THE MECHANICAL-BEHAVIOR OF AN AISI TYPE 310-STAINLESS-STEEL

An AISI type 310 austenitic stainless steel was tensile tested over a range of strain rates, epsilon = 5 x 10(-5) to 5 x 10(-1) s(-1), and t est temperatures, T = 298 to 1073 K, in order to determine the strain rate and temperature dependencies of the plastic deformation behavior. It is found that both the yield stress, sigma(Y), and the ultimate te nsile stress, sigma(UTS), are linearly related to the natural logarith m of strain rate, In epsilon, at all test temperatures. Serrated yield ing (dynamic strain aging) was observed within a certain range of temp eratures and strain rates. The dynamic strain hardening stress, Delta sigma(H) = sigma(UTS) - sigma(Y), is larger for lower strain rates, an d the peak of the Delta sigma(H) vs T plot moves from about 700 to 100 0 K when the strain rate is increased from 5 x 10(-5) to 5 x 10(-1) s( -1). Both the yield stress and the ultimate tensile stress decrease wi th temperature in a similar manner. The ductility of the steel is also dependent on both temperature and strain rate. For lower strain rates (epsilon = 5 x 10(-5) to 5 x 10(-3) s(-1)), the elongation to fractur e, delta%, increases with temperature from about 38% (T = 298 to 873 K ) up to 75% (T > 900 K); for higher strain rates (epsilon = 5 x 10(-2) to 5 x 10(-1) s(-1)), delta% is smaller lying within the range of 29- 39%. The experimental results are analyzed in terms of thermal activat ion processes for plastic deformation of crystalline materials. It is shown that the activation Volume and activation energy are smaller at lower temperatures (298-573 K) and larger at higher temperatures (673- 1073 K) indicating two distinctive flow processes for the low and high temperature regions.