Thick-zinc high-surface-quality hot-based flower-free galvanized sheet and production method thereof

Abstract

The invention belongs to the technical field of metal smelting, and particularly discloses a thick-zinc high-surface-quality hot-based flower-free galvanized sheet and a production method thereof.The galvanized sheet comprises the chemical components of 0.03%-0.05% of C, 0.03%-0.05% of Cr, 0.02%-0.04% of Si, 0.15%-0.2% of Mn, smaller than or equal to 0.02% of P, smaller than or equal to 0.01% of S, smaller than or equal to 0.01% of Ti, smaller than or equal to 0.01% of V, 0.01%-0.03% of Cu and the balance Fe and inevitable impurities; the production method comprises the procedures of hot rolling, pickling, annealing and galvanizing. The hot-based flower-free galvanized plate provided by the invention has the advantages of fewer oblique scars, lighter inclined grains and narrower edge thickness, avoids the problem of edge waves generated during uncoiling of a finished product due to the thick edge, improves the stability of continuously producing a high-surface-quality thick zinc layer, and can meet the use requirements of customers on the hot-based flower-free galvanized steel plate with the thick zinc layer.

Description

Technical Field

[0001] The invention belongs to the technical field of metal smelting, and in particular relates to a hot-base non-patterned galvanized sheet with a thick zinc layer and high surface quality and a production method thereof. Background Art

[0002] With the continuous improvement of technology and the optimization and upgrading of production equipment, in order to meet market needs, the corrosion resistance of hot-based non-patterned galvanized sheets needs to be increased, and the thickness of the zinc layer is constantly breaking through. At present, the market competition for thick zinc layer hot-based non-patterned galvanized sheets is particularly fierce. Whether it is possible to stably mass-produce products with high-quality surfaces directly affects the market share. Common defects of thick zinc layer products include oblique scars, diagonal lines on the edges, edge thickness, and wave shapes. These defects seriously affect the use effect of the product. Therefore, it is urgent to provide a production method for hot-based non-patterned galvanized sheets with thick zinc layers and high surface quality. Based on the existing equipment, thin-gauge thick zinc layer products with high surface quality can be stably mass-produced to meet customers' requirements for the use of thin-gauge thick zinc layer hot-based non-patterned galvanized steel sheets. Summary of the invention

[0003] The present invention aims to provide a hot-based non-patterned galvanized sheet with thick zinc layer and high surface quality and a production method thereof. The hot-based non-patterned galvanized sheet has ≤5 oblique scar defects on both sides of the upper and lower surfaces, ≤10cm diagonal line defects on the edges, and ≤10mm edge thickness.

[0004] In order to achieve the above-mentioned invention object, the present invention adopts the following technical scheme: A hot-dip galvanized sheet with thick zinc layer and high surface quality, whose chemical composition and mass percentage are as follows: C: 0.03-0.05%, Cr: 0.03-0.05%, Si: 0.02-0.04%, Mn: 0.15-0.2%, P≤0.02%, S≤0.01%, Ti≤0.01%, V≤0.01%, Cu: 0.01-0.03%, and the balance is Fe and unavoidable impurities.

[0005] The production method of the hot-base patternless galvanized sheet with thick zinc layer and high surface quality of the invention comprises the steps of hot rolling, pickling, annealing and galvanizing.

[0006] Preferably, in the hot rolling process, the finishing rolling outlet temperature is 850-890°C, and the coiling temperature is 580-600°C.

[0007] Preferably, in the pickling process, the pickling speed is 100-120 m / min, the rolling force of the leveler is ≥1200 kN, and the hydrochloric acid pickling corrosion inhibitor is 0.5%-0.7%.

[0008] In the pickling process, the process speed will fluctuate due to the influence of inlet welding and outlet slitting, but if the pickling speed is low, defects such as over-pickling and yellow spots will occur, affecting the surface quality, so the speed should be kept as stable as possible. After the substrate is flattened, it will have a uniform roughness, which will improve the adhesion of the subsequent coating, and the flatness of the substrate will also be improved. Adding a certain proportion of corrosion inhibitor can not only effectively remove the iron oxide, rust and other dirty impurities on the surface of the metal material, but also play a corrosion inhibition role to prevent the surface of the substrate from being invaded by corrosion. By adjusting the above pickling process parameters, the stability of the substrate surface quality can be guaranteed.

[0009] Preferably, the annealing process includes non-oxidation heating treatment, radiation tube heating treatment, electric uniform heating treatment and spray cooling treatment; the strip temperature of the non-oxidation heating treatment is 680-700°C; the strip temperature of the radiation tube heating treatment is 670-690°C; the strip temperature of the electric uniform heating treatment is 660-680°C; the strip temperature of the spray cooling treatment is 455-465°C, the oxygen content of the grate is <100ppm, and the dew point is ≤-26°C.

