Porosity
Pores are voids in the weld, caused by trapped gases during solidification. They lead to defects such as hot cracks and loss of strength.
Physical-Chemical Mechanism of Action
Porosity occurs when gases (like oxygen or hydrogen) are not sufficiently removed during welding. These gases dissolve in the molten pool and can get trapped as voids when the metal solidifies.
Metallurgical Relevance & Risks in Welding
Porosity is a serious problem because it significantly weakens the weld's mechanical strength. It can lead to hot cracking and contaminate the material. Also, porosity reduces corrosion resistance and thermal conductivity.
Workshop Practice & Action Guidelines
To minimize porosity, it's crucial to do thorough deoxidation. This can be done with deoxidizers and the right shielding gas atmosphere. Also, the weld should be cooled as quickly as possible to prevent pore growth. For heavy metals or high stress conditions, careful control of process parameters is essential.