Rezumat
Laser cladding technology utilizes a high-energy density laser beam to rapidly melt and solidify alloy powders with varying compositions and properties onto the surface of a substrate, forming a wear-resistant, corrosion-resistant, and oxidation-resistant cladding layer. This process significantly enhances the surface performance of the base material while saving costs. Furthermore, laser cladding can be used to repair damaged parts produced during manufacturing and service by building up material in non-compliant dimensions and restoring the part’s geometry through subsequent machining. This paper focuses on the repair of TC4 alloy fan blades used in an aircraft engine, which have suffered significant damage during production and use, leading to increased manufacturing and operational costs. By applying laser cladding for the repair and remanufacture of the damaged titanium alloy blades, the surface properties of the material are improved, and defective parts are restored, significantly reducing the cost of replacing new components. In this study, TC4 alloy was selected as the substrate material, and suitable TC4 alloy powder was chosen for cladding. The research systematically investigates the effects of key process parameters, such as laser power, scanning speed, and powder feed rate, on the cladding layer’s dimensions, microstructure, defect control, and mechanical properties, resulting in optimized laser cladding process parameters for TC4 alloy blade repair.

Repair Technology Details

Pre-repair Treatment: Non-destructive testing is conducted on the damaged blades to identify the affected areas and the extent of damage. A combination of mechanical grinding and chemical cleaning is used to remove the surface oxide and contamination layers, ensuring the substrate surface is clean and activated.

Cladding Material Selection: TC4 titanium alloy powder (particle size range 45–150 μm), which is close in composition to the substrate, is selected to ensure good metallurgical bonding and compatibility between the cladding layer and the substrate.

Process Parameter Optimization: Through orthogonal and single-factor experiments, the effects of laser power (800–2000 W), scanning speed (5–15 mm/s), and powder feed rate (1.5–4.5 g/min) on the cladding layer’s width, height, dilution rate, and microstructure are studied. It was found that the matching of laser power and scanning speed is crucial for suppressing defects such as porosity and cracking.

Cladding Process Control: The cladding is carried out using a coaxial powder feeding system in an argon-protected environment to prevent high-temperature oxidation of the titanium alloy. A multi-pass overlap strategy is used to achieve uniform repair of the large damage area, while controlling the interlayer temperature to below 200°C to reduce thermal stress accumulation.

Post-Repair Treatment and Performance Restoration: After cladding, a stress-relieving annealing treatment is performed (700–800°C for 2 hours). Precision machining methods, such as CNC grinding, are used to restore the blade profile and dimensional accuracy. Finally, surface polishing and shot peening are applied to enhance fatigue performance.

Quality Inspection and Validation: The repaired area is subjected to X-ray inspection, metallographic analysis, microhardness testing, and tensile testing to ensure that the cladding layer is defect-free, with a uniform microstructure, and that the mechanical properties meet the required specifications.