Laser Micro-Wire Cladding: From Fundamental Mechanisms to Application

Abstract Laser cladding using thin wires (<0.8 mm) presents significant potential for applications requiring high precision and minimal heat input, such as coatings for nuclear fuel rods. This work investigates Laser Micro-Wire Cladding (LMWC) using a 200 µm wire, showing the transition from fundamental process studies on single tracks and flat substrates to the application of FeCrAl coatings on 15-15Ti and 316L tubes relevant to nuclear fuel rods. High-resolution high-speed imaging (HSI) experiments revealed unique melt transfer characteristics, including a stable melt bridge and drop deposition mode. The mechanisms governing these modes were analysed. A novel wire-bending technique was developed to enhance process stability, crucial for consistent deposition. This understanding facilitated the successful deposition of thin (135 µm), low-dilution (< 7%), defect-free clad layers onto thin (500 µm) substrates. Characterization indicates that the coatings meet demanding requirements for nuclear applications.