CN117488208A

CN117488208A - Hot-rolled weather-resistant steel plate for thin 800 MPa-grade photovoltaic bracket and preparation method thereof

Info

Publication number: CN117488208A
Application number: CN202311549905.XA
Authority: CN
Inventors: 崔凯禹; 李正荣; 汪创伟; 邱涛; 李朝未; 付芹
Original assignee: Pangang Group Panzhihua Steel and Vanadium Co Ltd; Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd
Current assignee: Pangang Group Panzhihua Steel and Vanadium Co Ltd; Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd
Priority date: 2023-11-20
Filing date: 2023-11-20
Publication date: 2024-02-02

Abstract

The invention discloses a hot-rolled weather-resistant steel plate for a thin 800 MPa-grade photovoltaic bracket and a preparation method thereof, wherein elements such as Si, P, cr, cu and the like are added to realize that the atmospheric corrosion resistance is less than or equal to 35% relative to the corrosion rate of Q355B, and the uniform corrosion thinning amount of both sides of the hot-rolled weather-resistant steel plate is not more than 0.2mm in the use period of 25 years in the bare use under the C1-C3 environment specified by GB/T19292.1; through reasonable heating temperature and heating time setting, the performance is ensured, and the generation of copper embrittlement defects is avoided; the rolling of the thin-specification product is realized through reasonable heating temperature and intermediate blank thickness setting; the Ti microalloying mode is used for exerting fine crystal strengthening and precipitation strengthening effects, and the rolling and cooling control process is combined for regulating and controlling the tissue performance, so that the product realizes high strength and excellent plasticity, the tensile strength is more than or equal to 800MPa, the elongation after breaking is more than or equal to 20%, and the green and lightweight application requirements of the photovoltaic bracket can be met.

Description

Hot-rolled weather-resistant steel plate for thin 800 MPa-grade photovoltaic bracket and preparation method thereof

Technical Field

The invention belongs to the technical field of hot continuous rolling strip production, and particularly relates to a hot-rolled weather-resistant steel plate for a thin 800 MPa-grade photovoltaic bracket and a preparation method thereof.

Background

The photovoltaic support is an important supporting protection structure of the photovoltaic power generation device, and the photovoltaic industry provides urgent demands for the greening and light-weight application of the photovoltaic support in order to realize cost reduction, synergy, safe operation and real green environmental protection. At present, the commonly used materials of the photovoltaic bracket in the industry mainly comprise surface anodic aluminum alloy, 304 stainless steel, Q235 and Q355 hot galvanizing or zinc aluminum magnesium steel parts and the like, on one hand, the aluminum alloy and the stainless steel have high cost, the bearing capacity of the aluminum alloy is lower, the aluminum alloy cannot be applied to large-scale solar photovoltaic power station projects, on the other hand, the hot galvanizing or zinc aluminum magnesium bracket can have partial plating layer falling and corrosion, so that the durability of the bracket is lower, the safety of the bracket is reduced, and meanwhile, the galvanization or zinc aluminum magnesium technology has serious environmental pollution, high cost and long production period, thereby limiting the application of the hot galvanizing or zinc aluminum magnesium steel parts.

In order to meet the new requirements of the photovoltaic industry on the low-cost, light-weight, green and high-corrosion-resistance photovoltaic bracket, the reliability service of the photovoltaic bracket in a severe environment is realized, and the high-strength and high-corrosion-resistance weathering steel enters the field of vision of a photovoltaic user. The weather-resistant steel is exposed to the atmosphere for a long time, and a layer of oxidation product with good protectiveness is generated on the surface of the weather-resistant steel to isolate the steel substrate from external corrosive substances, so that the corrosion resistance of the weather-resistant steel is obviously improved, and therefore, the application of the weather-resistant steel in the photovoltaic bracket can be exposed or reduced according to the actual service environment, so that the coating and maintenance procedures and environmental pollution are reduced, and the service life of the photovoltaic bracket is prolonged. In addition, by combining a micro alloying technology with a TMCP process, the weathering steel can achieve high strength, and ensure excellent plasticity and toughness, so that the material thinning is achieved on the premise of ensuring the structural rigidity and safety of the photovoltaic bracket. Therefore, the application of the weathering steel in the photovoltaic bracket can effectively reduce the material consumption, the transportation cost, the construction period and the coating and maintenance cost, and becomes one of the main development directions of the photovoltaic bracket material.

In the prior art, chinese patent publication No. CN116240467A discloses a high weather resistant steel for a 800 MPa-grade photovoltaic bracket and a preparation method thereof, wherein Ni and Nb elements are added, the content of the Ti element is higher, the alloy cost is increased, and the smelting difficulty is increased; the N content is lower, and the smelting difficulty is further increased. The Chinese patent with publication number of CN116179961A discloses a low-cost 800 MPa-grade titanium-containing weathering steel for a photovoltaic bracket and a preparation method thereof, and the titanium-containing weathering steel has higher P content and increases the risk of low-temperature impact toughness deterioration; under the condition of no Ni element, the Cu content is higher, and the risk of copper embrittlement defect is increased; the Ti content is higher and the N content is lower, thus increasing the smelting difficulty. The Chinese patent with publication number of CN116219306A discloses an antimony-containing weathering steel for a low-cost 800 MPa-level photovoltaic bracket and a preparation method thereof, and the invention has higher P content and increases the risk of low-temperature impact toughness deterioration; the Cu content is higher, and Ni element is not added, so that the risk of copper embrittlement defect is increased; the Ti content is higher, the N content is lower, and the smelting difficulty is increased; the addition of a certain amount of Sb element increases the alloy cost and there is a risk that inclusions are formed to reduce the toughness of the material. The Chinese patent with publication number of CN115896613A discloses weather-resistant steel for a high-strength low-cost photovoltaic bracket and a preparation method thereof, wherein a laminar cooling procedure adopts sectional cooling and tempering procedures are added, so that the process control difficulty is increased; the corrosion rate of the product relative to Q355B is less than or equal to 45%, and the corrosion resistance needs to be further improved. The invention discloses a high-strength weathering steel for a photovoltaic bracket and a preparation method thereof, wherein the high-strength weathering steel is added with Ni and Nb elements, so that the alloy cost is increased; the tensile strength of the product is more than or equal to 720MPa, and the strength is lower; the atmospheric corrosion resistance index I of the product is more than or equal to 6.5, but the corrosion resistance is not detected. The invention discloses a high-strength high-weather-resistance steel for a photovoltaic bracket and a manufacturing method thereof, wherein the steel has higher Ti content and requires to control B content, thereby increasing smelting difficulty; the corrosion rate of the product relative to Q355B is less than or equal to 40%, and the corrosion resistance needs to be further improved.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention realizes excellent atmospheric corrosion resistance and has a corrosion rate less than or equal to 35% relative to Q355B by adding a certain amount of Si, P, cr, cu and other elements while reducing the alloy cost; through specific technological parameter setting, the performance is ensured, the copper embrittlement defect is avoided, the rolling of a thin product is realized, the product has high strength and excellent plasticity, and the green and light application requirements of the photovoltaic bracket can be met.

