Low-temperature-resistant marine high-toughness flat-bulb steel and processing technology thereof

Abstract

The invention discloses low-temperature-resistant marine high-toughness flat-bulb steel and a processing technology thereof, and relates to the technical field of stainless steel materials. According to the flat-bulb steel subjected to electro-deposition treatment, the low-temperature-resistant toughness of the flat-bulb steel is improved by adding Ba. And then the nickel-tungsten coating is electrically deposited, so that the corrosion resistance of the flat-bulb steel is improved. The molybdenum disulfide-titanium dioxide nanotube compound is added into the electro-deposition liquid, so that the corrosion resistance of the flat-bulb steel is improved. According to the invention, the titanium dioxide nanotube is prepared and is modified by using 8-hydroxyquinoline, so that the corrosion resistance is improved. Molybdenum disulfide used in the invention is of a micron structure and is modified by using ammonia monohydrate, so that the corrosion resistance of the modified molybdenum disulfide is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of stainless steel materials, and specifically to a marine high-toughness bulb flat steel with low-temperature resistance and its processing technology. Background Art

[0002] As an important marine structural material, bulb flat steel is widely used in the structural components of ships. With the development of the shipbuilding industry towards polar and deep-sea areas, higher requirements are put forward for the low-temperature resistance, high toughness, and corrosion resistance of bulb flat steel. Traditional bulb flat steel is prone to problems such as insufficient toughness, brittle fracture, and easy corrosion in low-temperature environments, which limits its application in polar and deep-sea ships.

[0003] Currently, the research on high-strength and high-toughness bulb flat steel at home and abroad mainly focuses on composition optimization and heat treatment process improvement. For example, through induction quenching and tempering processes, the grain size can be significantly refined, and the low-temperature toughness of bulb flat steel can be improved. However, there are still some deficiencies in the existing technologies. For example, the composition design cost of some high-strength and high-toughness bulb flat steel is relatively high, and the toughness still needs to be further improved, and the corrosion resistance is also not good.

[0004] In order to solve the above problems and improve the low-temperature toughness and corrosion resistance of bulb flat steel, the present invention provides a marine high-toughness bulb flat steel with low-temperature resistance and its processing technology. Summary of the Invention

[0005] The purpose of the present invention is to provide a marine high-toughness bulb flat steel with low-temperature resistance and its processing technology to solve the problems raised in the existing technologies.

[0006] To achieve the above purpose, the present invention provides the following technical solutions: A processing technology for a marine high-toughness bulb flat steel with low-temperature resistance, comprising the following steps: Step 1: Take Fe, C, Si, Mn, Ti, N, P, S, Ba, smelt, hot-roll, heat-treat, and cool to obtain a bulb flat steel matrix; Step 2: Use the bulb flat steel matrix as the cathode and a pure nickel rod as the anode, place them in an electrodeposition solution, set the temperature at 60 - 65 °C, and perform electrodeposition for 20 - 25 min at a current density of 5 A / dm 3 to obtain bulb flat steel A; Take bulb flat steel A, cold-roll it, and then perform surface nitriding treatment. Perform plasma nitriding treatment at 550 - 560 °C for 4 - 5 h, heat-treat, and cool to obtain a marine high-toughness bulb flat steel with low-temperature resistance; The electroplating solution consists of the following components: 100 - 104 g / L of sodium tungstate dihydrate, 28 - 30 g / L of nickel sulfate hexahydrate, 34 - 37 g / L of sodium citrate dihydrate, 25 - 26 g / L of ammonium chloride, 17 - 19 g / L of sodium bromide, 12 - 14 g / L of molybdenum disulfide - titanium dioxide nanotube composite; sulfuric acid and ammonia water are used to adjust the pH to 7.5 - 8.

[0007] More preferably, the bulb flat steel substrate consists of the following components by mass percentage: 0.10 wt% - 0.15 wt% of C, 0.25 wt% - 0.30 wt% of Si, 1.32 wt% - 1.35 wt% of Mn, 0.004 wt% - 0.008 wt% of Ti, 0.004 wt% - 0.006 wt% of N, 0.012 wt% - 0.015 wt% of P, 0.002 wt% - 0.004 wt% of S, 0.02 wt% - 0.05 wt% of Ba, and the balance is Fe and other inevitable impurities.

[0008] More preferably, the preparation method of the molybdenum disulfide - titanium dioxide nanotube composite is as follows: Take tris(hydroxymethyl)aminomethane and deionized water, stir evenly, add dilute hydrochloric acid dropwise to adjust the pH value to 8 - 8.3, mix evenly, add dopamine hydrochloride, stir for 15 - 20 min, add modified titanium dioxide nanotubes, ultrasonically disperse for 2 - 3 h, heat up to 55 - 60 °C, add modified molybdenum disulfide, ultrasonically disperse for 2 - 3 h, and react for 22 - 24 h to obtain the molybdenum disulfide - titanium dioxide nanotube composite.

[0009] More preferably, the preparation method of the modified titanium dioxide nanotubes is as follows: Take 8 - hydroxyquinoline, acetone, and titanium dioxide nanotubes, stir for 2 - 3 h, wash, centrifuge, and dry with deionized water to obtain the modified titanium dioxide nanotubes.

