Multi-gradient directional solidification method for high-carbon steel ingot for inhibiting quenching cracks in large-sized marine shafting

Abstract

Disclosed is a multi-gradient directional solidification method for a high-carbon steel ingot for inhibiting quenching cracks in large-sized marine shafting. Molten high-carbon steel starts solidifying from a bottom by controlling a plurality of independent temperature-controlled cooling zones distributed along an axial direction of a casting mold. In a solidification process, cooling parameters of each cooling zone are independently adjusted, and an axially-varying non-linear temperature gradient field is actively established and maintained within a pasty region of the ingot. The temperature gradient field at least forms three regions of action with different cooling intensities: high-intensity cooling is applied in a first region to form a fine-grained dense solidification initiation end; moderate-intensity and variable cooling is applied in a second region to control stable directional growth of columnar crystals; lower-intensity cooling is applied in a third region to promote feeding and reduce center porosity.