CN114016017B - Method for laser cladding copper alloy on cast iron surface and surface structure of explosion-proof impeller - Google Patents

Abstract

The invention relates to a method for laser melting of copper alloy on the surface of cast iron and an explosion-proof impeller surface structure. The method comprises the following steps: carrying out laser cladding on a nickel-chromium-iron alloy transition layer on the surface of the cast iron to form the nickel-chromium-iron alloy transition layer on the surface of the cast iron; and then carrying out laser cladding on the copper alloy functional layer on the nickel-chromium-iron alloy transition layer. The metallurgical bonding property of the workpiece interface obtained by the method is greatly enhanced, and the interface bonding strength is greater than the strength of cast iron. Provides a new process mode for the production of the explosion-proof impeller, greatly reduces the cost and improves the production flexibility compared with the original production mode of integral copper alloy casting.

Description

Method for laser cladding copper alloy on cast iron surface and surface structure of explosion-proof impeller

technical field

The invention belongs to the technical field of laser cladding surface modification, in particular to a method for laser cladding copper alloy on the surface of cast iron and a surface structure of an explosion-proof impeller.

Background technique

The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not necessarily be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person of ordinary skill in the art.

To realize the safe and efficient operation of the blower in a complex environment, the impeller is the key, and when dynamic or static friction occurs between the impeller and other relatively moving parts inside the blower, as well as the hot particles generated after the collision with each other, it will lead to mechanical sparks or high temperature surfaces and other phenomena It is very easy to cause safety accidents such as explosions.

At present, the non-explosion-proof impeller of the blower is generally made of cast iron, while the explosion-proof impeller is mostly made of copper alloy as a whole to avoid the occurrence of sparks caused by collision, which makes the explosion-proof fan expensive and consumes huge resources. However, the laser cladding copper alloy layer on the surface of cast iron has the problem of difficulty in forming, which leads to many defects after forming, and the quality of use is reduced.

SUMMARY OF THE INVENTION

In view of the above problems in the prior art, the purpose of the present invention is to provide a method for laser cladding copper alloy on the surface of cast iron and the surface structure of the explosion-proof impeller.

In order to solve the above technical problems, the technical scheme of the present invention is:

A first aspect, a method for laser cladding copper alloy on cast iron surface, the method is:

Carry out laser cladding of Nichrome transition layer on the surface of cast iron, and form Nichrome transition layer on the surface of cast iron;

Laser cladding of the copper alloy functional layer is then performed on the Nichrome transition layer.

Between the cast iron surface and the copper alloy layer, a Ni-Cr-Fe alloy transition layer is formed by the laser cladding process. The Ni-Cr-Fe alloy plays the role of connecting the cast iron and the copper alloy, compared to the direct laser cladding on the cast iron surface to form the copper alloy layer , which can greatly enhance the metallurgical bonding at the interface of each layer, and the bonding strength of the interface is greater than the strength of the cast iron itself.

Due to the strong repulsion between the atoms of the cast iron and the copper alloy during the crystallization process and the high reflectivity of the copper alloy to the laser, the laser cladding technology is difficult to form the high-reflection copper material, and the high-carbon content cast iron material is easy to crack. , There are problems such as porosity and crack defects at the bonding interface. Through the laser cladding method, the surface structure at the interface of cast iron and nickel-chromium-iron alloy and at the interface of nickel-chromium-iron alloy and copper alloy are uniform and dense, and have no pores and crack defects.

In some embodiments of the present invention, the copper alloy is one of a copper-nickel alloy, a copper-zinc alloy, a copper-tin alloy, and a copper-chromium alloy. The copper alloy has strong wear resistance and can improve the high temperature resistance of the surface of the impeller, and the copper-tin alloy has better spark resistance. Further, it is copper-tin alloy; CuSn15, CuSn10, CuSn12, CuSn20, CuSn30, etc.; preferably CuSn15, CuSn10, CuSn12.

