CN108677122B - Preparation method of high-hardness aluminized steel - Google Patents
Preparation method of high-hardness aluminized steel Download PDFInfo
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- CN108677122B CN108677122B CN201810530095.6A CN201810530095A CN108677122B CN 108677122 B CN108677122 B CN 108677122B CN 201810530095 A CN201810530095 A CN 201810530095A CN 108677122 B CN108677122 B CN 108677122B
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
- C23C2/12—Aluminium or alloys based thereon
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
- C23C10/02—Pretreatment of the material to be coated
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
- C23C10/18—Solid state diffusion of only metal elements or silicon into metallic material surfaces using liquids, e.g. salt baths, liquid suspensions
- C23C10/20—Solid state diffusion of only metal elements or silicon into metallic material surfaces using liquids, e.g. salt baths, liquid suspensions only one element being diffused
- C23C10/22—Metal melt containing the element to be diffused
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
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Abstract
The invention discloses a preparation method of high-hardness aluminized steel, which comprises the following steps: firstly, carrying out alkali washing oil removal, deionized water washing, acid washing rust removal and deionized water washing on raw material steel, and drying; step two, immersing the raw material steel into high-temperature salt solution for treatment for 10-30 minutes; step three, smelting raw material aluminum by using a crucible until aluminum liquid is formed; step four, sequentially adding copper, zinc, niobium and rare earth elements into the aluminum liquid in the step three, heating to 680-700 ℃, maintaining the temperature and uniformly stirring; and step five, taking out the raw material steel in the step two, immersing the raw material steel into the aluminum liquid in the step four, adding a permeation assistant agent before immersing the raw material steel into the aluminum liquid, performing infiltration treatment for 1-2 minutes, taking out the raw material steel, and naturally cooling. The invention provides a preparation method of aluminized steel which has high surface finish, does not influence the mechanical strength and toughness of a steel substrate and has a aluminized layer on the surface of the steel and higher hardness.
Description
Technical Field
The invention belongs to the field of metal manufacturing, and particularly relates to a preparation method of high-hardness aluminized steel.
Background
Steel is a metal material with the largest industrial use amount due to high strength, high toughness, easy processing and low cost, but the biggest defect of the steel is that the steel is easy to rust and wear, and huge economic loss is caused. Since corrosion and abrasion start from the steel surface, the application of surface engineering techniques to the surface modification of materials has become one of the most active frontier areas of material science.
The aluminized steel is prepared by immersing a workpiece with a purified surface in molten aluminum or aluminum alloy for a certain time to infiltrate the surface of the steel with aluminum liquid, dissolve iron and diffuse and react iron atoms and aluminum atoms with each other. The aluminized steel preparation process in the prior art has the following technical problems:
1. in the prior art, the hot dipping temperature is high, the time is long, and the hot dipping is often needed for more than 5 minutes, so that the crystal grains of the steel raw material grow rapidly, and the mechanical strength and the toughness of the steel raw material are reduced.
2. In the hot-dip aluminizing process, the dissolving speed of iron atoms in the molten aluminum is accelerated, a large amount of sediment is formed, the molten aluminum is polluted, the aluminizing quality is influenced, the service life of the crucible is also shortened, and the production cost is increased.
3. The pretreatment requirement of the steel piece is very strict, the infiltration assisting liquid is unstable, the aluminized steel quality is difficult to control in batch production, and the phenomena of leakage, virtual infiltration, pinholes and peeling are easy to occur on the surface.
4. If the surface smoothness of the steel raw material is low, the surface is easy to be adhered with oxidation slag, and the use is influenced.
5. After the aluminizing treatment of steel, the aluminized layer has low hardness and is easy to damage.
Disclosure of Invention
In order to solve the defects of the prior art, the invention provides a preparation method of aluminized steel which has high surface finish, does not influence the mechanical strength and toughness of a steel substrate and has higher hardness of an aluminized layer on the surface of the steel.
