STRAIN-RATE SENSITIVITY OF DUCTILITY AND FRACTURE BEHAVIORS IN A FE-28AL ALLOY

The mechanical properties of Fe-28Al under a strain rate ranging from 10(-4) to 1300 s(-1) were tested in air and water at room temperature. The ductility, yield stress and ultimate stress of Fe-28Al are sensit ive to the strain rate and gradually increase with strain rate in all test ranges. The fracture surface observations indicated that the frac ture mode of Fe-28Al varies from complete transgranular fracture to a mixture of transgranular cleavage and intergranular fracture with stra in rate increasing from 10(-4) to 1300 s(-1). It is proved that enviro nmental embrittlement is a main factor controlling the ductility of Fe -28Al, even at high strain rate, and grain boundaries play different r oles in the ductility of Fe-28Al at low and high strain rate. (C) 1997 Elsevier Science S.A.