Compositional and structural aspects of processing nickel-base alloys

Abstract

The effects of the principal alloying additions to nickel on the hot-working properties are considered and illustrated in terms of hot ductility and resistance to deformation. The reduction of hot-ductility and hot-working temperature range brought about by some major alloying additions is considered in relation to the restriction placed on the choice of hot-working processes. The effects on hot workability of minor elements are examined in two respects: a number of undesirable elements produce deleterious effects, whereas certain other elements are deliberately added to improve workability; precise control is required in the latter case. Macro- and microsegregation and grain size are reviewed in relation to the hot working of, primarily, the high-strength, high-temperature alloys. The benefits to be derived here from consumable electrode remelting and homogenizing sequences are considered. Recent developments which significantly influence the processing of the less easily worked alloys are examined, including thermomechanical processing and the pre-alloyed powder techniques for complex alloy manufacture.