Niobium microalloyed light high-strength steel and preparation process thereof

Abstract

The invention discloses niobium microalloyed light high-strength steel and a preparation process thereof, and relates to the technical field of low-density steel, the preparation process comprises the following steps: smelting and pouring raw materials to form a briquette; performing homogenizing heat treatment, forging and rolling to obtain a steel plate; and then nickel plating, annealing, chromizing, nitriding and laser cladding are conducted, and the light high-strength steel is obtained. The element niobium is used as a microalloy element of Fe-Mn-Al-C austenitic steel, solid solution structure grains are refined, the strength of the steel is improved, meanwhile, the toughness of the steel is improved, high-melting-point NbC and NbN are separated out, the precipitation strengthening effect of the steel is exerted to a certain extent, corrosion and oxidation of high-manganese steel are effectively prevented, precipitation of nitride at the grain boundary in the steel is inhibited, and the corrosion resistance of the high-manganese steel is improved. The corrosion sensitivity at the grain boundary is reduced; austenite phase transformation is controlled, austenite grain growth is inhibited, grains are refined, and the strength of the steel is improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of low-density steel, and particularly relates to a niobium micro-alloyed light high-strength steel and a preparation process thereof. BACKGROUND

[0002] With the gradual popularization of the human environmental protection and green concept, the problem of energy shortage becomes significant, and the lightweight design of an automobile begins to occupy the theme of market development. Compared with traditional steel, low-density steel is more inclined to be used. In Fe-Mn-Al-C austenitic steel, the contents of elements aluminum and carbon are relatively high, the density of the steel is greatly reduced, and the steel has good strength, toughness and other characteristics, so that the Fe-Mn-Al-C austenitic steel becomes the most potential low-density steel and is becoming the development direction of the future automobile steel.

[0003] However, the steel with high manganese and high aluminum contents has problems such as crack sensitivity in the hot / cold deformation process, low work hardening capacity, and the strength of the steel needs to be further improved. After deformation, there are a large number of high-surface-energy grain boundaries in the steel, the electrode potential of the main alloying element manganese is low and easy to dissolve, so that the corrosion resistance of the steel is poor. Therefore, the application provides a niobium micro-alloyed light high-strength steel and a preparation process thereof. SUMMARY

[0004] The application aims to provide a niobium micro-alloyed light high-strength steel and a preparation process thereof to solve the problems in the background.

[0005] In order to solve the above technical problems, the application provides the following technical scheme: a niobium micro-alloyed light high-strength steel, which comprises the following mass components: carbon C: 0.8% to 1.4%, manganese Mn: 27% to 28%, aluminum Al: 9% to 12%, vanadium V: 0.05% to 0.15%, niobium Nb: 0.01% to 0.1%, rare earth element RE: 0.05% to 0.15%, nitrogen N: less than or equal to 0.006%, phosphorus P: less than or equal to 0.015%, sulfur S: less than or equal to 0.006%, and the balance is iron Fe.

[0006] Further, in the mass components of the light high-strength steel, 0.10%≤Nb+V≤0.25%.

[0007] Further, the rare earth element is one or a mixture of multiple selected from cerium, lanthanum and yttrium.

[0008] In the above technical scheme, the role of carbon in the alloy steel is divided into two kinds, one is to promote the formation of single-phase austenite, and the other is to play a solid solution strengthening role to ensure the mechanical properties of the steel. In the high manganese alloy system, the composition range of the austenite phase zone changes greatly, and the carbon content needs to be as high as possible to ensure its mechanical properties. The increase of carbon element is beneficial to improve the austenite content in the steel, so as to obtain good strength and toughness. In high manganese steel, manganese and carbon elements can expand the austenite phase zone, and are austenite stabilizing elements, but too high manganese will cause the generation of β-Mn, resulting in the decline of steel performance.

[0009] Aluminum is the most effective element to reduce the density of steel and improve the stacking fault energy, which can reduce the austenite phase zone and inhibit the occurrence of martensite phase transformation, and is helpful to improve the strength and toughness of the steel. Higher content of manganese element combined with a certain content of aluminum element can effectively improve the hot deformation resistance of the steel, delay dynamic recrystallization, so that the austenite grains are refined after dynamic recrystallization, and play a role of fine-grain strengthening. And the addition of aluminum element can improve the corrosion resistance and oxidation resistance of the steel; effectively improve the dissolution line of intracrystalline and grain boundary κ-carbide, and control the precipitation of carbide.

