7122 Cold Forming

Stainless steels and nickel base alloys are readily cold formed because they possess excellent ductility in the as-supplied condition (solution annealed). However, in comparison to mild steel, these alloys have somewhat higher strength and hence the need to have forming equipment with sufficient power commensurate with the mechanical characteristics of these alloys. Table 7.21 gives the mechanical properties of some of these alloys. Another point to consider is that nickel alloys have high strain-hardening coefficients and hence are subject to rapid strain-hardening, but because of their excellent ductility and uniform elongation, are capable of being reduced or drawn extensively without rupturing. However, due to the high strain-hardening the number of reductions between anneals is limited. Hence the nickel alloys require more frequent anneals in a progressive forming sequence in comparison to mild steel or standard stainless steels.

Since forming is very often accomplished with the same tools and equipment normally used for mild steels, it is very important and necessary to remove any

TABLE 7.21 Typical Room Temperature Mechanical Properties of Various Alloys

Alloy

UNS #

UTS (N/mm2)

0.2% Yield (N/mm2)

% El

0 0

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