[0010] The hot-dip galvanized sheet substrate is subjected to non-oxidizing heating treatment, radiant tube heating treatment, electric uniform heating treatment and spray cooling treatment in sequence, and a specific treatment temperature is selected in each treatment process, which can make the deformed grains in the substrate recrystallize into uniform equiaxed grains, eliminate work hardening and residual stress, and further improve the mechanical properties and cold bending forming properties of the material; the selection of non-oxidizing atmosphere and dew point can further improve the adhesion of the hot-dip galvanized sheet substrate with thick zinc layer.

[0011] Preferably, in the galvanizing process, the galvanizing speed is 40-55 m / min, the zinc liquid temperature is 450-460° C., the mass content of Al in the zinc liquid is 0.19-0.21%, and the mass content of Fe is 0.01-0.02%.

[0012] Preferably, in the galvanizing process, the air knife pressure is 35-42 mbar, the distance between the air knife and the strip is 34-40 mm, the air knife height is 80-90 mm, the distance between the air knife baffle and the edge of the strip is 2-4 mm, the load power of the mobile bellows is 30-50%, the load power of the 1# fixed bellows is 60-80%, the load power of the 2#, 3# and 4# fixed bellows is automatically adjusted, and the air volume of the edge blowing device above the mobile bellows is 30-50%.

[0013] In the galvanizing process, the oblique scars, edge twill and edge thickness can be effectively controlled through the refined control and selection of various parameters of the air knife and the post-galvanizing cooling bellows, thereby further improving the surface quality of the thick zinc layer.

[0014] Preferably, in the galvanizing process, the roughness Ra of the working roll of the skin-pass mill is 2.5-4.0 μm, the convexity is 0.01-0.03 mm, and the rolling force of the skin-pass mill is 2500-3000 kN.

[0015] In the galvanizing process, the working rolls of the skin-pass mill use positive crown rolls, which can reduce the bending roll value, effectively avoid the occurrence of bending roll mark defects, and also facilitate the improvement of the rolling force of the skin-pass mill.

[0016] Preferably, in the galvanizing process, the outlet loop release speed is 80-100 m / min, the coiler tension is 60-90 kN, the coiler adopts staggered curling, the staggered length is 130-150 mm, the amplitude is 10-15 mm, and the slope is 20-30 mm.

[0017] By optimizing the curling parameters of the galvanizing process, small wave defects caused by edge thickness during uncoiling can be effectively avoided.

[0018] The thickness of the hot-dip galvanized sheet of the present invention is in the range of 2.5 to 4.0 mm; the zinc layer specification is 800 g / m 2 (double-sided), yield strength ≥300MPa, elongation after break ≥38%.

[0019] The hot-based patternless galvanized sheet of the present invention has ≤5 oblique scar defects on both sides of the upper and lower surfaces, ≤10cm of diagonal defects on the edges, and ≤10mm of edge thickness.

[0020] The beneficial technical effects of the technical solution of the present invention are: The present invention controls the substrate composition of the hot-based spotless galvanized sheet and the content range of each component, and adds trace amounts of titanium and vanadium elements, thereby ensuring the excellent mechanical properties and stamping properties of the galvanized sheet. The yield strength of the galvanized sheet is ≥300MPa, and the elongation after fracture is ≥38%.

[0021] The present invention uses a substrate of specific composition as a raw material, and can form a 800g / m2 surface of the substrate by setting parameters for the hot rolling process, pickling process, annealing process, and galvanizing process. 2 (Double-sided) zinc layer, while also ensuring the uniformity of the galvanized layer thickness.

[0022] The hot-based patternless galvanized steel sheet provided by the present invention has fewer oblique scars, lighter twill lines, and narrower edge thickness, which avoids the problem of edge waves when the finished product is unrolled due to edge thickness, improves the stability of continuous production of high surface quality thick zinc layer, and can meet customers' requirements for the use of thick zinc layer hot-based patternless galvanized steel sheet; and the method of the present invention is simple to operate, has a wide range of applications, and can be completed with conventional galvanized sheet preparation equipment. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Example 1

[0024] The chemical composition of the hot-dip galvanized sheet in this embodiment is: C: 0.03%, Cr: 0.03%, Si: 0.02%, Mn: 0.15%, P: 0.02%, S: 0.01%, Ti: 0.002%, V: 0.002%, Cu: 0.01%, and the balance is Fe and unavoidable impurities; its production method includes hot rolling, pickling, annealing and galvanizing processes, and the specific control is as follows: (1) Hot rolling process: finishing rolling outlet temperature 850℃, coiling temperature 580℃.

