Abstract
The ductile-to-brittle transition (DBT) and plastic deformation behaviors were investigated in Fe-(02)mass%Cu alloys to understand the effect of solute Cu on the mechanical properties of ferritic iron. The DBT temperature of ferritic iron in Charpy impact test was lowered by the solute Cu although the hardness at room temperature was increased owing to solid solution hardening. Tensile tests revealed that the yield stress of the Fe-1mass%Cu alloy becomes smaller than that of the Fe-0mass%Cu alloy in the temperature range below 223 K through solid solution softening by Cu. The solid solution softening makes slip deformation easy to occur even at such a lower temperature and also at high strain rate. This leads to suppressing twin deformation which induces brittle fracture of ferritic iron at low temperature, and resulting in the shift of DBT temperature to lower side.
