Dependence of the Detectability of Flaws on the Distribution of the Magnetizing Field in the Vicinity of a Flaw

It is shown that the flaw detectability of the magnetic-powder inspection method depends on the ratio of the normal H _n and tangential H _t components of the field in the flaw's vicinity and that H _n/H _t < 3 is a condition that ensures the detectability of surface flaws.