ISO 10275-2020 pdf download.Metallic materials – Sheet and strip – Determination of tensile strain hardening exponent.
5 Principle
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.
6 Test equipment
6.1 Tensile testing machine, verified and calibrated in accordance with ISO 7500-1 and of class 1 or
better. The method of gripping the test piece shall conform to the requirements of ISO 6892-1.
6.2 Extensometer, of class 2 or better (class I in the event of determination of the plastic strain ratio
r, see ISO 10113) in accordance with ISO 9513, for measuring changes in the gauge length.
6.3 Dimension-measuring equipment, capable of measuring the width and thickness of the parallel-
sided section of the test piece to within the tolerances specified for these dimensions in ISO 6892-1.
7 Test pieces
7.1 Sampling to obtain test pieces shall be in accordance with the requirements of the relevant product standard or, if not specified therein, by agreement. Machining tolerances, tolerances on shape, and the marking shall he as specified in ISO 6892-1.
7.2 In the event of the plastic strain ratio r and the tensile strain hardening exponent n being determined simultaneously, the conditions of ISO 10113 shall apply.
7.3 The thickness of the test piece shall be that of the full sheet, unless otherwise specified.
7.4 The surface of the test piece shall not be damaged (by scratches, etc.).
8 Procedure
8.1 In general, the test shall be carried out at ambient temperature, i.e. between 10 °C and 35 °C. Tests carried out under controlled conditions, where required, shall be made at a temperature of (23 ± 5) °C.
8.2 The test piece shall be mounted in the tensile testing machine (see 6J.) so that the force can be applied axially in accordance with ISO 6892-1.
8.3 In the plastic range, the strain rate of parallel length shall not exceed 0,008 s1, unless otherwise specified in the relevant standard. This rate shall be kept constant during the time interval over which the tensile strain hardening exponent is determined.
If a proof strength or the yield strength is determined during the same tensile test, the strain rate for this determination shall be as defined in ISO 6892-1.
8.4 When n is determined over the whole uniform plastic strain range, the upper limit for these data points shall be immediately prior to the strain at which the maximum force occurs.ISO 10275 pdf download.