CN107937911B - Laser cladding wear-resistant and impact-resistant coating method on cast steel surface - Google Patents

Abstract

The invention discloses a laser cladding wear-resistant and impact-resistant coating method on the surface of cast steel. The surface is polished with sandpaper for roughening treatment, and then the oil stain is cleaned with acetone for use; (3) The cast steel is pre-heated at 400-500 °C (4) The surface of the pre-heated cast steel is laser-melted; (5) After the laser melting treatment is completed, coaxial powder feeding laser cladding metal alloy primer layer is carried out on the formed laser melting layer; (6) Coaxial laser cladding is performed again on the formed metal alloy layer Powder feeding laser cladding metal alloy wear-resistant and impact-resistant layer.

Description

Laser cladding wear-resistant and impact-resistant coating method on cast steel surface

technical field

The invention belongs to the field of laser processing and relates to a method for laser cladding a wear-resistant and impact-resistant coating on the surface of cast steel.

Background technique

Cast steel is a general term for iron-based alloys used to produce castings that do not undergo eutectic transformation during solidification, in which carbon is the main element, and the content is between 0 and 2%. According to the carbon content in cast steel, cast steel can be divided into: low carbon steel, medium carbon steel and high carbon steel; according to the content of alloy elements in cast steel, cast steel can be divided into: casting Low alloy steel, cast medium alloy steel and cast high alloy steel. In addition to the above types, it also includes cast special steel, such as cast stainless steel, cast wear-resistant steel and cast heat-resistant steel. At present, cast steel materials are widely used in heavy industries such as machining, automobiles, ships, and petrochemicals because of their excellent performance. However, in the working environment of the above fields, the cast steel parts used for a long time are vulnerable to different degrees of impact and wear damage, and the service life is shortened sharply, resulting in a large amount of energy consumption, pollution and waste of resources.

In order to improve the wear resistance of steel castings, the working surface of steel castings is strengthened. At present, ordinary quenching and induction quenching are the main surface treatment methods, and some researchers also use laser quenching technology to strengthen the working surface properties of steel castings. However, since the quenching process cannot change the essential properties of the matrix material, the improvement in wear resistance is limited. The use of laser cladding technology to prepare metal alloy coatings on the surface of steel castings can realize the coating of high-performance materials on the surface of original materials, thereby greatly improving the wear resistance of steel castings. However, since cast steel may have many pores and slag inclusions in the casting process, a large number of defects will be generated in the metal alloy coating during the laser cladding process, making it difficult to form a good metallurgical bond between the coating and the cast steel substrate, reducing the The wear and impact resistance of the coating.

Contents of the invention

The technical solution of the present invention: In order to solve the problem of the degradation of the quality of the cladding layer caused by the pores and slag inclusion defects in the cast steel matrix during the laser cladding process of the cast steel material, a laser cladding wear-resistant laser cladding on the steel surface is provided. The impact-resistant coating method realizes the preparation of a high wear-resistant and impact-resistant coating without pores and slag inclusions.

Technical solution of the present invention: a method for laser cladding a wear-resistant and impact-resistant coating on the surface of cast steel, comprising the following steps:

Step 1. Weigh the metal alloy powder and dry it in vacuum for use in subsequent laser cladding;

Step 2, polishing the cast steel surface with sandpaper for roughening treatment, and then cleaning the oil stain with acetone for later use;

Step 3. Preheating the cast steel that has been degreased and rusted to prepare for laser melting;

Step 4. Perform high-power laser melting treatment on the surface of the preheated cast steel to form a laser fused layer to eliminate defects and pores on the cast steel surface;

Step 5. Laser cladding treatment is performed on the surface of the laser fused layer formed by cast steel. Argon is used as the protective gas. The cladding powder is made of metal alloy powder with good toughness and strong wettability. The metal alloy powder is sent through the coaxial powder method and use argon as the powder carrier gas to blow to the surface of the cast steel laser melting layer, and laser cladding metal alloy primer on the formed laser melting layer, which is mainly used as cast steel and metal alloy wear resistance and impact resistance The connecting layer of the layer makes the composite coating and the cast steel surface form a good combination without pores and cracks;

Step 6: Carry out laser cladding treatment on the surface of the metal alloy base layer formed by cast steel, argon gas is used as the protective gas, and the cladding powder is made of metal alloy powder with good wear resistance and impact resistance through the coaxial powder feeding method and using argon gas As a powder-carrying gas, it is blown to the surface of the cast steel metal alloy primer layer, and the laser cladding metal alloy wear-resistant and impact-resistant layer is formed on the formed metal alloy primer layer.

