An Anomaly in Young's Modulus of High-manganese Austenitic Steel in Cold-worked States

Abstract

High manganese austenitic steels show a marked anomaly in the temperature dependence of elastic constants: an abrupt drop near the Néel temperature T_N and successive lowering below T_N Young's moduli in annealed and cold-rolled states of 18Mn-4Cr steels were measured from 150K to 350K by the resonance method of free-free transverse vibration. The abrupt drop of Young's modulus of this steel near T_N was extremely large in the annealed state, amounting to the ratio of about 20%. Such a step-wise change in Young's modulus disappeared with increasing the reduction of area in cold rolling and recovered gradually by subsequent annealing. This effect of cold rolling seems to be attributed to the predominance of internal stresses of dislocations over the generation of magnetostriction in the antiferromagnetic range.