Laser cladding with a pulsed Nd:YAG laser and optical fibers

A new laser cladding technique for producing wear and corrosion resistant surfaces on engineering components is reported. The technique involves the combination of the pre-placed and injected powder delivery methods for producing clad layers, The clad layers were formed with a pulsed Nd:YAG laser and optical fibers, The results using a nickel-based alloy (Hastelloy C) indicate that uniform clad layers in excess of 1 mm in thickness can be achieved in a single pass with 240 W average power incident on the workpiece. The laser beam was delivered through a step-index glass fiber of length 5 m and core diameter 600 mu m. The clad layer obtained is homogeneous, without porosity or cracks, and has very low dilution (less than 2%) by the substrate, to which it is bonded, These results, combined with a relatively high powder utilization efficiency (about 60% when cladding a flat plate) and coverage rate (8 mm(2) s(-1)), make the technique competitive with that using continuous wave lasers with powers greater than 1 kW, but at a quarter of the input pow er. The low heat input makes the technique particularly attractive for cladding thin substrates and engineering components that require both corrosion- or wear-resistant surfaces and high dimensional stability. In addition, the use of fiber optics to deliver the laser beam to the workpiece offers great opportunities for surfacing components remote from the laser source.