[0010] As a micro-alloying element, niobium can refine the solid solution state grain size, improve the strength of the steel, and at the same time improve the toughness, precipitate high melting point NbC, NbN, and to a certain extent, play its precipitation strengthening effect, effectively prevent the corrosion and oxidation of high manganese steel, inhibit the precipitation of nitride at the grain boundary of the steel, reduce the corrosion sensitivity at the grain boundary; control the austenite transformation, inhibit the austenite grain growth, refine the grain, and improve the strength of the steel. But too much niobium will cause excessive precipitation of carbide and oxide, increase the brittleness of the steel, and reduce the toughness of the steel.

[0011] Rare earth elements (cerium, lanthanum, yttrium, etc.) can degas, desulfurize and remove slag from steel, purify molten steel and improve casting performance; and can change the nature, form and distribution of inclusions, inhibit grain growth, reduce and eliminate columnar grains, refine grains and reduce crack tendency, thereby improving the mechanical properties of the steel, improving its mechanical properties, impact toughness, increasing its wear resistance and prolonging its service life. Rare earth elements can also react with oxygen to form a dense oxide film, block further reaction of oxygen with steel, enhance the oxidation resistance of steel in high temperature environment, and reduce the formation and peeling of surface oxide skin.

[0012] A preparation process of a niobium micro-alloyed light high-strength steel, comprising the following processes:

[0013] Take the raw materials to melt and pour to obtain a billet;

[0014] Homogenization heat treatment, forging, rolling to obtain a plate

[0015] Annealing to obtain a steel; surface treatment to obtain a light high-strength steel.

[0016] Further, the smelting temperature is 1500-1700℃, and the pouring temperature is 1530-1550℃.

[0017] Further, the process condition of the homogenization heat treatment is: temperature 1170-1200℃, holding time 2h, and heating rate 10℃ / s.

[0018] After the homogenization heat treatment, the temperature is decreased to the forging temperature at a rate of 5℃ / s, and the temperature is kept for 15s.

[0019] Further, the forging temperature is 1135-1150℃, and the steel is air-cooled after forging; and the temperature is kept for 60min at 1130-1140℃ before forging.

[0020] Further, the rolling includes hot rolling and cold rolling.

[0021] Further, the process condition of the hot rolling is: open rolling temperature 950-1050℃, final rolling temperature 800-850℃, rolling pass 5-6 passes, and total reduction 80%-90%.

[0022] Further, the process condition of the cold rolling is: room temperature cold rolling, and cold rolling reduction 30%-60%.

[0023] Further, the process condition of the annealing is: temperature 870-900℃, holding time 1-3min, and water cooling; and the aging treatment is performed after the annealing, and the process is: temperature 550-650℃, holding time 10-90min.

[0024] In the above technical solution, the homogenization heat treatment makes the steel material reach a uniform state in the structure and performance, thereby improving the toughness and ductility of the steel material, reducing the internal stress of the steel material, improving the strength of the steel material, avoiding the deformation and cracks of the steel material in the processing process, and improving the processability and crack resistance.

[0025] Through the forging and rolling, high-density dislocations are generated in the steel material, and the carbon atom distribution is used to stabilize the austenite, which can significantly improve the strength of the steel material. Then, the annealing is performed, and the steel material is partially recrystallized, and the microstructure is composed of recrystallized grains and non-recrystallized grains containing dislocations, so that the steel material has excellent mechanical properties. Then, the aging treatment is performed, the content of κ-carbide increases, the strengthening effect of the fine and dispersed κ-carbide is more obvious, and the mechanical properties of the steel material are further improved.

[0026] Further, the surface treatment includes nickel plating, chromizing, nitriding, and laser cladding.

[0027] Further, the nickel plating includes the following process steps: placing the steel material in a nickel plating solution, electroplating to form a nickel layer;

[0028] Process conditions: current density 1.5-2.0 A / dm 2 , duty cycle 0.4-0.5, frequency 40 Hz, temperature 53-57℃, time length 5-10 min.

[0029] The nickel-containing plating solution comprises the following mass components: 300-320 g / L nickel sulfate hexahydrate, 45-50 g / L nickelous chloride hexahydrate, 27-30 g / L boric acid, 0.3-0.8 g / L sodium dodecyl sulfate, 40-60 g / L cerium dioxide, and pH is 4.0-4.2.

[0030] The cerium dioxide is nanoscale.

[0031] In the above technical solution, the nanoscale rare earth element cerium dioxide is contained in the nickel-containing plating solution, and a composite nickel plating layer containing cerium dioxide (denoted as a nickel layer) is deposited on the surface of the steel material by means of co-electrodeposition. The nickel layer is stable in air and can form a passivation layer, which can resist corrosion of oxygen, acid and alkali, etc., and is helpful to improve the corrosion resistance and prolong the service life of the steel material. The nickel layer has high hardness and can reduce the wear of the surface of the steel material and improve its wear resistance. The introduction of cerium dioxide can refine the size of nickel grains in the nickel layer, hinder the growth of nanocrystals, make the plating layer uniform and dense, and have a solid structure, further improving the corrosion resistance, wear resistance and other properties of the steel material; at the same time, the surface of the material has higher activity, can better adsorb ions, improve the efficiency of electroplating and subsequent processes, and improve the bonding strength of the nickel layer and the diffusion layer; the increase of grain boundaries significantly enhances the diffusion ability of chromium as a diffusion channel.

