For full-size 10 x 10mm specimens, the relation between Charpy impact energy and Charpy lateral expansion is shown in Fig.1. for various ferritic steels.
Up to a Charpy impact energy of about 100J, the corresponding lateral expansion can be approximated by:
LE(mm) = Charpy energy (J)/100
There is a reduction of lateral expansion at high Charpy energy levels for some ferritic steels, as can be seen, so this relation should not be used beyond 100J. For higher Charpy energies, a fit to the data is given in Fig.1.