Metallography is an invaluable tool for defect detection and the set-up of production cycles. It is the first step in obtaining information about the microstructure of the alloy being used and the effects heat treatments and metal-working processes have on it. The ability to correlate the process parameters (temperatures, times, level of work-hardening, cooling rate, etc.) with the alloy's microstructure is quite necessary to avoid errors, improve product quality, reduce production costs and eliminate customer complaints. This paper's aim is to demonstrate the potential of optical metallography and the wealth of additional information it offers when compared to more conventional methods of process control such as hardness measurement. The cases reported refer to very different alloys, such as gold, silver, platinum and palladium. Correlations of different microstructures are discussed, especially in reference to mechanical working and annealing cycles. Finally, the paper examines the possibility of further developing the performed analyses by means of scanning electron microscopy.

Author: Paolo Battaini