Hall-Petch relationship of a TWIP steel

The grain size dependence of the tensile properties of a TWIP steel has been determined for a wide range of grain sizes obtained by grain growth after complete recrystallization of cold rolled material. The near-linear stress-strain behaviour typical of either TWIP steels or other materials that deform by twinning has been observed, the work hardening rate being larger for the smaller grain sizes. The Hall-Petch slope increases as a function of strain, from 350 MPa mu m(1/2) for the yield stress to 630 MPa mu m(1/2) for the maximum uniform strain in the tensile tests, epsilon congruent to 0.40. Profuse twinning is observed in deformed specimens by means of FIB-ISE.