In some embodiments of the present invention, the cast iron includes one of gray cast iron, white cast iron, ductile cast iron, vermicular graphite cast iron, and alloy cast iron. The cast iron is a commonly used impeller material in a blower, and the blower can also be an induced draft fan, a blower or the like.

In some embodiments of the invention, the Inconel 718 is Inconel. The nickel-chromium-iron alloy has good matching with the cast iron of the impeller. The reason for choosing Inconel718 as the transition layer is: Compared with Ni-based alloys such as NiCrBSi, Inconel718 has better wettability with the matrix and copper alloy, the thermal expansion coefficient is between the two, and the microhardness is similar to the two. Therefore, the interface is smooth and smooth, without defects such as cracks and holes, and the interface bonding strength is also high. This solves the problems of warping and shedding caused by poor bonding between copper alloy and cast iron, and at the same time, compared with the direct deposition of copper alloy on cast iron, it makes copper alloy easier to form, and reduces the difficulty of forming the material due to the high reflectivity of copper alloy.

Before the present invention, there is no design method in which the explosion-proof impeller adopts the cast iron surface to prepare the copper alloy, all of which are produced by the method of integral casting of the copper alloy. There is also less research on the preparation of copper alloys on cast iron, because the hard and brittle cast iron itself and the high reflectivity of copper alloys make it difficult to form.

In some embodiments of the present invention, the particle size of the nickel-chromium-iron alloy powder ranges from 50 to 150 μm.

In some embodiments of the present invention, the laser cladding of the copper alloy functional layer is performed using copper alloy powder, and the particle size of the copper alloy powder is between 75 and 150 μm.

In some embodiments of the present invention, the cast iron is preheated before laser cladding is performed on the surface of the cast iron, and the preheating temperature of the cast iron is maintained during the laser cladding process. Further, the temperature of the preheating is 250-350°C.

In some embodiments of the present invention, the conditions for laser cladding are: laser power 1300-1600W, scanning speed 600-1000mm/min, powder feeding rate 14-18g/min, spot diameter 2-3mm, lap rate 35- 40%; further: laser power 1400-1600W, scanning speed 600-1000mm/min, powder feeding rate 15-17g/min, spot diameter 2-3mm, lap rate 36-38%; further: laser power 1500W , The scanning speed is 600～1000mm/min, the powder feeding rate is 16.36g/min, the spot diameter is 2.4mm, and the overlap rate is 37.5%. The laser scanning path is calculated according to the size of the workpiece and the motion relationship, and the program required by the corresponding CNC machine tool is generated at the same time.

In the process of laser cladding, alloy powder is deposited to form a cladding layer. For different substrates and different deposition results, the involved laser cladding process parameters are different, and this application also involves high reflectivity copper alloys Therefore, the selection of laser power, powder feeding rate and scanning speed determines the forming quality of each cladding layer. The selection of appropriate process parameters will help to solve the difficult forming problem caused by the high reflectivity of copper alloys, and realize its high performance in nickel-chromium alloys. Smooth forming of iron surfaces.

In some embodiments of the present invention, slow cooling treatment is performed after laser cladding, the temperature is first kept for 50-150 minutes, and then the temperature is lowered by 10-30° C. every 20 minutes until room temperature. Slow cooling treatment can effectively solve the problem of matrix material cracking during the cladding process.

In the second aspect, the surface structure of the explosion-proof impeller obtained by the above-mentioned method of laser cladding copper alloy on the surface of cast iron is the cast iron layer, the transition layer of nickel-chromium-iron alloy, and the functional layer of copper alloy from the inside to the outside.

In some embodiments of the present invention, the thickness of the Nichrome transition layer is 0.5-1 mm.

In some embodiments of the present invention, the thickness of the copper alloy functional layer is greater than 2 mm; further, it is 2.5-10 mm.

