The Dutch company Nedclad Technology BV has introduced lasercladding as an alternative to other techniques for the application of wear and corrosion-resistant coatings. Lasercladding results in surfaces with excellent properties, besides it can accommodate the restrictions of other techniques. The close control and minimal heat input of the laserclad process make it important for a wide range of products. The potential of laserclad technology as a repair tool is illustrated in the repair of corroded valves belonging to the Nederlandse Aardolie Maatschappij. The critical inner surfaces of the forged valve bodies and outer surfaces of the cylinders of a 0.4% C-steel were seriously affected by crevice corrosion resulting in pitting. An attempt to repair the valves by HVOF-spraying led to insufficient bonding of the coating and a density of less than 100%. Overlay welding could not be applied either, because the heat input, resulting in distortion and a large zone affected by heat, was too high. For repair of the valves the affected surfaces were machined to such a depth that all pitting craters disappeared. Next, the surfaces were clad with two layers of Inconel 625 to a thickness of 1.5mm, enough to machine the valves to their final dimensions. The valves have now been in service over two years and during intermediate inspections they show no sign of deterioration.