Further, the step 1 further includes: drying the weighed powder in a vacuum oven at 80-90° C. for 90-120 minutes.

Further, said step three further includes:

Preheating the cast steel at 400-500°C;

Further, said step four further includes:

The formed fused layer is 0.3-0.5mm deep, and the fused layer is uniform without defects and cracks;

Further, said step five further includes:

The thickness of the formed metal alloy primer layer is 0.3-0.5mm;

Further, said step five further includes:

The chemical composition (mass percentage of each element) of the metal alloy powder used in the bottom layer is: C: 0.02% ~ 0.03%, Si: 0.1% ~ 0.14%, Mn: 0.4% ~ 0.46%, Cr: 15.5% ~ 16.5% , Co: 2.0% ~ 2.8% Mo: 15.5% ~ 16.5%, W: 3.8% ~ 4.6%, Nb: 0.31% ~ 0.37%, Fe: 0.7% ~ 0.8%, Ni: the balance;

Further, said step six further includes:

The formed metal alloy wear-resistant and impact-resistant layer has a thickness of 0.8-1.0mm;

Further, said step six further includes:

The chemical composition (mass percentage of each element) of the metal alloy powder used in the wear-resistant and impact-resistant layer is: C: 0.30% ~ 0.34%, Si: 3.5% ~ 4.3%, Cr: 10.5% ~ 11.5%, B: 2.0% ～2.6%, Fe: 10.0%～11.0%, Ni: balance;

Further, in step 4, the laser power is 2000-3500W, the scanning rate is 200-350mm/min, and the spot diameter is 4-6mm;

Further, in step five, the laser power is 1500-2500W, the scanning rate is 200-350mm/min, the powder feeding rate is 3-5g/min, the spot diameter is 2-4mm, and the protective gas flow rate is 6-10l/min;

Further, in Step 6, the laser power is 1800-2600W, the scanning rate is 250-400mm/min, the powder feeding rate is 5-8g/min, the spot diameter is 2-4mm, and the protective gas flow rate is 8-15l/min.

The advantage of the present invention compared with prior art is:

(1) During the laser melting process, the laser can melt and re-solidify the surface of the steel casting. During this process, the defects such as casting pores and slag inclusions on the surface of the cast steel will be eliminated, thereby effectively reducing the laser cladding metal alloy. The defects in the bonding area between the coating and the substrate make a good metallurgical bond between the cast steel substrate and the metal alloy primer;

(2) The metal alloy base layer formed by laser cladding is mainly made of metal alloy powder with good toughness and strong wettability and spreadability. It is the connecting layer between cast steel and metal alloy wear-resistant and impact-resistant layer. It has good toughness and wettability, and a metallurgical bonding zone without porosity and cracks is formed between the cast steel and the metal alloy primer, which proves that the cast steel substrate and the metal alloy primer have a good bonding effect.

(3) The metal alloy wear-resistant and impact-resistant layer formed by laser cladding is mainly made of metal alloy powder with wear-resistant and impact-resistant properties. Due to the good wear-reducing, wear-resistant and impact-resistant properties of the alloy powder, relevant experiments have proved that the formed The metal alloy layer has good wear-resistance and impact-resistance properties.

Description of drawings

Fig. 1 is a process flow diagram of the method of the present invention;

Fig. 2 is the metallographic picture of the laser cladding wear-resistant and impact-resistant coating on the surface of 42CrMo cast steel in embodiment 1;

Fig. 3 is the comparison chart of wear rate under the different surface treatment mode conditions of 42CrMo cast steel in embodiment 1;

Fig. 4 is the friction coefficient contrast chart under the different surface treatment mode conditions of 42CrMo cast steel in embodiment 1;

Fig. 5 is the average impact energy contrast figure under the different surface treatment mode conditions of 42CrMo cast steel in embodiment 1;

Fig. 6 is a graph showing microhardness curves of the laser cladding wear-resistant and impact-resistant coating on 42CrMo cast steel in Example 1 at room temperature and after tempering at a high temperature of 500°C.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. But the following embodiments are only limited to explain the present invention, and the protection scope of the present invention should include the entire content of the claims, not only limited to the present embodiment.