[0032] The nickel plating process is placed before the annealing process, and the nickel atoms in the nickel layer diffuse and penetrate into the steel material, forming an iron-nickel transition zone and generating iron-nickel intermetallic compounds, which have high hardness, high strength and good corrosion resistance and oxidation resistance, and are helpful to the surface performance strengthening of the steel material.

[0033] Further, the process conditions for chromium diffusion are as follows: the steel material is embedded in a 500-610℃ chromium diffusion agent for 3-5h to form a diffusion layer.

[0034] The diffusion agent comprises the following mass components: 50-60 parts of chromium powder, 42-50 parts of aluminum oxide, 10-20 parts of chromium chloride, 1-3 parts of potassium fluoborate, 1-7 parts of cerium chloride, and 3-5 parts of ammonium chloride.

[0035] Further, the process conditions for nitriding are as follows: pure NH3 is introduced, and the temperature is kept at 245-255℃ for 1-2h, then raised to 445-455℃ for 3-5h, kept at 535-545℃ for 36-72h, cooled to 180-200℃ in the furnace and then taken out for air cooling to form a nitriding layer.

[0036] In the technical scheme, the rare earth elements in the penetrant and the nickel layer can purify the surface of the steel material, activate to form an activation center, accelerate the decomposition of the chromium chloride and the adsorption of the chromium atom, increase the vacancies on the surface of the steel material, promote the chromizing process, help the penetration of the chromium atom and the migration of the nickel, increase the depth and hardness of the permeation layer, and improve the wear resistance and corrosion resistance of the steel material. The chromium atom and the nickel atom form a chromium-nickel intermetallic compound, which can significantly improve the corrosion resistance, high-temperature strength and oxidation resistance of the surface of the steel material. The chromium chloride in the penetrant can replace the chromium powder to effectively improve the diffusion speed of the chromium atom; a small amount of potassium fluoroborate is added to the penetrant to react with the oxides on the surface of the steel base, the chromium powder or the chromium-iron powder to play a purifying role.

[0037] Then, the steel material is subjected to nitriding, nitrogen diffuses into the permeation layer and reacts with the chromium to form a nitriding layer on the surface of the steel material, which contains chromium nitride in the organization. Influenced by the purification and fine-grain effect of the rare earth elements in the permeation layer, the organization and grain are refined to form nanocrystalline CrN and Cr2N, so as to improve the corrosion resistance and wear resistance of the steel material; and through the setting of the sequence of the nickel plating, the chromizing and the nitriding processes, the formation of iron nitride, manganese nitride and chromium carbide on the surface of the steel material is reduced, and the improvement of the wear resistance, corrosion resistance and mechanical properties of the steel material is optimal.

[0038] Further, laser cladding is performed after nitriding, and the specific process is as follows: the metal powder is mixed with the binder, coated on the surface of the steel material, dried, and then subjected to laser cladding to form a cladding layer.

[0039] Further, the metal powder comprises the following mass components: 50-70 parts of nickel powder, 7.7-10.7 parts of aluminum powder, 6-12 parts of niobium powder, 1-6 parts of graphite powder, and 1-3 parts of cerium dioxide.

[0040] The binder is selected from 3-20wt% polyvinyl alcohol;

[0041] The volume ratio of the metal powder to the binder is 10: (1-4).

[0042] Further, the process conditions of the laser cladding are as follows: spot diameter 2-4mm, laser power 1600-2200W, scanning speed 300-400mm / min, argon flow rate 5-10L / min, and overlap rate 30%-50%;

[0043] The coating thickness is 0.2-1.0mm;

[0044] The drying process is as follows: drying at 120℃ for 2h.

