THE DIMENSIONAL STABILITY OF SELECTED ALLOY SYSTEMS
Final rept. for 1 Jun 1963-31 Aug 1964
ALLOYD GENERAL CORP CAMBRIDGE MA
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Elastic limits, elastic moduli, stress-total strain and stress-plastic strain curves were determined for free cutting Invar 36, 356-T6 aluminum, 310 stainless steel, 6061 aluminum and AZ92A magnesium at 75, 150 and 200F. The creep behavior of these alloys was studied at the same temperatures of interest at stresses above, below and at the elastic limit. In all cases it was found that the precision elastic limit did not define the minimum stress to cause creep, in fact creep took place at stresses below the elastic limit at a much reduced rate. The data was analyzed in the light of current creep theory and microyield theory. A dislocation model was used to derive analytic expressions for creep near the 1000000 elastic limit stress. Below the elastic limit creep was found to follow an exponential time dependence, while above the elastic limit a tn time dependence was followed with values of n from 13 to 12. The dimensional changes taking place in these alloys under storage conditions at the three temperatures of interest is also presented.
- Properties of Metals and Alloys