As shown in Figure 1, the specific implementation steps of a laser cladding wear-resistant and impact-resistant coating method on the surface of cast steel of the present invention are as follows:

Step 1, weighing the metal alloy powder and drying it in a vacuum oven at 80-90°C for 90-120 minutes;

Step 2, polishing the surface of the cast steel part to be treated with sandpaper for roughening treatment, and then cleaning the oil stain with acetone for use;

Step 3: Preheat the cast steel that has been degreased and rusted at 400-500°C to prepare for laser melting;

Step 4. Perform high-power laser melting treatment on the surface of the preheated cast steel to form a laser fused layer to eliminate defects and pores on the cast steel surface;

The process parameters used are: laser power 2000-3500W, scanning speed 200-350mm/min, spot diameter 4-6mm, the depth of the formed fused layer is 0.3-0.5mm, and the fused layer is uniform without defects and cracks;

Step 5. Laser cladding treatment is performed on the surface of the laser fused layer formed by cast steel. Argon gas is used as a protective gas. The cladding powder is made of metal alloy powder with good toughness and strong wettability and spreadability. The powder is fed through the coaxial powder method. And use argon as the carrier gas to blow it to the surface of the cast steel laser melting layer, and laser cladding the metal alloy primer layer on the formed laser melting layer, which is mainly used as the wear-resistant and impact-resistant layer of cast steel and metal alloy Connecting layer, so that the composite coating and the cast steel surface form a good combination without pores and cracks;

The process parameters used are: laser cladding process parameters are: laser power 1500~2500W, scanning speed 200~350mm/min, powder feeding rate 3~5g/min, spot diameter 2~4mm, protective gas flow 6~10l/min , the thickness of the formed metal alloy primer layer is 0.3-0.5mm; the chemical composition (mass percentage of each element) of the metal alloy powder used in the primer layer is: C: 0.02%-0.03%, Si: 0.1%-0.14%, Mn: 0.4% to 0.46%, Cr: 15.5% to 16.5%, Co: 2.0% to 2.8%, Mo: 15.5% to 16.5%, W: 3.8% to 4.6%, Nb: 0.31% to 0.37%, Fe: 0.7%～0.8%, Ni: balance;

Step 6. Laser cladding treatment is performed on the surface of the metal alloy base layer formed by cast steel. Argon gas is used as the protective gas. The cladding powder is made of metal alloy powder with good wear resistance and impact resistance. The powder is fed through the coaxial powder method and used The argon gas is blown to the surface of the cast steel metal alloy primer layer as a carrier gas, and the metal alloy wear-resistant and impact-resistant layer is laser cladding on the formed metal alloy primer layer.

The process parameters used are: laser cladding process parameters are: laser power 1800~2600W, scanning speed 250~400mm/min, powder feeding rate 5~8g/min, spot diameter 2~4mm, protective gas flow 8~15l/min , the thickness of the formed metal alloy wear-resistant and impact-resistant layer is 0.8-1.0mm;

The chemical composition (mass percentage of each element) of the metal alloy powder used in the wear-resistant and impact-resistant layer is: C: 0.30% ~ 0.34%, Si: 3.5% ~ 4.3%, Cr: 10.5% ~ 11.5%, B: 2.0% ～2.6%, Fe: 10.0%～11.0%, Ni: balance;

Example 1

In this embodiment, cast steel ZG 42CrMo is used as the matrix, and the base layer material is nickel-based alloy powder. The chemical composition (mass percentage of each element) is: C:0.02%, Si:0.1%, Mn:0.4%, Cr:15.5%, Co: 2.0%, Mo: 15.5%, W: 3.8%, Nb: 0.31%, Fe: 0.7%, Ni: balance; the wear-resistant and impact-resistant layer material is iron-based alloy powder, chemical composition (mass percentage of each element) For: C: 0.30%, Si: 3.5%, Cr: 10.5%, B: 2.0%, Fe: 10.0%, Ni: balance;

The specific implementation steps are as follows:

(1) After weighing the nickel-based alloy powder and the iron-based alloy powder, dry them in a vacuum oven at 80°C for 90 minutes;

(2) Grinding the ZG 42CrMo surface to be treated with sandpaper for roughening treatment, and then cleaning the oil stain with acetone for later use;

(3) Preheat ZG 42CrMo at 400°C for 1 hour;

