High-strength hot-dip galvanized steel plate and preparation process thereof

Abstract

The invention discloses a high-strength hot-dip galvanized steel plate and a preparation process thereof, and belongs to the technical field of hot-dip galvanized steel plates, the high-strength hot-dip galvanized steel plate comprises the following chemical components in percentage by weight: 0.1-0.2% of C, 0.001-0.002% of Si, 1.02-1.06% of Mn, 0.035-0.041% of P, 0.011-0.013% of S, 0.003-0.005% of V, 0.10-0.14% of Nb, 0.001-0.003% of Mo and the balance of Fe and inevitable impurities; the hot galvanizing layer comprises the following chemical components in percentage by weight: 14 to 15 percent of Al, 4 to 7 percent of Mg, 0.12 to 0.14 percent of Ti and the balance of Zn and inevitable impurities; the yield strength of the high-strength hot-dip galvanized steel plate is larger than 500 MPa, and the tensile strength is larger than 700 MPa. In this way, the hot-dip galvanized steel plate is high in strength, and according to detection (GB / T 228.1-2021), the yield strength is larger than 500 MPa, the tensile strength is larger than 700 MPa, and the percentage elongation after fracture is larger than 34%. And the adhesive force (GB / T 9286-2021) of the passivated hot galvanizing layer is detected to be level 0.

Description

Technical Field

[0001] The invention relates to the technical field of hot-dip galvanized steel sheets, and in particular to a high-strength hot-dip galvanized steel sheet and a preparation process thereof. Background Art

[0002] The development of high-strength steel and ultra-high-strength steel is a hot topic in the current research of the steel industry, and galvanized high-strength steel for construction, high-strength steel for automobile plates, and high-strength steel for home appliances are the top priorities. As hot-dip galvanized high-strength steel, it should have good forming properties, welding properties, low cost, environmental friendliness and other characteristics, and has good application prospects. Compared with ordinary steel, the general characteristics of high-strength steel are high strength and a large number of alloy elements in the steel body. At present, the main high-strength steels for galvanizing are IF steel (interstitial-free atom steel), BH steel (bake hardening performance steel), TRIP steel (phase transformation induced plasticity steel), TWIP steel (high plasticity steel), etc. In order to increase the service life, most of these material parts need to be treated with surface coating to improve corrosion resistance. Hot-dip galvanizing is one of the common methods for surface coating treatment.

[0003] CN115404426B discloses a high-strength hot-dip galvanized steel sheet and a preparation method thereof, which comprises the following processes: mixing chromium powder and chromium oxide, vacuum-sealing with the steel sheet, heat treatment, and alkali washing; assisting plating, hot-dip galvanizing, and forming a coating; taking shellac resin and monomer, and heating the reaction; adding hydrazine hydrate to react; adding mercapto-terminated polyethylene glycol to react to obtain modified shellac; mixing the modified shellac, ammonium metavanadate, sodium silicate, and anhydrous ethanol to obtain a passivation solution; immersing the galvanized steel sheet therein to form a passivation layer, and obtaining a high-strength hot-dip galvanized steel sheet.

[0004] However, the yield strength of the galvanized steel sheet is at most 388MPa, which is difficult to reach above 500MPa, and the tensile strength is at most 473MPa, which is difficult to reach above 700MPa, and the high strength effect needs to be further improved. Based on this, the present invention designs a high-strength hot-dip galvanized steel sheet and its preparation process to solve the above problems. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the present invention provides a high-strength hot-dip galvanized steel sheet and a preparation process thereof.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] A high-strength hot-dip galvanized steel sheet, comprising:

[0008] Steel plate, the chemical composition of which is as follows by weight: C 0.1-0.2%, Si 0.001-0.002%, Mn 1.02-1.06%, P 0.035-0.041%, S 0.011-0.013%, V 0.003-0.005%, Nb 0.10-0.14%, Mo 0.001-0.003%, the balance being Fe and unavoidable impurities;

[0009] Hot-dip galvanized layer, the chemical composition of which is as follows by weight: Al 14-15%, Mg 4-7%, Ti 0.12-0.14%, the balance being Zn and unavoidable impurities;

[0010] The yield strength of the high-strength hot-dip galvanized steel sheet is greater than 500 MPa, and the tensile strength is greater than 700 MPa.

[0011] Furthermore, in the hot-dip galvanized layer, the total mass of Al, Mg and Fe is less than 50% of the mass of Zn, and the total mass of Al, Mg and Fe is greater than 40% of the mass of Zn.