In order to achieve the aim of the invention, the invention provides a hot-rolled weather-resistant steel plate for a thin 800 MPa-grade photovoltaic bracket, which comprises the following components in percentage by weight: 0.05 to 0.10 percent of C, 0.35 to 0.55 percent of Si, 0.85 to 1.05 percent of Mn, 0.070 to 0.100 percent of P, less than or equal to 0.008 percent of S, 1.10 to 1.30 percent of Cr, 0.25 to 0.35 percent of Cu, 0.080 to 0.100 percent of Ti, 0.010 to 0.040 percent of Als, less than or equal to 0.0050 percent of N, and the balance of Fe and unavoidable impurities.

The action and mechanism of the elements are as follows:

carbon: carbon is an effective strengthening element in steel, can be dissolved into a matrix to play a role in solid solution strengthening, and can be combined with titanium to form carbide precipitation particles to play a role in fine grain strengthening and precipitation strengthening, so that the improvement of the carbon content is beneficial to the improvement of strength. However, an excessively high carbon content causes formation of a large number of coarse and brittle carbide particles in the steel, which is disadvantageous in terms of plasticity and toughness, and causes formation of a segregation zone in the center of the steel sheet, which is disadvantageous in terms of bending property, formability, and the like. Therefore, the value range of C in the present invention is set to 0.05 to 0.10%.

Silicon: silicon can be dissolved in ferrite and austenite to improve the hardness and strength of steel, which is favorable for refining rust layer structure and reducing the corrosion rate of the whole steel, but too high content can reduce the plasticity and toughness of the steel, so that descaling is difficult during rolling. Therefore, the value range of Si in the present invention is set to 0.35 to 0.55%.

Manganese: manganese has a strong solid solution strengthening effect, can obviously reduce the phase transition temperature of steel, refines the microstructure of the steel, is an important strengthening element, but when the Mn content is excessive, the continuous casting process is easy to generate casting blank cracks, and meanwhile, the core component segregation of the steel plate can be caused. Therefore, the Mn value range in the present invention is set to 0.85 to 1.05%.

Phosphorus: the high content of phosphorus can obviously reduce the plasticity and low-temperature toughness of the steel, but the phosphorus element can effectively improve the atmospheric corrosion resistance of the steel and has low cost. Therefore, the value range of P in the invention is set to be 0.070-0.100%.

Sulfur: sulfur can adversely affect the structural properties of the steel sheet, and excessive sulfur content can increase the tendency of the steel to heat embrittlement, while sulfur can form sulfide inclusions that deteriorate the properties of the steel. Therefore, the value range of S in the invention is set to be less than or equal to 0.008 percent.

Chromium: chromium has remarkable effect of improving the passivation capability of steel, can promote the surface of the steel to carry out compact passivation film or protective rust layer, and the enrichment of the chromium in the rust layer can effectively improve the selective permeability characteristic of the rust layer to corrosive media; however, too high a chromium content increases the production cost. Therefore, the range of Cr in the present invention is set to 1.10 to 1.30%.

Copper: copper is added into the steel, so that a compact amorphous oxide (hydrocarbyloxy) protective layer with good adhesiveness is formed on the surface of the steel, and the corrosion resistance is obvious; in addition, copper and sulfur generate insoluble sulfides, thereby counteracting the harmful effect of S on the corrosion resistance of the steel; however, when the copper content is too high, the melting point of copper is lower than the heating temperature of a steel billet, precipitated copper is gathered at an austenite grain boundary in a liquid state, and when the content of the precipitated copper reaches a certain degree, cracks, namely 'copper brittleness' defects are easily generated during heating or hot rolling; in addition, according to the calculation formula of the atmospheric corrosion resistance index I, the calculated value of I is reduced by too small or too large copper content. Therefore, the value range of Cu in the present invention is set to 0.25 to 0.35%.

Titanium, nitrogen: ti (C, N) precipitates formed by titanium, carbon and nitrogen can effectively refine austenite grains, and can generate precipitation strengthening effect at the same time: increasing the titanium and nitrogen content can increase the volume fraction of Ti (C, N) precipitates and enhance the fine-grain strengthening and precipitation strengthening effects, but too high a titanium and nitrogen content is easy to form micron-sized TiN, which results in the reduction of formability, and too high a nitrogen content can increase the ageing tendency, cold brittleness and hot brittleness of the steel, which damages the cold bending performance of the steel. Therefore, in the present invention, the value range of Ti is set to 0.080 to 0.100%, and the value range of N is set to 0.0050% or less.