One or more technical solutions of the present invention have the following beneficial effects:

Compared with the existing preparation method for copper alloy modification on the surface of cast iron, the present invention adopts the method of laser cladding, and the method of laser cladding can promote better fusion of cast iron, transition layer and functional layer to form an explosion-proof impeller surface structure, so as to successfully manufacture an explosion-proof impeller using only copper alloy on the surface.

Compared with the existing preparation method for copper alloy modification on the surface of cast iron, the present invention first forms a transition layer of nickel-chromium-iron alloy on the surface of cast iron, and then forms a functional layer of copper alloy, so that the metallurgical bonding at the interface of the workpiece is greatly enhanced, and the interface is greatly enhanced. The bonding strength is greater than the strength of cast iron itself.

In the laser cladding process of the invention, the cast iron matrix does not crack during and after the laser cladding process, and the cladding layer does not warp and fall off.

The method of the invention provides a new technological method for the production of explosion-proof impeller, greatly reduces the cost and improves the flexibility of production compared with the original production method of integral copper alloy casting.

Description of drawings

The accompanying drawings forming a part of the present invention are used to provide further understanding of the present application, and the exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

Figure 1 is an optical microscope photo of the microscopic morphology of the interface between the CuSn15 functional layer and the base ductile iron QT400 in Comparative Example 1. The spherical area in the figure is the pore defect generated at the interface.

2 is an optical microscope photograph of the microscopic topography of the interface between the CuSn15 functional layer and the Inconel 718 transition layer prepared in Example 1.

3 is an optical microscope photograph of the microscopic topography of the interface between the transition layer of Inconel 718 and the base ductile iron QT400 prepared in Example 1.

4 is an optical microscope photo of the microscopic morphology of the interface between the CuSn15 functional layer and the base gray cast iron HT250 in Comparative Example 2.

FIG. 5 is an optical microscope photograph of the microscopic topography of the interface between the transition layer of Inconel 718 prepared in Example 2 and the base gray cast iron HT250.

6 is an optical microscope photograph of the microscopic topography of the interface between the Inconel 718 transition layer and the CuSn15 functional layer prepared in Example 2.

Figure 7 is a comparison diagram of the appearance of the workpiece without the preheating and slow cooling process and the workpiece appearance after the preheating and slow cooling process prepared in Example 2; wherein Figure A is the workpiece prepared without the slow cooling process, Picture B is the workpiece prepared by slow cooling process.

8 is a micrograph of the microscopic topography of the interface between the NiCrBSi transition layer and the base ductile iron QT400 and the CuSn15 functional layer prepared in Comparative Example 3.

FIG. 9 is a comparison diagram of the interfacial bonding strength measured in the tensile test of the tensile members prepared in Comparative Example 1, Example 1 and Comparative Example 3. FIG.

10 is a comparison diagram of the microhardness distribution at the bonding interface measured by the microhardness tester for the mosaic blocks prepared in Comparative Example 1, Example 1 and Comparative Example 3.

FIG. 11 is a geometrical dimension drawing of the impeller in Embodiment 3. FIG.

12 is a comparison diagram of the blower impeller before and after laser cladding prepared in Example 3, wherein A is a picture before laser cladding, and B, C, and D are pictures at different angles after laser cladding, respectively.

Detailed ways

It should be noted that the following detailed description is exemplary and intended to provide further explanation of the invention. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It should be noted that the terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural as well, furthermore, it is to be understood that when the terms "comprising" and/or "including" are used in this specification, it indicates that There are features, steps, operations, devices, components and/or combinations thereof.

Below in conjunction with embodiment, the present invention is further described

The Inconel 718 powder and the CuSn15 powder used in the examples of the present invention are both powders produced by gas atomization.

The equipment used for drying the powder in the embodiment of the present invention is a vacuum dryer.

The model of the optical microscope used to observe the interface morphology in the embodiment of the present invention is SOIF-6XB.

