Effect of overlap rate on the microstructure and corrosion behavior of pure copper laser cladding.

Compared with cold spraying and electroplating, laser cladding is also an efficient and reliable surface modification technique to prepare pure copper coating, yet with uniqueness such as the combination of forming metallurgical bonding with substrate and high deposition rate. As such, pure copper coating with different overlap rates was successfully prepared on the Q245R substrate. The surface quality, defects quantity, phase composition, grain orientation, and corrosion behavior were investigated by surface profiler, scanning electron microscope, energy dispersive spectrometer, X-ray diffraction, electron backscattered diffraction, and electrochemical analysis. As the overlap rate increases, the surface roughness decreases then increases, and the pores and unfused defects disappear then reappear. The grain formation changes from columnar to equiaxed crystals and then to columnar crystals, with the orientation of grains shifting from 100 to 101 direction. Further analysis revealed that the pure copper coating with a 70% overlap rate possesses fewer pores, unfused defects, and no interfacial cracks, thus the best compactness. Moreover, the pure copper coating with a 70% overlap rate in 3 mol/L NaCl solution exhibits the best corrosion resistance. [ABSTRACT FROM AUTHOR]