(4) Perform laser melting treatment on the preheated ZG 42CrMo, wherein the laser melting process parameters are: laser power 2000W, scanning rate 200mm/min, spot diameter 5mm, and the thickness of the formed laser melting layer is 0.4mm , the fused layer is uniform without defects and cracks;

(5) After the laser melting treatment is completed, the coaxial powder feeding laser cladding nickel-based alloy primer layer is carried out on the formed laser melting layer. The laser cladding process parameters are: laser power 1500W, scanning speed 200mm/min , the powder feeding rate is 4g/min, the spot diameter is 2mm, the protective gas and powder carrier gas are both argon, and the protective gas flow rate is 6l/min, and the thickness of the formed nickel-based alloy primer layer is 0.4mm;

(6) Carry out coaxial powder-feeding laser cladding on the formed nickel-based alloy primer layer again. The wear-resistant and impact-resistant layer of iron-based alloy is carried out. The powder rate is 7g/min, the spot diameter is 4mm, the protective gas and powder carrier gas are both argon, and the protective gas flow rate is 15l/min, the thickness of the wear-resistant and impact-resistant layer of the metal alloy formed is 0.9mm, and the final laser cladding The coating has no pores and cracks, is well combined with the surface of cast steel ZG42CrMo, and has no defects. The wear resistance test proves that the wear rate of cast steel ZG42CrMo after laser cladding treatment is significantly lower than that of laser quenched and untreated cast steel ZG 42CrMo , the friction coefficient is significantly reduced, the impact energy is increased, and its wear resistance and impact resistance are significantly improved.

Example 2

In this embodiment, cast steel ZG 40Cr is used as the substrate, and the base layer material is nickel-based alloy powder. The chemical composition (mass percentage of each element) is: C:0.025%, Si:0.12%, Mn:0.43%, Cr:16%, Co: 2.4%, Mo: 16%, W: 4.2%, Nb: 0.34%, Fe: 0.75%, Ni: balance; the wear-resistant and impact-resistant layer material is nickel-based alloy powder, chemical composition (mass percentage of each element) For: C: 0.32%, Si: 3.9%, Cr: 11, B: 2.3%, Fe: 10.5%, Ni: balance; the specific implementation steps are as follows:

(1) After weighing the nickel-based alloy powder and the iron-based alloy powder, dry them in a vacuum oven at 85°C for 100 minutes;

(2) Grinding the surface of ZG 40Cr to be treated with sandpaper for roughening treatment, and then cleaning the oil stain with acetone for later use;

(3) Preheat ZG 40Cr at 450°C for 1 hour;

(4) Perform laser melting treatment on the preheated ZG 35SiMn, wherein the laser melting process parameters are: laser power 2500W, scanning speed 250mm/min, spot diameter 4mm, and the thickness of the formed laser melting layer is 0.5mm , the fused layer is uniform without defects and cracks;

(5) After the laser melting treatment is completed, the coaxial powder feeding laser cladding nickel-based alloy primer layer is carried out on the formed laser melting layer. The laser cladding process parameters are: laser power 2500W, scanning speed 350mm/min , the powder feeding rate is 5g/min, the spot diameter is 3mm, the protective gas and the carrier gas are both argon, and the flow rate of the protective gas is 8l/min, and the thickness of the formed nickel-based alloy primer layer is 0.5mm;

(6) Carry out coaxial powder-feeding laser cladding on the formed nickel-based alloy primer layer again, the wear-resistant and impact-resistant layer of iron-based alloy, the laser cladding process parameters are: laser power 2200W, scanning speed 350mm/min, send The powder rate is 5g/min, the spot diameter is 2mm, the protective gas and powder carrier gas are both argon, and the protective gas flow rate is 10l/min, the thickness of the formed metal alloy wear-resistant and impact-resistant layer is 0.8mm, and the final laser cladding The coating has no pores and cracks, is well combined with the surface of cast steel ZG 40Cr, and has no defects. The test results of wear resistance and impact resistance are similar to those of Example 1, and the wear resistance and impact resistance properties are significantly improved.