[0010] More preferably, the preparation method of the titanium dioxide nanotubes includes the following steps: S1: Take anhydrous ethanol, glacial acetic acid, and deionized water, mix evenly to obtain a glacial acetic acid solution; take anhydrous ethanol and tetrabutyl titanate, mix evenly to obtain a tetrabutyl titanate solution; place the tetrabutyl titanate solution in an ice - water bath and ultrasonically oscillate for 10 - 15 min, add the glacial acetic acid solution dropwise, age for 22 - 26 h to obtain a gel, dry, and heat - treat at 330 - 350 °C for 6 - 7 h to obtain nano - titanium dioxide powder; S2: Take sodium hydroxide solid and deionized water, stir evenly to obtain a sodium hydroxide solution; take the nano - titanium dioxide powder, add the sodium hydroxide solution, ultrasonically disperse, then place it in a microwave chemical reactor, react for 60 - 80 min, centrifuge, wash, and dry to obtain titanium dioxide nanotubes.

[0011] Preferably, the preparation method of the modified molybdenum disulfide is as follows: Take molybdenum disulfide and deionized water, stir evenly, add ammonia monohydrate, heat up to 90 - 92 °C and react for 10 - 12 h, add β-diketone, disperse evenly, react for 10 - 14 h, carry out vacuum filtration, washing, and drying to obtain the modified molybdenum disulfide.

[0012] Preferably, the preparation method of the β-diketone is as follows: Take sodium ethoxide and ethylene glycol dimethyl ether, pass nitrogen, dropwise add acetophenone, add ethyl propionate, heat up to 83 - 85 °C, carry out condensation reflux for 10 - 14 h, evaporate the solvent to dryness, add dilute hydrochloric acid to adjust the pH value to 5, then add sodium carbonate to adjust the pH value to 7, filter and dry to obtain the β-diketone.

[0013] Preferably, the particle size of the molybdenum disulfide is 12 - 16 μm.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention provides a bulb flat steel treated by electroplating. By adding Ba, its low-temperature toughness is improved. Then, by electroplating a nickel-tungsten coating, the corrosion resistance of the bulb flat steel is improved.

[0015] 2. The present invention adds a molybdenum disulfide - titanium dioxide nanotube composite in the electroplating solution to improve the corrosion resistance of the bulb flat steel. The present invention prepares a titanium dioxide nanotube with an outer diameter of 8 - 16 nm, an inner diameter of 6 - 12 nm, and a length of 40 - 100 nm. It is modified with 8-hydroxyquinoline to improve its corrosion resistance. The molybdenum disulfide used in the present invention has a micron structure and is modified with ammonia monohydrate to improve the corrosion resistance of the modified molybdenum disulfide. The titanium dioxide nanotube of the present invention is a nanoscale particle, while the molybdenum disulfide is a micron-scale particle. When the two are used in combination, the agglomeration problem can be improved, the surface roughness of the coating can be increased, and the compactness of the coating can be improved, thereby further improving the corrosion resistance of the bulb flat steel.

[0016] 3. The present invention prepares a β-diketone and uses the β-diketone to modify molybdenum disulfide. The β-diketone can react with iron ions on the steel surface in the electroplating solution to produce a chelating effect, enhancing the corrosion resistance of the bulb flat steel surface. Specific Embodiments

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0018] There are no special restrictions on the source and model of the substances involved in the present invention. Exemplarily, they include: the micron molybdenum disulfide used in Examples 1 - 3 and Comparative Examples 1 and 3 of the present invention. Micron molybdenum disulfide: Model: M886514, 12 - 16um, which can be purchased from Shanghai Macklin Biochemical Co., Ltd.; the nano molybdenum disulfide used in Comparative Example 2 of the present invention. Nano molybdenum disulfide: Model: M888682, 100nm, which can be purchased from Shanghai Macklin Biochemical Co., Ltd.

