About the intensity evaluation by the strength reduction of flake graphite cast iron by mixing of Pb, and acoustic velocity

Hatori, Masakazu; Kobayashi, Takanori; Sakamoto, Tsutomu; Nakae, Hideo*

Since the fall of tensile strength was accepted in high P cast iron which is a kind of flake graphite cast iron, when chemical component analysis was carried out, content of a little Pb(s) and Ca was checked. The Widmannstatten black lead which abnormalities produced in the form of flake graphite was observed by the metal organization of the elegance concerned. For this reason, evaluation of the soundness about other having existing delivered is called for. Although evaluation by the SUMP method was also possible about the existence of Widmannstatten black lead, since carrying out to having existing delivered had a big problem in workability, the valuation method by a non-destructive test was searched for. From it having been reported to the acoustic velocity which spreads the inside of tensile strength and a sample in flake graphite cast iron that correlation is seen, About whether the same relation is realized also in the flake graphite cast iron which widow Widmannstatten black lead which is black lead-shaped abnormalities generated, it checked by carrying out sonic measurement by an ultrasonic thickness gage. Generating of the abnormalities (Widmannstatten black lead) of the black lead form by mixing of Pb and the fall of the tensile strength accompanying this were accepted, and the result checked that correlation was between the acoustic velocity which spreads the inside of a sample, and tensile strength. Thereby, it is thought that discernment by un-destroying of flake graphite cast iron with the possibility of Pb mixing was attained.