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Copper alloys of composition Cu–35Zn–3Pb and Cu–31Ni–1·9Cr were laser treated and characterised using optical and scanning electron microscopy and stress corrosion experiments. Laser induced defects in the former alloy increased the variability in the time to failure by stress corrosion cracking in the laser treated specimens relative to the bulk. The latter alloy, when laser treated, has a defect free surface which is more resistant to pitting in sea water than that of the bulk and is not susceptible to stress corrosion cracking despite the stress corrosion cracking sensitivity of conventional gas metal arc welds in this alloy. Practically, the results suggest that laser induced defects may limit the acceptable process window of laser treated copper alloys intended for use in sea water.MST/1975

The effect of heat input in the laser cladding of nickel aluminum bronze was investigated. Nickel aluminum bronze castings were clad with a consumable of the composition Cu-9.0Al-4.6Ni-3.9Fe-1.2Mn and exposed to a variety of heat inputs from 42.5 to 595 J/mm. At the lowest heat input, the deposit microstructure was almost entirely martensitic. Increases in heat input caused the amount of αto increase. Depending upon heat input, the αwas present as grain boundary allotriomorphs, secondary Widmanstätten αsideplates, and intragranular Widmanstätten αprecipitates. The reheated zones were of lower hardness and, at all heat inputs, consisted of a mixture of grain boundary allotriomorphs and Widmanstätten αand martensite. Laser cladding improved the corrosion- and cavitation-erosion resistance of the surfaces but reduced their ductility. The properties of the clad surfaces depended on heat input.