[0019] Example 1: A processing technology for a marine high - toughness bulb flat steel with low - temperature resistance, comprising the following steps: Step 1: Take Fe, C, Si, Mn, Ti, N, P, S, Ba, smelt, hot - roll, heat - treat, and cool to obtain a bulb flat steel matrix; The bulb flat steel matrix is composed of the following components, calculated by mass percentage: 0.12wt% of C, 0.28wt% of Si, 1.33wt% of Mn, 0.006wt% of Ti, 0.005wt% of N, 0.013wt% of P, 0.003wt% of S, 0.04wt% of Ba, and the balance is Fe and other inevitable impurities; Step 2: Use the bulb flat steel matrix as the cathode and a pure nickel rod as the anode, place them in an electrodeposition solution, set the temperature to 62°C, and at a current density of 5A / dm 3 electrodeposit for 22 minutes to obtain bulb flat steel A; take bulb flat steel A, cold - roll it, and then perform surface nitriding treatment. Carry out plasma nitriding treatment at 555°C for 4.5h, heat - treat and cool to obtain a marine high - toughness bulb flat steel with low - temperature resistance; The electrodeposition solution is composed of the following components: 102g / L of sodium tungstate dihydrate, 29g / L of nickel sulfate hexahydrate; 35g / L of sodium citrate dihydrate, 25g / L of ammonium chloride, 18g / L of sodium bromide, 13g / L of molybdenum disulfide - titanium dioxide nanotube composite; adjust to pH = 7.9 using sulfuric acid and ammonia water; Step 3: Preparation of β - diketone: Take 22.5g of sodium ethoxide, 500mL of ethylene glycol dimethyl ether, pass nitrogen, dropwise add 30g of acetophenone, add 50g of ethyl propionate, heat up to 84°C, carry out condensation reflux for 12h, evaporate the solvent, add dilute hydrochloric acid to adjust the pH value to 5, then add sodium carbonate to adjust the pH value to 7, filter and dry to obtain β - diketone; Step 4: Preparation of modified molybdenum disulfide: Take 0.5g of molybdenum disulfide, 40mL of deionized water, stir evenly, add 12mL of ammonia monohydrate, react at 91°C for 11h, add 1g of β - diketone, disperse evenly, react for 12h, carry out vacuum filtration, washing, and drying to obtain modified molybdenum disulfide; Step Five: Preparation of Modified Titanium Dioxide Nanotubes: S1: Take 80 mL of absolute ethanol, 20 mL of glacial acetic acid, and 20 mL of deionized water, mix them evenly to obtain a glacial acetic acid solution; take 80 mL of absolute ethanol and 40 mL of tetrabutyl titanate, mix them evenly to obtain a tetrabutyl titanate solution; place the tetrabutyl titanate solution in an ice-water bath and ultrasonically oscillate it for 12 min, then dropwise add the glacial acetic acid solution, age for 24 h to obtain a gel, dry it, and heat-treat it at 332 °C for 6.5 h to obtain titanium dioxide nanopowder; S2: Take 40 g of sodium hydroxide solid and 100 mL of deionized water, stir them evenly to obtain a sodium hydroxide solution; take 0.5 g of titanium dioxide nanopowder, add it to the sodium hydroxide solution, ultrasonically disperse it, then place it in a microwave chemical reactor with a power of 195 W, react for 70 min, centrifuge, wash, and dry to obtain titanium dioxide nanotubes; S3: Take 3 g of 8-hydroxyquinoline, 30 mL of acetone, and 2 g of titanium dioxide nanotubes, stir for 2.5 h, wash with deionized water, centrifuge, and dry to obtain modified titanium dioxide nanotubes; Step Six: Preparation of Molybdenum Disulfide-Titanium Dioxide Nanotube Composite: Take 0.8 g of tris(hydroxymethyl)aminomethane and 500 mL of deionized water, stir evenly, dropwise add dilute hydrochloric acid to adjust the pH value to 8.2, mix evenly, add 1.6 g of dopamine hydrochloride, stir for 18 min, add 2 g of modified titanium dioxide nanotubes, ultrasonically disperse for 2.5 h, heat up to 58 °C, add 1 g of modified molybdenum disulfide, ultrasonically disperse for 2.5 h, and react for 23 h to obtain a molybdenum disulfide-titanium dioxide nanotube composite.

