抄録
The S-curves of 0.5%Mo-1.3%Cu cast irons containing 0.26 or 0.87% of aluminum and 0.12 or 0.26% of titanium were determined by metallographic and dilatometric methods. For subsequent experiment, cast irons containing 0.2 to 1.2% molybdenum and 0.5 to 2.3% copper were remelted in an alumina crucible, using a Tamman furnace. After addition of aluminum and titanium, molten iron was poured into sand mould to investigate the structure and hardness.
The isothermal pearlite transformation was retarded by the addition of aluminum, but in bainite range was not affective. By the addition of titanium, the transformation were extremely accelerated and S-curve moved to the left in both ranges of pearlite and bainite, and also the nucleation of both reactions was independed by inclusions of titanium compounds.
From the result of casting experiments, it was concluded as follows : Addition of aluminum showed a tendency to promote the formation of acicular bainite and to decrease pearlite matrix in the Mo-Cu cast iron studied. By addition of titanium, an acicular matrix having low hardness appeared in higher alloyed irons, which consisted of almost martensite matrix without its addition.
