MINIATURE DRILL MADE OF PRESSURE SINTERED BODY OF MICROSTRUCTURE DISPLAYING EXCELLENT BREAKAGE RESISTANCE AT HIGH-SPEED BORING WORK

摘要

PROBLEM TO BE SOLVED: To provide a miniature drill made of a pressure sintered body of microstructure displaying excellent breakage resistance at high-speed boring work. ;SOLUTION: This miniature drill having a shank part and a groove forming part using a point face as a cutter face and having an outer diameter of 0.1-1.6 mm, is composed of a pressure sintered body having a fine grained structure in which a dispersion phase finely grained by including Cr, occupies 85-98 area % in average on the basis of the observation of the structure by a scanning electron microscope, the remained area is composed of a binding phase and an unavoidable impurity, the dispersion phase forming the pressure sintered body is composed of a single phase of a composite carbide solid solution of W, Co, Cr, including Co and Cr in tungsten carbide in a solid solution state in observing the structure by a transmission-type electron microscope under a condition that a content of Co is 0.1-3 wt.%, and that of Cr is 0.1-2 wt.% in average in the dispersion phase, and further the binding phase is composed of a Co group alloy single phase including 1-8 wt.% of Cr in average in the binding phase, in observing the structure by the transmission-type electron microscope.;COPYRIGHT: (C)2001,JPO