Example 1

1. Use ductile iron QT400 as the base material, use an angle grinder and sandpaper to polish the surface to remove the oxide layer, and use anhydrous ethanol to clean the oil on the surface of the base.

2. The spherical Inconel 718 powder was dried in a vacuum environment at 120°C for 120 minutes for standby use, and the spherical CuSn15 powder was dried in a vacuum environment at 100°C for 60 minutes for standby use. 150μm.

3. Heat the ductile iron base to 300°C and keep the temperature during the laser cladding process to prevent the cast iron base from cracking during the laser cladding process.

4. Laser cladding of Inconel 718 transition layer on the surface of ductile iron substrate. The laser cladding process parameters are laser power 1500W, scanning speed 600mm/min, powder feeding rate 16.36g/min, spot diameter 2.4mm, and lap rate 37.5%. The laser scanning path is linear cyclic scanning.

5. Continue the laser cladding of the CuSn15 functional layer on the Inconel 718 transition layer. The laser cladding process parameters are laser power 1500W, scanning speed 800mm/min, powder feeding rate 16.36g/min, spot diameter 2.4mm, and lap rate 37.5%.

6. After the laser cladding is completed, a slow cooling process is adopted. First, the temperature is kept at 300 °C for 60 minutes, and then the temperature is lowered by 30 °C every 20 minutes until it reaches room temperature.

Comparative Example 1

1. Use ductile iron QT400 as the base material, use an angle grinder and sandpaper to polish the surface to remove the oxide layer, and use anhydrous ethanol to clean the oil on the surface of the base.

2. The spherical CuSn15 powder is dried in a vacuum environment at 100℃ for 60min. The particle size of the standby CuSn15 powder is between 75 and 150μm.

3. Heat the ductile iron base to 300°C and keep the temperature during the laser cladding process to prevent the cast iron base from cracking during the laser cladding process.

4. Laser cladding of CuSn15 functional layer on ductile iron. The laser cladding process parameters are laser power 1500W, scanning speed 800mm/min, powder feeding rate 16.36g/min, spot diameter 2.4mm, and lap rate 37.5%.

5. After the laser cladding is completed, a slow cooling process is adopted. First, the temperature is kept at 300 °C for 60 minutes, and then the temperature is lowered by 30 °C every 20 minutes until it reaches room temperature.

The cross section of the bonding interface is made into a mosaic block, and the interface morphology is observed under a light microscope. The morphology photos obtained in Example 1 are shown in Figure 2 and Figure 3. After magnifying the bonding interface in Figure 1, holes can be found, which is the same as Figure 1. By comparison, it can be found that after the interface of Example 1 is enlarged, it can be seen that the entire interface is smooth and smooth, and no obvious cracks and holes are generated.

Circular graphite can be seen in the ductile iron QT400 in Figure 3.

Example 2

1. Use gray cast iron HT250 as the base material, use an angle grinder and sandpaper to polish the surface to remove the oxide layer, and use anhydrous ethanol to clean the oil on the surface of the base.

2. The spherical Inconel 718 powder was dried in a vacuum environment at 120°C for 120 minutes for standby use, and the spherical CuSn15 powder was dried in a vacuum environment at 100°C for 60 minutes for standby use. 150μm.

3. Heat the gray cast iron base to 300°C and maintain the temperature during the laser cladding process to prevent the cast iron base from cracking during the laser cladding process.

4. Laser cladding of Inconel 718 transition layer on the surface of gray cast iron substrate. The laser cladding process parameters are laser power 1500W, scanning speed 600mm/min, powder feeding rate 16.36g/min, spot diameter 2.4mm, and lap rate 37.5%.

5. Continue the laser cladding of the CuSn15 functional layer on the Inconel 718 transition layer. The laser cladding process parameters are laser power 1500W, scanning speed 600mm/min, powder feeding rate 16.36g/min, spot diameter 2.4mm, and lap rate 37.5%. The laser scanning path is linear cyclic scanning.

