack after the workpiece is repaired is D r The average value of the maximum gap between the crack before repair D m The ratio is less than 0.6, the average value of the maximum gap of the crack refers to the average value of the maximum gap of the cracks in n sample areas selected from the surface of the workpiece, n ≥ 2; and / or, the Mg2Zn in the reaction product generated after the zinc-aluminum-magnesium coating of the workpiece is heated 11 The mass ratio of MgZn2 is 20 <Mg2Zn 11 / (MgZn2+Mg2Zn 11 )<100.

9. The workpiece according to claim 8, characterized in that The average value D of the maximum gap of the crack after the workpiece is repaired r The average value of the maximum gap between the crack before repair D m The ratio is less than 0.4, and / or 40 <Mg2Zn 11 / (MgZn2+Mg2Zn 11 )<100.

10. The workpiece according to claim 9, characterized in that The average value D of the maximum gap of the crack after the workpiece is repaired r The average value of the maximum gap between the crack before repair D m The ratio is less than 0.2, and / or 20 <Mg2Zn 11 / (MgZn2+Mg2Zn 11 )≤40.

11. The workpiece according to any one of claims 7 to 10, characterized in that The workpiece is a steel frame, a steel angle bracket and / or a steel purlin.

12. A photovoltaic module, characterized in that: The photovoltaic assembly comprises the workpiece according to any one of claims 7 to 11.

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