| This thesis reports on a two-level three-factor design of experiments conducted in order to develop a mathematical model of the micro-welding process. The effects of process parameters on the deposition rate, porosity content, crack density and coating hardness were investigated using statistical analysis software. Oxidation tests were conducted to study the effect of aluminum + chromium concentration on the oxidation resistance of micro-welded nickel based coatings. Parabolic oxidation rate constants were obtained and energy dispersive spectroscopy was used to provide semi-quantitative results on the composition of protective oxide scales and internal precipitates. A residual stress experiment was also conducted to determine the nature and provide an approximation of magnitude for residual stresses in micro-weld deposits.; Micro-welding has been found to be a suitable process for the application of high aluminum + titanium content filler alloys to Inconel 738. High deposition rates were obtained with high pulse power parameters but produced higher amounts of porosity and cracking. (Abstract shortened by UMI.)... |