[0045] In the technical scheme, in the laser cladding process, the metal powder is melted on the surface of the steel material to form a micro-melt pool, form a Ni3Al-based alloy, and has high melting point, light weight, low density characteristics, good high-temperature stability, good oxidation corrosion resistance, and excellent toughness. And metallurgical bonding occurs with the nickel layer, the infiltration layer, and the nitriding layer, and the aluminum, nickel, chromium, and niobium elements are fused to form a solid solution alloy, so that the chromium is melted in the nickel-aluminum alloy, which can promote the formation of the alpha-Al2O3 protective layer, effectively improving the oxidation resistance and corrosion resistance; the chromium is melted in the nickel-aluminum alloy, which can precipitate a strengthening phase, increase the dislocation density in the cladding layer, hinder the movement of dislocations, improve the strength and hardness, and improve the high-temperature corrosion resistance of the cladding layer; the aluminum-chromium and niobium-aluminum elements can form intermetallic compounds, which have high hardness, zirconium strength and excellent high-temperature and oxidation resistance, and can play a strengthening role, which is helpful to improve the heat resistance, oxidation resistance and corrosion resistance and mechanical properties of the cladding layer, and achieve good strength and toughness cooperation, which is helpful to improve the wear resistance of the cladding layer.

[0046] The solid solution nitrogen in the nitriding layer overflows, the chromium nitride decomposes after high-energy laser irradiation, the nitrogen atoms enter the melt pool and contact with aluminum atoms and niobium atoms to react to form aluminum and niobium nitrides, and act as a particle to promote the formation of carbonitride, and play a strengthening role. The chromium and its nitride in the nickel layer, the infiltration layer, and the nitriding layer, and the nickel enter the melt pool and diffuse, and after cooling, a nickel-based composite layer doped with chromium nitride and niobium chromium intermetallic compound (denoted as cladding layer) is formed, and the phase composition forms a gradient distribution on the surface of the steel material, which can effectively enhance the hardness and wear resistance of the cladding layer, improve the corrosion resistance of the surface of the steel material, and can smooth the surface of the steel material and optimize the comprehensive performance. The combination of the cladding layer formed by nickel plating, chromium infiltration, nitriding, and laser cladding with the steel substrate makes the surface of the steel material obtain performance strengthening, which helps to improve the tensile strength and yield strength of the light steel. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the present application will be described below. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0048] In the following detailed description, the "parts" are all mass parts;

[0049] The smelting raw materials are high-purity iron, high-purity aluminum, high-purity manganese, high-purity carbon, high-purity niobium, high-purity vanadium, and high-purity cerium according to the mass ratio of the elements of the steel material;

[0050] After pouring, a 70mm thick ingot is formed, and after forging, a 20mm thick plate is formed, and after hot rolling, the thickness is 3mm, and after cold rolling, the thickness of the steel material is 2.1mm;

[0051] Cerium dioxide: average particle size 7nm, from Nanjing Jikuo Biotechnology Co., Ltd.;

[0052] Chromium powder: chromium oxide (Cr2O3), purity ≥ 99.95%, average particle size 75μm, from Nangong Xindun Alloy Welding Material Spraying Co., Ltd.;

[0053] Aluminum oxide: purity ≥ 99.8%, average particle size 75μm, from Changsha Xinsheng New Material Co., Ltd.;

[0054] Nickel powder: Ni60AACuMo, average particle size 50μm, from Nangong Xindun Alloy Welding Material Spraying Co., Ltd.;

[0055] Aluminum powder: purity ≥ 99%, average particle size 50μm, from Beijing Juguang Yingchuang Technology Co., Ltd.;

[0056] Niobium powder: purity ≥ 99.9%, particle size < 28μm, from Nangong Naiyate Alloy Welding Material Co., Ltd.;

[0057] Graphite powder: XF078, average particle size < 48μm, from Jiangsu Xianfeng Nanometer Material Technology Co., Ltd.

[0058] Example 1: A preparation process of a niobium micro-alloyed light high-strength steel, comprising the following processes:

[0059] (1) Melting the raw materials, the melting temperature is 1700℃; pouring, the pouring temperature is 1530℃; homogenizing heat treatment, the process conditions are: temperature 1170℃, holding time 2h, heating rate 10℃ / s; forging, the forging temperature is 1135℃, air cooling after forging; before forging, holding at 1130℃ for 60min; hot rolling, the process conditions are: opening rolling temperature 950℃, final rolling temperature 800℃, rolling pass 6 passes, total reduction 85%; cold rolling, reduction 30%;

[0060] (2) Surface treatment:

[0061] Nickel plating: placing the steel material in a nickel-containing plating solution, electroplating to form a nickel layer; the process conditions are: current density 1.5A / dm2, duty cycle 0.5, frequency 40Hz, temperature 53℃, time 5min; the nickel-containing plating solution comprises the following mass components: 300g / L nickel sulfate hexahydrate, 45g / L nickelous chloride hexahydrate, 27g / L boric acid, 0.3g / L sodium dodecyl sulfate, 40g / L cerium dioxide, pH 4.0;

