PURPOSE: To detect crack generating characteristics of steel members non-destructively by comparing the specific resistances of said members before and after use.
CONSTITUTION: A change in the specific resistance of a steel member is determined by a four-terminal potential difference method. Af this time, the temp. of the member and a standard piece are made equal and the potential differences of the member and the standard piece are measured roughly simultaneously. Fluctuations in feed current, the sensitivity of a potential difference measuring instrument, and the temp. coefft. of specific resistance are removed. Since the relations between the specific resistance ρ0 of the member before use and the specific resistance ρx after use are expressed by the equation (I), crack generation characteristics are detected from this formula.
WATANABE HIROSHI
MATSUZAKA KIYOU
