Book Description

A comparison was made of the surface quality, dimensions, chemistry, hardness, tensile properties, and recrystallization behavior of extrusions produced on a Model 1810 Dynapak highvelocity machine and on a 700-ton Loewy high speed extrusion press. Three temperatures were established which represented hot work, cold work, and a combination of hot and cold work, by making preliminary extrusions on the Dynapak machine. Arc cast billets, with a nominal diameter of 3 in. of two refractory alloys, a Mo-25W-0.1Zr alloy and a W-0.6Cb alloy, were then extruded at a constant 4/1 reduction ratio from the same three temperatures on both machines. The results of this work indicate that equally good surfaces can be obtained from either process when proper lubrication and die preparation techniques are used; a lower hot working temperature can be used for high-velocity extrusions; and, a lower recrystallization temperature is obtained in material cold worked on the Dynapak. The latter fact indicates that high-velocity-extruded metals retain a high degree of internal stress than conventionally-extruded metals.