Semi-solid extrusion of steel grade X210CrW12 under isothermal conditions using ceramic dies

A self-heating ceramic tool is presented allowing for the semi-solid extrusion of steel grade X210CrW12 (material number 1.2436; AISI D6) under near-isothermal conditions at 1250–1350 °C. High-purity alumina (Al2O3) is used as recipient and die material. Steel bars of axis-symmetric geometry were extruded at very low process forces, as targeted in thixoforming. Except for process-related imperfections, good formability and reproduction of die geometry were observed. Extruded bars show excellent microstructural homogeneity. Apart from work piece quality the high die temperatures and thus reduced thermal shock impacts during extrusion allow for the application of thermal shock-sensitive oxide ceramics, e.g. alumina, as die material.