ABRASION RESISTANCE OF THE COLUMNAR ZONE IN HIGH CR WHITE CAST IRONS

High chromium white cast irons are extremely abrasion resistant materi als due primarily to their high carbide content. In the columnar zone of cast structures, eutectic carbides grow parallel to the direction o f heat flow, forming a highly anisotropic morphology. In this US Burea u of Mines investigation, specimens taken from the columnar zone of th ese castings were tested utilizing a pin abrasion technique in order t o understand the abrasive wear behavior of the eutectic carbides in tw o directions: parallel (longitudinal) and perpendicular (transverse) t o the long axis of carbides. Also the effect of the matrix, as modifie d through a series of heat treatments, on wear rate was investigated. The longitudinal specimens showed 27-67% less volume loss than the tra nsverse specimens depending upon heat treatment.