Treatment of Steel with Alkaline-earth Elements

To evaluate the potential benefits of strontium treatment of steel compared to calcium, steel-clad wires of calcium-silicon, calcium and strontium were fabricated. Lengths of these wires were injected to 35 kg heats of AISI 1045 steel. Samples for total calcium or strontium, oxygen, sulphur, and aluminum were taken as frequently as possible during and after the injection. The recoveries of the alkaline-earth elements in steel for the three wires were 8.3, 4.6 and 0.41%, respectively. There was virtually no inclusion modification with the strontium wire compared to the calcium-containing wires. It was found that the absorption rate of the alkaline-earth elements increased with the sulphur and oxygen contents of the steel. A mathematical model for this enhanced dissolution rate was developed which identifies the fundamental limitations of the alkaline-earth elements for steel treatment.