Surface Roughness Effect
Surface roughness affects welding by increasing the contact area and altering the stress between steel and shielding gas. Excessive roughness can lead to porosity.
Physical-Chemical Mechanism of Action
Surface roughness affects welding through the increased contact area between steel and shielding gas. A smooth surface offers fewer attraction points for oxygen molecules, leading to better deoxidation. A rough surface, on the other hand, enlarges the contact area and can hold oxygen, which may lead to porosity.
Metallurgical Relevance & Welding Risks
High surface roughness increases the risk of porosity and can lead to poor arc starting and a wet weld pool. This can cause loss of strength and toughness in the weld and reduce the component's service life.
Workshop Practice & Action Guidelines
To minimize the risk of porosity, the surface roughness of the steel should be kept as low as possible before welding. Avoid very rough methods like filing or grinding with coarse grit. For hard-to-reach surfaces, chemical deoxidation can help reduce roughness.