6. After the laser cladding is completed, a slow cooling process is adopted. First, the temperature is maintained at 300 °C for 60 minutes, and then the temperature is lowered by 20 °C every 20 minutes until room temperature.

Comparative Example 2

1. Use gray cast iron HT250 as the base material, use an angle grinder and sandpaper to polish the surface to remove the oxide layer, and use anhydrous ethanol to clean the oil on the surface of the base.

2. The CuSn15 powder is dried in a vacuum environment of 100℃ for 60min for use. The particle size of the CuSn15 powder is between 75 and 150μm.

3. Heat the gray cast iron base to 300°C and maintain the temperature during the laser cladding process to prevent the cast iron base from cracking during the laser cladding process.

4. Laser cladding of CuSn15 functional layer on gray cast iron substrate. The laser cladding process parameters are laser power 1500W, scanning speed 600mm/min, powder feeding rate 16.36g/min, spot diameter 2.4mm, and lap rate 37.5%. The laser scanning path is linear cyclic scanning.

5. After the laser cladding is completed, a slow cooling process is adopted. First, the temperature is maintained at 300 °C for 60 minutes, and then the temperature is lowered by 20 °C every 20 minutes until it reaches room temperature.

The cross section of the bonding interface is made into a mosaic block, and the interface morphology is observed under a light microscope. The morphology photos obtained in Example 2 are shown in Figures 5 and 6. Although the interface in Figure 4 is not enlarged, large cracks are still visible. , compared with Figure 4, it can be found that the interface of Example 2 can still see a flat and smooth interface even after magnification, and no obvious cracks and holes are generated.

At the same time, as shown in Figures A and B in Figure 7, the morphology of the workpiece prepared under the preheating and slow cooling process is compared with that of the workpiece prepared without this process, and it can be seen that the preheating and slow cooling process effectively solves the problem. The problem of matrix material cracking during the cladding process is solved.

Comparative Example 3

1. Use ductile iron QT400 as the base material, use an angle grinder and sandpaper to polish the surface to remove the oxide layer, and use anhydrous ethanol to clean the oil on the surface of the base.

2. The spherical NiCrBSi powder was dried in a vacuum environment at 120°C for 120 minutes for standby use, and the spherical CuSn15 powder was dried in a vacuum environment at 100°C for 60 minutes for standby use.

3. Heat the ductile iron base to 300°C and keep the temperature during the laser cladding process to prevent the cast iron base from cracking during the laser cladding process.

4. Laser cladding of NiCrBSi transition layer on the surface of ductile iron substrate. The laser cladding process parameters are laser power 1500W, scanning speed 600mm/min, powder feeding rate 16.36g/min, spot diameter 2.4mm, and lap rate 37.5%. The laser scanning path is linear cyclic scanning.

5. Continue the laser cladding of the CuSn15 functional layer on the NiCrBSi transition layer. The laser cladding process parameters are laser power 1500W, scanning speed 800mm/min, powder feeding rate 16.36g/min, spot diameter 2.4mm, and lap rate 37.5%.

6. After the laser cladding is completed, a slow cooling process is adopted. First, the temperature is kept at 300 °C for 60 minutes, and then the temperature is lowered by 30 °C every 20 minutes until it reaches room temperature.

The cross-section of the bonding interface was made into a mosaic block, and the interface morphology was observed under a light microscope. The morphology photo obtained in Comparative Example 3 is shown in Figure 8. It can be found that cracks and holes appear in the transition layer, and the cracks extend to the vicinity of the interface.

At the same time, as shown in Figure 9, the interface bonding strength obtained in Comparative Example 3 is slightly weaker than that obtained in Comparative Example 1, and far lower than the interface bonding strength obtained in Example 1; as shown in Figure 10, Comparative Example 3 The obtained hardness distribution curve at the bonding interface fluctuates greatly, while the hardness distribution curve at the bonding interface obtained in Example 1 is relatively flat, indicating that using Inconel 718 as the transition layer can have better metallurgical bonding with cast iron and copper alloys.

