MATERIAL STRENGTH EVALUATION METHOD OF METAL MATERIAL AND METHOD AND DEVICE FOR DIFFUSION LAYER THICKNESS EVALUATION

摘要

PROBLEM TO BE SOLVED: To make possible evaluation of material strength by measuring conductivity of precipitation strengthened metal material strengthened by precipitating a precipitation phase in a parent phase and obtaining a mutual boundary length based on relationship between a predetermined conductivity and the mutual boundary length of the precipitation phase. ;SOLUTION: For a precipitation strengthened nickel group ultra-alloy IN 738 LC, a precipitation phase of a NI₃AI phase is dispersed in a parent phase of a Ni solid solution body, material strength of a material in which a fine precipitation phase is dispersed evenly is generally strong. This conductivity is measured by a tetra terminal method. The conductivity of this material varies depending upon a mutual boundary length L of the precipitation phase. That is, when the mutual boundary length L is long the conductivity is lowered, and when the mutual boundary length L is short the conductivity is higher. Assuming that an average mutual particle size of the precipitation phase is d and that a distance between crystal granules is λ, the result is L=πd/λ² and d/λ² has correlation with a creep strength. Consequently, the mutual boundary length L is obtained from correlation database predetermined by measuring conductivity and converted into d/λ², making it possible to estimate the creep strength.;COPYRIGHT: (C)1998,JPO