Sulfur influence on surface tension
Sulfur atoms in the melt increase surface tension, which strengthens convection currents and increases penetration depth during welding.
Physicochemical Mechanism of Action
Sulfur atoms in the molten pool interact with metal ions and form sulfur-bound compounds. These compounds have a higher surface tension than the pure metal, which increases the stress at the surface.
Metallurgical Relevance & Welding Risks
The increased surface tension leads to stronger convection currents in the melt. This can cause the penetration depth of the weld to increase, leading to greater distortion and possibly stress zones in the structure. Too high penetration depths can also lead to hot cracking or destruction of the metal.
Workshop Practice & Action Instructions
To minimize the influence of sulfur on surface tension, the sulfur content in the melt should be kept as low as possible. For high-sulfur alloys, the penetration depth can be reduced by controlling convection currents or increasing the melt temperature. It is important to regularly clean the melt and avoid sulfur fumes.