Loss on Ignition
Loss on annealing is the mass loss of a material sample when heated to high temperatures due to the driving off of volatile components or decomposition. This can lead to changes in the microstructure and mechanical properties.
Physico-Chemical Mechanism of Action
During loss on annealing, volatile substances such as oxygen, hydrogen, or carbon escape from the metal. This occurs through diffusion and can lead to decomposition of certain chemical compounds.
Metallurgical Relevance & Risks in Welding
High loss on annealing can change the microstructure of the material, leading to a softer or more susceptible material. This increases the risk of cracking and reduces weld strength.
Workshop Practice & Instructions
To minimize loss on annealing, metals should be treated at low temperatures or welded in a closed system. In high-temperature processes, it is important to deoxidize the environment and increase shielding gas pressure.