[A pattern analysis of stress-strain curves for Ag alloys. (Part 1) On stress-strain curves for Ag-Cu alloys (author's transl)].

Mechanical properties of the dental metals have been estimated from the value of tensile strength, yield point, elastic limit, elongation and so on. But when applying these values to practical dental problems, they are often find to be not available enough. And recently the electoronic computer has been developed and widyly used in various fields, so the author tried to analyze true stress-true strain curves for alloys as pattern by the computer. The flow curves in the region of uniform plastic deformation was expressed by the Hollomon model, sigma=FepsilonN, and in this paper, Ag-Cu alloys were studied in various contents and heat treatments. Results obtained are as follows [1] Theoretically, the equations should hold between experimental values--epsilonT, ST and calculated values --N, F(F/e)N, that is epsilonT=N, and ST=F(N/e)N. In the case of Ag-Cu alloys, these relations agree well with the theoretical equations. In other words, the shape of true stress-true strain curves for Ag-Cu alloys almost coincide with the theoretical approximate curves, sigma=FepsilonN. [2] Strain hardening exponent N is very dependent on the micro structures of Ag-Cu alloys, but plastic coefficient F is independent of the micro structures. Coefficient F is directly proportional to sigma T. [3] The relationship of F to N can be expressed by equation of F=R(N+1)/NN+1. This equation may be described to be another form of the strain energy equation. Therefore parameter R is dependent on the strain energy. And the plots by computer agreed well with the experimental values.