Example 3

In this embodiment, cast steel ZG 35SiMn is used as the substrate, and the base layer material is nickel-based alloy powder. The chemical composition (mass percentage of each element) is: C:0.03%, Si:0.14%, Mn:0.46%, Cr:16.5%, Co: 2.8%, Mo: 16.5%, W: 4.6%, Nb: 0.37%, Fe: 0.8%, Ni: balance; the wear-resistant and impact-resistant layer material is nickel-based alloy powder, chemical composition (mass percentage of each element) For: C: 0.34%, Si: 4.3%, Cr: 11.5%, B: 2.6%, Fe: 11.0%, Ni: balance; concrete implementation steps are as follows:

(1) Dry the nickel-based alloy powder and the iron-based alloy powder in a vacuum oven at 90°C for 120 minutes after weighing;

(2) Grinding the surface of ZG 35SiMn to be treated with sandpaper for roughening treatment, and then cleaning the oil stain with acetone for later use;

(3) Preheat ZG 35SiMn at 500°C for 1 hour;

(4) Perform laser melting treatment on the preheated ZG 35SiMn, wherein the laser melting process parameters are: laser power 3500W, scanning speed 350mm/min, spot diameter 6mm, and the thickness of the formed laser melting layer is 0.3mm , the fused layer is uniform without defects and cracks;

(5) After the laser melting treatment is completed, the coaxial powder feeding laser cladding nickel-based alloy primer layer is carried out on the formed laser melting layer. The laser cladding process parameters are: laser power 1700W, scanning speed 300mm/min , the powder feeding rate is 3g/min, the spot diameter is 2mm, the shielding gas and the carrier gas are both argon, and the flow rate of the shielding gas is 6l/min, and the thickness of the formed nickel-based alloy primer layer is 0.3mm;

(6) Coaxial powder feeding laser cladding of iron-based alloy wear-resistant and impact-resistant layer is carried out again on the formed nickel-based alloy primer layer. The laser power is 1800W, the scanning rate is 250mm/min, the powder feeding rate is 8g/min, and the spot The diameter is 2mm, the protective gas and powder carrier gas are both argon, and the protective gas flow rate is 8l/min. The thickness of the wear-resistant and impact-resistant layer of the metal alloy formed is 1.0mm. The final laser cladding coating has no pores and cracks. The surface of the cast steel ZG 35SiMn is well bonded and no defects are generated. The test results of wear resistance and impact resistance are similar to those of Example 1, and the wear resistance and impact resistance properties are significantly improved.

As shown in Figure 2, the wear-resistant composite coating forms a good metallurgical bond with the surface of the 42CrMo cast steel, and the bonding part is basically free of pores and defects, and the coating has no cracks.

As shown in Figure 3, the wear rate of 42CrMo cast steel gradually decreases under the conditions of untreated surface, laser melting treatment and laser cladding treatment, indicating that laser cladding treatment can effectively improve the wear resistance of the surface of vermicular graphite cast steel.

As shown in Figure 4, the friction coefficient of 42CrMo cast steel gradually decreases under the conditions of untreated surface, laser melting treatment and laser cladding treatment, indicating that laser cladding treatment can effectively improve the wear reduction of the surface of vermicular graphite cast steel.

As shown in Figure 5, the average impact energy of the 42CrMo cast steel in Example 1 increases sequentially under the conditions of laser melting treatment, untreated surface and laser cladding treatment, and the greater the impact energy, the better the impact resistance, indicating that Laser cladding treatment can effectively improve the impact resistance of the surface of compacted graphite cast steel.

As shown in Figure 6, the wear-resistant and impact-resistant coating prepared by laser cladding of 42CrMo cast steel in Example 1 has basically no change in the hardness of the wear-resistant layer after tempering at room temperature and at a high temperature of 500 °C, while the hardness of the laser-melted layer decreases significantly , indicating that laser cladding treatment can effectively improve the high temperature tempering performance of the surface of vermicular graphite cast steel.

It should be noted that, according to the above-mentioned embodiments of the present invention, those skilled in the art can fully realize the full scope of the independent claims and dependent rights of the present invention, and the implementation process and method are the same as the above-mentioned embodiments; and the present invention is not elaborated Some of them belong to well-known technologies in the art.

The above examples are provided only for the purpose of describing the present invention, not to limit the scope of the present invention, and the experimental results are close to those of Example 1. The scope of the invention is defined by the appended claims. Various equivalent replacements and modifications made without departing from the spirit and principle of the present invention shall fall within the scope of the present invention.

