鋳鉄の焼入硬化に関する研究（第3報）鋳鉄の焼入歪と残留応力との関係

Abstract

Quenching strain and crack have an intimate relation with internal stress originate from quenching. Experiments were carried out to investigate this relation in cast iron treated by ordinary quenching and high frequency induction heating. The specimens used were flake graphite, and spheroidal graphite cast iron, which contain the typical form of graphite in cast iron, and 0.5%C steel. This relation changes considerably according to the quenching method and the form of graphite in cast iron. Strain and residual stress in specimens treated by ordinary quenching were found passably larger than that in induction heated specimens. Nodular graphite cast iron shows a tendency similar to 0.5%C steel on the stress distribution and strain, but flake graphite cast-iron shows a different tendency from both of them. As a characteristic in stress distribution and its strain of flake graphite cast iron different from the case of nodular graphite cast iron and steel, the value of compressive stress on the tangential direction near the surface is rather small, in spite of the large value of the expansion of the outer diameter, while that of the inner diameter is small, that is, the relative difference of the two values is larger than in the case of nodular graphite cast iron and steel.