Aluminum: aluminum is added into steel to play a deoxidizing role, so that the steel can be improved, but the aluminum content is too high, and nitrogen oxides are easy to separate out at an austenite grain boundary to cause casting blank cracks. Therefore, the value range of Als in the present invention is set to 0.010 to 0.040%.

In the technical scheme, the atmospheric corrosion resistance index I of the hot-rolled weather-resistant steel plate for the photovoltaic bracket is more than or equal to 7.5.

Further, the yield strength of the hot-rolled weather-resistant steel plate for the photovoltaic bracket is more than or equal to 690MPa, the tensile strength is more than or equal to 800MPa, the elongation after break is more than or equal to 20%, and the 180-degree bending test D=2a.

Further, the corrosion rate of the hot-rolled weather-resistant steel plate for the photovoltaic bracket relative to Q355B is less than or equal to 35 percent.

Further, the hot rolled weathering steel plate for photovoltaic brackets is corrosive to metals and alloys in corrosive atmosphere part 1: the double-sided uniform corrosion thinning amount in the use period of 25 years for bare is not more than 0.2mm (double-sided) under the environment of C1-C3 specified in classification, measurement and evaluation (GB/T19292.1-2018).

Further, the thickness of the hot-rolled weather-resistant steel plate for the photovoltaic bracket is 1.5-6.0 mm.

Further, the metallographic structure of the hot-rolled weather-resistant steel plate for the photovoltaic bracket is polygonal ferrite and a small amount of pearlite; the volume fraction of the ferrite is 92-97% and the pearlite is 3-8%.

The preparation method of the hot-rolled weather-resistant steel plate for the thin 800 MPa-grade photovoltaic bracket comprises the following steps: according to the technical scheme, the hot-rolled weather-resistant steel plate for the photovoltaic bracket is smelted into a plate blank, and then the plate blank is sequentially subjected to the steps of heating, rough rolling, finish rolling, laminar cooling, coiling and the like, so that the hot-rolled weather-resistant steel plate for the photovoltaic bracket is obtained.

In the technical scheme, in the heating step, the casting blank is subjected to hot feeding, the heating temperature is 1230-1270 ℃, and the heating time is 150-250 min.

Heating the slab in a regenerative heating furnace to homogenize the cast structure and component segregation and to make the alloy element solid solution, while the hot rolled weather-resistant steel plate for the photovoltaic bracket has more alloy element types and higher content and higher Ti precipitate solid solution temperature, so that the heating process needs enough temperature and time; in addition, the temperature of the thin steel plate is reduced rapidly in the hot rolling process, and the hot rolling weather-resistant steel plate for the photovoltaic bracket is high in strength, so that the rolling load in the finish rolling process is high easily, and the heating temperature is required to be increased; however, the problems of burning loss, overheating, overburning and the like can occur when the heating temperature is too high and the heating time is too long; meanwhile, compared with the traditional weathering steel, in order to reduce the alloy cost, a certain amount of Cu is added in the hot-rolled weathering steel plate for the photovoltaic bracket, and Ni is not added, so that a Ni-containing copper-rich phase cannot be formed to reduce the chance of forming a liquid copper-rich phase, and the defect of copper embrittlement can be caused due to the fact that the heating temperature is too high and the heating time is too long.

Further, in the rough rolling step, 6 times of rough rolling are carried out, and the deformation of each time is more than or equal to 18%; when the thickness of the finished product is 1.5 to less than 2.0mm, the thickness of the intermediate blank is 34 to 38mm; when the thickness of the finished product is 2.0 to less than 4.0mm, the thickness of the intermediate blank is 36 to 40mm; when the thickness of the finished product is 4.0-6.0 mm, the thickness of the intermediate blank is 40-44 mm.

The rough rolling needs to reach enough deformation to ensure austenite recrystallization, refine austenite grains and prevent mixed crystal structures; if the thickness of the intermediate billet is too large, the rough rolling deformation amount may be insufficient, and when the thickness of the finished product is thinner, the finish rolling load is too large; if the intermediate billet thickness is too small, the finish rolling deformation amount may be insufficient.

Further, in the finish rolling step, 7 passes of finish rolling are carried out, the reduction rates of the three frames are respectively more than or equal to 17%, more than or equal to 13% and more than or equal to 10%, the finish rolling start temperature is less than or equal to 1080 ℃, and the finish rolling temperature is 840-880 ℃.

The three frames are basically rolled in an austenite non-recrystallization zone after finish rolling, austenite grains which are rolled in the recrystallization zone and have been thinned to a certain extent can be flattened and elongated by adopting a large deformation rate, the grain boundary area of austenite in unit volume is increased, and a large number of deformation bands and high-density dislocation are generated in the grains at the same time, so that the ferrite nucleation rate is improved, and a fine structure is obtained after phase transformation; if the finish rolling start temperature is too high, the deformation of the finish rolling process in the austenite non-recrystallization region is insufficient, which is not beneficial to tissue refinement; if the finishing temperature is too low, the finishing temperature is too far away from the starting temperature, so that the cooling speed in the finish rolling process is too high, the risk that a plurality of racks roll in a two-phase region after finish rolling exists, and the comprehensive performance of the product is poor; if the finishing temperature is too high, the deformation of the non-recrystallized region is insufficient, which is unfavorable for the final tissue refinement.

Further, in the laminar cooling step, a front-stage cooling mode is adopted, and the cooling speed is 40-80 ℃/s.

The adoption of the front-stage cooling mode can realize larger supercooling degree so as to refine a final structure, and the adoption of larger cooling speed can improve the strip-shaped structure of the core to a certain extent, and simultaneously improve the precipitation driving force of Ti element, so that the second phase of the Ti which is finely dispersed is precipitated to strengthen fine crystal strengthening and precipitation strengthening effects.

Further, in the coiling step, when the thickness of a finished product is 1.5-4.0 mm, the coiling temperature is 610-650 ℃; when the thickness of the finished product is 4.0-6.0 mm, the coiling temperature is 590-630 ℃.

