Stress relaxation of an AISI 1080 steel

Abstract

Stress relaxation is a simple test which offers means for evaluating the deformation dynamics of materials. The principal advantage of this method is that it scans a broad range of strain rates while straining the specimen by only a small amount. Therefore, it is possible to assume that the substructure of the material remains approximately constant during the test in order to obtain the stress as a function of the strain rate during this particular strain condition. The principal inconvenience of this test is the requirement of a highly stable testing machine—especially at very slow strain rates. In the present investigation, stress relaxation tests have been done at room temperature on an AISI 1080 steel fabricated by Companhia Belgo-Mineira and used for prestressed concrete. The tests were done using a servohydraulic machine in the strain control mode. The results indicate the existence of a mechanical equation of state.