16Determination of percentage reduction of area (Z)

Percentage reduction of area shall be determined in accordance with the definition given in 4.7.

The two broken pieces of the test piece are carefully fitted back together so that their axes lie in a straight line. The minimum cross-sectional area after fracture ( $S_{\mathrm{u}}$ ) shall be measured to an accuracy of $\pm 2 \%$ (see annexes A to D). The difference between the area $\left(S_{\mathrm{u}}\right)$ and the original cross-sectional area $\left(S_{\mathrm{o}}\right)$ expressed as a percentage of the original area gives the percentage reduction of area.