[0025] (2) Pickling process: pickling speed: 120m / min, flat mill rolling force: 1200kN, hydrochloric acid pickling corrosion inhibitor (supplier: Lubaoli): 0.5%.

[0026] (3) Annealing process: Strip temperature for non-oxidizing heating treatment: 680°C, strip temperature for radiant tube heating treatment: 670°C, strip temperature for electric uniform heating treatment: 660°C, strip temperature for spray cooling treatment: 455°C, grate oxygen content <100ppm, dew point ≤-26°C.

[0027] (4) Galvanizing process: galvanizing speed: 55 m / min, zinc liquid temperature: 460 °C, Al mass content in zinc liquid: 0.21%, Fe mass content: 0.02%; Air knife pressure: 35mbar, distance between air knife and strip: 34mm, air knife height: 90mm, distance between air knife baffle and strip edge: 4mm, mobile bellows load power: 30%, 1# fixed bellows load power: 60%, 2#, 3#, 4# fixed bellows load power selection automatic adjustment, air volume of edge blowing device above mobile bellows: 30%; The roughness of the skin-pass mill working roll is Ra: 2.5μm, the crown is 0.03mm, and the rolling force of the skin-pass mill is 3000kN; The exit loop release speed is 100m / min, the coiler tension is 60kN, the coiler adopts staggered curling, the staggered length is 130mm, the amplitude is 10mm, and the slope is 20mm.

[0028] The hot-dip galvanized sheet obtained in this embodiment has a thickness of 2.5 mm and a width of 1250 mm, a cold bending D=0.5a (qualified), a good surface quality, and a uniform zinc layer. According to the GB / 6462-2005 standard, the zinc layer thickness meets the zinc layer specification of 800 g / m 2(double-sided). Example 2

[0029] The chemical composition of the hot-base non-patterned galvanized sheet in this embodiment is: C: 0.04%, Cr: 0.04%, Si: 0.02%, Mn: 0.17%, P: 0.018%, S: 0.008%, Ti: 0.004%, V: 0.004%, Cu: 0.015%, and the balance is Fe and unavoidable impurities; its production method includes hot rolling, pickling, annealing and galvanizing processes, and the specific control is as follows: (1) Hot rolling process: finishing rolling outlet temperature 870℃, coiling temperature 585℃.

[0030] (2) Pickling process: pickling speed: 110 m / min, flat mill rolling force: 1200 kN, hydrochloric acid pickling corrosion inhibitor (supplier: Lu Baoli): 0.6%.

[0031] (3) Annealing process: Strip temperature for non-oxidizing heating treatment: 685°C, strip temperature for radiant tube heating treatment: 675°C, strip temperature for electric uniform heating treatment: 665°C, strip temperature for spray cooling treatment: 458°C, grate oxygen content <100ppm, dew point ≤-26°C; (4) Galvanizing process: galvanizing speed: 50 m / min, zinc liquid temperature: 458 °C, Al mass content in zinc liquid: 0.208%, Fe mass content: 0.02%; Air knife pressure: 38mbar, distance between air knife and strip: 36mm, air knife height: 90mm, distance between air knife baffle and strip edge: 4mm, mobile bellows load power: 40%, 1# fixed bellows load power: 70%, 2#, 3#, 4# fixed bellows load power selection automatic adjustment, air volume of edge blowing device above mobile bellows: 40%; The roughness of the skin-pass mill working roll is Ra: 3.0μm, the crown is 0.02mm, and the rolling force of the skin-pass mill is 3000kN; The exit loop release speed is 100m / min, the coiler tension is 80kN, the coiler adopts staggered curling, the staggered length is 140mm, the amplitude is 10mm, and the slope is 25mm.

[0032] The hot-dip galvanized sheet obtained in this embodiment has a thickness of 3.0 mm and a width of 1250 mm, a cold bending D=0.5a (qualified), a good surface quality, and a uniform zinc layer. According to the GB / 6462-2005 standard, the zinc layer thickness meets the zinc layer specification of 800 g / m 2 (double-sided). Example 3