[0012] In order to better achieve the purpose of the present invention, the present invention also provides a preparation process of the high-strength hot-dip galvanized steel sheet, comprising the following steps:

[0013] Step 1: Pretreatment of steel plate: heat the steel plate to 600-750°C, then raise the temperature to 900-905°C, keep it warm for 2-3 minutes, make it completely austenite, and then quench it into martensite;

[0014] Step 2: hot-dip galvanizing the surface of the steel plate to obtain a hot-dip galvanized steel plate;

[0015] Step 3: Heat treatment of hot-dip galvanized steel plate: Heat the hot-dip galvanized steel plate to 800-850°C, then raise the temperature to 870-885°C, keep it warm for 3-5 minutes, make it completely austenite, and then quench it into martensite;

[0016] Step 4: Surface passivation treatment of hot-dip galvanized steel sheet: immerse the hot-dip galvanized steel sheet in a passivation solution for surface treatment to form a passivation layer; the modified passivation solution comprises the following raw materials in weight percentage: polyaniline 11-12%, nano α-Al 2 O 3 8-11%, water-based acrylic resin 22-28%, organosilane 6-10%, phytic acid 5-12%, and the balance is deionized water;

[0017] Step 5: Annealing: heat up to 650-680℃, heating rate 5-8℃ / s; continue to heat up to 780-790℃, heating rate 3-5℃ / s, isothermal for 45-50s; then cool down to 605-610℃, cooling rate 3-5℃ / s, isothermal for 5-10s; then cool to room temperature, cooling rate 5-8℃ / s, to obtain high-strength hot-dip galvanized steel sheet.

[0018] Furthermore, in step 1, the steel plate is heated to 600-750° C. at a heating rate of 30-50° C. / min.

[0019] Furthermore, in step 1, the temperature is raised to 900-905° C., with a heating rate of 45-50° C. / min.

[0020] Furthermore, in step 2, after hot-dip galvanizing, the steel is cooled to room temperature at a cooling rate of 8 to 11°C / s.

[0021] Furthermore, in step three, the hot-dip galvanized steel sheet is heated to 800-850°C at a heating rate of 20-40°C / min, and then heated to 870-885°C at a heating rate of 40-50°C / min.

[0022] Furthermore, in step 4, the preparation method of the passivation solution is: polyaniline and nano α-Al 2 O 3 Mix evenly, add water-based acrylic resin, organosilane, phytic acid and deionized water, stir and mix at a high speed of 2000-3000 r / min to obtain a passivation solution.

[0023] Furthermore, before the surface passivation treatment, it also includes: ultrasonic cleaning of the hot-dip galvanized steel sheet for 3 to 5 minutes.

[0024] In order to better achieve the purpose of the present invention, the present invention also provides a high-strength hot-dip galvanized steel plate prepared by the preparation process.

[0025] Compared with the prior art, the invention has the following beneficial effects: the hot-dip galvanized steel sheet of the invention has high strength, and the yield strength is greater than 500MPa, the tensile strength is greater than 700MPa, and the elongation after fracture is greater than 34% after testing (GB / T228.1-2021). The hot-dip galvanized layer after passivation is tested for adhesion (GB / T 9286-2021): Grade 0, excellent adhesion. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Embodiment 1: In some embodiments, a process for preparing a high-strength hot-dip galvanized steel sheet comprises the following steps:

[0028] Step 1, steel plate pretreatment: the steel plate, whose chemical composition weight percentage is: C 0.1%, Si 0.002%, Mn 1.02%, P 0.041%, S 0.011%, V 0.005%, Nb 0.10%, Mo 0.003%, the balance is Fe and inevitable impurities; the steel plate is heated to 600°C, the heating rate is 50°C / min, and then heated to 900°C, the heating rate is 50°C / min, and the temperature is kept for 2 minutes to make it completely austenitized, and then quenched into martensite;

[0029] Step 2: hot-dip galvanizing the surface of the steel plate to obtain a hot-dip galvanized steel plate; after hot-dip galvanizing, the steel plate is cooled to room temperature at a cooling rate of 11°C / s; the chemical composition weight percentage of the hot-dip galvanized layer is: Al 14%, Mg 7%, Ti 0.12%, and the balance is Zn and unavoidable impurities;

[0030] Step 3: Heat treatment of hot-dip galvanized steel plate: Heat the hot-dip galvanized steel plate to 800°C at a heating rate of 40°C / min, then to 870°C at a heating rate of 50°C / min, and keep warm for 3 minutes to make it completely austenitized, and then quench it into martensite;

