High-speed tool steel gear cutting tool and manufacturing method therefor

A method of manufacturing a high-speed tool steel gear cutting tool, the method comprising:

• quenching a tool material comprising high-speed tool steel and which has been rough processed to a shape corresponding to a final shape of a gear cutting tool, to transform a structure of said tool material into martensite;
• tempering said tool material after quenching to transform any residual austenite dispersingly distributed throughout a matrix of said martensite structure formed by the quenching, into martensite;
• and
• finishing said tool material after tempering to a final shape,
• wherein said tool material after quenching is subjected to sub-zero treatment involving cooling and holding at a temperature of less than −150° C., and transferring any residual austenite which is dispersingly distributed throughout the matrix into martensite, to thereby transform the structure of said tool material after tempering into a structure in which residual austenite which is a starting point for chipping at the time of high-speed gear cutting does not exist in the matrix of said martensite.