COMPRESSION TESTING AT CONSTANT TRUE STRAIN RATES

A cam plastometer was designed and built to test metal specimens in compression over a range of constant true strain rates and temperatures. Commercially pure aluminum specimens were tested at room temperature at three strain rates. Repleted uranium specimens were tested at several strain rates and temperatures. True stress versus true strain curves were calculated and found to fit an equation of the form sigma = A (1 - e/sup B epsilon /) + C epsilon , where sigma is the true stress, epsilon is the true strain, and A, B, and C are parameters. The parameters A and C were found te increase with decreasing temperature and with lange increases in strain rate. The parameter B was found to be essentially independent of temperature, but a large increase of strain rate produced an increase in B. The use of the cam plastometer with statistical methods provides an accurate means of investigating the effects of temperature and strain rate on the resistance of specimens to compression. The effects of alloying elements, impurities, grain size, and thermal treatments on the resistance to compression may also be determined by this method. (auth)