[0020] Example 2: A processing technology for a marine high-toughness bulb flat steel with low-temperature resistance, comprising the following steps: A processing technology for a marine high-toughness bulb flat steel with low-temperature resistance, comprising the following steps: Step One: Take Fe, C, Si, Mn, Ti, N, P, S, Ba, smelt, hot-roll, heat-treat, and cool to obtain a bulb flat steel matrix; The bulb flat steel matrix is composed of the following components, calculated by mass percentage: 0.10 wt% of C, 0.25 wt% of Si, 1.32 wt% of Mn, 0.004 wt% of Ti, 0.004 wt% of N, 0.012 wt% of P, 0.002 wt% of S, 0.02 wt% of Ba, and the balance is Fe and other inevitable impurities; Step Two: Use the bulb flat steel matrix as the cathode and a pure nickel rod as the anode, place them in an electroplating solution, set the temperature to 60 °C, and at 5 A / dm 3At a current density of [value], electro-deposit for 20 minutes to obtain bulb flat steel A; take bulb flat steel A, cold roll it, and then perform surface nitriding treatment. Carry out plasma nitriding treatment at 550 °C for 4 hours, followed by heat treatment and cooling to obtain a marine high-toughness bulb flat steel with low-temperature resistance; The electro-deposition solution consists of the following components: 100 g / L of sodium tungstate dihydrate, 28 g / L of nickel sulfate hexahydrate; 34 g / L of sodium citrate dihydrate, 25 g / L of ammonium chloride, 17 g / L of sodium bromide, 12 g / L of molybdenum disulfide-titanium dioxide nanotube composite; adjust to pH = 7.9 using sulfuric acid and ammonia water; Step three: Preparation of β-diketone: Take 22.5 g of sodium ethoxide and 500 mL of ethylene glycol dimethyl ether, pass nitrogen, dropwise add 30 g of acetophenone, add 50 g of ethyl propionate, heat up to 83 °C, condense and reflux for 10 hours, evaporate the solvent, add dilute hydrochloric acid to adjust the pH value to 5, and then add sodium carbonate to adjust the pH value to 7. Filter and dry to obtain β-diketone; Step four: Preparation of modified molybdenum disulfide: Take 0.5 g of molybdenum disulfide and 40 mL of deionized water, stir evenly, add 12 mL of ammonia monohydrate, react at 90 °C for 10 hours, add 1 g of β-diketone, disperse evenly, react for 10 hours, perform vacuum filtration, washing, and drying to obtain modified molybdenum disulfide; Step five: Preparation of modified titanium dioxide nanotubes: S1: Take 80 mL of absolute ethanol, 20 mL of glacial acetic acid, and 20 mL of deionized water, mix evenly to obtain a glacial acetic acid solution; take 80 mL of absolute ethanol and 40 mL of tetrabutyl titanate, mix evenly to obtain a tetrabutyl titanate solution; place the tetrabutyl titanate solution in an ice-water bath and ultrasonically oscillate for 10 minutes, dropwise add the glacial acetic acid solution, age for 22 hours to obtain a gel, dry it, and perform heat treatment at 330 °C for 6 hours to obtain nano-titanium dioxide powder; S2: Take 40 g of solid sodium hydroxide and 100 mL of deionized water, stir evenly to obtain a sodium hydroxide solution; take 0.5 g of nano-titanium dioxide powder, add it to the sodium hydroxide solution, ultrasonically disperse it, and then place it in a 195 W microwave chemical reactor and react for 60 minutes. Centrifuge, wash, and dry to obtain titanium dioxide nanotubes; S3: Take 3 g of 8-hydroxyquinoline, 30 mL of acetone, and 2 g of titanium dioxide nanotubes, stir for 2 hours, wash with deionized water, centrifuge, and dry to obtain modified titanium dioxide nanotubes; Step six: Preparation of molybdenum disulfide-titanium dioxide nanotube composite: Take 0.8 g of tris(hydroxymethyl)aminomethane and 500 mL of deionized water, stir evenly, add dilute hydrochloric acid dropwise to adjust the pH value to 8, mix evenly, add 1.6 g of dopamine hydrochloride, stir for 15 min, add 2 g of modified titanium dioxide nanotubes, ultrasonically disperse for 2 h, heat up to 55 °C, add 1 g of modified molybdenum disulfide, ultrasonically disperse for 2 h, and react for 22 h to obtain a molybdenum disulfide-titanium dioxide nanotube composite.

[0021] Example 3: A processing technology for a marine high-toughness bulb flat steel with low-temperature resistance, comprising the following steps: A processing technology for a marine high-toughness bulb flat steel with low-temperature resistance, comprising the following steps: Step 1: Take Fe, C, Si, Mn, Ti, N, P, S, Ba, smelt, hot-roll, heat-treat, and cool to obtain a bulb flat steel matrix; The bulb flat steel matrix is composed of the following components, calculated by mass percentage: 0.15 wt% of C, 0.30 wt% of Si, 1.35 wt% of Mn, 0.008 wt% of Ti, 0.006 wt% of N, 0.015 wt% of P, 0.004 wt% of S, 0.05 wt% of Ba, and the balance is Fe and other inevitable impurities; Step 2: Use the bulb flat steel matrix as the cathode and a pure nickel rod as the anode, place them in the electrodeposition solution, set the temperature to 65 °C, and at a current density of 5 A / dm 3 electrodeposit for 25 min to obtain bulb flat steel A; take bulb flat steel A, cold-roll it, and then perform surface nitriding treatment, carry out plasma nitriding treatment at 560 °C for 5 h, heat-treat and cool to obtain a marine high-toughness bulb flat steel with low-temperature resistance; The electrodeposition solution is composed of the following components: 104 g / L of sodium tungstate dihydrate, 30 g / L of nickel sulfate hexahydrate; 37 g / L of sodium citrate dihydrate, 26 g / L of ammonium chloride, 19 g / L of sodium bromide, 14 g / L of molybdenum disulfide-titanium dioxide nanotube composite; adjust to pH = 7.9 using sulfuric acid and ammonia water; Step 3: Preparation of β-diketone: Take 22.5 g of sodium ethoxide and 500 mL of ethylene glycol dimethyl ether, pass nitrogen, add 30 g of acetophenone dropwise, add 50 g of ethyl propionate, heat up to 85 °C, condense and reflux for 14 h, evaporate the solvent, add dilute hydrochloric acid to adjust the pH value to 5, and then add sodium carbonate to adjust the pH value to 7, filter and dry to obtain β-diketone; Step 4: Preparation of modified molybdenum disulfide: Take 0.5 g of molybdenum disulfide and 40 mL of deionized water, stir evenly, add 12 mL of ammonia monohydrate, react at 92 °C for 12 h, add 1 g of β-diketone, disperse evenly, react for 14 h, vacuum filter, wash, and dry to obtain modified molybdenum disulfide; Step 5: Preparation of modified titanium dioxide nanotubes: S1: Take 80 mL of absolute ethanol, 20 mL of glacial acetic acid, and 20 mL of deionized water, mix them evenly to obtain a glacial acetic acid solution; take 80 mL of absolute ethanol and 40 mL of tetrabutyl titanate, mix them evenly to obtain a tetrabutyl titanate solution; place the tetrabutyl titanate solution in an ice-water bath and ultrasonically oscillate it for 15 min, then dropwise add the glacial acetic acid solution, age for 26 h to obtain a gel, dry it, and heat-treat it at 350 °C for 7 h to obtain titanium dioxide nanopowder; S2: Take 40 g of solid sodium hydroxide and 100 mL of deionized water, stir evenly to obtain a sodium hydroxide solution; take 0.5 g of titanium dioxide nanopowder, add it to the sodium hydroxide solution, ultrasonically disperse it, then place it in a microwave chemical reactor with a power of 195 W, react for 80 min, centrifuge, wash, and dry to obtain titanium dioxide nanotubes; S3: Take 3 g of 8-hydroxyquinoline, 30 mL of acetone, and 2 g of titanium dioxide nanotubes, stir for 3 h, wash with deionized water, centrifuge, and dry to obtain modified titanium dioxide nanotubes; Step 6: Preparation of molybdenum disulfide-titanium dioxide nanotube composite: Take 0.8 g of tris(hydroxymethyl)aminomethane and 500 mL of deionized water, stir evenly, dropwise add dilute hydrochloric acid to adjust the pH value to 8.3, mix evenly, add 1.6 g of dopamine hydrochloride, stir for 20 min, add 2 g of modified titanium dioxide nanotubes, ultrasonically disperse for 3 h, raise the temperature to 60 °C, add 1 g of modified molybdenum disulfide, ultrasonically disperse for 3 h, and react for 24 h to obtain a molybdenum disulfide-titanium dioxide nanotube composite.

