Examination of Elastic and Plastic Deformation Mechanisms of Aluminum using Temperature Measurement Method

Abstract

It is widely known that elastic deformation is a reversible process and plastic deformation is an irreversible one in metal. In this paper, the temperature change of various aluminum specimens during the tension or compression tests up to the plastic region was measured by using copper-constantan thermcouples of 50μm diameter and the deformation process was examined by comparing the experimental results with the numerical ones in which the heat conduction and heat transfer are taken into consideration. The specimens were deformed up to about 16 percent strain under a range of strain rate from 4×10-4S-1 to 3×10-2S-1.The following results are obtained. In the compression test, the yield point was clearly observed in the temperature curve obtained at a low strain-rate level. The intermittent plastic deformation like the serration appearing in a stress-strain curve produced the serrated temperature change. Consequently, it is supposed that the temperature change of a specimen corresponds to the micro deformation mechanism. The loss due to heat transfer is weaker than that due to heat conduction, so that the specimen temperature is mainly determined heat generation due to the conversion of plastic work and heat loss to the tool by means of heat conduction.