Abstract
The metallurgical properties such as the hardness, toughness and grain size of carbide tools P 10, 30 and 25 are measured, and the relations between these properties and the cutting performance in turning and face-milling of carbon steels are examined. The results obtained are as follows. Although the carbide grades of high hardness are inferior to toughness and the resistance to early fracture, they are superior to the resistance to wearing and cracking in machining. The grain size of carbide grades is related with the wear resistance of the tools, and the carbide grades having coarse grains show the favourable performance in turning. In face-milling, the carbide grades having coarse grains and low hardness simultaneously show the poor performance and the moderate combination of the hardness and grain size exists in P 25. Furthermore in face-milling, the high grade such as P 10 has good wear resistance, but its range of cutting speed where the normal wear type appears is narrower than P 30 because of its poor toughness.
