Free-machining stainless steel containing sulfur has been continuously cast in square shape of 165 mm×165 mm and its surface grade and hot-workability as well as mechanical property have been tested under various casting conditions.
The results are summarized as follows;
(1) The increase in sulfur content in the range 0.014 to 0.32 wt% decreased the surface quality. The number of transverse cracks on the surface depended on the property of mold powders used. The mold powders with slow melting property and low viscosity after melting decreased remarkably the number of the surface cracks.
(2) The number of the longitudinal cracks was related to the carbon content and to the secondary cooling rate. When the carbon content was more than 0.09 wt% and the secondary cooling rate was 0.8 1/kg, internal cracks have been observed in the as-cast blooms.
(3) Surface smoothing by mechanical polishers was very effective for the improvement of the hotworkability of the cast blooms. A deep oscillation mark behaved as a notch upon hot rolling. A succssful hot-rolling was practiced, only when the ratio of manganese content to sulfur content was more than 9.0 and the oxygen content was less than 130ppm.
(4) The bars hot-rolled from the blooms continuously cast showed same mechanical properties as the conventional ones. Because the forging ratio of the continuous-cast bars is smaller than that of the conventional ones, the non-metallic inclusions are not elongated and thus, the former has shown the better machinability.