[0022] Comparative Example 1: Do not use β-diketone to modify molybdenum disulfide, and the rest is the same as in Example 1: Step 1: Take Fe, C, Si, Mn, Ti, N, P, S, Ba, smelt, hot-roll, heat-treat, and cool to obtain a bulb flat steel substrate; The bulb flat steel substrate is composed of the following components, calculated by mass percentage: 0.12 wt% of C, 0.28 wt% of Si, 1.33 wt% of Mn, 0.006 wt% of Ti, 0.005 wt% of N, 0.013 wt% of P, 0.003 wt% of S, 0.04 wt% of Ba, and the balance is Fe and other inevitable impurities; Step 2: Use the bulb flat steel substrate as the cathode and a pure nickel rod as the anode, place them in an electroplating solution, set the temperature to 62 °C, and at a current density of 5 A / dm 3 electrodeposit for 22 min to obtain bulb flat steel A; take bulb flat steel A, cold-roll it, then perform surface nitriding treatment, carry out plasma nitriding treatment at 555 °C for 4.5 h, heat-treat and cool to obtain a marine high-toughness bulb flat steel with low-temperature resistance; The electroplating solution consists of the following components: 102 g / L of sodium tungstate dihydrate, 29 g / L of nickel sulfate hexahydrate, 35 g / L of sodium citrate dihydrate, 25 g / L of ammonium chloride, 18 g / L of sodium bromide, and 13 g / L of molybdenum disulfide-titanium dioxide nanotube composite; adjusted to pH = 7.9 using sulfuric acid and ammonia water. Step 3: Preparation of modified molybdenum disulfide: Take 0.5 g of molybdenum disulfide and 40 mL of deionized water, stir evenly, add 12 mL of ammonia monohydrate, heat up to 91 °C and react for 12 h, then perform vacuum filtration, washing, and drying to obtain modified molybdenum disulfide. Step 4: Preparation of modified titanium dioxide nanotubes: S1: Take 80 mL of absolute ethanol, 20 mL of glacial acetic acid, and 20 mL of deionized water, mix evenly to obtain a glacial acetic acid solution; take 80 mL of absolute ethanol and 40 mL of tetrabutyl titanate, mix evenly to obtain a tetrabutyl titanate solution; place the tetrabutyl titanate solution in an ice-water bath and ultrasonically oscillate for 12 min, then dropwise add the glacial acetic acid solution, age for 24 h to obtain a gel, dry it, and perform heat treatment at 332 °C for 6.5 h to obtain nano-titanium dioxide powder. S2: Take 40 g of solid sodium hydroxide and 100 mL of deionized water, stir evenly to obtain a sodium hydroxide solution; take 0.5 g of nano-titanium dioxide powder, add it to the sodium hydroxide solution, ultrasonically disperse it, then place it in a microwave chemical reactor with 195 W and react for 70 min, followed by centrifugation, washing, and drying to obtain titanium dioxide nanotubes. S3: Take 3 g of 8-hydroxyquinoline, 30 mL of acetone, and 2 g of titanium dioxide nanotubes, stir for 2.5 h, wash with deionized water, centrifuge, and dry to obtain modified titanium dioxide nanotubes. Step 5: Preparation of molybdenum disulfide-titanium dioxide nanotube composite: Take 0.8 g of tris(hydroxymethyl)aminomethane and 500 mL of deionized water, stir evenly, adjust the pH value to 8.2 by dropwise adding dilute hydrochloric acid, mix evenly, add 1.6 g of dopamine hydrochloride, stir for 18 min, add 2 g of modified titanium dioxide nanotubes, ultrasonically disperse for 2.5 h, heat up to 58 °C, add 1 g of modified molybdenum disulfide, ultrasonically disperse for 2.5 h, and react for 23 h to obtain molybdenum disulfide-titanium dioxide nanotube composite.