[0062] annealing, process condition is: holding for 1 min at 870℃, water cooling; after annealing, aging treatment is carried out, process is: holding for 10 min at 550℃, to obtain the steel material; the steel material comprises the following mass components: C: 1.2%, Mn: 27.7%, Al: 10.4%, V: 0.12%, Nb: 0.08%, Ce: 0.10%, N: 0.0025%, P: 0.007%, S: 0.0013%, and the balance is Fe;

[0063] chromizing: embedding the steel material in a chromizing agent at 500℃, chromizing for 3h to form a chromizing layer; the chromizing agent comprises the following mass components: 60 parts of chromium powder, 42 parts of aluminum oxide, 10 parts of chromium chloride, 1 part of potassium fluoborate, 1 part of cerium chloride, and 3 parts of ammonium chloride;

[0064] nitriding: passing pure NH3, holding for 1h at 245℃, increasing the temperature to 445℃ and holding for 5h, holding for 36h at 535℃, furnace cooling to 180℃ and then taking out and air cooling to form a nitriding layer;

[0065] laser cladding, mixing metal powder and adhesive, coating on the surface of the steel material, coating thickness is 0.2mm, drying at 120℃ for 2h, then laser cladding to form a cladding layer, to obtain a lightweight high-strength steel; process condition is: spot diameter 2mm, laser power 1600W, scanning speed 300mm / min, argon flow rate 5L / min, and overlap rate 30%; the metal powder comprises the following mass components: 50 parts of nickel powder, 7.7 parts of aluminum powder, 6 parts of niobium powder, 1 part of graphite powder, and 1 part of cerium dioxide; the adhesive is 10wt% polyvinyl alcohol; the volume ratio of metal powder to adhesive is 10:2.

[0066] Example 2: a preparation process of a niobium microalloyed lightweight high-strength steel, comprising the following processes:

[0067] (1) melting raw materials, melting temperature is 1700℃; pouring, pouring temperature is 1540℃; homogenizing heat treatment, process condition is: temperature 1180℃, holding time 2h, and heating rate 10℃ / s; forging, forging temperature is 1142℃, and air cooling after forging; holding for 60min at 1135℃ before forging; hot rolling, process condition is: starting rolling temperature 1000℃, final rolling temperature 825℃, rolling pass 6 passes, and total reduction 85%; cold rolling, reduction 30%;

[0068] (2) surface treatment:

[0069] Nickel plating: the steel material is placed in a nickel-containing plating solution for electroplating to form a nickel layer; the process conditions are: current density 1.8 A / dm2, duty cycle 0.5, frequency 40 Hz, temperature 55℃, time 8 min; the nickel-containing plating solution includes the following mass components: 310 g / L nickel sulfate hexahydrate, 48 g / L nickelous chloride hexahydrate, 28 g / L boric acid, 0.5 g / L sodium dodecyl sulfate, 50 g / L cerium dioxide, and the pH is 4.1;

[0070] Annealing, process conditions: temperature 885℃, holding time 2 min, water cooling; after annealing, aging treatment is carried out, process: temperature 600℃, holding time 50 min, to obtain a steel material with the same composition by mass as in Example 1;

[0071] Chromizing: the steel material is embedded in a chromizing agent at 550℃ for 4h to form a chromizing layer; the chromizing agent includes the following mass components: 55 parts of chromium powder, 46 parts of aluminum oxide, 15 parts of chromium chloride, 2 parts of potassium fluoborate, 4 parts of cerium chloride, and 4 parts of ammonium chloride;

[0072] Nitriding: pure NH3 is introduced, and the temperature is held at 250℃ for 1.5h, then raised to 450℃ for 4h, held at 540℃ for 54h, and then cooled to 190℃ in the furnace before being taken out and air-cooled to form a nitriding layer;

[0073] Laser cladding: metal powder is mixed with a binder, coated on the surface of the steel material, and dried at 120℃ for 2h before laser cladding to form a cladding layer, obtaining a lightweight high-strength steel; process conditions: spot diameter 3mm, laser power 1800W, scanning speed 400mm / min, argon flow rate 8L / min, overlap rate 40%; the metal powder includes the following mass components: 60 parts of nickel powder, 9.2 parts of aluminum powder, 9 parts of niobium powder, 3 parts of graphite powder, and 2 parts of cerium dioxide; the binder is 10wt% polyvinyl alcohol; the volume ratio of metal powder to binder is 10:2.

