Aluminum as Deoxidizer
Aluminum reduces oxygen and binds nitrogen to suppress porosity and grain growth.
Physicochemical mechanism of action
Aluminum reacts in the molten pool with oxygen to form aluminum oxide. This prevents the formation of free oxygen atoms that could cause porosity in the weld. Simultaneously, aluminum binds nitrogen into stable nitrides, suppressing austenite grain growth and increasing strength.
Metallurgical relevance & risks in welding
Too high aluminum content can lead to excessive hardness, reducing formability. Additionally, surface cracking and fine porosity can occur if the material is not properly treated.
Workshop practice & action guidelines
Use aluminum in the amounts specified in the filler metal. Ensure that melting temperature and cooling time are optimally set for flawless deoxidation. If hardness or surface defects are an issue, check aluminum content and welding parameters.