If the coiling temperature is too low, the cooling speed in the cooling process is too high, so that medium and low temperature tissues such as martensite are generated, plasticity is reduced, and meanwhile, precipitation resistance of Ti is reduced, and fine crystal strengthening and precipitation strengthening effects are reduced; if the coiling temperature is too high, the grains and the second phase particles of Ti become coarse, resulting in a decrease in strength and toughness.

Compared with the prior art, the invention has the beneficial effects that:

according to the invention, a certain amount of Si, P, cr, cu and other elements are added, so that the atmospheric corrosion resistance index I is more than or equal to 7.5, and the atmospheric corrosion resistance of the product is obviously improved; compared with the traditional weathering steel, the alloy cost is reduced because Ni element is not added; through reasonable heating temperature and heating time setting, the performance is ensured, and the generation of copper embrittlement defects is avoided; the rolling of the thin-specification product is realized through reasonable heating temperature and intermediate blank thickness setting; the Ti microalloying mode is used for exerting fine grain strengthening and precipitation strengthening effects, the rolling and cooling control process is combined for regulating and controlling the structure performance, and under the condition that noble metal elements such as Nb, V, mo and the like are not added, the product realizes high strength and excellent plasticity, and the metallographic structure is uniform and fine polygonal ferrite and a small amount of pearlite. The yield strength of the hot-rolled weather-resistant steel plate for the photovoltaic bracket, which is prepared by the components and the preparation method thereof, is more than or equal to 690MPa, the tensile strength is more than or equal to 800MPa, the elongation after break is more than or equal to 20%, the 180-degree bending test D=2a, and the relative Q355B corrosion rate is less than or equal to 35%, and the hot-rolled weather-resistant steel plate can effectively reduce the material consumption, the transportation cost, the construction period and the coating and maintenance cost when applied to the photovoltaic bracket, thereby realizing the green and lightweight application.

Drawings

FIG. 1 is a metallographic structure diagram of a hot-rolled weathering steel plate for a thin 800MPa grade photovoltaic scaffold prepared in example 1.

Detailed Description

The invention is further illustrated below in connection with specific examples, but is not limited in any way. For the sake of brevity, the raw materials in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods unless otherwise specified.

The hot-rolled weather-resistant steel plate for the photovoltaic bracket with the thin specification of 800MPa comprises the following components in percentage by weight: 0.05 to 0.10 percent of C, 0.35 to 0.55 percent of Si, 0.85 to 1.05 percent of Mn, 0.070 to 0.100 percent of P, less than or equal to 0.008 percent of S, 1.10 to 1.30 percent of Cr, 0.25 to 0.35 percent of Cu, 0.080 to 0.100 percent of Ti, 0.010 to 0.040 percent of Als, less than or equal to 0.0050 percent of N, and the balance of Fe and unavoidable impurities.

For further understanding of the present invention, three examples of compositions and preparation methods of hot rolled weathering steel plates for photovoltaic brackets according to the present invention are provided and ten comparative examples are presented for comparison.

The atmospheric corrosion resistance index I=26.01 (% Cu) +3.88 (% Ni) +1.20 (% Cr) +1.49 (% Si) +17.28 (% P) -7.29 (% Cu) (% Ni) -9.10 (% Ni) (% P) -33.39 (% Cu) of the hot rolled weather resistant steel plate for the thin-specification 800 MPa-grade photovoltaic bracket ² . The hot-rolled weather-resistant steel plate is suitable for quality requirements of a thin 800 MPa-grade photovoltaic bracket, so that the atmospheric corrosion resistance index I is more than or equal to 7.5, and the atmospheric corrosion resistance of the product is obviously improved.

The yield strength, the tensile strength and the elongation after fracture of the hot-rolled weather-resistant steel plate for the photovoltaic bracket are as follows in section 1 of the tensile test of a metal material: room temperature test method (GB/T228.1) test; bending properties were tested according to the method for bending test of metallic materials (GB/T232); corrosion resistance was tested according to the method for periodic infiltration Corrosion test of weathering Steel for railway (TB/T2375).

Table 1 mass percent/wt% of the chemical compositions of examples and comparative examples

	C	Si	Mn	P	S	Cr	Ni	Cu	Nb	Ti	Sb	W	Als	N	B	Ca	I
																		Example 1	0.06	0.45	0.88	0.097	0.005	1.12	0.31	0.081		0.037	0.0048		8.5
Example 2	0.09	0.37	0.97	0.073	0.004	1.28		0.25		0.090			0.019	0.0045			8.0
																		Example 3	0.07	0.54	1.02	0.082	0.005	1.21	0.33	0.097		0.028	0.0045		8.6
Comparative example 1	0.09	0.37	0.97	0.073	0.004	1.28		0.25		0.090			0.019	0.0045			8.0
																		Comparative example 2	0.09	0.37	0.97	0.073	0.004	1.28	0.25	0.090		0.019	0.0045		8.0
Comparative example 3	0.07	0.54	1.02	0.082	0.005	1.21		0.33		0.097			0.028	0.0045			8.6
																		Comparative example 4	0.07	0.54	1.02	0.082	0.005	1.21	0.33	0.097		0.028	0.0045		8.6
Comparative example 5	0.08	0.30	0.58	0.020	0.010	2.95	0.39	0.35	0.031	0.142				0.0034			9.8
																		Comparative example 6	0.08	0.50	0.60	0.12	0.010	1.00	0.35	0.165			0.0040		9.0
Comparative example 7	0.06	0.49	0.58	0.12	0.009	0.98		0.36		0.168	0.07			0.0039			9.0
																		Comparative example 8	0.03	0.11	1.62	0.007	0.002	0.55	0.41		0.05				6.0
Comparative example 9	0.06	0.35	0.85	0.018	0.003	0.65	0.20	0.30	0.040	0.080			0.030	0.0040		0.0015	6.7
																		Comparative example 10	0.07	0.16	0.47	0.008	0.001	2.4	0.20	0.090		0.022	0.0035	0.00032	7.1

Example 1

A hot-rolled weather-resistant steel plate for a photovoltaic bracket with a thin specification of 800MPa has chemical compositions shown in Table 1, and the balance of Fe and unavoidable impurities.