[0033] The chemical composition of the hot-base flat galvanized sheet in this embodiment is: C: 0.045%, Cr: 0.045%, Si: 0.035%, Mn: 0.18%, P: 0.016%, S: 0.008%, Ti: 0.006%, V: 0.006%, Cu: 0.02%, and the balance is Fe and unavoidable impurities; its production method includes hot rolling, pickling, annealing and galvanizing processes, and the specific control is as follows: (1) Hot rolling process: finishing rolling outlet temperature 880°C, coiling temperature 590°C; (2) Pickling process: pickling speed: 110 m / min, skin-pass mill rolling force: 1200 kN, hydrochloric acid pickling corrosion inhibitor (supplier: Lubaoli): 0.6%; (3) Annealing process: Strip temperature for non-oxidizing heating treatment: 690°C, strip temperature for radiant tube heating treatment: 680°C, strip temperature for electric uniform heating treatment: 670°C, strip temperature for spray cooling treatment: 460°C, grate oxygen content <100ppm, dew point ≤-26°C; (4) Galvanizing process: galvanizing speed: 45 m / min, zinc liquid temperature: 455°C, Al mass content in zinc liquid: 0.2%, Fe mass content: 0.015%; Air knife pressure: 40mbar, distance between air knife and strip: 38mm, air knife height: 90mm, distance between air knife baffle and strip edge: 4mm, mobile bellows load power: 40%, 1# fixed bellows load power: 80%, 2#, 3#, 4# fixed bellows load power selection automatic adjustment, air volume of edge blowing device above mobile bellows: 50%; The roughness of the skin-pass mill working roll is Ra: 3.5μm, the crown is 0.02mm, and the rolling force of the skin-pass mill is 2700kN; The exit loop release speed is 90m / min, the coiler tension is 85kN, the coiler adopts staggered curling, the staggered length is 140mm, the amplitude is 15mm, and the slope is 25mm.

[0034] The hot-dip galvanized sheet obtained in this embodiment has a thickness of 3.5 mm and a width of 1250 mm, a cold bending D=0.5a (qualified), a good surface quality, and a uniform zinc layer. According to the GB / 6462-2005 standard, the zinc layer thickness meets the zinc layer specification of 800 g / m 2 (double-sided). Example 4

[0035] The chemical composition of the hot-base flat galvanized sheet in this embodiment is: C: 0.05%, Cr: 0.05%, Si: 0.04%, Mn: 0.2%, P: 0.015%, S: 0.005%, Ti: 0.01%, V: 0.01%, Cu: 0.03%, and the balance is Fe and unavoidable impurities; its production method includes hot rolling, pickling, annealing and galvanizing processes, and the specific control is as follows: (1) Hot rolling process: finishing rolling outlet temperature 890℃, coiling temperature 600℃. ; (2) Pickling process: pickling speed: 100 m / min, skin-pass mill rolling force: 1200 kN, hydrochloric acid pickling corrosion inhibitor (supplier: Lubaoli): 0.7%; (3) Annealing process: Strip temperature for non-oxidizing heating treatment: 700°C, strip temperature for radiant tube heating treatment: 690°C, strip temperature for electric uniform heating treatment: 680°C, strip temperature for spray cooling treatment: 465°C, grate oxygen content <100ppm, dew point ≤-26°C; (4) Galvanizing process: galvanizing speed: 40 m / min, zinc liquid temperature: 450°C, Al mass content in zinc liquid: 0.19%, Fe mass content: 0.01%; Air knife pressure: 42mbar, distance between air knife and strip: 40mm, air knife height: 80mm, distance between air knife baffle and strip edge: 2mm, mobile bellows load power: 50%, 1# fixed bellows load power: 80%, 2#, 3#, 4# fixed bellows load power selection automatic adjustment, air volume of edge blowing device above mobile bellows: 50%; The roughness of the skin-pass mill working roll is Ra: 4.0μm, the crown is 0.01mm, and the rolling force of the skin-pass mill is 2500kN; The exit loop release speed is 80m / min, the coiler tension is 60kN, the coiler adopts staggered curling, the staggered length is 150mm, the amplitude is 15mm, and the slope is 30mm.

[0036] The hot-dip galvanized sheet obtained in this embodiment has a thickness of 4.0 mm and a width of 1250 mm, a cold bending D=0.5a (qualified), a good surface quality, and a uniform zinc layer. According to the GB / 6462-2005 standard, the zinc layer thickness meets the zinc layer specification of 800 g / m 2 (double-sided).

[0037] The zinc layer of the hot-dip galvanized sheets obtained in Examples 1 to 4 was tested by a laboratory wet method. The test results are shown in Table 1.

[0038] Table 1 Weight of zinc layer of hot-dip galvanized sheet in each example (g / ㎡)

[0039] As shown in Table 1, the zinc layer of the hot-dip galvanized sheets obtained in Examples 1 to 4, measured according to GB / 6462-2005 standard, has a zinc layer thickness that meets the zinc layer specification of 800 g / m 2 (double-sided).

