鍛造した球状黒鉛鋳鉄の生長について

抄録

  In order to investigate the effect of the shapes of graphite on the growth of forged spheroidal graphite cast iron with flattened graphite nodule was cyclically heated to 950°C and examined. Both as-cast and grown irons were forged with the forging ratio of 25% and 50%. The growth of spheroidal graphite iron increased by forging, and especially in grown iron, the growth characteristics which had declined recovered extremely.
  The growth of spheroidal graphite iron increased by about 20% with the forging ratio of 25%, and by 10%, with the forging ratio of 50%. At the tip of the graphite nodule which was flattened by forging, there was a preferential reprecipitation of graphite after cyclic heating. Though the microstructure of the matrix did not change by forging, specific gravity and hardness of grown iron increased remarkably. Growth rate of iron decreased after previous 10% growth in air, but increased more than 2.0 times by forging with reduction of 25% compared with the unforged specimen. The characteristics of the growth of iron can be explained generally by the mechanism of irreversible migration of graphite. The recovery of growth by forging in grown iron may be due to the increase of graphite migration due to the mechanical reduction of grown voids.