二，三の方法で製造したパーライト可鍛鋳鉄の機械的性質に対する統計的研究

抄録

  The prevalent processes to produce pearlitic malleable cast iron are as follows : 1) reheating of black-heart malleable cast iron, oil quenching and drawing. 2) direct oil quenching after the first stage graphitization and drawing. 3) air-cooling after the first stage graphitization and drawing. The authors investigated the influence of these different manufacturing processes on the relationship between several pairs of mechanical properties by “Streufeldanalysis”. It was confirmed that the relationship between Brinell hardness and tensile strength was almost independent on the manufacturing processes. It was, however, not the case with the relation between elongation and tensile strength or Brinell hardness. Elongation of pearlitic malleable cast iron produced by the process 1) was the lowest at each level of tensile strength or hardness, while that by the process 2) was the highest. It was also found that the 99.5%W_u-curve of elongation over tensile strength or Brinell hardness in pearlitic malleable cast iron was lower than the 50%W_u-curve of as cast spheroidal graphite cast iron which the authors obtained earlier.