Claims (8)

1. A method for laser cladding of a wear-resistant and impact-resistant coating on the surface of cast steel is characterized by comprising the following steps: the method comprises the following steps:

step one, drying metal alloy powder in vacuum, and using the metal alloy powder for subsequent laser cladding;

secondly, performing texturing treatment on the surface to be treated of the cast steel, and then cleaning oil stains;

step three, preheating the cast steel cleaned in the step three;

step four, carrying out laser melting treatment on the surface of the preheated cast steel to form a laser melting layer, and eliminating defects and pores on the surface of the cast steel;

step five, after the laser fusion treatment is finished, performing laser cladding treatment on the surface of the laser fusion layer formed in the step four, blowing metal alloy powder to the surface of the cast steel laser fusion layer by using a coaxial powder feeding method and using protective gas as powder carrying gas, performing laser cladding on a metal alloy priming layer on the formed laser fusion layer, and using the metal alloy priming layer as a connecting layer of cast steel and a metal alloy wear-resistant and impact-resistant layer to enable the composite coating and the surface of the cast steel to form good combination without pore cracks;

step six, carrying out laser cladding treatment on the surface of the metal alloy priming layer formed in the step five, blowing metal alloy powder to the surface of the cast steel metal alloy priming layer by a coaxial powder feeding method and using protective gas as powder carrying gas, and carrying out laser cladding on a metal alloy wear-resistant and impact-resistant layer on the formed metal alloy priming layer; the wear-resistant and impact-resistant layer adopts metal alloy powder comprising the following chemical components in percentage by mass: 0.30 to 0.34 percent of C, 3.5 to 4.3 percent of Si, 10.5 to 11.5 percent of Cr, 2.0 to 2.6 percent of B, 10.0 to 11.0 percent of Fe and the balance of Ni; the metal alloy priming coat adopts metal alloy powder with the chemical components and the mass percentages of the elements as follows: 0.02-0.03 percent of C, 0.1-0.14 percent of Si, 0.4-0.46 percent of Mn, 15.5-16.5 percent of Cr, 2.0-2.8 percent of Co, 15.5-16.5 percent of Mo, 3.8-4.6 percent of W, 0.31-0.37 percent of Nb, 0.7-0.8 percent of Fe and the balance of Ni.

In the sixth step, when the surface of the cast steel is subjected to laser cladding treatment, the laser power is 1800-2600W, the laser scanning speed is 250-400 mm/min, the powder feeding speed is 5-8 g/min, and the diameter of a laser spot is 2-4 mm; the thickness of the metal alloy wear-resistant and impact-resistant layer is 0.8-1.0 mm.

2. The method for laser cladding of the wear-resistant and impact-resistant coating on the surface of the cast steel according to claim 1, which is characterized by comprising the following steps: and step four, the laser power in the laser fusing treatment is 2000-3500W, the laser scanning speed is 200-350 mm/min, and the laser spot diameter is 4-6 mm.

3. The method for laser cladding of the wear-resistant and impact-resistant coating on the surface of the cast steel according to claim 1, which is characterized by comprising the following steps: in the fourth step, the thickness of the laser fused layer is 0.3-0.5 mm, and the fused layer is uniform and free of defects and cracks.

4. The method for laser cladding of the wear-resistant and impact-resistant coating on the surface of the cast steel according to claim 1, which is characterized by comprising the following steps: in the fifth step, the laser power in the laser cladding treatment is 1500-2500W, the laser scanning speed is 200-350 mm/min, the powder feeding speed is 3-5 g/min, and the diameter of a laser spot is 2-4 mm.

5. The method for laser cladding of the wear-resistant and impact-resistant coating on the surface of the cast steel according to claim 1, which is characterized by comprising the following steps: in the fifth step and the sixth step, the protective gas is argon; the flow of protective gas in the fifth step is 6-10 l/min; in the sixth step, the protective gas flow is 8-15 l/min.

6. The method for laser cladding of the wear-resistant and impact-resistant coating on the surface of the cast steel according to claim 1, which is characterized by comprising the following steps: in the fifth step, the thickness of the metal alloy priming layer is 0.3-0.5 mm.

7. The method for laser cladding of the wear-resistant and impact-resistant coating on the surface of the cast steel according to claim 1, which is characterized by comprising the following steps: in the third step, the pretreatment temperature of the cast steel is 400-500 ℃.

8. The method for laser cladding of the wear-resistant and impact-resistant coating on the surface of the cast steel according to claim 1, which is characterized by comprising the following steps: in the first step, the metal alloy powder is dried in a vacuum drying oven at 80-90 ℃ for 90-120 min.