Porosity susceptibility
Pore susceptibility is the tendency to form gas bubbles in the weld metal. In aluminum, these often occur due to dissolved hydrogen in the melt.
Physical-Chemical Mechanism of Action
Porosity susceptibility arises from gas bubbles forming in the solidifying weld metal. For aluminum, the main gas is hydrogen, which dissolves in the molten pool and outgasses during cooling.
Metallurgical Relevance & Risks in Welding
Porosity can severely affect the mechanical strength of the weld. It causes cracks and shrinkage, making the material softer. With aluminum, high porosity susceptibility can lead to hot cracking and low toughness.
Workshop Practice & Action Guidelines
To reduce porosity susceptibility in aluminum, it's important to keep the melt clean and remove hydrogen from it. This can be done with careful deoxidation. Cooling steps should be controlled to allow rapid outgassing of hydrogen.