低温焼鈍を施した強靭鋳鉄の黒鉛化と機械的性質におよぼす炭素飽和度と硫黄の影響

抄録

  The purpose of this research is that the effects of the melting conditions and the relation between the degree of carbon saturation and sulphur on the low temperature annealing treatment are examined. The oxygen amounts in the chill-cast samples were analized. The annealing of the specimens was carried out at 500°, 550° and 600°C for hours then specimens were cooled in a furnace. The results obtained are summarized as follows;
  (1) The amounts of oxygen in the specimens prepared by the reducing refining which contain from 0.02 to 0.05 per cent sulphur were from 9 to 35 p.p.m. and those of oxygen in the specimens prepared by the oxidizing refining which contain from 0.02 to 0.07 per cent sulphur were from 26 to 60 p.p.m..
  (2) In the various degree of carbon saturation, the rate of graphitization of specimens prepared by the reducing refining which contain 0.05 per cent sulphur is lowest and the mechanical properties of this specimens are best. Generally, the tensile strength and hardness of the specimens which were annealed at 600°C for 6 hours are much lowered with the increase in silicon content from 1.8 per cent silicon.
  (3) In both as-cast and annealed state, when comparison was made in a constant tensile strength and deflective load, the hardness of the specimens prepared by the reducing refining is lower compared with that of the specimens prepared by the oxidizing refining. This means that the relative hardness of the former is lower than that of latter. Therefore, it may be said that the quality of the former is superior.