阅读说明：本技术 一种高耐蚀亚微-纳米晶Fe基激光熔覆层及其制备方法 (High-corrosion-resistance submicron-nanocrystalline Fe-based laser cladding layer and preparation method thereof ) 是由 张辉 饶伟锋 肖光春 赵伟 白雪 于 2020-07-17 设计创作，主要内容包括：本发明公开了一种高耐蚀亚微-纳米晶Fe基激光熔覆层及其制备方法,本发明高耐蚀亚微-纳米晶Fe基激光熔覆层制备方法,在基材上采用激光熔覆的方法制备熔覆层,激光熔覆采用的合金粉末由还原铁粉、钒铁粉及石墨粉组成,钒铁粉采用FeV50,合金粉末中钒碳原子摩尔比为1：1.5-1：1.7。本发明制得的高耐蚀亚微-纳米晶Fe基激光熔覆层中碳化钒的纳米化以及熔覆层Fe基体的亚微米化,使得熔覆层耐蚀性显著提升。(The invention discloses a high corrosion resistance submicron-nanocrystalline Fe-based laser cladding layer and a preparation method thereof, the preparation method of the high corrosion resistance submicron-nanocrystalline Fe-based laser cladding layer is characterized in that a laser cladding method is adopted on a base material to prepare the cladding layer, alloy powder adopted by laser cladding consists of reduced iron powder, ferrovanadium powder and graphite powder, the ferrovanadium powder adopts FeV50, and the molar ratio of vanadium to carbon atoms in the alloy powder is 1: 1.5-1: 1.7. the nanocrystallization of vanadium carbide and the submicron of the Fe matrix of the cladding layer in the high-corrosion-resistance submicron-nanocrystalline Fe-based laser cladding layer prepared by the method obviously improve the corrosion resistance of the cladding layer.)

1. A preparation method of a high corrosion resistance submicron-nanocrystalline Fe-based laser cladding layer is characterized by comprising the following steps: preparing a cladding layer on a base material by adopting a laser cladding method, wherein alloy powder adopted by laser cladding consists of reduced iron powder, ferrovanadium powder and graphite powder, the ferrovanadium powder adopts FeV50, and the molar ratio of vanadium to carbon atoms in the alloy powder is 1: 1.5-1: 1.7.

2. the method for preparing the high corrosion resistance submicron-nanocrystalline Fe-based laser cladding layer according to claim 1, characterized in that: the adopted alloy powder is gradient-particle-size alloy powder, wherein the particle size range of reduced iron powder is 75-150 mu m, the average particle size is 110 mu m, the particle size range of ferrovanadium powder is 23-38 mu m, the average particle size is 30 mu m, the particle size range of graphite powder is 8-12 mu m, and the average particle size is 10 mu m; the alloy powder comprises the following components: 61.54 wt.% of reduced iron powder, 32.36 wt.% of ferrovanadium powder, FeV50, and 6.10 wt.% of graphite powder.

3. The method for preparing the high corrosion resistance submicron-nanocrystalline Fe-based laser cladding layer according to claim 2, characterized in that: firstly, mixing alloy powder in a V-shaped powder mixer for 2 hours; and presetting the mixed alloy powder on the surface of the substrate by using water glass as a binder to obtain a preset layer, wherein the thickness of the preset layer is 0.4-0.6 mm.

4. The method for preparing the high corrosion resistance submicron-nanocrystalline Fe-based laser cladding layer according to claim 2, characterized in that: and cladding the preset layer by adopting pulse laser, wherein the duty ratio of the pulse laser is 90-95%, and the pulse frequency of the laser is 4400-4600 Hz.

5. The method for preparing the high corrosion resistance submicron-nanocrystalline Fe-based laser cladding layer according to claim 4, characterized in that: the laser power is 800W-1000W, the diameter of a light spot is 2.0mm, the laser scanning speed is 10mm/s-15mm/s, and the flow of protective argon gas sprayed to a cladding point is 10L/min.

6. A high corrosion resistance submicron-nanocrystalline Fe-based laser cladding layer is characterized in that: the high corrosion resistance submicron-nanocrystalline Fe-based laser cladding layer prepared by the method of any one of claims 1-5.