[0074] Example 3: A preparation process of a niobium micro-alloyed lightweight high-strength steel, including the following processes:

[0075] (1) Melting of raw materials, melting temperature 1700℃; pouring, pouring temperature 1550℃; homogenizing heat treatment, process conditions: temperature 1200℃, holding time 2h, heating rate 10℃ / s; forging, forging temperature 1150℃, air cooling after forging; before forging, holding at 1140℃ for 60min; hot rolling, process conditions: starting temperature 1050℃, finishing temperature 850℃, rolling passes 6 passes, total reduction 85%; cold rolling, reduction 30%;

[0076] (2) Surface treatment:

[0077] Nickel plating: the steel material is placed in a nickel-containing plating solution for electroplating to form a nickel layer; the process conditions are: current density 2.0 A / dm2, duty cycle 0.4, frequency 40 Hz, temperature 57℃, time length 10 min; the nickel-containing plating solution comprises the following mass components: 320 g / L nickel sulfate hexahydrate, 50 g / L nickelous chloride hexahydrate, 30 g / L boric acid, 0.8 g / L sodium dodecyl sulfate, 60 g / L cerium dioxide, and the pH is 4.2;

[0078] Annealing, process conditions: 900℃ temperature for 3 min, water cooling; after annealing, aging treatment is carried out, process: 650℃ temperature for 90 min, to obtain a steel material, the same composition as example 1;

[0079] Chromizing: the steel material is embedded in a 610℃ chromizing agent for 5h to form a chromizing layer; the chromizing agent comprises the following mass components: 50 parts of chromium powder, 50 parts of aluminum oxide, 20 parts of chromium chloride, 3 parts of potassium fluoborate, 7 parts of cerium chloride, and 5 parts of ammonium chloride;

[0080] Nitriding: pure NH3 is introduced, and the temperature is kept at 255℃ for 2h, then increased to 455℃ for 3h, and kept at 545℃ for 72h, then cooled to 200℃ in the furnace and taken out for air cooling to form a nitriding layer;

[0081] Laser cladding, the metal powder is mixed with the adhesive, coated on the surface of the steel material, the coating thickness is 0.2mm, dried at 120℃ for 2h, then laser cladding is carried out to form a cladding layer, and a lightweight high-strength steel is obtained; the process conditions are: spot diameter 4mm, laser power 2000W, scanning speed 400mm / min, argon flow rate 10L / min, and overlap rate 30%; the metal powder comprises the following mass components: 70 parts of nickel powder, 10.7 parts of aluminum powder, 12 parts of niobium powder, 6 parts of graphite powder, and 3 parts of cerium dioxide; the adhesive is 10wt% polyvinyl alcohol; the volume ratio of the metal powder to the adhesive is 10:2.

[0082] Comparative example 1: a preparation process of a niobium micro-alloyed lightweight high-strength steel, comprising the following processes:

[0083] (1) Melting the raw materials, the melting temperature is 1700℃; pouring, the pouring temperature is 1530℃; homogenizing heat treatment, process conditions: temperature 1170℃, holding time 2h, heating rate 10℃ / s; forging, forging temperature 1135℃, air cooling after forging; before forging, the temperature is kept at 1130℃ for 60min; hot rolling, process conditions: opening rolling temperature 950℃, final rolling temperature 800℃, rolling pass 6 passes, total reduction 85%; cold rolling, reduction 30%; annealing, process conditions: 870℃ temperature for 1min, water cooling; after annealing, aging treatment is carried out, process: 550℃ temperature for 10min, to obtain a steel material;

[0084] (2) Surface treatment:

[0085] Nickel plating: the steel material is placed in a nickel-containing plating solution for electroplating to form a nickel layer; the process conditions are: current density 1.5 A / dm2, duty cycle 0.5, frequency 40 Hz, temperature 53℃, time 5 min; the nickel-containing plating solution includes the following mass components: 300 g / L nickel sulfate hexahydrate, 45 g / L nickelous chloride hexahydrate, 27 g / L boric acid, 0.3 g / L sodium dodecyl sulfate, 40 g / L cerium dioxide, and the pH is 4.0;

[0086] Nitriding: pure NH3 is introduced, and the temperature is kept at 245℃ for 1h, then increased to 445℃ for 5h, and kept at 535℃ for 36h, then cooled to 180℃ in the furnace and taken out for air cooling to form a nitriding layer;

[0087] Chromizing: the steel material is embedded in a 500℃ chromizing agent for 3h to form a chromizing layer; the chromizing agent includes the following mass components: 60 parts of chromium powder, 42 parts of aluminum oxide, 10 parts of chromium chloride, 1 part of potassium fluoborate, 1 part of cerium chloride, and 3 parts of ammonium chloride;

[0088] Laser cladding: the metal powder is mixed with the binder, coated on the surface of the steel material, and dried at 120℃ for 2h before laser cladding to form a cladding layer, obtaining a lightweight high-strength steel; the process conditions are: spot diameter 2mm, laser power 1600W, scanning speed 300mm / min, argon flow rate 5L / min, and overlap rate 30%; the metal powder includes the following mass components: 50 parts of nickel powder, 7.7 parts of aluminum powder, 6 parts of niobium powder, 1 part of graphite powder, and 1 part of cerium dioxide; the binder is 10wt% polyvinyl alcohol; the volume ratio of metal powder to binder is 10:2.

