Solidification of high-Cr white cast iron–WC particle reinforced composites

A double casting technique using sand casting that has been developed to produce a high-Cr white cast iron (WCI) based material having an in situ and ex situ carbide particle reinforced wear resistant composite region that extends to a depth of 5–8 mm below the working surface is described. The WC particles were directed to a specific location in the ingot and were distributed uniformly in the working region of the material. The casting technique ensured chemical bonding between the high-Cr WCI and the particle reinforced composite (working region) at a well defined interface parallel to the working surface. The solidification of the melt started around the WC particles after they had settled in the near surface region of the casting. Around the WC particles three reaction zones were formed. Owing to partial dissolution of the WC particles and the resulting interdiffusion of elements such as W, Co, Fe, C and Cr, carbides containing Fe, Cr, W and Co were formed in the reaction zones. The wear behaviour of the WCI based composite material was significantly better compared with that of the standard material used in an industrial application.