[0031] Step 4: Surface passivation treatment of hot-dip galvanized steel sheet: immerse the hot-dip galvanized steel sheet in a passivation solution for surface treatment to form a passivation layer;

[0032] The modified passivation solution comprises the following raw materials in weight percentage: polyaniline 11%, nano α-Al 2 O 3 11%, water-based acrylic resin 22%, organosilane 10%, phytic acid 5%, and the balance is deionized water;

[0033] The preparation method of the passivation solution is: polyaniline and nano α-Al 2 O 3 Mix well, add acrylic resin, organosilane, phytic acid and deionized water, stir and mix at a high speed of 2000r / min to obtain a passivation solution;

[0034] Preferably, before the surface passivation treatment, the method further comprises: ultrasonically cleaning the hot-dip galvanized steel sheet for 3 minutes to remove surface grease, etc.;

[0035] Step 5: Annealing: heat up to 650℃, heating rate 8℃ / s; continue to heat up to 780℃, heating rate 5℃ / s, isothermal for 45s; then cool down to 610℃, cooling rate 3℃ / s, isothermal for 10s; then cool to room temperature, cooling rate 5℃ / s, to obtain high-strength hot-dip galvanized steel plate.

[0036] The high-strength hot-dip galvanized steel sheet (test thickness 1 mm) prepared in this embodiment was subjected to performance testing (GB / T228.1-2021): the yield strength was 519.3 MPa, the tensile strength was 736.0 MPa, and the elongation after fracture was 32.5%. The hot-dip galvanized layer after passivation was subjected to adhesion testing (GB / T 9286-2021): Grade 0.

[0037] Embodiment 2: In some embodiments, a process for preparing a high-strength hot-dip galvanized steel sheet comprises the following steps:

[0038] Step 1, steel plate pretreatment: the steel plate, whose chemical composition weight percentage is: C 0.2%, Si 0.001%, Mn 1.06%, P 0.035%, S 0.013%, V 0.003%, Nb 0.14%, Mo 0.001%, the balance is Fe and inevitable impurities; the steel plate is heated to 750°C, the heating rate is 30°C / min, and then heated to 905°C, the heating rate is 45°C / min, and the temperature is kept for 3 minutes to make it completely austenitized, and then quenched into martensite;

[0039] Step 2: hot-dip galvanizing the surface of the steel plate to obtain a hot-dip galvanized steel plate; after hot-dip galvanizing, the steel plate is cooled to room temperature at a cooling rate of 8°C / s; the chemical composition weight percentage of the hot-dip galvanized layer is: Al 15%, Mg 4%, Ti 0.14%, and the balance is Zn and unavoidable impurities;

[0040] Step 3: Heat treatment of hot-dip galvanized steel plate: Heat the hot-dip galvanized steel plate to 850°C at a heating rate of 20°C / min, then to 885°C at a heating rate of 40°C / min, and keep warm for 5 minutes to make it completely austenitized, and then quench it into martensite;

[0041] Step 4: Surface passivation treatment of hot-dip galvanized steel sheet: immerse the hot-dip galvanized steel sheet in a passivation solution for surface treatment to form a passivation layer;

[0042] The modified passivation solution comprises the following raw materials in weight percentage: 12% polyaniline, nano-α-Al 2 O 38%, water-based acrylic resin 28%, organosilane 6%, phytic acid 12%, and the balance is deionized water;

[0043] The preparation method of the passivation solution is: polyaniline and nano α-Al 2 O 3 Mix well, add water-based acrylic resin, organosilane, phytic acid and deionized water, stir and mix at a high speed of 3000r / min to obtain a passivation solution;

[0044] Preferably, before the surface passivation treatment, the method further comprises: ultrasonically cleaning the hot-dip galvanized steel sheet for 5 minutes to remove surface grease, etc.;

[0045] Step 5: Annealing: heat up to 680℃, heating rate 5℃ / s; continue to heat up to 790℃, heating rate 3℃ / s, isothermal for 50s; then cool down to 605℃, cooling rate 5℃ / s, isothermal for 5s; then cool to room temperature, cooling rate 8℃ / s, to obtain high-strength hot-dip galvanized steel plate.