[0089] Comparative Example 2: A preparation process of a niobium micro-alloyed lightweight high-strength steel, including the following processes:

[0090] Step (1) is the same as Comparative Example 1;

[0091] (2) Surface treatment:

[0092] Nitriding: pure NH3 is introduced, and the temperature is kept at 245℃ for 1h, then increased to 445℃ for 5h, and kept at 535℃ for 36h, then cooled to 180℃ in the furnace and taken out for air cooling to form a nitriding layer;

[0093] Chromizing: the steel material is embedded in a 500℃ chromizing agent for 3h to form a chromizing layer; the chromizing agent includes the following mass components: 60 parts of chromium powder, 42 parts of aluminum oxide, 10 parts of chromium chloride, 1 part of potassium fluoborate, 1 part of cerium chloride, and 3 parts of ammonium chloride;

[0094] Laser cladding involves mixing metal powder with a binder and coating the steel surface with a coating thickness of 0.2 mm. The mixture is dried at 120°C for 2 hours before laser cladding is performed to form a cladding layer, resulting in lightweight, high-strength steel. The process conditions are: a spot diameter of 2 mm, a laser power of 1600 W, a scanning speed of 300 mm / min, an argon flow rate of 5 L / min, and an overlap rate of 30%. The metal powder consists of the following mass components: 50 parts nickel powder, 6 parts niobium powder, 1 part graphite powder, and 1 part cerium dioxide. The binder is 10 wt% polyvinyl alcohol. The volume ratio of metal powder to binder is 10:2.

[0095] Comparative Example 3: A process for preparing niobium microalloyed lightweight high-strength steel, comprising the following processes:

[0096] Step (1) is the same as in Example 1;

[0097] (2) Surface treatment:

[0098] Laser cladding involves mixing metal powder with a binder and coating the steel surface with a coating thickness of 0.2 mm. The mixture is dried at 120°C for 2 hours before laser cladding is performed to form a cladding layer, resulting in lightweight, high-strength steel. The process conditions are: a spot diameter of 2 mm, a laser power of 1600 W, a scanning speed of 300 mm / min, an argon flow rate of 5 L / min, and an overlap rate of 30%. The metal powder consists of the following mass components: 50 parts nickel powder, 6 parts niobium powder, 1 part graphite powder, and 1 part cerium dioxide. The binder is 10 wt% polyvinyl alcohol. The volume ratio of metal powder to binder is 10:2.

[0099] Comparative Example 4: A process for preparing niobium microalloyed lightweight high-strength steel, comprising the following processes:

[0100] The process steps are the same as step (1) in Example 1.

[0101] The lightweight high-strength steel includes the following mass composition: C: 1.2%, Mn: 27.5%, Al: 10.7%, Ce: 0.11%, N: 0.0023%, P: 0.008%, S: 0.0012%, and the balance is Fe.

[0102] Experiment: The lightweight high-strength steel obtained in Examples 1-3 and Comparative Examples 1-4 was used to prepare samples, and their properties were tested and the test results were recorded:

[0103] Mechanical properties test: GB / T 228 was used as the reference standard, and a universal tensile testing machine was used to test the room temperature tensile properties of the sample at a tensile rate of 5×10 -4 / s;

[0104] Wear resistance test: Use a micro Vickers hardness tester to test the fiber hardness of the sample, with a holding pressure of 10N and a holding time of 10s;

[0105] Adopting a wear testing machine, taking GCr15 as the counter ring, the friction coefficient of the sample is detected, the rotating speed is 400 r / min, the load is 98-147-95 N, and the wear time is 10-90 min.

[0106] Corrosion resistance test: an electrochemical workstation is adopted to detect the corrosion resistance of the sample in 3.5wt% NaCl solution, the scanning rate is 5mv / s, the frequency is 10 5 ~10 -2 Hz;

[0107] High temperature oxidation resistance test: a comprehensive thermal analyzer is adopted to detect the high temperature oxidation resistance of the sample, the heating rate is 5℃ / min, and the termination temperature is 800℃.

[0108]

[0109] According to the data in the above table, the following conclusions can be clearly obtained:

[0110] The light high-strength steel obtained in examples 1-3 is compared with the light high-strength steel obtained in comparative examples 1-4, and the test results show that,

[0111] Compared with comparative example 1-4, the light high-strength steel obtained in example 1-3 and the steel material in comparative example 1 have higher tensile strength, yield strength, microhardness data and lower friction coefficient self-corrosion current density data. This fully illustrates that the application realizes the improvement of the mechanical properties, wear resistance and corrosion resistance of the steel material and light high-strength steel.