A preparation method of a hot-rolled weather-resistant steel plate for a photovoltaic bracket with a thin specification of 800MPa grade comprises the steps of smelting a plate blank by adopting a conventional method according to components, continuously processing the smelted plate blank, and sequentially heating, rough rolling, finish rolling, laminar cooling and coiling, wherein the specific processing technology comprises the following steps: the heating temperature is 1270 ℃ and the heating time is 160min; after 6 times of rough rolling, the deformation of each pass is 19%, 21%, 24%, 25%, 28% and 31%, and the thickness of the intermediate blank is 36mm; after 7 passes of finish rolling, the rolling reduction rates of the three frames are respectively 17%, 13% and 10%, the initial rolling temperature of finish rolling is 1040-1060 ℃, and the final rolling temperature is 850-870 ℃; and cooling to the target coiling temperature by adopting a front-stage cooling mode, wherein the cooling speed is about 80 ℃/s, and the coiling temperature is 610-650 ℃. The metallographic structure is uniform polygonal ferrite and a small amount of pearlite, and as shown in fig. 1, the ferrite volume fraction is 95% and the pearlite volume fraction is 5%.

The hot-rolled weather-resistant steel plate for a thin 800 MPa-grade photovoltaic bracket prepared in example 1 has specific properties shown in Table 2.

Example 2

A preparation method of a hot-rolled weather-resistant steel plate for a photovoltaic bracket with a thin specification of 800MPa grade comprises the steps of smelting a plate blank by adopting a conventional method according to components, continuously processing the smelted plate blank, and sequentially heating, rough rolling, finish rolling, laminar cooling and coiling, wherein the specific processing technology comprises the following steps: the heating temperature is 1255 ℃, and the heating time is 175min; after 6 times of rough rolling, the deformation of each pass is 18%, 21%, 23%, 26%, 27% and 33%, and the thickness of the intermediate blank is 38mm; after 7 passes of finish rolling, the rolling reduction rates of the three frames are 19%, 14% and 10%, the initial rolling temperature of finish rolling is 1020-1040 ℃, and the final rolling temperature is 860-880 ℃; and cooling to the target coiling temperature by adopting a front-stage cooling mode, wherein the cooling speed is about 60 ℃/s, and the coiling temperature is 620-650 ℃. The metallographic structure is uniform polygonal ferrite and a small amount of pearlite, the ferrite volume fraction is 97%, and the pearlite volume fraction is 3%.

The hot-rolled weather-resistant steel plate for a thin 800 MPa-grade photovoltaic bracket prepared in example 2 has the specific properties shown in Table 2.

Example 3

A preparation method of a hot-rolled weather-resistant steel plate for a photovoltaic bracket with a thin specification of 800MPa grade comprises the steps of smelting a plate blank by adopting a conventional method according to components, continuously processing the smelted plate blank, and sequentially heating, rough rolling, finish rolling, laminar cooling and coiling, wherein the specific processing technology comprises the following steps: the heating temperature is 1245 ℃ and the heating time is 220min; after 6 times of rough rolling, the deformation of each pass is 19%, 20%, 22%, 25%, 27% and 35%, and the thickness of the intermediate blank is 42mm; after 7 passes of finish rolling, the rolling reduction rates of the three frames are 18%, 14% and 11%, the initial rolling temperature of the finish rolling is 1010-1030 ℃ and the final rolling temperature is 860-880 ℃; and cooling to the target coiling temperature by adopting a front-stage cooling mode, wherein the cooling speed is about 45 ℃/s, and the coiling temperature is 590-620 ℃. The metallographic structure is uniform polygonal ferrite and a small amount of pearlite, the ferrite volume fraction is 93%, and the pearlite volume fraction is 7%.

The hot-rolled weather-resistant steel plate for a thin 800 MPa-grade photovoltaic bracket prepared in example 3 has the specific properties shown in Table 2.

Comparative example 1

The hot rolled weather resistant steel plate for the thin photovoltaic bracket has chemical compositions shown in table 1, and the balance of Fe and unavoidable impurities.

A preparation method of a hot-rolled weather-resistant steel plate for a thin photovoltaic bracket comprises the steps of smelting a plate blank by adopting a conventional method according to components, continuously processing the smelted plate blank, and sequentially heating, rough rolling, finish rolling, laminar cooling and coiling, wherein the specific processing technology comprises the following steps: heating at 1210 ℃ for 130min; after 6 times of rough rolling, the deformation of each pass is 18%, 20%, 22%, 26%, 27% and 35%, and the thickness of the intermediate blank is 38mm; after 7-pass finish rolling, the reduction rates of the three frames are 18%, 13% and 11%, the finish rolling start temperature is 1030-1060 ℃, and the finish rolling temperature is 840-860 ℃; and cooling to the target coiling temperature by adopting a front-stage cooling mode, wherein the cooling speed is about 65 ℃/s, and the coiling temperature is 620-650 ℃. The metallographic structure is uniform polygonal ferrite and a small amount of pearlite, the ferrite volume fraction is 94%, and the pearlite volume fraction is 6%.

The specific properties of the hot-rolled weather-resistant steel plate for a thin photovoltaic bracket prepared in comparative example 1 are shown in Table 2.

