Metallurgical Test Laboratory
AHT has a state-of-the-art metallurgical test laboratory, enabling onsite Nadcap conforming furnace qualification testing and monthly furnace control metallurgical testing, required for maintenance of aircraft approved furnaces, where conformance tests are required to test for evidence of: High Temperature Oxidation (HTO), Eutectic Melting (EM), Cladding Diffusion (CD) and Intergranular Attack (IGA).
Other testing performed on behalf of AHT customers are SDAS measurements, Macros and Porosity measurements, backed up with photography and reporting.
The Technical details:
HTO – occurs at solution treatment or annealing temperatures and are seen as surface blisters or intrusive oxides caused by hydrogen diffusion from excessive moisture or contaminants on the product surface reacting with the product’s protective oxide layer, allowing diffusion of nascent Hydrogen.
EM – occurs due to being solution treated at too high a temperature resulting with insipient melting at grain boundaries and is seen is small voids at grain boundary interfaces. Excessive eutectic melting will result in loss of strength and ductility
CD – caused by prolonged solution treatment or annealing soaking, causing elemental diffusion of copper (sourced from the base alloy) to diffuse into the pure aluminium cladding
IGA – is caused by excessive grain boundary precipitation of alloying elements during a slow quench, where the grain boundary precipitates are more anodic than the grains themselves, hence, causing corrosion in the presence of an electrolyte.