METHOD OF DETERMINING THE TENSILE STRENGTH OF METALS
FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OHIO
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The most important task in modern metallurgy in the field of improving the strength of metals consists in finding means for changing the strength through the composition, heat treatment, etc. that will not only insure at any moment of strain an increase in the absolute values of resistance to displacement and tear but also in the difference between them. Test methods are described which were used to determine the distribution of the axial stresses at the moment of tear in grooved tensile specimens of St-45 steel. Results indicate that the resistance to tear as a characteristic of the strength of metal in a given state, determinable by the proposed method, possibly will prove to be a constant of the material. Experiments showed that, with the increase of plastic strain under tensile or torsional stress, the resistance to tear can be considerably increased or decreased, depending on the condition of the metal. It increases with the lowering of the temperature of the tests and follows an increase in resistance to strain limit of fluidity of St-45 steel down to the temperature of -110 degrees.