Comparative example 2

A preparation method of a hot-rolled weather-resistant steel plate for a thin photovoltaic bracket comprises the steps of smelting a plate blank by adopting a conventional method according to components, continuously processing the smelted plate blank, and sequentially heating, rough rolling, finish rolling, laminar cooling and coiling, wherein the specific processing technology comprises the following steps: the heating temperature is 1280 ℃ and the heating time is 300min; after 6 times of rough rolling, the deformation of each pass is 19%, 21%, 23%, 24%, 26% and 35%, and the thickness of the intermediate blank is 38mm; after 7-pass finish rolling, the reduction rates of the three frames are 17%, 14% and 10%, the initial rolling temperature of finish rolling is 1030-1050 ℃, and the final rolling temperature is 840-870 ℃; and cooling to a target coiling temperature by adopting a front-stage cooling mode, wherein the cooling speed is about 65 ℃/s, and the coiling temperature is 600-620 ℃. The metallographic structure is uniform polygonal ferrite and a small amount of pearlite, the ferrite volume fraction is 93%, and the pearlite volume fraction is 7%.

The hot-rolled weather-resistant steel plate for a thin photovoltaic bracket prepared in comparative example 2 has the specific properties shown in Table 2.

Comparative example 3

A preparation method of a hot-rolled weather-resistant steel plate for a thin photovoltaic bracket comprises the steps of smelting a plate blank by adopting a conventional method according to components, continuously processing the smelted plate blank, and sequentially heating, rough rolling, finish rolling, laminar cooling and coiling, wherein the specific processing technology comprises the following steps: heating at 1210 ℃ for 130min; after 6 times of rough rolling, the deformation of each pass is 18%, 22%, 23%, 24%, 27% and 34%, and the thickness of the intermediate blank is 42mm; after 7-pass finish rolling, the rolling reduction rates of the three frames are 18%, 15% and 10%, the initial rolling temperature of finish rolling is 1030-1060 ℃, and the final rolling temperature is 860-880 ℃; and cooling to the target coiling temperature by adopting a front-stage cooling mode, wherein the cooling speed is about 90 ℃/s, and the coiling temperature is 550-580 ℃. The metallographic structure is uniform polygonal ferrite and a small amount of pearlite, the ferrite volume fraction is 90%, the pearlite volume fraction is 5%, and the bainite volume fraction is 5%.

The hot-rolled weather-resistant steel plate for a thin photovoltaic bracket prepared in comparative example 3 has the specific properties shown in Table 2.

Comparative example 4

A preparation method of a hot-rolled weather-resistant steel plate for a thin photovoltaic bracket comprises the steps of smelting a plate blank by adopting a conventional method according to components, continuously processing the smelted plate blank, and sequentially heating, rough rolling, finish rolling, laminar cooling and coiling, wherein the specific processing technology comprises the following steps: heating at 1210 ℃ for 130min; after 6 times of rough rolling, the deformation of each pass is 19%, 20%, 23%, 26%, 27% and 33%, and the thickness of the intermediate blank is 42mm; after 7 passes of finish rolling, the rolling reduction rates of the three frames are respectively 17%, 13% and 11%, the initial rolling temperature of the finish rolling is 1030-1070 ℃, and the final rolling temperature is 850-880 ℃; and cooling to a target coiling temperature by adopting a front-stage cooling mode, wherein the cooling speed is about 30 ℃/s, and the coiling temperature is 660-680 ℃. The metallographic structure is uniform polygonal ferrite and a small amount of pearlite, the ferrite volume fraction is 96%, and the pearlite volume fraction is 4%.

The hot-rolled weather-resistant steel plate for a thin photovoltaic bracket prepared in comparative example 4 has the specific properties shown in Table 2.

Comparative example 5

Specific reference is made to example 1 of patent publication No. CN116240467A, "high weathering steel for 800MPa grade photovoltaic bracket and preparation method thereof," the chemical composition is shown in Table 1, and the balance is Fe and unavoidable impurities.

The preparation method of the hot rolled steel coil for the 800 MPa-level photovoltaic bracket comprises the following production processes: billet, hot rolling, laminar cooling and coiling. In the hot rolling step, the thickness of a finish rolling inlet is 40mm, the initial rolling temperature of finish rolling is 985 ℃, the final rolling temperature is 880 ℃, the laminar cooling is the cooling of the front stage, and the coiling temperature is 630 ℃.

The specific properties of the hot rolled steel coil for the 800 MPa-grade photovoltaic bracket prepared in comparative example 5 are shown in Table 2.

Comparative example 6

With specific reference to example 1 of patent publication No. CN116179961A, namely, titanium-containing weathering steel for low-cost 800 MPa-level photovoltaic brackets and preparation method thereof, the chemical compositions are shown in Table 1, and the balance is Fe and unavoidable impurities.

The production process of the titanium-containing weathering steel for the low-cost 800 MPa-level photovoltaic bracket comprises the following steps: billet, hot rolling, laminar cooling and coiling. The heating time in the hot rolling step is 60min, the thickness of a finish rolling inlet is 40mm, the initial rolling temperature of finish rolling is 980 ℃, the final rolling temperature is 880 ℃, the laminar cooling is the cooling of the front stage, and the coiling temperature is 580 ℃.

The concrete properties of the titanium-containing weathering steel for the low-cost 800 MPa-grade photovoltaic brackets prepared in comparative example 6 are shown in Table 2.

Comparative example 7

Referring to the embodiment 1 of patent publication No. CN116219306A, namely, an antimony-containing weathering steel for a low-cost 800 MPa-grade photovoltaic bracket and a preparation method thereof, the chemical composition is shown in Table 1, and the balance is Fe and unavoidable impurities.

The production process of the antimony-containing weathering steel for the low-cost 800 MPa-level photovoltaic bracket comprises the following steps: billet, hot rolling, laminar cooling and coiling. The heating time in the hot rolling step is 65min, the thickness of a finish rolling inlet is 40mm, the initial rolling temperature of finish rolling is 985 ℃, the final rolling temperature is 880 ℃, the laminar cooling is the cooling of the front stage, and the coiling temperature is 585 ℃.

