THE EFFECT OF CALCIUM ADDITIONS TO ALUMINUM CONTAINING FLUX ON THE MECHANICAL-PROPERTIES OF STRUCTURAL-STEEL

The effect of treatment of plain carbon liquid steel with mixtures of CaO-CaF2-Al and CaO-CaF2-Al with calcium added either pure or as CaAl or CaC2 on steel quality has been investigated. Both mixtures reduce total oxygen and sulphur contents to low levels, improve inclusion morphology and increase toughness properties, but the improvement obtained with added calcium as CaAl or CaC2 is striking. Total oxygen and sulphur contents were reduced to below 5 ppm and 10 ppm, respectively, alumina and MnS inclusions completely transformed, anisotropy eliminated and the transition temperature lowered to below 60-degrees-C. The influence of oxygen and sulphur content, and of inclusion morphology, on the toughness properties of the steel has been demonstrated.