Abstract
Machinability of spheroidal vanadium carbide cast irons (SVI) containing spheroidal vanadium carbide (VC) in structure was investigated. SVI contains carbon of 2∼3 mass% and vanadium about 10 mass% in addition to alloy composition of SUS 304. Specimen A containing VC and considerable plate-like type Cr-carbides, specimen B little Cr-carbides and specimen C very few Cr-carbides were produced by casting. SVI was markedly inferior to SUS 304 in machinability. In the turning of SVI, tool coating TiC and TiN on Al2O3 showed the longest tool life, and cutting had to be performed at low speed in carbide tool P20 or K20 because of increased thermal wear, and unsuitability ceramic tool is due to large grooving wear on the side cutting edge. In both turning and drilling, specimen C showed the best machinability, and specimen A worst among the three specimens. Reduction of Cr-carbide in structure is required in order to raise the machinability of SVI.
