Abstract
Following the first report (Tetu to Hagane, Vol. 23 (1937) p.787), the present paper dealt mainly with the effect of the forging ratio on the hardness at ordinary and high temperatures, the microstructure and the cutting efficiency of high speed steel tools. The author then gave a theoretical explanation of temper hardening phenomenon in the quenched and tempered high speed steels (especially, at different tempering temperatures between 500-600°C), by means of hardness test, thermal expansion test and microseopic test.
Moreover, the author studied the effect of the two different methods of producing sintered tungsten carbide series tools. One method is the direct production from the powder by using a self-recording compression tester attached to the specially devised apparatus which has been described in the first report. Another method is to prepare the tool by sintering after pressing the powder at ordinary temperature by using the specially devised apparatus. Finally, the author studied the effect of the grain size of the powder on the sintered carbide tool.
