Paul D. Eason

A Structure Property Processing Comparison of Cold rolled PM Copper and Cold Gas Dynamically Sprayed Copper

Cold gas dynamic spray processing (cold spray) is a solid-state material deposition process used for coating and repair processes in many alloy systems. Cold spray has long been proposed as a potential method for freeform fabrication. The cold spray process imparts great deformation to the impacting particles, affecting the final properties of the deposit through work hardening, grain refinement and inter-particle bonding. For the purpose of demonstrating the feasibility of cold spray as a viable freeform fabrication method, the microstructure and hardness of bulk cold sprayed samples were characterized in as received and annealed condition, then compared to cold rolled material, which was previously vacuum hot pressed from the same powder stock used in spraying. Microstructure was analyzed via scanning electron microscopy and electron channeling contrast imaging to assess grain refinement and thermal annealing response in the cold sprayed and cold rolled materials. Vickers micro hardness was measured to assess the effects of cold spray impact on the properties of bulk, as-sprayed copper relative to cold rolled copper. In postannealed materials, greater hardness is achieved with the cold spray process through the suspected mechanism of grain refinement unachievable in the rolling process.

On Si Redistribution During Friction Stir Processing of Cast Al-7%Si–0.4%Mg Alloys

The evolution of microstructure, specifically Si eutectic particles, was investigated after friction stir processing of A356 castings with single and multiple passes in this study. Si particles were found to coarsen with each pass. The nearest neighbor distance for Si particles also increased with each FSP pass, indicating that microstructure became more homogeneous after each pass.

Evolution of Filling System Design for an A356-T6 Aluminum Housing Casting

The results of a student project to produce two housing halves for an engine dynamometer are presented in this paper. The filling systems were designed to minimize turbulence and damage to the metal. The results of small changes in the filling system design are discussed. A new method of using different parts of the filling system (rigging) to evaluate the results of quality improvement efforts is introduced.

Fatigue Life of Ablation Cast 6061-T6 Components

The fatigue life of 6061-T6 alloy, normally used in its wrought form, was investigated in this study in cast form from parts produced by the new ablation casting process. Specimens excised from military castings were first tested in unidirectional tensile test yielding elongation values comparable to forgings. Fatigue specimens tested by rotating cantilever beam revealed that the fatigue life of these castings is superior to the data from the 6061 forgings published in the literature.