For the purpose of quick and precise estimation of hot deformation resistance in Ni-base alloy, hot torsional tests were carried out on solid sectioned specimens of 42 kinds of alloys. The results were analyzed by means of a multiple regression equation based on Ludwick's semi-logarithmic formula and Zener-Hollomon's relation. Variables of the equation are not only strain rate and temperature but also alloy contents of 11 elements, i. e. C, Si, Mn, Cr, Co, Fe, Mo, W, Al, Ti and Nb.
Examinations of fitness of the equation were made on all of the Ni-base alloys, some 18-8 stainless steels and a low alloy steel. Consequently the fitness of the equation was fairly well except for an alloy containing a large amount of γ′ particles and the confidential limit for the estimation at 95% level was ±3.6kg/mmmm2. The equation also applied to prediction of deformation resistance under hot extrusion conditions and good correlation was found between the observed and calculated values.
Among the elements, W, Mo, Cr and Co strengthened, in the order of magnitude, the Ni matrix, while Fe softened slightly. C and Nb also showed considerable strengthening effect, though its reliability was a little bit low. It was found that hot deformation resistance was strongly influenced by lattice constant, diffusion constant, Young's modulus and melting point but not by stacking fault energy. This leads to predict that Ta sholud show considerable strengthening effect.