Structure and properties of Thixocast steels

Abstract

AbstractAbstractA die-casting system is described which utilizes the thixotropic nature of semisolid Rheocast slurries. This system has been developed to a pilot-plant scale at the Massachusetts Institute of Technology. This plant comprises a continuous Rheocaster which is used to produce ingot stock, a reheating furnace to reheat individual charges to the semisolid state, a 'softness indicator' to determine when the reheated charges are suitable for casting, and a commercial cold-chamber diecasting machine. This paper deals primarily with the structure and properties of Thixocast ferrous alloys. Discussion is given of control of primary particle size, phases, oxide inclusions, and microsegregation in AISI 304, 440C, and other steels. Structure–property relationships are also presented and comparisons made with the properties of conventionally cast and wrought alloys.