What is ISO 10275- Determination of tensile strain hardening exponent about?

ISO 10275 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.

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), is used to give reproducible results.

Who is ISO 10275 - Determination of tensile strain hardening exponent for?

ISO 10275 on determining the tensile strain hardening exponent is relevant to:

Testing authorities
Sheet metal engineers
Metal forming technologies

Why should you use ISO 10275 - Determination of tensile strain hardening exponent?

The strain hardening exponent is the measure of hardness and strength caused by plastic deformation.

In the previous edition, for the calculation of the true strain, the elastic strain did not need to be subtracted from the total strain if it was lower than 10 % of the total strain. In ISO 10275, the elastic strain is subtracted from the total strain for calculation of the true strain, which is now referred to as “true plastic strain”. ISO 10275 is about a test method where a 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.

Overall, ISO 10275 is helpful as it assists the user with the sampling to obtain test pieces that would be in accordance with the requirements of the relevant product standard or, if not specified therein, by agreement.

What’s changed since the last update?

BS EN ISO 10275:2020 supersedes BS EN ISO 10275:2014, which is withdrawn. BS EN ISO 10275:2020 replaces the second edition (ISO 10275:2007), of which it constitutes a minor revision.

The main changes compared to the previous edition are as follows:

Clause 2 has been updated
New Clause 3 "Terms and definitions" has been added as per the latest Directives, Part 2
The symbol for true plastic strain has been changed from ε to εp

BS EN ISO 10275:2020

Metallic materials. Sheet and strip. Determination of tensile strain hardening exponent

Current, Under Review

Published:

30 Sep 2020