The antimony-containing weathering steel for the low-cost 800 MPa-grade photovoltaic brackets prepared in comparative example 7 has the specific properties shown in Table 2.

Comparative example 8

Specific reference is made to example 4 of patent publication CN115896613a, "weather-resistant steel for high strength low cost photovoltaic brackets and method for preparing same," which has the chemical composition shown in table 1, and the balance being Fe and unavoidable impurities.

The production process of the weather-resistant steel for the high-strength low-cost photovoltaic bracket comprises the following steps: heating a casting blank, rough rolling, finish rolling, sectional cooling, tempering and cooling. Wherein the heating temperature of the casting blank is 1250+/-20 ℃; the initial rolling temperature is 1080+/-20 ℃, and the final rolling temperature is 950+/-20 ℃; the initial rolling temperature of the finish rolling is 900+/-20 ℃, and the final rolling temperature is 790+/-20 ℃; control the first stage when cooling in stages: the cooling rate is 2-4 ℃/s, and the temperature is cooled to 650+/-20 ℃; and a second stage: the cooling rate is 20-35 ℃/s, so that the steel plate is rapidly cooled to 100-300 ℃; the tempering temperature is 200-300 ℃, and the temperature is kept for 28min.

The specific properties of the weather resistant steel for the high-strength low-cost photovoltaic brackets prepared in comparative example 8 are shown in Table 2.

Comparative example 9

Specific reference is made to example 1 of patent publication CN115786822a, "high strength weathering steel for photovoltaic brackets and method for preparing same," the chemical composition is shown in table 1, and the balance is Fe and unavoidable impurities.

The production process of the high-strength weather-resistant steel for the photovoltaic bracket sequentially comprises the following steps of:

1) Desulfurizing molten iron: s in the desulfurized molten iron: 0.003%; 2) Smelting in a converter: feeding the molten iron desulfurized in the step S1 into a converter, and tapping the converter by P:0.010%, N:0.0018%; alloying: according to the chemical components and the mass percentage of the high-strength weathering steel for the photovoltaic bracket, adding a Cu plate, a Ni-Fe alloy or a Cu-Ni alloy in front of the furnace, beginning to add the Si-Mn alloy, the Si-Fe alloy, the low-carbon Cr-Fe alloy and the Nb-Fe alloy when tapping 1/3 of the steel after the furnace, and finishing the addition when tapping 2/3 of the steel; 3) Argon blowing and LF ladle furnace calcium treatment are performed at an argon station: feeding the steel ladle into an LF ladle furnace to adjust the temperature to 1590 ℃, deeply desulfurizing, finely adjusting the components to meet the requirements of chemical components and mass percent thereof, adding Ti-Fe alloy after the components are stable, carrying out inclusion modified calcium treatment, feeding calcium wires according to the estimated Als% before leaving a station according to the calcium-aluminum ratio of 0.08-0.12, and ensuring that the Ar blowing time is more than or equal to 8min after the calcium treatment; 4) Continuous casting and slow cooling of casting blanks: the ladle casting adopts long nozzle argon seal protection casting, molten steel is continuously cast into a plate blank stack with the thickness of 210mm, the plate blank stack is slowly cooled, and the cold-filling temperature of the plate blank is room temperature; 5) Heating: heating the plate blank at 1280 ℃ for 190min in a furnace; 6) Hot continuous rolling: the two-stage temperature control rolling of rough rolling and finish rolling are adopted in sequence: the finishing temperature of rough rolling is 1050 ℃, and the thickness of the steel plate after rough rolling is 32mm; the finish rolling temperature of the finish rolling is 880 ℃; 7) Cooling, coiling and slow cooling: and (3) after hot continuous rolling, adopting front-end laminar cooling, wherein the cooling speed is 20 ℃/s, the coiling temperature is 610 ℃, and the hot rolled plate coil with the thickness of 3.0mm is prepared, and is hung into a slow cooling box to be slowly cooled to room temperature, so that the high-strength weather-resistant steel plate for the photovoltaic bracket is prepared.

The specific properties of the high-strength weathering steel for photovoltaic brackets prepared in comparative example 9 are shown in Table 2.

Comparative example 10

Specific reference is made to example 1 of patent publication CN116623099a, "high strength and high weather resistance steel for photovoltaic brackets and method for manufacturing same," the chemical composition is shown in table 1, and the balance is Fe and unavoidable impurities.

The production process of the high-strength high-weather-resistance steel for the photovoltaic bracket sequentially comprises the following steps of: 1) The molten iron is subjected to KR desulfurization pretreatment, and the S content of the molten iron is controlled; 2) Smelting molten iron through a converter, and controlling the end temperature of the converter and the O, C, B content of the end molten steel; 3) Adding aluminum iron into converter tapping to completely deoxidize, and controlling the ALs content of molten steel; alloying according to the chemical components of the steel, and adding low-boron low-carbon ferrochrome in the alloying process; controlling tapping slag discharging quantity; 4) Argon is blown to the bottom of the molten steel through an argon blowing station, and the ALs content of the molten steel is controlled; 5) Molten steel is subjected to deep desulfurization treatment by an LF furnace, and a low-boron magnesia carbon brick is adopted at a ladle slag line of the LF furnace; adding aluminum particles into the slag in the earlier stage of desulfurization, and feeding aluminum wires when the S content of molten steel is reduced to below 0.002%; controlling LF smelting time and S, B, ALs content of the discharged molten steel; 6) The molten steel is degassed through RH vacuum circulation, and the vacuum degree, the vacuum circulation time and the vacuum ending temperature are controlled; 7) Continuous casting of molten steel into billets, and the crystallizer casting powder adopts ultra-low carbon steel special slag, and has higher viscosity, alkalinity and melting point compared with common casting powder; 8) And (5) rolling and coiling the plate blank after heating to obtain the high-strength high-weather-resistance steel for the photovoltaic bracket.