[0046] The high-strength hot-dip galvanized steel sheet (test thickness 1 mm) prepared in this embodiment was subjected to performance testing (GB / T228.1-2021): the yield strength was 505.2 MPa, the tensile strength was 781.1 MPa, and the elongation after fracture was 33.9%. The hot-dip galvanized layer after passivation was subjected to adhesion testing (GB / T 9286-2021): Grade 0.

[0047] Embodiment 3: In some embodiments, a process for preparing a high-strength hot-dip galvanized steel sheet comprises the following steps:

[0048] Step 1, steel plate pretreatment: the steel plate, whose chemical composition weight percentage is: C 0.13%, Si 0.0015%, Mn 1.03%, P 0.036%, S 0.012%, V 0.004%, Nb 0.11%, Mo 0.002%, the balance is Fe and inevitable impurities; the steel plate is heated to 620°C, the heating rate is 32°C / min, and then heated to 902°C, the heating rate is 47°C / min, and the temperature is kept for 2.5 minutes to make it completely austenitized, and then quenched into martensite;

[0049] Step 2: hot-dip galvanizing the surface of the steel plate to obtain a hot-dip galvanized steel plate; after galvanizing, the steel plate is cooled to room temperature at a cooling rate of 8 to 11°C / s; the chemical composition weight percentage of the hot-dip galvanized layer is: Al 14.3%, Mg 5%, Ti 0.13%, and the balance is Zn and unavoidable impurities;

[0050] Step 3: Heat treatment of hot-dip galvanized steel plate: Heat the hot-dip galvanized steel plate to 835°C at a heating rate of 25°C / min, then heat it to 875°C at a heating rate of 42°C / min, keep it warm for 4 minutes, make it completely austenitized, and then quench it into martensite;

[0051] Step 4: Surface passivation treatment of hot-dip galvanized steel sheet: immerse the hot-dip galvanized steel sheet in a passivation solution for surface treatment to form a passivation layer;

[0052] The modified passivation solution comprises the following raw materials in weight percentage: polyaniline 11.6%, nano α-Al 2 O 3 9%, water-based acrylic resin 27%, organosilane 7%, phytic acid 6%, and the balance is deionized water;

[0053] The preparation method of the passivation solution is: polyaniline and nano α-Al 2 O 3 Mix well, add water-based acrylic resin, organosilane, phytic acid and deionized water, stir and mix at a high speed of 2500r / min to obtain a passivation solution;

[0054] Preferably, before the surface passivation treatment, the method further comprises: ultrasonically cleaning the hot-dip galvanized steel sheet for 4 minutes to remove surface grease, etc.;

[0055] Step 5: Annealing: heat up to 660℃, heating rate 6℃ / s; continue to heat up to 784℃, heating rate 3.5℃ / s, isothermal for 46s; then cool down to 608℃, cooling rate 4℃ / s, isothermal for 6s; then cool to room temperature, cooling rate 6℃ / s, to obtain high-strength hot-dip galvanized steel plate.

[0056] The high-strength hot-dip galvanized steel sheet (test thickness 1 mm) prepared in this embodiment was subjected to performance testing (GB / T228.1-2021): the yield strength was 535.0 MPa, the tensile strength was 731.5 MPa, and the elongation after fracture was 30.8%. The hot-dip galvanized layer after passivation was subjected to adhesion testing (GB / T 9286-2021): Grade 0.

[0057] Embodiment 4: In some embodiments, a process for preparing a high-strength hot-dip galvanized steel sheet comprises the following steps:

[0058] Step 1, steel plate pretreatment: the steel plate, whose chemical composition weight percentage is: C 0.13%, Si 0.0014%, Mn 1.04%, P 0.037%, S 0.012%, V 0.004%, Nb 0.13%, Mo 0.002%, the balance is Fe and inevitable impurities; the steel plate is heated to 690°C, the heating rate is 42°C / min, and then heated to 904°C, the heating rate is 48°C / min, and the temperature is kept for 2 minutes to make it completely austenitized, and then quenched into martensite;

[0059] Step 2: hot-dip galvanizing the surface of the steel plate to obtain a hot-dip galvanized steel plate; after hot-dip galvanizing, the steel plate is cooled to room temperature at a cooling rate of 10°C / s; the chemical composition weight percentage of the hot-dip galvanized layer is: Al 14.3%, Mg 6%, Ti 0.14%, and the balance is Zn and unavoidable impurities;

[0060] Step 3: Heat treatment of hot-dip galvanized steel plate: heat the hot-dip galvanized steel plate to 845°C at a heating rate of 28°C / min, then heat it to 880°C at a heating rate of 43°C / min, keep it warm for 4.5 minutes, make it completely austenite, and then quench it into martensite;