[0112] Compared with the light high-strength steel in example 1, the surface treatment process of the steel material in comparative example 1-3 is different; compared with the steel material in comparative example 1, the composition of the steel material in comparative example 4 is different. The tensile strength, yield strength and microhardness data of the steel material and light high-strength steel obtained in comparative examples 1-4 decrease, and the friction coefficient self-corrosion current density data increases. It can be seen that the setting of the composition of the steel material and its treatment process can promote the comprehensive improvement of its mechanical properties, wear resistance and corrosion resistance.

[0113] It is obvious for those skilled in the art that the application is not limited to the details of the above exemplary embodiments, and the application can be realized in other specific forms without departing from the spirit or essential characteristics of the application. Therefore, the examples should be regarded as exemplary and non-limiting in any aspect, and the scope of the application is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the application.

Claims

1. A process for preparing niobium microalloyed lightweight high-strength steel, characterized by: Including the following processes: The raw materials are melted and poured to form billets; homogenized heat treatment, forging, and rolling are performed to obtain steel; Then nickel plating, annealing, chromizing, nitriding and laser cladding are carried out to obtain lightweight and high-strength steel.

2. The process for preparing a niobium microalloyed lightweight high-strength steel according to claim 1, characterized in that: The steel includes the following mass components: C: 0.8% to 1.4%, Mn: 27% to 28%, Al: 9% to 12%, V: 0.05% to 0.15%, Nb: 0.01% to 0.1%, Ce: 0.05% to 0.15%, N≤0.006%, P≤0.015%, S≤0.006%, and the balance is Fe.

3. The process for preparing niobium microalloyed lightweight high-strength steel according to claim 2, characterized in that: In the mass composition of the steel material, 0.10%≤Nb+V≤0.25%.

4. The process for preparing niobium microalloyed lightweight high-strength steel according to claim 1, characterized in that: The nickel plating process comprises the following steps: placing the steel material in a nickel-containing plating solution and electroplating the steel material to form a nickel layer; The nickel-containing plating solution comprises the following components by mass: 300-320 g / L nickel sulfate hexahydrate, 45-50 g / L nickelous chloride hexahydrate, 27-30 g / L boric acid, 0.3-0.8 g / L sodium lauryl sulfate, 40-60 g / L cerium dioxide, and a pH of 4.0-4.2; The nickel plating process conditions are: current density 1.5 ~ 2.0A / dm 2 , duty cycle 0.4~0.5, frequency 40Hz, temperature 53~57℃, duration 5~10min.

5. The process for preparing niobium microalloyed lightweight high-strength steel according to claim 1, characterized in that: The chromizing process comprises the following steps: embedding the steel in a chromizing agent at 500-610°C, chromizing for 3-5 hours, and forming a chromized layer; The penetrant includes the following components by mass: 50-60 parts of chromium powder, 42-50 parts of aluminum oxide, 10-20 parts of chromium chloride, 1-3 parts of potassium fluoroborate, 1-7 parts of cerium chloride, and 3-5 parts of ammonium chloride.

6. The process for preparing niobium microalloyed lightweight high-strength steel according to claim 1, characterized in that: The nitriding process steps are: introducing pure NH3, keeping the temperature at 245-255°C for 1-2 hours, heating to 445-455°C and keeping the temperature for 3-5 hours, keeping the temperature at 535-545°C for 36-72 hours, cooling to 180-200°C with the furnace, and then taking the furnace out of the furnace for air cooling to form a nitrided layer.

7. The process for preparing niobium microalloyed lightweight high-strength steel according to claim 1, characterized in that: The laser cladding process comprises the following steps: mixing metal powder with an adhesive, applying the mixture to the surface of the steel material, and then performing laser cladding after drying to form a cladding layer.

8. The process for preparing niobium microalloyed lightweight high-strength steel according to claim 7, characterized in that: The metal powder comprises the following components by mass: 50 to 70 parts of nickel powder, 7.7 to 10.7 parts of aluminum powder, 6 to 12 parts of niobium powder, 1 to 6 parts of graphite powder, and 1 to 3 parts of cerium dioxide.

9. The process for preparing niobium microalloyed lightweight high-strength steel according to claim 1, characterized in that: The annealing process conditions are: keeping the temperature at 870-900° C. for 1-3 minutes and water cooling; and performing aging treatment after annealing, the process is: keeping the temperature at 550-650° C. for 10-90 minutes.

10. A niobium microalloyed lightweight high-strength steel prepared according to the preparation process according to any one of claims 1 to 9.

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