ISO 2566-2:2021

This document specifies a method of converting room temperature percentage elongations after fracture obtained on various proportional and non-proportional gauge lengths to other gauge lengths.
Formula (1), on which conversions are based, is considered to be reliable when applied to austenitic stainless steels within the tensile strength range 450 to 750 N/mm2 and in the solution treated condition.
These conversions are not applicable to:
a) cold reduced steels;
b) quenched and tempered steels;
c) non-austenitic steels.
These conversions are not applicable when the gauge length exceeds  or where the width to thickness ratio of the test piece exceeds 20.