[0061] Step 4: Surface passivation treatment of hot-dip galvanized steel sheet: immerse the hot-dip galvanized steel sheet in a passivation solution for surface treatment to form a passivation layer;

[0062] The modified passivation solution comprises the following raw materials in weight percentage: polyaniline 11.6%, nano α-Al 2 O 3 9.4%, water-based acrylic resin 24%, organosilane 8%, phytic acid 9%, and the balance is deionized water;

[0063] The preparation method of the passivation solution is: polyaniline and nano α-Al 2 O 3 Mix well, add water-based acrylic resin, organosilane, phytic acid and deionized water, stir and mix at a high speed of 2800r / min to obtain a passivation solution;

[0064] Preferably, before the surface passivation treatment, the method further comprises: ultrasonically cleaning the hot-dip galvanized steel sheet for 4.6 minutes to remove surface grease, etc.;

[0065] Step 5: Annealing: heat up to 665℃, heating rate 7℃ / s; continue to heat up to 788℃, heating rate 4℃ / s, isothermal for 49s; then cool down to 609℃, cooling rate 4.2℃ / s, isothermal for 9s; then cool to room temperature, cooling rate 7℃ / s, to obtain high-strength hot-dip galvanized steel plate.

[0066] The high-strength hot-dip galvanized steel sheet (test thickness 1 mm) prepared in this embodiment was subjected to performance testing (GB / T228.1-2021): the yield strength was 542.1 MPa, the tensile strength was 739.4 MPa, and the elongation after fracture was 34.7%. The hot-dip galvanized layer after passivation was subjected to adhesion testing (GB / T 9286-2021): Grade 0.

[0067] Embodiment 5: In some embodiments, a process for preparing a high-strength hot-dip galvanized steel sheet comprises the following steps:

[0068] Step 1, steel plate pretreatment: the steel plate, whose chemical composition weight percentage is: C 0.17%, Si 0.0018%, Mn 1.05%, P 0.04%, S 0.012%, V 0.004%, Nb 0.13%, Mo 0.002%, the balance is Fe and inevitable impurities; the steel plate is heated to 710°C, the heating rate is 31°C / min, and then heated to 900°C, the heating rate is 48°C / min, and the temperature is kept for 2 minutes to make it completely austenitized, and then quenched into martensite;

[0069] Step 2: hot-dip galvanizing the surface of the steel plate to obtain a hot-dip galvanized steel plate; after hot-dip galvanizing, the steel plate is cooled to room temperature at a cooling rate of 9°C / s; the chemical composition weight percentage of the hot-dip galvanized layer is: Al 14%, Mg 5.5%, Ti 0.13%, and the balance is Zn and unavoidable impurities;

[0070] Step 3: Heat treatment of hot-dip galvanized steel plate: heat the hot-dip galvanized steel plate to 840°C at a heating rate of 33°C / min, then heat it to 881°C at a heating rate of 46°C / min, keep it warm for 4 minutes, make it completely austenite, and then quench it into martensite;

[0071] Step 4: Surface passivation treatment of hot-dip galvanized steel sheet: immerse the hot-dip galvanized steel sheet in a passivation solution for surface treatment to form a passivation layer;

[0072] The modified passivation solution comprises the following raw materials in weight percentage: polyaniline 11.5%, nano α-Al 2 O 3 10.5%, water-based acrylic resin 26%, organosilane 8%, phytic acid 10%, and the balance is deionized water;

[0073] The preparation method of the passivation solution is: polyaniline and nano α-Al 2 O 3 Mix well, add water-based acrylic resin, organosilane, phytic acid and deionized water, stir and mix at a high speed of 2400r / min to obtain a passivation solution;

[0074] Preferably, before the surface passivation treatment, the method further comprises: ultrasonically cleaning the hot-dip galvanized steel sheet for 4 minutes to remove surface grease, etc.;

[0075] Step 5: Annealing: heat up to 660℃, heating rate 6℃ / s; continue to heat up to 780℃, heating rate 4℃ / s, isothermal for 46s; then cool down to 608℃, cooling rate 4℃ / s, isothermal for 6s; then cool to room temperature, cooling rate 6℃ / s, to obtain high-strength hot-dip galvanized steel plate.

