Oxygen affinity of alloying elements
Oxygen affinity determines how strongly a metal or alloying element absorbs and binds oxygen. Elements with high affinity are strong deoxidizers, prevent porosity, and increase strength.
Physical-Chemical Mechanism of Action
A element's oxygen affinity is a measure of its chemical bonding ability with oxygen. Elements with high affinity have a strong tendency to bind oxygen and react to form stable oxides.
Metallurgical Relevance & Welding Risks
In the molten phase, elements with high oxygen affinity like silicon or titanium can be strong deoxidizers. They bind oxygen and prevent pore formation in the weld. However, too high an oxygen content can lead to embrittlement, which reduces the hardness and toughness of the steel.
Workshop Practice & Action Guidelines
When welding alloys with high oxygen affinity elements (e.g., silicon), it's important to carefully control the melting temperature and the deoxidizer. Too high a content of such elements can lead to embrittlement, which reduces the hardness and toughness of the steel. For aluminum alloyed with silicon, the melting process should be done under protected oxygen or in a liquid deoxidizer.