[0023] Comparative Example 2: Use nano-molybdenum disulfide instead of micro-molybdenum disulfide, and the rest is the same as in Example 1. Step 1: Take Fe, C, Si, Mn, Ti, N, P, S, Ba, smelt, hot-roll, heat-treat, and cool to obtain a bulb flat steel substrate. The bulb flat steel substrate is composed of the following components by mass percentage: 0.12 wt% of C, 0.28 wt% of Si, 1.33 wt% of Mn, 0.006 wt% of Ti, 0.005 wt% of N, 0.013 wt% of P, 0.003 wt% of S, 0.04 wt% of Ba, and the balance is Fe and other inevitable impurities; Step 2: Use the bulb flat steel substrate as the cathode and a pure nickel rod as the anode, place them in the electrodeposition solution, set the temperature at 62 °C, and at a current density of 5 A / dm 3 , carry out electrodeposition for 22 min to obtain bulb flat steel A; Take bulb flat steel A, cold roll it, and then carry out surface nitriding treatment, perform plasma nitriding treatment at 555 °C for 4.5 h, conduct heat treatment and cooling to obtain a low-temperature-resistant marine high-toughness bulb flat steel; The electrodeposition solution is composed of the following components: 102 g / L of sodium tungstate dihydrate, 29 g / L of nickel sulfate hexahydrate; 35 g / L of sodium citrate dihydrate, 25 g / L of ammonium chloride, 18 g / L of sodium bromide, 13 g / L of molybdenum disulfide-titanium dioxide nanotube composite; Adjust to pH = 7.9 using sulfuric acid and ammonia water; Step 3: Preparation of β-diketone: Take 22.5 g of sodium ethoxide and 500 mL of ethylene glycol dimethyl ether, pass nitrogen, dropwise add 30 g of acetophenone, add 50 g of ethyl propionate, heat up to 84 °C, carry out condensation reflux for 12 h, evaporate the solvent, add dilute hydrochloric acid to adjust the pH value to 5, and then add sodium carbonate to adjust the pH value to 7, filter and dry to obtain β-diketone; Step 4: Preparation of modified molybdenum disulfide: Take 0.5 g of nano molybdenum disulfide and 40 mL of deionized water, stir evenly, add 12 mL of ammonia monohydrate, react at 91 °C for 11 h, add 1 g of β-diketone, disperse evenly, react for 12 h, carry out vacuum filtration, washing, and drying to obtain modified molybdenum disulfide; Step 5: Preparation of modified titanium dioxide nanotubes: S1: Take 80 mL of absolute ethanol, 20 mL of glacial acetic acid, and 20 mL of deionized water, mix evenly to obtain a glacial acetic acid solution; Take 80 mL of absolute ethanol and 40 mL of tetrabutyl titanate, mix evenly to obtain a tetrabutyl titanate solution; Place the tetrabutyl titanate solution in an ice-water bath and ultrasonically oscillate for 12 min, dropwise add the glacial acetic acid solution, age for 24 h to obtain a gel, dry it, and perform heat treatment at 332 °C for 6.5 h to obtain nano titanium dioxide powder; S2: Take 40 g of sodium hydroxide solid and 100 mL of deionized water, stir evenly to obtain a sodium hydroxide solution; take 0.5 g of nano-titanium dioxide powder, add it to the sodium hydroxide solution, disperse it by ultrasonic wave, then place it in a microwave chemical reactor with a power of 195 W, react for 70 min, centrifuge, wash, and dry to obtain titanium dioxide nanotubes; S3: Take 3 g of 8-hydroxyquinoline, 30 mL of acetone, and 2 g of titanium dioxide nanotubes, stir for 2.5 h, wash with deionized water, centrifuge, and dry to obtain modified titanium dioxide nanotubes; Step Six: Preparation of molybdenum disulfide-titanium dioxide nanotube composite: Take 0.8 g of tris(hydroxymethyl)aminomethane and 500 mL of deionized water, stir evenly, add dilute hydrochloric acid dropwise to adjust the pH value to 8.2, mix evenly, add 1.6 g of dopamine hydrochloride, stir for 18 min, add 2 g of modified titanium dioxide nanotubes, disperse by ultrasonic wave for 2.5 h, heat up to 58 °C, add 1 g of modified molybdenum disulfide, disperse by ultrasonic wave for 2.5 h, and react for 23 h to obtain a molybdenum disulfide-titanium dioxide nanotube composite.