[0076] The high-strength hot-dip galvanized steel sheet (test thickness 1 mm) prepared in this embodiment was subjected to performance testing (GB / T228.1-2021): the yield strength was 523.4 MPa, the tensile strength was 740.6 MPa, and the elongation after fracture was 36.1%. The hot-dip galvanized layer after passivation was subjected to adhesion testing (GB / T 9286-2021): Grade 0.

[0077] Embodiment 6: In some embodiments, a process for preparing a high-strength hot-dip galvanized steel sheet comprises the following steps:

[0078] Step 1, steel plate pretreatment: the steel plate, whose chemical composition weight percentage is: C 0.17%, Si 0.0018%, Mn 1.03%, P 0.036%, S 0.011%, V 0.0035%, Nb 0.11%, Mo 0.002%, the balance is Fe and inevitable impurities; the steel plate is heated to 620°C, the heating rate is 40°C / min, and then heated to 900°C, the heating rate is 50°C / min, and the temperature is kept for 3 minutes to make it completely austenitized, and then quenched into martensite;

[0079] Step 2: hot-dip galvanizing the surface of the steel plate to obtain a hot-dip galvanized steel plate; after hot-dip galvanizing, the steel plate is cooled to room temperature at a cooling rate of 9°C / s; the chemical composition weight percentage of the hot-dip galvanized layer is: Al 14%, Mg 6.5%, Ti 0.12%, and the balance is Zn and unavoidable impurities;

[0080] Step 3: Heat treatment of hot-dip galvanized steel plate: Heat the hot-dip galvanized steel plate to 830°C at a heating rate of 30°C / min, then to 875°C at a heating rate of 42°C / min, and keep warm for 4 minutes to make it completely austenitized, and then quench it into martensite;

[0081] Step 4: Surface passivation treatment of hot-dip galvanized steel sheet: immerse the hot-dip galvanized steel sheet in a passivation solution for surface treatment to form a passivation layer;

[0082] The modified passivation solution comprises the following raw materials in weight percentage: polyaniline 11.6%, nano α-Al 2 O 38.8%, water-based acrylic resin 23.8%, organosilane 7.4%, phytic acid 8.2%, and the balance is deionized water;

[0083] The preparation method of the passivation solution is: polyaniline and nano α-Al 2 O 3 Mix well, add water-based acrylic resin, organosilane, phytic acid and deionized water, stir and mix at a high speed of 2200r / min to obtain a passivation solution;

[0084] Preferably, before the surface passivation treatment, the method further comprises: ultrasonically cleaning the hot-dip galvanized steel sheet for 4 minutes to remove surface grease, etc.;

[0085] Step 5: Annealing: heat up to 675℃, heating rate 7℃ / s; continue to heat up to 785℃, heating rate 5℃ / s, isothermal for 45s; then cool down to 608℃, cooling rate 4℃ / s, isothermal for 6s; then cool to room temperature, cooling rate 7℃ / s, to obtain high-strength hot-dip galvanized steel plate.

[0086] The high-strength hot-dip galvanized steel sheet (test thickness 1 mm) prepared in this embodiment was subjected to performance testing (GB / T228.1-2021): the yield strength was 520.1 MPa, the tensile strength was 736.9 MPa, and the elongation after fracture was 34.8%. The hot-dip galvanized layer after passivation was subjected to adhesion testing (GB / T 9286-2021): Grade 0.

[0087] Embodiment 7: In some embodiments, a process for preparing a high-strength hot-dip galvanized steel sheet comprises the following steps:

[0088] Step 1, steel plate pretreatment: the steel plate, whose chemical composition weight percentage is: C 0.13%, Si 0.0012%, Mn 1.04%, P 0.036%, S 0.012%, V 0.003%, Nb 0.12%, Mo 0.002%, the balance is Fe and inevitable impurities; the steel plate is heated to 640°C, the heating rate is 40°C / min, and then heated to 901°C, the heating rate is 47°C / min, and the temperature is kept for 2 minutes to make it completely austenitized, and then quenched into martensite;

[0089] Step 2: hot-dip galvanizing the surface of the steel plate to obtain a hot-dip galvanized steel plate; after hot-dip galvanizing, the steel plate is cooled to room temperature at a cooling rate of 10°C / s; the chemical composition weight percentage of the hot-dip galvanized layer is: Al 14.5%, Mg 6.6%, Ti 0.12%, and the balance is Zn and unavoidable impurities;

