ISO 20032:2013 pdf free
ISO 20032:2013 pdf free.Method for evaluation of tensile properties of metallic superplastic materials
On one test piece, conduct tests at 5 or more velocities (i.e. jump tests) to obtain the relationship between 10 % flow stress at each cross-head velocity and the corresponding true strain rate, which should be plotted on a log-log scale. This procedure may be repeated on several test pieces to determine the uncertainty in the m-value. Linear regression should be applied to this relationship by the method of least squares. Then round off the m-value, as the slope of a straight line, to the first decimal place in accordance with ISO 80000-1.
The strain rate sensitivity exponent, m-value, shall be determined from the force and test-piece dimensions immediately before interruption as follows. The tensile test shall be interrupted when the elongation of the R portion reaches the specified values at two or more different cross-head velocities.
The minimum and maximum cross-head velocities shall be selected in such a manner that the difference between them amounts to between twofold and tenfold. Furthermore, it is specified that the amount of elongation of the R portion shall be normally 3 mm +0,5 mm, that can be regarded as the elongation in the initial deformation. For each test, the true stress σ[i] and true strain rate ε[i] at each division of a scale (see Figure 4) shall be determined as described in a) to g).
a) In the middle region of the R portion, five divisions shall be set at intervals of 3 mm in the tensile-axis direction. The test piece shall be placed with its tensile axis horizontal as shown in Figure 3.The division at the centre on the minimum cross-section of the R portion is named as division [0], those at the left side as divisions [-6] and [-3] and those at the right side as divisions [+3] and [+6].ISO 20032 pdf download.
