Laser Surface Additive Manufacturing

Laser cladding, a mainstream surface modification technology, also known as laser coating or laser cladding process, operates on the principle of applying selected coating materials to the substrate surface using various additive methods. Laser irradiation causes the coating material and the thin layer on the substrate surface to melt simultaneously, resulting in a tightly bonded surface coating with extremely low dilution after rapid solidification. This process significantly optimizes the wear resistance, corrosion resistance, heat resistance, oxidation resistance, and electrical properties of the substrate surface, achieving the dual goals of material surface modification and component repair. It precisely matches the specific performance requirements of the material surface while significantly saving expensive alloying elements and reducing material costs. In laser cladding repair of railway rails, the main cladding material is wear-resistant alloy powder with a hardness reaching HRC58-60, greatly  extending the service life of the rails.

Laser cladding technology boasts advantages such as low dilution, dense cladding layer structure, and strong bonding with the substrate, exhibiting extremely high stability and reliability in practical applications. Our company focuses on applying this technology to the field of rail transit track repair. Laser cladding technology, with its advantages of precise thermal control, metallurgical bonding, and micro-deformation, achieves efficient and high-quality repair in rail maintenance, significantly extending rail life and reducing maintenance costs, especially suitable for the complex conditions of heavy-load and high-speed lines. Before the introduction of laser cladding repair technology, most damaged parts were scrapped, resulting in resource waste and increased replacement costs. However, after adopting this special repair technology, the secondary utilization rate of parts has been greatly improved, effectively reducing maintenance expenses and significantly shortening the maintenance cycle, bringing considerable economic benefits to the rail transit sector.

(Top cladding before, middle cladding after, rear cladding after machining effect)

The process flow for laser cladding repair of parts is simple and highly controllable. The specific operation steps are as follows:

Step 1: Remove the fatigue layer from the repair area of the part. This is usually done by local grinding or turning. This step does not have strict requirements on the surface roughness of the part; it is only necessary to ensure that the fatigue layer is completely removed.

Step 2: Targeted preheating treatment. Based on the characteristics of the base material of the part, preheating is performed to prevent quality defects such as cracks caused by excessive temperature differences during the cladding process.

The third step is laser cladding. After preheating, laser cladding is performed on the damaged area of the part, with a typical cladding thickness of 3 to 4 millimeters. If higher hardness is required for the repaired area, the cladding thickness needs to be appropriately reduced—this is because cladding thickness and hardness are positively correlated, and without subsequent heat treatment, large-area, thick, high-hardness cladding can easily lead to cracks and other hidden dangers.

After the cladding operation, stress-relief annealing and dye penetrant testing are performed sequentially to ensure that the part is free of potential defects and that the repair quality meets standards. Finally, the cladding layer is precision machined to ensure that the part dimensions accurately match the drawing standards. Specialized machining is required to improve surface precision and assembly compatibility.