[0024] Comparative Example 3: Without adding molybdenum disulfide, the rest is the same as in Example 1: Step One: Take Fe, C, Si, Mn, Ti, N, P, S, Ba, smelt, hot roll, heat treat, and cool to obtain a bulb flat steel substrate; The bulb flat steel substrate is composed of the following components, calculated by mass percentage: 0.12 wt% of C, 0.28 wt% of Si, 1.33 wt% of Mn, 0.006 wt% of Ti, 0.005 wt% of N, 0.013 wt% of P, 0.003 wt% of S, 0.04 wt% of Ba, and the balance is Fe and other inevitable impurities; Step Two: Use the bulb flat steel substrate as the cathode and a pure nickel rod as the anode, place them in the electrodeposition solution, set the temperature to 62 °C, and at a current density of 5 A / dm 3 electrodeposit for 22 min to obtain bulb flat steel A; take bulb flat steel A, cold roll it, and then perform surface nitriding treatment, carry out plasma nitriding treatment at 555 °C for 4.5 h, heat treat and cool to obtain a low-temperature-resistant marine high-toughness bulb flat steel; The electrodeposition solution is composed of the following components: 102 g / L of sodium tungstate dihydrate, 29 g / L of nickel sulfate hexahydrate; 35 g / L of sodium citrate dihydrate, 25 g / L of ammonium chloride, 18 g / L of sodium bromide, 13 g / L of modified titanium dioxide nanotubes; adjust to pH = 7.9 using sulfuric acid and ammonia water; Step Three: Preparation of modified titanium dioxide nanotubes: S1: Take 80 mL of absolute ethanol, 20 mL of glacial acetic acid, and 20 mL of deionized water, mix them evenly to obtain a glacial acetic acid solution; take 80 mL of absolute ethanol and 40 mL of tetrabutyl titanate, mix them evenly to obtain a tetrabutyl titanate solution; place the tetrabutyl titanate solution in an ice-water bath and ultrasonically oscillate for 12 min, then dropwise add the glacial acetic acid solution, age for 24 h to obtain a gel, dry it, and heat-treat it at 332 °C for 6.5 h to obtain nano-titanium dioxide powder; S2: Take 40 g of solid sodium hydroxide and 100 mL of deionized water, stir evenly to obtain a sodium hydroxide solution; take 0.5 g of nano-titanium dioxide powder, add it to the sodium hydroxide solution, ultrasonically disperse it, then place it in a microwave chemical reactor with a power of 195 W, react for 70 min, centrifuge, wash, and dry to obtain titanium dioxide nanotubes; S3: Take 3 g of 8-hydroxyquinoline, 30 mL of acetone, and 2 g of titanium dioxide nanotubes, stir for 2.5 h, wash with deionized water, centrifuge, and dry to obtain modified titanium dioxide nanotubes.

[0025] Experiment: Take the low-temperature-resistant high-toughness bulb flat steel prepared in Examples 1 - 3 and Comparative Examples 1 - 3 of the present invention for performance testing; refer to GB / T 19748 - 2019 to conduct a -60 °C Charpy V-notch pendulum impact test on the low-temperature-resistant high-toughness bulb flat steel to characterize its low-temperature toughness; cut the low-temperature-resistant high-toughness bulb flat steel into specimens of 150 mm × 150 mm × 1 mm, then place them in a salt spray chamber at 35 °C with a sodium chloride concentration of 55 g / L and a pH of 7.0, and record the surface corrosion resistance situation; the obtained data are shown in Table 1 below: Table 1

[0026] Conclusion: It can be known from the comparison of the data in the table that in Comparative Example 1, without using β-diketone to modify molybdenum disulfide, the corrosion resistance of the surface of the bulb flat steel becomes worse. In Comparative Example 2, using nano-molybdenum disulfide instead of micro-molybdenum disulfide, the surface roughness of the coating becomes worse, the compactness of the coating decreases, and the corrosion resistance of the bulb flat steel becomes worse. In Comparative Example 3, without adding molybdenum disulfide, the corrosion resistance of the bulb flat steel is greatly reduced. In Examples 1 - 3 of the present invention, molybdenum disulfide - titanium dioxide nanotube composites are added to the electrodeposition solution to improve the corrosion resistance of the bulb flat steel. The molybdenum disulfide used in the present invention is in a micro-structure, the titanium dioxide nanotubes are nano-scale particles, and the molybdenum disulfide is in a micro-scale particle. When the two are used in combination, it can improve the agglomeration problem while increasing the surface roughness of the coating and improving the compactness of the coating, thereby further improving the corrosion resistance of the bulb flat steel. The present invention prepares a β-diketone and uses the β-diketone to modify molybdenum disulfide. The β-diketone can react with iron ions on the surface of the steel in the electrodeposition solution to produce a chelating effect, enhancing the corrosion resistance of the surface of the bulb flat steel.

[0027] It is obvious to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Accordingly, all changes that fall within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention.

