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Principles of Laser Cladding Process Equipment
Laser cladding technology refers to the placement of selected coating materials on the surface of the coated substrate with different filler methods. Laser irradiation melts with the surface layer of the substrate. and rapidly solidified to form extremely low dilution and with The base material becomes a metallurgical combined surface coating, which significantly improves the wear resistance, corrosion resistance, heat resistance, oxidation resistance, and electrical characteristics of the base material surface.
Divide the laser cladding into two categories. It is according to the supply of cladding materials, namely, preset laser cladding and synchronous laser cladding. Pre-positioned laser cladding is to place the cladding material on the cladding part of the substrate surface in advance. And then use laser beam irradiation to scan and melt. The cladding material is added in the form of powder or wire, most commonly used in the form of powder. Synchronous laser cladding is to send powder or wire cladding materials synchronously into the molten pool during the cladding process through a nozzle. The cladding material is added in the form of powder or wire, of which the form of powder is the most commonly used.
Laser Cladding Technology Introduction
Laser cladding technology is a new surface modification technology that emerged with the development of high-power lasers in the 1970s. It means that laser surface cladding technology combines alloy powder or ceramic powder with the surface of the substrate under the action of a laser beam. Rapid heating and melting, self-excited cooling after the beam is removed, forming a surface coating with extremely low dilution rate, and metallurgical bonding with the substrate material.
Thereby significantly improving the wear resistance, corrosion resistance, heat resistance, oxidation resistance, and electrical characteristics of the substrate surface strengthening method. For example, after carbon-tungsten laser cladding of 60# steel, the hardness is up to 2200HV or more, and the wear resistance is about 20 times that of the base 60# steel. After laser cladding, CoCrSiB alloy on the surface of Q235 steel. Compare the wear resistance, and the corrosion resistance of flame spraying. And we found that the corrosion resistance of the former was significantly higher than that of the latter.
Laser Cladding Technology in Ship Repair
In the long-term operation of the ship, the service performance of the ship. It is often gradually reduced due to the influence of various factors. When parts are damaged during ship repair, how to quickly repair them and make them continue to operate with high quality. It has always been one of the technical problems that people seek to solve.
Damaged parts and components of much large-scale equipment on ships will often cause major economic losses and hazards. For example, the rotor shaft of the key components of the generator, because of its high operating accuracy and fast speed, once damaged will directly cause the output power of the entire unit to drop or even paralyze. For the sake of insurance, usually replace the damaged parts directly. However, because the parts and components in the shipbuilding industry are usually expensive and the order period is long, they cannot meet the needs of ship repairs. Therefore, the ship repair industry is facing an urgent problem: the development of new low-cost, fast, and highly reliable repair technology.
Laser cladding technology is a new technology with high economic benefits. It can prepare high-performance alloy surfaces on cheap metal substrates without affecting the properties of the substrate, reducing costs, and saving valuable and rare metal materials. Therefore, the world’s advanced industrial countries attach great importance to the research and application of laser cladding technology.
Commonly used traditional repair processes mainly include ordinary electrode surfacing, spraying, and electroplating. For less important parts, these traditional processes can solve the problem. But for important parts, these traditional process methods have varying degrees of defects. For example, surfacing and electric welding are easy to deform too much. For less important parts will only use it. while spraying and electroplating methods have no deformation, but their repairable thickness is limited, and the bonding force of the repair layer and the substrate It is not strong and cannot be used in high-speed, impact, and heavy-duty situations.
Laser cladding uses a high-energy laser beam to irradiate the metal surface, through rapid melting, expansion, solidification, and cooling to cladding a layer of material with special physical, chemical, or mechanical properties on the surface of the substrate, thereby forming a new composite material. To make up for the lack of high performance of the body, this composite material can give full play to the advantages of the two and make up for the deficiencies between each other. According to the requirements of the working conditions of the workpiece, the surface coating with heat resistance, wear resistance, corrosion resistance, oxidation resistance, fatigue resistance, or optical, electrical, and magnetic properties can be cladding.
Advantage of Laser Cladding Technology
Compared with the commonly used surfacing, spraying, and electroplating in traditional repair, laser cladding has the following advantages:
- The cladding layer and the substrate are metallurgical welded, which is dense and has high bonding strength. And it is not easy to fall off;
- While changing or restoring the geometric dimensions of the work piece, realize synchronous surface strengthening;
- The use of functional materials can realize the customization of the surface properties of the work piece. Change the surface properties of the parts, such as wear resistance, high temperature resistance, corrosion resistance, etc.;
- The heat-affected zone and thermal deformation of the repaired part are small. Can’t change the metal properties of the work piece matrix;
- The repair process is automatically controlled by the machine to ensure the quality of the work piece;
- High repair efficiency and short construction period;
- It can repair work pieces of various materials; We can choose the cladding layer accoring the requirements of use. The hardness of the cladding layer is in the range of HRC20～HRC60.
The Laser Cladding Repair Technology
Because the repair layer produced by the laser cladding repair technology is metallurgical bonding. Its structure is dense, the bonding strength is high, and it is not easy to fall off. It has gradually become one of the best repair processes for ships. Combining the characteristics and advantages of laser cladding repair technology. The wear of various steel, cast iron, and stainless steel parts on ships. We can use laser cladding technology to repair it, and the overall performance after repair can reach or exceed the new workpiece. And for those repair problems that have caused headaches for technicians in the ship repair industry in the past. Laser cladding repair technology shows its uniqueness, such as the repair of shafts.
Laser cladding repair technology can control the amount of deformation to 0. 01 ~ 0.02 mm, the larger shaft does not even have deformation. For the repair of workpieces made of cast iron and stainless steel. Laser cladding repair technology can also solve the problem, and the effect is significant, without cracks; We can also repair the workpieces with complex shapes repair them accurately and efficiently. The most important thing is that laser cladding repair technology uses a wide range of cladding materials. You can use materials similar to the matrix to achieve the purpose of repairing the size. You can also use alloy materials with better performance. To achieve the purpose of surface modification. These problems are often difficult to achieve with traditional repair techniques.
Laser cladding repair technology, as a brand-new process, with its unique advantages. It brings the possibility of repairing important parts in the ship repair industry. As mentioned above, the various characteristics of laser cladding repair technology determine that laser must have broad application prospects in the ship repair industry. The widespread application of laser cladding technology in the ship repair industry. It will bring considerable benefits to ship repair yards and ship owners. At the same time, due to the saving of material consumption and scrap. The remanufacturing and repair of damaged parts are in line with the development of the national industry. Policy, therefore, also has huge social benefits and is worthy of active promotion and application.
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