Example 3

1. Use gray cast iron HT250 blower impeller as the base, use an angle grinder and sandpaper to polish the surface to remove the oxide layer, and use anhydrous ethanol to clean the oil on the surface of the base.

2. The spherical Inconel 718 powder was dried in a vacuum environment at 120°C for 120 min for use, and the spherical CuSn15 powder was dried in a vacuum environment at 100°C for 90 min for use. 150μm.

3. Heat the cast iron base to 300°C and maintain the temperature during the laser cladding process to prevent the cast iron base from cracking during the laser cladding process.

4. Laser cladding of Inconel 718 transition layer on the surface of ductile iron substrate. The laser cladding process parameters are laser power 1500W, scanning speed 600mm/min, powder feeding rate 16.36g/min, spot diameter 2.4mm, and lap rate 37.5%. The laser scanning path is calculated by the corresponding kinematic relationship of the impeller geometric dimensions shown in Figure 11, and the corresponding formula is generated from this.

5. Continue the laser cladding of the CuSn15 functional layer on the Inconel 718 transition layer. The laser cladding process parameters are laser power 1500W, scanning speed 600mm/min, powder feeding rate 16.36g/min, spot diameter 2.4mm, and lap rate 37.5%. The cladding path is calculated by the corresponding kinematic relationship of the impeller geometric dimensions shown in Figure 11, and the corresponding formula is generated from this.

6. After the laser cladding is completed, a slow cooling process is adopted. First, the temperature is kept at 300 °C for 90 minutes, and then the temperature is lowered by 15 °C every 20 minutes until room temperature.

As shown in Figure 12, the blower impeller has a good appearance after cladding, the surface is smooth, and there are no obvious defects.

Example 4

1. Use gray cast iron HT250 as the base material, use an angle grinder and sandpaper to polish the surface to remove the oxide layer, and use anhydrous ethanol to clean the oil on the surface of the base.

2. The spherical Inconel 718 powder was dried in a vacuum environment at 120°C for 120 minutes for standby use, and the spherical CuSn10 powder was dried in a vacuum environment at 100°C for 60 minutes for standby use. 150μm.

3. Heat the gray cast iron base to 300°C and maintain the temperature during the laser cladding process to prevent the cast iron base from cracking during the laser cladding process.

4. Laser cladding of Inconel 718 transition layer on the surface of gray cast iron substrate. The laser cladding process parameters are laser power 1500W, scanning speed 600mm/min, powder feeding rate 16.36g/min, spot diameter 2.4mm, and lap rate 37.5%.

5. Continue the laser cladding of the CuSn10 functional layer on the Inconel 718 transition layer. The laser cladding process parameters are laser power 1500W, scanning speed 600mm/min, powder feeding rate 16.36g/min, spot diameter 2.4mm, and lap rate 37.5%. The laser scanning path is linear cyclic scanning.

6. After the laser cladding is completed, a slow cooling process is adopted. First, the temperature is maintained at 300 °C for 60 minutes, and then the temperature is lowered by 20 °C every 20 minutes until room temperature.

The impeller surface structure obtained in Example 4 has no obvious defects at the bonding interface, but there are some pores on the surface of the functional layer.

Comparative Example 4

1. Use ductile iron QT400 as the base material, use an angle grinder and sandpaper to polish the surface to remove the oxide layer, and use anhydrous ethanol to clean the oil on the surface of the base.

2. The spherical Inconel 718 powder was dried in a vacuum environment at 120°C for 120 minutes for standby use, and the spherical CuSn15 powder was dried in a vacuum environment at 100°C for 60 minutes for standby use. 150μm.

3. Heat the ductile iron base to 300°C and keep the temperature during the laser cladding process to prevent the cast iron base from cracking during the laser cladding process.