The technical effect to be achieved by the invention is realized by the following scheme:
the preparation method of the high-hardness aluminized steel provided by the invention comprises the following steps:
firstly, carrying out alkali washing oil removal, deionized water washing, acid washing rust removal and deionized water washing on raw material steel, and drying;
step two, mixing sodium chloride, barium nitrate, sodium nitrite and potassium nitrate according to a mass ratio of 1: (0.2-0.3): (1.2-1.5): (0.1-0.2): (0.1-0.2) mixing to prepare mixed salt, placing the mixed salt in a salt bath furnace, preheating to the temperature of 120-200 ℃, introducing low-voltage large-current alternating current into the salt bath furnace through a metal electrode to enable the mixed salt to form salt solution, and immersing the raw material steel in the step one in the salt solution for treatment for 10-30 minutes;
step three, smelting raw material aluminum by using a crucible until aluminum liquid is formed;
step four, sequentially adding copper, zinc, niobium and rare earth elements into the aluminum liquid in the step three, heating to 680-700 ℃, adding the latter metal after the former metal is completely melted, and keeping the temperature and stirring uniformly, wherein the interval between the two metal additions is 10-15 minutes;
and step five, taking out the raw material steel in the step two, immersing the raw material steel into the aluminum liquid in the step four, adding a permeation assistant agent before immersing the raw material steel into the aluminum liquid, performing infiltration treatment for 1-2 minutes, taking out the raw material steel, and naturally cooling.
In the invention, the surface of the raw material steel to be treated is firstly degreased and derusted, so that the surface of the steel is in a clean and smooth state. In the hot dipping process, too long time and too high temperature have bad influence on steel, and the dissolution speed of iron atoms in molten aluminum is accelerated, so that a large amount of sediment is formed, the quality of aluminized steel and the quality of steel are influenced, a crucible for smelting is damaged, and the production cost is increased. In the invention, raw steel is treated by using a mixed salt bath, and the mixed salt bath is heated by using a low-voltage large-current (alternating current) heating mode, so that the operation is more convenient, an external heat source is not needed, and high-frequency current has a certain skin effect, so that the surface of the steel entering the mixed salt bath can be purified to a certain degree, and the surface gloss of the steel is improved.
The copper and zinc elements added into the aluminum liquid can effectively improve the components of the aluminum liquid, so that the aluminizing process is smoother, an aluminum alloy layer is formed on the surface of steel, the protection effect of the aluminized layer is improved, and the added niobium matched with the aluminized layer can form AlNb and CuNb alloys to improve the hardness of the aluminized layer. The rare earth elements are added to improve the alloy composition of the aluminized layer and improve the strength of the aluminized layer, and on the other hand, the rare earth elements can form scum with free Fe atoms generated in the aluminizing process and cannot be attached to the surface of steel in the treatment process.
Further, in the second step, the metal electrode is a stainless steel electrode or a platinum electrode.
Further, in the second step, the voltage of the low-voltage large current is 5-12V, and the alternating current frequency is 500-5000 Hz. The current frequency may be adaptively set according to the heating set time.
Further, in the second step, the temperature of the salt solution is 500-600 ℃. The sodium chloride is used as a main component with a higher salt bath melting point, the temperature of salt solution formed by the mixed salt can be effectively reduced by adding barium nitrate, sodium nitrite and potassium nitrate, and the nitrate is electrified and then has a micro-explosion effect, so that the temperature of the mixed salt can be rapidly increased in a short time.
Further, in the third step, the crucible is a graphite crucible or a zirconia crucible.
Further, in the fourth step, the addition amount of copper is 2-3% of the mass of the aluminum liquid, the addition amount of zinc is 2-3% of the mass of the aluminum liquid, the addition amount of niobium is 0.1-0.2% of the mass of the aluminum liquid, and the addition amount of rare earth elements is 0.005-0.1% of the mass of the aluminum liquid.
Further, in the fourth step, the rare earth element is one or a combination of more of Ce, La, Nd, Er, Gd and Y.
Further, in the fifth step, the permeation promoter is nano graphite powder, and the addition amount of the permeation promoter is 0.005-0.01% of the mass of the aluminum liquid.
Further, in the fifth step, the permeation enhancer is nano-grade graphite powder, and the addition amount of the permeation enhancer is 0.005-0.01% of the mass of the aluminum liquid. The addition of the permeation aid enables the aluminized layer to be smoother and more uniform.
The invention has the following advantages:
1. the molten aluminum in the invention has short hot dipping time, the grain size of the processed steel raw material is hardly influenced, and the mechanical strength and toughness of the steel raw material after the infiltration process are also not influenced.
