Plastic deformation of 1020 steel over a wide range of strain rates and temperatures

The response of hot-rolled 1020 steel over a wide range of temperatures and strain rates is investigated. Pure shear tests have been conducted at strain rates of 5x10(-4), 2 and 1000 s(-1), and temperatures of 25, 200, 400, and 600 degrees C. Results show that temperature and strain rate greatly affect material response. In general, the stress decreases with increasing temperature and decreasing strain rate. At temperatures of 200-400 degrees C, however, effects of dynamic strain aging are very significant. At this temperature range, negative strain rate sensitivity is observed as well as a region of increasing stress with increasing temperature. Constitutive equations are developed for modeling the material response. The relations are based on a model of thermally activated motion of dislocations that include the effect of dynamic strain aging. The parameters in the constitutive relations are determined, and there is good agreement between the model and the tests. (C) 1997 Elsevier Science Ltd.