Gas cavity
Gas trapping occurs in the weld pool due to trapped gases that don't escape in time. This leads to spherical voids in the weld metal.
Physical-Chemical Mechanism of Action
Gas occlusion occurs when gases are dissolved into the metal during the melting phase and cannot be released in time during cooling. These gases form spherical voids in the weld metal.
Metallurgical Relevance & Welding Risks
Gas occlusion can lead to porosity, which impairs the strength and toughness of the weld metal. It can also cause hot cracking and distortion in the weld metal, especially when the metal is under stress or load.
Shop Practice & Instructions
To avoid gas occlusion, you should:
• Prepare a clean melt and remove gases from the weld pool.
• Allow the weld to cool slowly to give enough time for gas release.
• For metals with high gas content (like carbon steel), carry out careful degassing and controlled cooling.