2. In the preparation process of the aluminized steel, a small amount of dissolved iron atoms can form scum instead of sediment, and the scum can be removed by using a filtering or covering agent without affecting aluminum liquid and affecting a crucible.
3. In the preparation process of the aluminized steel, the pretreatment process of the steel part is simple and easy, the treatment effect is good, and the surface of the steel part has high glossiness and high hardness.
Detailed Description
The present invention will be described in detail with reference to examples.
Example 1
The preparation method of the high-hardness aluminized steel in the embodiment comprises the following steps:
step one, washing Q295 steel with alkali to remove oil, washing with deionized water, washing with acid to remove rust, washing with deionized water, and drying. The alkaline washing solution is 10wt% sodium hydroxide and 3wt% sodium bicarbonate water solution, and the acid washing solution is 2wt% sulfuric acid water solution.
Step two, mixing sodium chloride, barium nitrate, sodium nitrite and potassium nitrate according to a mass ratio of 1: 0.2: 1.4: 0.15: 0.1, mixing to prepare mixed salt, placing the mixed salt in a salt bath furnace, preheating to 150 ℃, introducing low-voltage large-current alternating current into the salt bath furnace through a stainless steel electrode, enabling the mixed salt to form a salt solution with the voltage of 12V and the alternating current frequency of 1000Hz, enabling the temperature of the salt solution to be 550 ℃, and immersing the raw material steel in the step one in the salt solution for treatment for 20 minutes.
And step three, smelting raw material aluminum by using a graphite crucible until aluminum liquid is formed.
And step four, sequentially adding copper, zinc, niobium and rare earth elements into the aluminum liquid in the step three, heating to 680 ℃, adding the latter metal after the former metal is completely melted, adding the two metals at an interval of 10 minutes, and maintaining the temperature and stirring uniformly. Wherein, the addition amount of copper is 2 percent of the mass of the aluminum liquid, the addition amount of zinc is 2 percent of the mass of the aluminum liquid, the addition amount of niobium is 0.1 percent of the mass of the aluminum liquid, and the addition amount of rare earth elements is 0.005 percent of the mass of the aluminum liquid. The rare earth element is Ce.
Step five, taking out the raw material steel in the step two, immersing the raw material steel into the aluminum liquid in the step four, adding permeation assistant agent nano graphite powder before immersing the raw material steel into the aluminum liquid, wherein the nano graphite powder is a commercially available product and has an average particle size of 20nm, performing infiltration treatment for 1 minute, taking out the raw material steel, and naturally cooling.
Example 2
The preparation method of the aluminized steel in the present example is substantially the same as that of example 1, except that: in the second step, the mixing mass ratio of the sodium chloride, the barium nitrate, the sodium nitrite and the potassium nitrate is 1:0.3:1.3:0.2:0.2, and the preheating temperature is 200 ℃.
Example 3
The preparation method of the aluminized steel in the present example is substantially the same as that of example 1, except that: in the second step, the mixing mass ratio of the sodium chloride, the barium nitrate, the sodium nitrite and the potassium nitrate is 1:0.3:1.4:0.11:0.2, and the preheating temperature is 150 ℃.
Example 4
The preparation method of the aluminized steel in the present example is substantially the same as that of example 1, except that: in the second step, the voltage of the low-voltage large current is 6V, and the alternating current frequency is 5000 Hz.
Example 5
The preparation method of the aluminized steel in the present example is substantially the same as that of example 1, except that: in the fourth step, the addition amount of copper is 3% of the mass of the aluminum liquid, the addition amount of zinc is 3% of the mass of the aluminum liquid, the addition amount of niobium is 0.2% of the mass of the aluminum liquid, and the addition amount of rare earth elements is 0.1% of the mass of the aluminum liquid.
Example 6
The preparation method of the aluminized steel in the present example is substantially the same as that of example 1, except that: in the fourth step, the rare earth element is a mixture of La and Nd with the mass ratio of 1: 1.
Example 7
The preparation method of the aluminized steel in the present example is substantially the same as that of example 1, except that: in the fourth step, the rare earth element is Gd.
Example 8
The preparation method of the aluminized steel in the present example is substantially the same as that of example 1, except that: the permeation assistant agent is nano-grade graphite powder, and the addition amount of the permeation assistant agent is 0.01 percent of the mass of the aluminum liquid.
