Moisture-Induced Gas Porosity
Gas porosity from moisture occurs when adsorbed water or hydrocarbons on the powder surface evaporate during melting, forming round pores in the structure. Careful powder drying prevents this defect.
Physicochemical Mechanism of Action
Adsorbed moisture or hydrocarbons on the surface of the welding powder evaporate during melting and form round pores in the structure. This process can be aided by the high temperature and low pressure during welding.
Metallurgical Relevance & Risks in Welding
Gas porosity reduces mechanical properties such as strength and toughness. The pores can also serve as sources of corrosion, shortening the component's lifespan. Additionally, high gas porosity can contaminate the structure and lead to uneven stresses, causing cracks or deformation.
Workshop Practice & Instructions
To avoid gas porosity, careful powder drying is essential. Store the powder in a dry location for at least 24 hours before welding. In humid or cool environments, extend the drying time. Additionally, set welding parameters such as temperature and pressure to control the evaporation of moisture and prevent the formation of large pores.