| 摘要 |
PURPOSE:To obtain surface hardened metal suitable for use as material of cutting tools such as for high speed cutting, heavy cutting etc. by forming a carburized layer on the surface of shaped pure Ti and hardening by quenching. CONSTITUTION:After putting pure Ti 1 formed to desired shape in a vacuum furnace 2, the furnace is exhausted 2a to a vacuum. Then, the furnace is heated, and when the pure Ti 1 becomes about 650 deg.C, heating is stopped once and the temperature is maintained for a while by remaining heat. The pure Ti 1 is reheated to 1,050 deg.C and mixed gas of gaseous hydrocarbon such as propane and gaseous N2 is introduced 2b into the furnace 2 keeping the temperature constant, and surface hardening is performed by carburizing. That is, reducing atmosphere is made by the mixed gas, and activated C is generated, and the surface of the pure Ti 1 is carburized therewith to form a carburized layer. Consequently, surface hardened metal in which hardness equivalent to hard metal is given to the surface and toughness is given to the center to correct brittleness can be obtained. |