Technical Field

The invention relates to the technical field of laser cladding, in particular to a high-corrosion-resistance submicron-nanocrystalline Fe-based laser cladding layer and a preparation method thereof.

Background

The laser cladding technology is characterized in that a high-energy laser beam is used for melting an added material on the surface of a base material to form a high-performance cladding layer which is in metallurgical bonding with the base material. The laser cladding complete equipment is very expensive, the cost of cladding materials becomes a problem to be considered in a key way, and the preparation of a cladding layer with low price and excellent performance becomes a key point for the wide application of the technology. The Fe-based cladding powder has obvious price advantage, but the corrosion resistance of the Fe-based cladding powder needs to be improved. The VC reinforced Fe-based composite laser cladding layer has better wear resistance, but the corrosion resistance is relatively poor. The corrosion potential of the Fe matrix can be increased by alloying, but this results in an increase in the powder cost. The corrosion resistance and the toughness of the VC/Fe cladding layer can be obviously improved by regulating the particle size of the powder and refining the cladding layer structure by the cladding process.

The 'in-situ autogenous TiC-VC reinforced Fe-based laser cladding layer structure refinement and performance research' of Qilu university Kaiki discloses cladding alloy powder, which consists of 26.00 wt.% of ferrotitanium powder, 16.57 wt.% of ferrovanadium powder, 6.23 wt.% of graphite and 51.20 wt.% of reduced iron powder. When the particle size of graphite is reduced, the particle size of carbide obtained by in-situ self-generation reaction is reduced, but aggregation phenomenon is easy to occur, so that the refinement of the cladding layer matrix grains is influenced, and the average grain size can only reach 1.79 mu m.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: provides a high corrosion resistance submicron-nanocrystalline Fe-based laser cladding layer and a preparation method thereof so as to obtain the high corrosion resistance Fe-based composite cladding layer.

In order to solve the technical problems, the preparation method of the high-corrosion-resistance submicron-nanocrystalline Fe-based laser cladding layer comprises the steps of preparing the cladding layer on a base material by adopting a laser cladding method, wherein alloy powder adopted by laser cladding consists of reduced iron powder, ferrovanadium powder and graphite powder, the ferrovanadium powder adopts FeV50, and the molar ratio of vanadium to carbon atoms in the alloy powder is 1: 1.5-1: 1.7.

preferably, the alloy powder used is a gradient-particle-size alloy powder, wherein the reduced iron powder has a particle size in the range of 75 μm to 150 μm and an average particle size of 110 μm, the ferrovanadium powder has a particle size in the range of 23 μm to 38 μm and an average particle size of 30 μm, the graphite powder has a particle size in the range of 8 μm to 12 μm and an average particle size of 10 μm, and the alloy powder consists of: 61.54 wt.% of reduced iron powder, 32.36 wt.% of ferrovanadium powder, FeV50, and 6.10 wt.% of graphite powder.

Preferably, the alloy powder is mixed for 2 hours in a V-shaped powder mixer; and presetting the mixed alloy powder on the surface of the substrate by using water glass as a binder to obtain a preset layer, wherein the thickness of the preset layer is 0.4-0.6 mm.

Preferably, pulse laser is adopted to clad the preset layer, the duty ratio of the pulse laser is 90% -95%, and the pulse frequency of the laser is 4400Hz-4600 Hz.

Preferably, the laser power is 800W-1000W, the spot diameter is 2.0mm, the laser scanning speed is 10mm/s-15mm/s, and the flow of protective argon gas sprayed to the cladding point is 10L/min.

The high corrosion resistance submicron-nanocrystalline Fe-based laser cladding layer is prepared by adopting any one of the preparation methods of the high corrosion resistance submicron-nanocrystalline Fe-based laser cladding layer.

