Abstract: A rotary cutting tool for processing a metal workpiece includes an elongated solid body composed of cemented carbide containing cobalt. The body has cutting edge means at its forward end and an axis of rotation therethrough. The body has a surface of which cobalt content is greater than that of the remainder of the body. Part of the surface of the body is ground to remove the cobalt-rich surface therefrom.

Abstract: A method of manufacturing a cermet having high toughness and high hardness, which exhibits excellent impact resistance and wear resistance when used in cutting tools. A mixed powder is prepared which consists essentially of: titanium nitride, from 25 to 50 percent by weight; titanium carbide, from 10 to 30 percent by weight; at least one selected from the group consisting of tantalum carbide, niobium carbide, and zirconium carbide, from 5 to 25 percent by weight; tungsten carbide, from 10 to 25 percent by weight; and at least one selected from the group consisting of Co and Ni, and Al if required, from 7.5 to 25 percent by weight in total. The above mixed powder is compressed into a green compact. The green compact is sintered in a nitrogen atmosphere under a pressure within a range from 0.1 to 100 torr, and at a temperature within a range from 1400.degree. to 1550.degree. C.

Abstract: A tungsten cermet for use in cutting tools, including a carbonitride, having titanium and tungsten, and aluminum oxide. The cermet contains about 10 to about 50% by weight of the carbonitride, about 0.5 to about 10% by weight of aluminum oxide and tungsten as a binder. The tungsten cermet has excellent properties in toughness, impact resistance and oxidation resistance, combined with wear resistance and plastic deformation resistance, and is useful for cutting tools used in heavy cutting, hot working and the like.

Abstract: A super heatresistant cermet and process of producing the same. A mixture, which contains about 10 to about 65% by weight of a powder of the carbonitride having titanium and tungsten, about 0.5 to about 10.0% by weight of a magnesium oxide powder and a tungsten powder, is pressed to form a compact, which is thereafter sintered in a vacuum or in an atmosphere of a nitrogen gas or an inert gas within the temperature range of about 1800.degree. to 2700.degree. C. to thereby decarburize the carbonitride with the magnesium oxide evaporated during the sintering, whereby there is produced a super heatresistant cermet containing about 10 to about 65% by weight of a carbonitride containing titanium and tungsten, about 0.01 to about 1.0% by weight of magnesium oxide, and tungsten as a binder. The super heatresistant cermet is excellent in impact resistance, wear resistance and plastic deformation resistance, and suitable for cutting tools.

Abstract: A blade member for cutting tools comprises a cermet substrate having on a surface thereof a reaction layer. The reaction layer is composed of carbo-nitride of at least two metals in groups IV.sub.A, V.sub.A and VI.sub.A, the metals including Ti. The reaction layer may be composed of oxy-carbo-nitride of the above metals. The reaction layer may consist of inner and outer layers, the inner layer being composed of carbo-nitride of the above metals while the outer layer is composed of oxy-carbo-nitride of the above metals. The blade members with the reaction layer exhibits excellent toughness, wear resistance and thermoplastic deformation resistance. There is also disclosed a process for producing the above blade member.