[0040] The defects of the hot-dip galvanized sheets obtained in Examples 1 to 4 were statistically analyzed, and the results are shown in Table 2.

[0041] Table 2 Defects of hot-dip galvanized sheets in various examples

[0042] The mechanical properties of the hot-dip galvanized sheets obtained in Examples 1 to 4 are shown in Table 3.

[0043] Table 3 Mechanical properties of hot-dip galvanized sheets in various examples

[0044] It can be seen from Table 2 and Table 3 that the thick zinc layer hot-based non-patterned galvanized sheet provided by the present invention has good mechanical properties and stamping properties, yield strength ≥300MPa, tensile strength ≥365MPa, elongation after fracture ≥38%, fewer oblique scars, lighter twill, and narrower edge thickness, avoiding the problem of edge waves when the finished product is unrolled due to edge thickness.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A hot-base non-patterned galvanized sheet with thick zinc layer and high surface quality, characterized in that: Its chemical composition and mass percentage are: C: 0.03~0.05%, Cr: 0.03~0.05%, Si: 0.02~0.04%, Mn: 0.15~0.2%, P≤0.02%, S≤0.01%, Ti≤0.01%, V≤0.01%, Cu: 0.01~0.03%, and the balance is Fe and unavoidable impurities.

2. A hot-base non-patterned galvanized sheet with thick zinc layer and high surface quality as claimed in claim 1, characterized in that: The thickness of the hot-dip galvanized sheet is 2.5-4.0 mm, and the double-sided zinc layer specification is 800 g / m 2 .

3. A hot-base non-patterned galvanized sheet with thick zinc layer and high surface quality as claimed in claim 1, characterized in that: The yield strength of the hot-dip galvanized sheet is ≥300MPa, and the elongation after fracture is ≥38%.

4. A hot-base non-patterned galvanized sheet with thick zinc layer and high surface quality as claimed in claim 1, characterized in that: The number of oblique scar defects on both sides of the upper and lower surfaces of the hot-dip galvanized sheet is ≤5, the number of diagonal defects on the edge is ≤10cm, and the edge thickness is ≤10mm.

5. The method for producing a hot-base non-patterned galvanized sheet with a thick zinc layer and high surface quality according to any one of claims 1 to 4, characterized in that: Including hot rolling, pickling, annealing and galvanizing processes.

6. The method for producing a hot-base non-patterned galvanized sheet with a thick zinc layer and high surface quality as claimed in claim 5, characterized in that: The annealing process includes non-oxidation heating treatment, radiation tube heating treatment, electric uniform heating treatment and spray cooling treatment; the strip temperature of the non-oxidation heating treatment is 680-700°C; the strip temperature of the radiation tube heating treatment is 670-690°C; the strip temperature of the electric uniform heating treatment is 660-680°C; the strip temperature of the spray cooling treatment is 455-465°C, the oxygen content of the grate is <100ppm, and the dew point is ≤-26°C.

7. The method for producing a hot-base non-patterned galvanized sheet with a thick zinc layer and high surface quality as claimed in claim 5, characterized in that: The galvanizing process has a galvanizing speed of 40 to 55 m / min, a zinc liquid temperature of 450 to 460° C., an Al content of 0.19 to 0.21% by mass in the zinc liquid, and an Fe content of 0.01 to 0.02% by mass.

8. The method for producing a hot-base non-patterned galvanized sheet with a thick zinc layer and high surface quality as claimed in claim 5, characterized in that: In the galvanizing process, the air knife pressure is 35-42 mbar, the distance between the air knife and the strip is 34-40 mm, the air knife height is 80-90 mm, the distance between the air knife baffle and the edge of the strip is 2-4 mm, the load power of the mobile bellows is 30-50%, the load power of the 1# fixed bellows is 60-80%, the load power of the 2#, 3# and 4# fixed bellows is automatically adjusted, and the air volume of the edge blowing device above the mobile bellows is 30-50%.

9. The method for producing a hot-base non-patterned galvanized sheet with a thick zinc layer and high surface quality as claimed in claim 5, characterized in that: In the galvanizing process, the roughness Ra of the working roll of the skin-pass mill is 2.5-4.0 μm, the convexity is 0.01-0.03 mm, and the rolling force of the skin-pass mill is 2500-3000 kN.

10. The method for producing a hot-base non-patterned galvanized sheet with a thick zinc layer and high surface quality as claimed in claim 5, characterized in that: In the galvanizing process, the outlet loop release speed is 80-100 m / min, the coiler tension is 60-90 kN, the coiler adopts staggered curling, the staggered length is 130-150 mm, the amplitude is 10-15 mm, and the slope is 20-30 mm.

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