[0090] Step 3: Heat treatment of hot-dip galvanized steel plate: Heat the hot-dip galvanized steel plate to 835°C at a heating rate of 22°C / min, then to 880°C at a heating rate of 45°C / min, and keep warm for 4 minutes to make it completely austenitized, and then quench it into martensite;

[0091] Step 4: Surface passivation treatment of hot-dip galvanized steel sheet: immerse the hot-dip galvanized steel sheet in a passivation solution for surface treatment to form a passivation layer;

[0092] The modified passivation solution comprises the following raw materials in weight percentage: polyaniline 11.2%, nano α-Al 2 O 3 10%, water-based acrylic resin 25%, organosilane 7%, phytic acid 10%, and the balance is deionized water;

[0093] The preparation method of the passivation solution is: polyaniline and nano α-Al 2 O 3 Mix well, add water-based acrylic resin, organosilane, phytic acid and deionized water, stir and mix at a high speed of 2500r / min to obtain a passivation solution;

[0094] Preferably, before the surface passivation treatment, the method further includes: ultrasonically cleaning the hot-dip galvanized steel sheet for 3.5 minutes to remove surface grease, etc.;

[0095] Step 5: Annealing: heat up to 665℃, heating rate 6℃ / s; continue to heat up to 788℃, heating rate 4℃ / s, isothermal for 46s; then cool down to 608℃, cooling rate 4℃ / s, isothermal for 8s; then cool to room temperature, cooling rate 6℃ / s, to obtain high-strength hot-dip galvanized steel plate.

[0096] The high-strength hot-dip galvanized steel sheet (test thickness 1 mm) prepared in this embodiment was subjected to performance testing (GB / T228.1-2021): the yield strength was 518.5 MPa, the tensile strength was 737.4 MPa, and the elongation after fracture was 33.7%. The hot-dip galvanized layer after passivation was subjected to adhesion testing (GB / T 9286-2021): Grade 0.

[0097] Embodiment 8: In some embodiments, a process for preparing a high-strength hot-dip galvanized steel sheet comprises the following steps:

[0098] Step 1, steel plate pretreatment: the steel plate, whose chemical composition weight percentage is: C 0.16%, Si 0.0014%, Mn 1.05%, P 0.039%, S 0.012%, V 0.0035%, Nb 0.13%, Mo 0.002%, the balance is Fe and inevitable impurities; the steel plate is heated to 665°C, the heating rate is 40°C / min, and then heated to 901°C, the heating rate is 47°C / min, and the temperature is kept for 3 minutes to make it completely austenitized, and then quenched into martensite;

[0099] Step 2: hot-dip galvanizing the surface of the steel plate to obtain a hot-dip galvanized steel plate; after hot-dip galvanizing, the steel plate is cooled to room temperature at a cooling rate of 8°C / s; the chemical composition weight percentage of the hot-dip galvanized layer is: Al 14.3%, Mg 4.9%, Ti 0.13%, and the balance is Zn and unavoidable impurities;

[0100] Step 3: Heat treatment of hot-dip galvanized steel plate: Heat the hot-dip galvanized steel plate to 803°C at a heating rate of 25°C / min, then to 875°C at a heating rate of 46°C / min, and keep warm for 3.6 minutes to make it completely austenitized, and then quench it into martensite;

[0101] Step 4: Surface passivation treatment of hot-dip galvanized steel sheet: immerse the hot-dip galvanized steel sheet in a passivation solution for surface treatment to form a passivation layer;

[0102] The modified passivation solution comprises the following raw materials in weight percentage: polyaniline 11.5%, nano α-Al 2 O 3 10.3%, water-based acrylic resin 26.5%, organosilane 8.5%, phytic acid 7.4%, and the balance is deionized water;

[0103] The preparation method of the passivation solution is: polyaniline and nano α-Al 2 O 3 Mix well, add water-based acrylic resin, organosilane, phytic acid and deionized water, stir and mix at a high speed of 2900r / min to obtain a passivation solution;

[0104] Preferably, before the surface passivation treatment, the method further comprises: ultrasonically cleaning the hot-dip galvanized steel sheet for 4 minutes to remove surface grease, etc.;

[0105] Step 5: Annealing: heat up to 675℃, heating rate 7℃ / s; continue to heat up to 788℃, heating rate 4℃ / s, isothermal for 48s; then cool down to 608℃, cooling rate 4℃ / s, isothermal for 6s; then cool to room temperature, cooling rate 7℃ / s, to obtain high-strength hot-dip galvanized steel plate.