The invention has the beneficial effects that: the high corrosion resistance submicron-nanocrystalline Fe-based laser cladding layer prepared by the invention has the advantages that the corrosion resistance of the cladding layer is obviously improved due to the nanocrystallization of vanadium carbide in the cladding layer and the submicron of a Fe matrix of the cladding layer. Particularly, gradient grain diameter alloy powder is adopted, pulse laser is used for cladding, under the condition of specific laser energy, more than 95% of in-situ self-generated vanadium carbide in a cladding layer can reach the nanometer scale, and the average grain diameter size of a cladding layer Fe matrix reaches the submicron superfine crystal scale; the hardness of the obtained cladding layer is improved by more than 600HV0.2 compared with that of low-carbon steel; the corrosion resistance of the obtained cladding layer is about 21 times of that of the mild steel base material.

Drawings

FIG. 1 is an optical microscopic topography image of a cladding layer obtained in the present embodiment;

FIG. 2 is a secondary electron topography image of a cladding layer scanning electron microscope obtained by the embodiment of the present invention;

FIG. 3 is a bright field image of a transmission electron microscope of a cladding layer obtained according to an embodiment of the present invention;

FIG. 4 is a high resolution image of a transmission electron microscope of a cladding layer obtained according to an embodiment of the present invention;

FIG. 5 is a cross-sectional microhardness profile of a cladding layer and a mild steel substrate obtained in accordance with an embodiment of the present invention;

FIG. 6 is a zeta potential polarization curve of the clad layer and the low carbon steel substrate in a 3.5 wt.% NaCl solution according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

The cladding layer was prepared according to the following method in this specific example:

preparing a cladding layer on a base material by adopting a laser cladding method, wherein the laser cladding method adopts alloy powder comprising the following components: 61.54 wt.% reduced iron powder, 32.36 wt.% ferrovanadium powder (FeV50), 6.10 wt.% graphite powder; the molar ratio of vanadium to carbon atoms is 1: 1.6.

The alloy powder reduced iron powder has a particle size range of 75-150 μm and an average particle size of 110 μm, the ferrovanadium powder has a particle size range of 23-38 μm and an average particle size of 30 μm, and the graphite powder has a particle size range of 8-12 μm and an average particle size of 10 μm. Firstly, mixing alloy powder in a V-shaped powder mixer for 2 hours; and then the mixed alloy powder is preset on the surface of the base material by using water glass as a binder, and the thickness of the prefabricated layer is 0.5 mm.

Preparing a cladding layer on a low-carbon steel base material by adopting a laser cladding method, wherein the laser cladding process comprises the following steps:

pulse wave laser is adopted, the laser power is 850W, the laser spot diameter is 2.0mm, the laser duty ratio is 95%, the laser pulse frequency is 4500Hz, the laser scanning speed is 12mm/s, and the flow of argon gas sprayed to a cladding point is 10L/min.

The structure and performance of the cladding layer obtained in the present embodiment are shown in fig. 1 to 6. FIG. 1 is an optical microscopic morphology image of the cladding layer obtained in the present embodiment, which shows that the cladding layer is lath martensite structure, and the analyzed average grain size of the Fe matrix of the cladding layer is 0.90 μm. FIG. 2 is a scanning electron microscope secondary electron morphology image of the cladding layer, and through analysis, the average grain size of carbide is 53nm, and more than 95% of in-situ self-generated vanadium carbide in the cladding layer reaches the nanometer scale. FIGS. 3 and 4 are a bright field image and a high resolution lattice image of a transmission electron microscope, respectively, of a cladding layer, and it can be determined that nano-carbides in situ and obtained by self-generation in the cladding layer are V₆C₅. FIG. 5 is a cross-sectional microhardness distribution curve of the cladding layer and the low carbon steel substrate, the average microhardness of the cladding layer is 770HV0.2, and the average microhardness of the low carbon steel substrate is 165HV 0.2. FIG. 6 shows the% of the clad layer and the low carbon steel substrate at 3.5wt. -%Potentiodynamic polarization curves measured in NaCl solution. Table 1 shows the results of the polarization curve fitting, and it is known from the corrosion rate that the corrosion resistance of the obtained cladding layer is 21.6 times that of the mild steel substrate.

TABLE 1 polarization curve fitting results of cladding and low carbon steel

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.