The specific properties of the high-strength and high-weather-resistance steel for photovoltaic stents prepared in comparative example 10 are shown in Table 2.

Table 2 results of product performance tests of examples and comparative examples

Note that: bending indenter diameter D, sample thickness a.

The results of the performance tests of the examples and comparative examples obtained from the chemical compositions of table 1 and table 2, in combination with the preparation methods of the examples and comparative examples, are shown as follows: the preparation method of the embodiment is simple; by adding a certain amount of Si, P, cr, cu and other elements, the alloy cost is reduced, and meanwhile, the excellent atmospheric corrosion resistance is realized, compared with the Q355B corrosion rate, which is less than or equal to 35%, and the corrosion of the metal and the alloy in the corrosive atmosphere part 1: the double-sided uniform corrosion thinning amount in the use period of 25 years for bare is not more than 0.2mm (double-sided) under the environment of C1-C3 specified in classification, measurement and evaluation (GB/T19292.1-2018); through reasonable heating temperature and heating time setting, the performance is ensured, and the generation of copper embrittlement defects is avoided; the rolling of the thin-specification product is realized through reasonable heating temperature and intermediate blank thickness setting; the Ti microalloying mode is used for exerting fine crystal strengthening and precipitation strengthening effects, and the rolling and cooling control process is combined for regulating and controlling the tissue performance, so that the product realizes high strength and excellent plasticity, the tensile strength is more than or equal to 800MPa, and the elongation after breaking is more than or equal to 20%. Therefore, the hot-rolled weather-resistant steel plate for the photovoltaic bracket with the thin specification of 800MPa and the preparation method thereof can meet the green and light application requirements of the photovoltaic bracket, and have good application prospects.

Many possible variations and modifications of the disclosed technology can be made by anyone skilled in the art without departing from the scope of the technology, or the technology can be modified to be equivalent. Therefore, any simple modification, equivalent variation and modification of the above embodiments according to the technical substance of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. The hot-rolled weather-resistant steel plate for the photovoltaic support with the thin specification of 800MPa is characterized by comprising the following components in percentage by weight: 0.05 to 0.10 percent of C, 0.35 to 0.55 percent of Si, 0.85 to 1.05 percent of Mn, 0.070 to 0.100 percent of P, less than or equal to 0.008 percent of S, 1.10 to 1.30 percent of Cr, 0.25 to 0.35 percent of Cu, 0.080 to 0.100 percent of Ti, 0.010 to 0.040 percent of Als, less than or equal to 0.0050 percent of N, and the balance of Fe and unavoidable impurities.

2. The hot-rolled weather-resistant steel sheet as claimed in claim 1, wherein the hot-rolled weather-resistant steel sheet for photovoltaic brackets has an atmospheric corrosion resistance index I of 7.5 or more.

3. The hot-rolled weather-resistant steel sheet according to claim 1, wherein the yield strength of the hot-rolled weather-resistant steel sheet for a photovoltaic bracket is equal to or more than 690MPa, the tensile strength is equal to or more than 800MPa, the elongation after break is equal to or more than 20%, and the 180 ° bending test d=2a.

4. The hot-rolled weathering steel plate of claim 1, wherein the photovoltaic scaffold hot-rolled weathering steel plate has a corrosion rate of less than or equal to 35% relative to Q355B.

5. The hot-rolled weather-resistant steel sheet as claimed in claim 1, wherein the photovoltaic support hot-rolled weather-resistant steel sheet has a double-sided uniform corrosion thinning of not more than 0.2mm in a 25-year service cycle for bare use in a C1-C3 environment specified in GB/T19292.1-2018.

6. The hot-rolled weather-resistant steel sheet as claimed in claim 1, wherein the thickness of the hot-rolled weather-resistant steel sheet for a photovoltaic bracket is 1.5 to 6.0mm.

7. The hot-rolled weather-resistant steel sheet according to claim 1, wherein the metallographic structure of the hot-rolled weather-resistant steel sheet for a photovoltaic bracket is polygonal ferrite+pearlite; the volume fraction of the ferrite is 92-97% and the pearlite is 3-8%.

8. A method for preparing the hot-rolled weather-resistant steel plate for the thin-gauge 800 MPa-level photovoltaic bracket according to claim 1, characterized in that the preparation method comprises: smelting the hot-rolled weather-resistant steel plate for the photovoltaic bracket into a plate blank according to the components of the hot-rolled weather-resistant steel plate for the photovoltaic bracket, and sequentially performing the steps of heating, rough rolling, finish rolling, laminar cooling and coiling on the plate blank to obtain the hot-rolled weather-resistant steel plate for the photovoltaic bracket;

in the heating step, the casting blank is hot-fed and hot-packed, the heating temperature is 1230-1270 ℃, and the heating time is 150-250 min;

in the rough rolling step, 6 times of rough rolling are carried out, and the deformation of each time is more than or equal to 18%; when the thickness of the finished product is 1.5 to less than 2.0mm, the thickness of the intermediate blank is 34 to 38mm; when the thickness of the finished product is 2.0 to less than 4.0mm, the thickness of the intermediate blank is 36 to 40mm; when the thickness of the finished product is 4.0-6.0 mm, the thickness of the intermediate blank is 40-44 mm;

in the coiling step, when the thickness of a finished product is 1.5 to less than 4.0mm, the coiling temperature is 610 to 650 ℃; when the thickness of the finished product is 4.0-6.0 mm, the coiling temperature is 590-630 ℃.

9. The method according to claim 8, wherein in the finish rolling step, 7 passes of finish rolling are performed, the reduction rates of the last three frames are respectively equal to or more than 17%, equal to or more than 13% and equal to or more than 10%, the initial rolling temperature of finish rolling is equal to or less than 1080 ℃, and the final rolling temperature is 840-880 ℃.

10. The method according to claim 8, wherein in the laminar cooling step, a front stage cooling mode is adopted, and the cooling rate is 40 to 80 ℃/s.