Claims

1. A processing technology for low temperature resistant high toughness bulb flat steel for ships, characterized by: The following steps are involved: Step 1: Take Fe, C, Si, Mn, Ti, N, P, S, and Ba, smelt, hot-roll, heat-treat, and cool to obtain a bulb flat steel matrix; Step 2: Place the spherical flat steel substrate as the cathode and the pure nickel rod as the anode in the electrodeposition solution, set the temperature to 60-65°C, and operate at 5A / dm 3 At a current density of , electrodeposition is performed for 20-25 minutes to obtain a bulb flat steel A; the bulb flat steel A is taken, cold rolled, and then subjected to surface nitriding treatment, plasma nitriding treatment is performed at 550-560°C for 4-5 hours, heat treatment is performed, and cooling is performed to obtain a low-temperature resistant ship-use high-toughness bulb flat steel; The electrodeposition solution is composed of the following components: 100-104 g / L of sodium tungstate dihydrate, 28-30 g / L of nickel sulfate hexahydrate; 34-37 g / L of sodium citrate dihydrate, 25-26 g / L of ammonium chloride, 17-19 g / L of sodium bromide, and 12-14 g / L of molybdenum disulfide-titanium dioxide nanotube composite; sulfuric acid and ammonia water are used to adjust the pH to 7.5-8.

2. The processing technology of a low temperature resistant high toughness bulb flat steel for ships according to claim 1 is characterized in that: The bulb flat steel matrix is ​​composed of the following components, calculated by mass percentage: 0.10wt%-0.15wt% C, 0.25wt%-0.30wt% Si, 1.32wt%-1.35wt% Mn, 0.004wt%-0.008wt% Ti, 0.004wt%-0.006wt% N, 0.012wt%-0.015wt% P, 0.002wt%-0.004wt% S, 0.02wt%-0.05wt% Ba, and the remainder is Fe and other inevitable impurities.

3. The processing technology of the low temperature resistant high toughness bulb flat steel for ships according to claim 1 is characterized in that: The preparation method of the molybdenum disulfide-titanium dioxide nanotube composite is as follows: tris(hydroxymethyl)aminomethane and deionized water are taken, stirred evenly, diluted hydrochloric acid is added dropwise to adjust the pH value to 8-8.3, mixed evenly, dopamine hydrochloride is added, stirred for 15-20 minutes, modified titanium dioxide nanotubes are added, ultrasonic dispersion is performed for 2-3 hours, the temperature is raised to 55-60° C., modified molybdenum disulfide is added, ultrasonic dispersion is performed for 2-3 hours, and the reaction is performed for 22-24 hours to obtain the molybdenum disulfide-titanium dioxide nanotube composite.

4. The processing technology of the low temperature resistant high toughness bulb flat steel for ships according to claim 3 is characterized in that: The preparation method of the modified titanium dioxide nanotubes is as follows: 8-hydroxyquinoline, acetone and titanium dioxide nanotubes are taken, stirred for 2-3 hours, washed with deionized water, centrifuged and dried to obtain the modified titanium dioxide nanotubes.

5. The processing technology of the low temperature resistant high toughness bulb flat steel for ships according to claim 4 is characterized in that: The preparation method of the titanium dioxide nanotubes comprises the following steps: S1: Take anhydrous ethanol, glacial acetic acid, and deionized water, mix them evenly to obtain a glacial acetic acid solution; take anhydrous ethanol and tetra-n-butyl titanate, mix them evenly to obtain a tetra-n-butyl titanate solution; put the tetra-n-butyl titanate solution in an ice water bath for ultrasonic oscillation for 10-15 minutes, add the glacial acetic acid solution dropwise, age it for 22-26 hours to obtain a gel, dry it, and heat-treat it at 330-350°C for 6-7 hours to obtain a nano titanium dioxide powder; S2: Take sodium hydroxide solid and deionized water, stir evenly to obtain sodium hydroxide solution; take nano titanium dioxide powder, add sodium hydroxide solution, ultrasonically disperse, and then place in a microwave chemical reactor, react for 60-80 minutes, centrifuge, wash, and dry to obtain titanium dioxide nanotubes.

6. The processing technology of the low temperature resistant high toughness bulb flat steel for ships according to claim 3 is characterized by: The preparation method of the modified molybdenum disulfide is as follows: take molybdenum disulfide and deionized water, stir evenly, add ammonia monohydrate, heat to 90-92° C. and react for 10-12 hours, add β-diketone, disperse evenly, react for 10-14 hours, vacuum filter, wash, and dry to obtain the modified molybdenum disulfide.

7. The processing technology of the low temperature resistant high toughness bulb flat steel for ships according to claim 6 is characterized in that: The preparation method of the β-diketone is as follows: sodium ethoxide and ethylene glycol dimethyl ether are taken, nitrogen is passed through, acetophenone is added dropwise, ethyl propionate is added, the temperature is raised to 83-85° C., condensed and refluxed for 10-14 hours, the solvent is evaporated, dilute hydrochloric acid is added to adjust the pH value to 5, and then sodium carbonate is added to adjust the pH value to 7, and the β-diketone is obtained by filtering and drying.

8. The processing technology of the low temperature resistant high toughness bulb flat steel for ships according to claim 6 is characterized in that: The particle size of the molybdenum disulfide is 12-16 um.

9. Low temperature resistant shipboard high toughness bulb flat steel obtained by processing the low temperature resistant shipboard high toughness bulb flat steel processing technology according to any one of claims 1 to 8.

Images