With the continuous deepening of the development and utilization of marine resources, various marine equipment plays a vital role in marine engineering, shipping, marine energy development and other fields. However, due to the complexity and harshness of the marine environment, marine equipment is under high salt, high humidity, high pressure, strong corrosion and other conditions for a long time, which is prone to various damages and failures and needs to be repaired in time. As an advanced surface repair technology, laser cladding technology has the advantages of small heat-affected zone, high bonding strength and high repair accuracy, providing an effective solution for the repair of marine equipment.
1. Common types of damage to marine equipment and situations requiring repair
1.1 Corrosion damage
The seawater in the ocean is highly corrosive. The surface of marine equipment that has been in contact with seawater for a long time is prone to electrochemical corrosion, resulting in a decrease in the structural strength of the equipment and failure of parts. For example, the hull, propeller, and steel structure of the offshore platform of the ship are susceptible to corrosion damage.
1.2 Wear damage
During the operation of marine equipment, friction and wear between parts are inevitable. For example, the engine parts, transmission system parts, and drilling equipment parts of the offshore platform of the ship, long-term wear will lead to a decrease in the dimensional accuracy of the parts and an increase in the matching clearance, affecting the normal operation of the equipment.
1.3 Fatigue damage
Marine equipment is prone to fatigue cracks and fractures under the action of long-term alternating loads. For example, the hull structure of a ship and the supporting structure of an offshore platform are prone to fatigue damage under the action of alternating loads such as waves and sea breeze.
1.4 Collision damage
During marine operations, marine equipment may collide with other objects, causing structural deformation of the equipment and damage to parts. For example, collisions between ships, collisions between offshore platforms and ships or other objects, etc.
2. Principles and advantages of laser cladding technology for repairing marine equipment
2.1 Repair principle
Laser cladding technology uses a high-energy laser beam as a heat source to quickly melt the preset or synchronously fed cladding material (powder, wire, etc.) on the surface of the substrate to form a cladding layer that is metallurgically bonded to the substrate. By reasonably selecting cladding materials and process parameters, the cladding layer can have excellent wear resistance, corrosion resistance, fatigue resistance and other properties, thereby realizing the repair of marine equipment.
2.2 Advantages
Small heat-affected zone
The heating and cooling speeds during the laser cladding process are very fast, the heat-affected zone is small, and the performance of the substrate material is less affected, avoiding problems such as reduced equipment accuracy due to thermal deformation.
High bonding strength
A strong metallurgical bond is formed between the laser cladding layer and the substrate, with high bonding strength, and it is not easy to have problems such as peeling and cracking, ensuring that the repaired equipment has good reliability and service life.
High repair accuracy
The laser beam has good directionality and focusing, which can achieve precise local repairs. It has unique advantages for marine equipment parts with complex shapes and high dimensional accuracy requirements.
In-situ repair is possible
For some large marine equipment, such as offshore platforms and ships, laser cladding technology can be used for in-situ repair at the equipment site, without the need to disassemble the equipment and transport it back to the factory, which greatly shortens the maintenance cycle and reduces the maintenance cost.
3. Process flow of repairing marine equipment with laser cladding technology
3.1 Preparation before repair
Carry out a comprehensive inspection and evaluation of the damaged marine equipment to determine the damaged part, degree of damage and repair scope.
Pre-treat the repair part to remove pollutants such as oil, rust, and oxide layer, and use mechanical processing, sandblasting, pickling and other methods to make the surface roughness meet certain requirements.
Select appropriate cladding materials and process parameters according to the material, working conditions and repair requirements of the equipment.
3.2 Laser cladding repair
Install the pretreated equipment on the workbench of the laser cladding equipment, and adjust the relative position and angle between the laser head and the repair part.
Start the laser cladding equipment and perform cladding repair according to the preset process parameters. During the cladding process, the quality of the cladding layer should be monitored in real time and the process parameters should be adjusted in time.
3.3 Post-repair treatment
Post-process the repaired parts after cladding, such as grinding and polishing, so that the surface roughness and dimensional accuracy of the repaired parts meet the design requirements.
Perform quality inspection on the repaired equipment, including appearance inspection, dimensional measurement, non-destructive testing, mechanical property testing, etc., to ensure that the repair quality meets the requirements.
4. Application examples of laser cladding technology in marine equipment repair
4.1 Ship propeller repair
Ship propellers rotate at high speed in seawater for a long time and are susceptible to seawater corrosion and wear. Using laser cladding technology to clad a layer of wear-resistant and corrosion-resistant alloy coating on the surface of the propeller blade can effectively increase the service life of the propeller.
4.2 Offshore platform steel structure repair
Offshore platform steel structures are exposed to the marine environment for a long time and are susceptible to corrosion and fatigue damage. Using laser cladding technology to repair damaged parts can restore the strength and stability of the steel structure and extend the service life of the offshore platform.
4.3 Ship engine component repair
Ship engine components are prone to wear and crack damage under high temperature, high pressure and high wear working conditions. Using laser cladding technology to repair engine components can improve the wear resistance, corrosion resistance and fatigue resistance of the components and ensure the normal operation of the engine.
As an advanced surface repair technology, laser cladding technology has broad application prospects in marine equipment repair. By rationally selecting cladding materials and process parameters and adopting scientific repair process flow, it can effectively repair damage to various marine equipment, improve the reliability and service life of the equipment, and provide strong technical support for the development and utilization of marine resources. With the continuous development and improvement of laser cladding technology, it is believed that its application in the field of marine equipment repair will become more and more extensive.
