Sulfur morphology modification
Chemical modification of sulfide inclusions through calcium or selenium to transform elongated sulfide stringers into globular shapes and reduce their harmfulness.
Physical-Chemical Mechanism of Action
Sulfide morphology modification means chemically changing the sulfide inclusions in metal by adding calcium or selenium. This turns elongated manganese sulfide stringers into globular shapes. The globular shape is less prone to cracking and boosts the material's toughness.
Metallurgical Relevance & Welding Risks
Elongated manganese sulfide stringers can cause hot cracking and distortion, especially at high heat. Sulfide morphology modification reduces these hazards because the globular shapes resist cracking better. But if you don't add enough calcium or selenium, the modification is incomplete and the risks stay.
Shop Practice & Action Items
To get sulfide morphology modification right, follow these steps:
1. Work out the correct calcium or selenium level for your metal and the desired modification.
2. Add it during melting so it spreads evenly.
3. Keep an eye on the cooling temperature and time to get the best modification.
4. Use exact amounts of calcium or selenium to avoid incomplete modification.