This International Standard specifies a method for determining the tensile strain hardening exponent n of flat products (sheet and strip) made of metallic materials.
The method is valid only for that part of the stress-strain curve in the plastic range where the curve is continuous and monotonic (see 7.4).
In the case of materials with a serrated stress-strain curve in the work hardening range (materials which show the Portevin-Le Chatelier effect, e.g. AlMg-alloys) the automatic determination (linear regression of the logarithm true stress vs. the logarithm true plastic strain, see 7.7) should be used to give reproducible results.
A test piece is subjected to uniaxial tensile strain at a prescribed constant rate within the region of uniform plastic strain. The tensile strain hardening exponent n is calculated either by considering a portion of the stress-strain curve in the plastic region, or by considering the whole uniform plastic strain region.
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