Aerofin Laboratories can evaluate samples that have been exposed to high temperatures for Alpha Case and Heat Affected Zone.
Titanium has low oxidation resistance when exposed for long periods in elevated temperatures containing oxygen. When exposed to these conditions titanium reacts with oxygen forming an oxide scale on the surface of the material. Beneath this oxide scale a hard and brittle oxygen enriched layer is produced known as Alpha Case.
Alpha Case reduces the mechanical properties of titanium. Decreasing ductility, fracture toughness and fatigue life.
Heat Affected Zone (HAZ) is an area that didn’t melt during cutting/welding, but has had its micro structural and mechanical properties altered as a result of the exposure to heat. Heat Affected Zone will be evident at the weld/cut interface where its size can vary depending on factors including: exposure time, temperature and material type.
Changes in micro structure in the Heat Affected Zone cause stresses that reduces the strength of the material. High-temperature exposure and welding can significantly affect the micro structure and properties of the heat-affected zone that makes them more susceptible to corrosion.
BSEN 2003 – 009