[0106] The high-strength hot-dip galvanized steel sheet (test thickness 1 mm) prepared in this embodiment was subjected to performance testing (GB / T228.1-2021): the yield strength was 524.1 MPa, the tensile strength was 741.8 MPa, and the elongation after fracture was 36.4%. The hot-dip galvanized layer after passivation was subjected to adhesion testing (GB / T 9286-2021): Grade 0.

[0107] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-strength hot-dip galvanized steel sheet, characterized in that: include: Steel plate, the chemical composition of which is as follows by weight: C 0.1-0.2%, Si 0.001-0.002%, Mn 1.02-1.06%, P 0.035-0.041%, S 0.011-0.013%, V 0.003-0.005%, Nb 0.10-0.14%, Mo 0.001-0.003%, the balance being Fe and unavoidable impurities; Hot-dip galvanized layer, the chemical composition of which is as follows by weight: Al 14-15%, Mg 4-7%, Ti 0.12-0.14%, the balance being Zn and unavoidable impurities; The yield strength of the high-strength hot-dip galvanized steel sheet is greater than 500 MPa, and the tensile strength is greater than 700 MPa.

2. The high-strength hot-dip galvanized steel sheet according to claim 1, characterized in that: In the hot-dip galvanized layer, the total mass of Al, Mg and Fe is less than 50% of the mass of Zn, and the total mass of Al, Mg and Fe is greater than 40% of the mass of Zn.

3. A process for preparing a high-strength hot-dip galvanized steel sheet according to claim 2, characterized in that: The following steps are involved: Step 1: Pretreatment of steel plate: heat the steel plate to 600-750°C, then raise the temperature to 900-905°C, keep it warm for 2-3 minutes, make it completely austenite, and then quench it into martensite; Step 2: hot-dip galvanizing the surface of the steel plate to obtain a hot-dip galvanized steel plate; Step 3: Heat treatment of hot-dip galvanized steel plate: Heat the hot-dip galvanized steel plate to 800-850°C, then raise the temperature to 870-885°C, keep it warm for 3-5 minutes, make it completely austenite, and then quench it into martensite; Step 4: Surface passivation treatment of hot-dip galvanized steel sheet: immerse the hot-dip galvanized steel sheet in a passivation solution for surface treatment to form a passivation layer; the modified passivation solution comprises the following raw materials in weight percentage: polyaniline 11-12%, nano-α-Al2O3 8-11%, water-based acrylic resin 22-28%, organosilane 6-10%, phytic acid 5-12%, and the balance is deionized water; Step 5: Annealing: heat up to 650-680℃, heating rate 5-8℃ / s; continue to heat up to 780-790℃, heating rate 3-5℃ / s, isothermal for 45-50s; then cool down to 605-610℃, cooling rate 3-5℃ / s, isothermal for 5-10s; then cool to room temperature, cooling rate 5-8℃ / s, to obtain high-strength hot-dip galvanized steel sheet.

4. The process for preparing a high-strength hot-dip galvanized steel sheet according to claim 3, characterized in that: In step 1, the steel plate is heated to 600-750°C at a heating rate of 30-50°C / min.

5. The process for preparing a high-strength hot-dip galvanized steel sheet according to claim 4, characterized in that: In step 1, the temperature is raised to 900-905° C. at a rate of 45-50° C. / min.

6. The process for preparing a high-strength hot-dip galvanized steel sheet according to claim 5, characterized in that: In step 2, after hot-dip galvanizing, the steel is cooled to room temperature at a cooling rate of 8 to 11°C / s.

7. The process for preparing a high-strength hot-dip galvanized steel sheet according to claim 6, characterized in that: In step three, the hot-dip galvanized steel sheet is heated to 800-850°C at a heating rate of 20-40°C / min, and then heated to 870-885°C at a heating rate of 40-50°C / min.

8. The process for preparing a high-strength hot-dip galvanized steel sheet according to claim 7, characterized in that: In step 4, the preparation method of the passivation solution is: polyaniline and nano-α-Al2O3 are mixed evenly, water-based acrylic resin, organosilane, phytic acid and deionized water are added, and the mixture is stirred at a high speed of 2000-3000 r / min to obtain the passivation solution.

9. The process for preparing a high-strength hot-dip galvanized steel sheet according to claim 8, characterized in that: Before the surface passivation treatment, it also includes: ultrasonic cleaning of the hot-dip galvanized steel sheet for 3 to 5 minutes.

10. A high-strength hot-dip galvanized steel sheet prepared according to the preparation process according to claim 9.