4. Laser cladding of Inconel 718 transition layer on the surface of ductile iron substrate. The laser cladding process parameters are laser power 1300W, scanning speed 600mm/min, powder feeding rate 15g/min, spot diameter 2.4mm, and lap rate 37.5%. The laser scanning path is linear cyclic scanning.

5. Continue the laser cladding of the CuSn15 functional layer on the Inconel 718 transition layer. The laser cladding process parameters are laser power 1300W, scanning speed 800mm/min, powder feeding rate 15g/min, spot diameter 2.4mm, and lap rate 37.5%.

6. After the laser cladding is completed, a slow cooling process is adopted. First, the temperature is kept at 300 °C for 60 minutes, and then the temperature is lowered by 30 °C every 20 minutes until it reaches room temperature.

The surface structure of the impeller obtained in Comparative Example 4 shows that there are small pores at the bonding interface, and the surface of the CuSn15 functional layer is relatively rough, with many pores and a small layer thickness.

Comparative Example 5

Compared with Example 1, the powder feeding rate was 19 g/min, and other conditions were the same.

The surface structure of the impeller obtained in Comparative Example 5, the metallurgical bonding between the different layers deteriorated, the bonding strength decreased, and the powder utilization rate decreased.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. a method for laser cladding copper alloy on cast iron surface, is characterized in that: described method is: Carry out laser cladding of Nichrome transition layer on the surface of cast iron, and form Nichrome transition layer on the surface of cast iron; Then, the laser cladding of the copper alloy functional layer is carried out on the transition layer of nickel-chromium iron alloy, and the nickel-chromium iron alloy is Inconel 718; The conditions of laser cladding are: laser power 1300-1600W, scanning speed 600-1000mm/min, powder feeding rate 14-18g/min, spot diameter 2-3mm, lap rate 35-40%. 2 . The method for laser cladding copper alloy on cast iron surface according to claim 1 , wherein the copper alloy is one of copper-nickel alloy, copper-zinc alloy, copper-tin alloy and copper-chromium alloy. 3 . 3. The method for laser cladding copper alloy on cast iron surface as claimed in claim 1, wherein the cast iron comprises one of gray cast iron, white cast iron, ductile cast iron, vermicular graphite cast iron and alloy cast iron. 4 . The method for laser cladding copper alloy on the surface of cast iron according to claim 1 , wherein the particle size of the nickel-chromium-iron alloy powder is between 50 and 150 μm. 5 . 5 . The method for laser cladding copper alloy on the surface of cast iron according to claim 1 , wherein the laser cladding of the copper alloy functional layer is performed by using copper alloy powder, and the particle size of the copper alloy powder is medium. 6 . at 75~150μm. 6. The method for laser cladding copper alloy on the surface of cast iron as claimed in claim 1, characterized in that: the cast iron is preheated before the laser cladding is carried out on the surface of the cast iron, and the preheating temperature of the cast iron is maintained during the laser cladding process. . 7. The method for laser cladding copper alloy on cast iron surface as claimed in claim 1, wherein the conditions of the laser cladding are: laser power 1400-1600W, scanning speed 600-1000mm/min, powder feeding rate 15 -17g/min, spot diameter 2-3mm, lap rate 36-38%. 8. The method for laser cladding copper alloy on cast iron surface as claimed in claim 7, characterized in that: after laser cladding, slow cooling is carried out, firstly keeping the temperature for 50-150min, then reducing the temperature by 10-30°C every 20min until room temperature . 9. The impeller surface structure obtained by the method for laser cladding copper alloy on the surface of cast iron according to any one of claims 1-8, it is characterized in that: the surface structure is successively cast iron layer, nickel-chromium-iron alloy transition layer, Copper alloy functional layer; The thickness of the nickel-chromium-iron alloy transition layer is 0.5-1mm; The thickness of the copper alloy functional layer is greater than 2 mm. 10. The impeller surface structure according to claim 9, wherein the thickness of the copper alloy functional layer is 2.5-10 mm.

Images