Explain why a metal with a fine-grain microstructure

is better suited for fine blanking

than a coarse-grained metal.

A fine-blanking operation can be demanding;

the clearances are very low, the tooling is elaborate

(including stingers and a lower pressure

cushion), and as a result the sheared surface

quality is high. The sheared region (see Fig. 7.6

on p. 353) is well defined and constrained to

a small volume. It is beneficial to have many

grain boundaries (in the volume that is fracturing)

in order to have a more uniform and

controlled crack.