The effect of pre-deformation on the ductility of chromium

Pure chromium produced via a powder metallurgical route exhibits brittleness at room temperature (RT) in the recrystallized condition. The ductile to brittle transition temperature (DBTT) lies between 220 °C (bending and tensile tests) and 300 °C (fracture toughness experiments). To increase the ductility at RT the effect of plastic pre-deformation has been investigated. Small pre-deformations above the DBTT result in ductility in bending and in tension at RT. Severe plastic deformation (SPD) by equal channel angular extrusion and by a special developed procedure leads to a significant increase in both in strength and in ductility. However it is important to avoid the nucleation of small cracks during SPD in order to achieve a very good ductility.