Cold work loss during heat treatment and extrusion of Nb-46.5 wt.% Ti composites as measured by microhardness

The authors utilized the simple technique of hardness measurement as a probe of the retained cold work in variously treated Nb-Ti monofilament rod stock, and they compare these results on extruded multifilament rod stock. In this experiment the cold work loss which occurs during monofilament heat treatment and multifilamentary extrusion was directly measured by comparing the Vickers hardness of the same Nb-46.5wt.%Ti alloy stock which had been cold drawn at room temperature, heat treated and cold drawn, and warm extruded. Depending on the strain state of the filaments prior to extrusion, a strain loss between 1.4 and 5.4 was determined in the extruded billet filaments. This is a very significant loss range given that the total strain space of most multifilamentary stacks lies in the range of 11-12.<>