The mechanical strength and the toughness of the aluminized steel prepared by the embodiment of the invention are not affected, and the hardness of the aluminized layer on the surface can reach 400 (measured by Vickers hardness HV 3). The preparation method can be seen that the hot dipping time of the molten aluminum is short, the grain size of the processed steel raw material is hardly influenced, and the mechanical strength and the toughness of the steel raw material after the infiltration process are also not influenced. In the preparation process of the aluminized steel, a small amount of dissolved iron atoms can form scum instead of sediment, and the scum can be removed by using a filtering or covering agent without affecting aluminum liquid and affecting a crucible. In the preparation process of the aluminized steel, the pretreatment process of the steel part is simple and easy, the treatment effect is good, and the surface glossiness of the steel part is high.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the embodiments of the present invention and not for limiting the same, and although the embodiments of the present invention are described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the embodiments of the present invention, and these modifications or equivalent substitutions cannot make the modified technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (9)
1. A preparation method of high-hardness aluminized steel is characterized by comprising the following steps:
firstly, carrying out alkali washing oil removal, deionized water washing, acid washing rust removal and deionized water washing on raw material steel, and drying;
step two, mixing sodium chloride, barium nitrate, sodium nitrite and potassium nitrate according to a mass ratio of 1: (0.2-0.3): (1.2-1.5): (0.1-0.2): (0.1-0.2) mixing to prepare mixed salt, placing the mixed salt in a salt bath furnace, preheating to the temperature of 120-200 ℃, introducing low-voltage large-current alternating current into the salt bath furnace through a metal electrode to enable the mixed salt to form salt solution, and immersing the raw material steel in the step one in the salt solution for treatment for 10-30 minutes;
step three, smelting raw material aluminum by using a crucible until aluminum liquid is formed;
step four, sequentially adding copper, zinc, niobium and rare earth elements into the aluminum liquid in the step three, heating to 680-700 ℃, adding the latter metal after the former metal is completely melted, and keeping the temperature and stirring uniformly, wherein the interval between the two metal additions is 10-15 minutes;
and step five, taking out the raw material steel in the step two, immersing the raw material steel into the aluminum liquid in the step four, adding a permeation assistant agent before immersing the raw material steel into the aluminum liquid, performing infiltration treatment for 1-2 minutes, taking out the raw material steel, and naturally cooling.
2. The method for producing a high-hardness alumetized steel according to claim 1, characterized by: in the second step, the metal electrode is a stainless steel electrode or a platinum electrode.
3. The method for producing a high-hardness alumetized steel according to claim 1, characterized by: in the second step, the voltage of the low-voltage large current is 5-12V, and the alternating current frequency is 500-5000 Hz.
4. The method for producing a high-hardness alumetized steel according to claim 1, characterized by: in the second step, the temperature of the salt solution is 500-600 ℃.
5. The method for producing a high-hardness alumetized steel according to claim 1, characterized by: in the third step, the crucible is a graphite crucible or a zirconia crucible.
6. The method for producing a high-hardness alumetized steel according to claim 1, characterized by: in the fourth step, the addition amount of copper is 2-3% of the mass of the aluminum liquid, the addition amount of zinc is 2-3% of the mass of the aluminum liquid, the addition amount of niobium is 0.1-0.2% of the mass of the aluminum liquid, and the addition amount of rare earth elements is 0.005-0.1% of the mass of the aluminum liquid.
7. The method for producing a high-hardness alumetized steel according to claim 1, characterized by: in the fourth step, the rare earth element is one or a combination of more of Ce, La, Nd, Er, Gd and Y.
8. The method for producing a high-hardness alumetized steel according to claim 1, characterized by: in the fifth step, the permeation-assistant agent is nano graphite powder, and the addition amount of the permeation-assistant agent is 0.005-0.01 percent of the mass of the aluminum liquid.
9. The method for producing a high-hardness alumetized steel according to claim 1, characterized by: in the fifth step, the permeation enhancer is nano-grade graphite powder, and the addition amount of the permeation enhancer is 0.005-0.01% of the mass of the aluminum liquid.
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| CN101660116A (en) * | 2009-09-04 | 2010-03-03 | 高远新 | Hot dipping alumetizing process of steel radiator |
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