ISO 20032-2013 pdf free download

ISO 20032-2013 pdf free download.Method for evaluation of tensile properties of metallic superplastic materials
Méthode de determination des caractéristiques de traction des ma téria ux mnétalliq ties superplastiques.
The rn-value in Formula (7) can be obtained from the slope of the line in a double logarithmic plot of stress and strain rate. In general, the rn-value depends on deformation conditions and materials in the range from 0 to 1, and a higher in-value leads to larger superplastic elongation.
On one test piece, conduct tests at S or more velocities (i.e. ‘ump 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 rn-value. Linear regression should be applied to this relationship by the method of least squares. Then round off the rn-value, as the slope of a straight line, to the first decimal place in accordance with ISO 80000-1.
7.8 Determination of the rn-value with the R-type test piece
The strain rate sensitivity exponent, rn-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 a(i1 and true strain rate E[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 beset at intervals of 3mm in the tensile-
axis direction. The Lest 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 101,
those at the left side as divisions 1—61 and 1—31 and those at the right side as divisions f+3j and 1+61.ISO 20032-2013 pdf free download.