Microscopic Gas Pore
Microscopic gas pores are small, spherical cavities in the weld metal caused by dissolved gases that don't escape in time during solidification. They hurt strength and can lead to cracks.
Physical-Chemical Mechanism of Action
Dissolved gases in molten metal become gas bubbles during cooling if they do not escape in time. These bubbles remain as microspheres in the solid metal and form pores.
Metallurgical Relevance & Risks in Welding
These pores impair the static strength of the material because they can concentrate stresses and cause cracks. They also reduce dynamic strength, which can lead to fractures under mechanical loads.
Workshop Practice & Action Instructions
To minimize microscopic gas pore inclusions, it is important to ensure a clean melt and a careful cooling process. Use suitable deoxidizers like silicon or potassium fluoride. Pay attention to correct gas supply and avoid too rapid cooling rates.