Sulfur Morphology Control
Sulfide morphology control improves transverse toughness by converting plastic manganese sulfide stringers into globular, non-deformable particles using calcium or rare earth additions.
Physical-Chemical Mechanism of Action
Sulfide morphology control means deliberately influencing the shape of sulfide inclusions in steel by adding calcium or rare earth additions. These additions react with the sulfur in the steel and turn the plastic manganese sulfide stringers into globular, non-deformable particles.
Metallurgical Relevance & Welding Risks
Proper sulfide morphology control improves the transverse toughness and formability of the steel. Not enough calcium or rare earth leaves plastic manganese sulfide stringers that hurt toughness and can cause cracking. Too much addition, on the other hand, can coarsen the structure and increase corrosion susceptibility.
Shop Practice & Action Items
To put sulfide morphology control into practice, do the following:
• Figure out the right amount of calcium or rare earth based on the steel grade and the specific job.
• Add the addition during melting so it distributes evenly.
• Watch the cooling curve closely to stay in the critical temperature window for the sulfide transformation.
• Use the right welding process and parameters to get the best structure.