Hot Gas Corrosion
Hot gas corrosion is an oxidation of metals at high temperatures in gases such as oxygen or hydrogen sulfide, intensified by alkali sulfides. It leads to porous scale layers and can cause cracking and loss of strength.
Physical-Chemical Mechanism
Hot gas corrosion occurs at high temperatures when metals are exposed to gases like oxygen or hydrogen sulfide. Alkali sulfides and vanadates can intensify this reaction. Metal atoms react with the gases, forming layers of oxide and sulfide compounds that are porous.
Metallurgical Relevance & Welding Risks
This corrosion can lead to cracking in the weld, as the porous scale layers do not adhere well. It also coarsens the grain and reduces material strength. This can be particularly dangerous for components subjected to high temperatures.
Workshop Practice & Action Items
To avoid hot gas corrosion, metals should be cleaned before welding and stored in protected environments. At high temperatures, it is important to control air quality in the welding area and shut off any gas sources. Use appropriate corrosion-resistant materials or compounds.