Provning av metalliska material

This part of ISO 14577 specifies the method of instrumented indentation test for determination of hardness and other materials parameters for the following three ranges: — macro range: 2 N ≤ F ≤ 30 kN; — micro range: 2 N > F; h > 0,2 µm; — nano range: h ≤ 0,2 µm. For the nano range, the mechanical deformation strongly depends on the real shape of indenter tip and the calculated material parameters are significantly influenced by the contact area function of the indenter used in the testing machine. Therefore, careful calibration of both instrument and indenter shape is required in order to achieve an acceptable reproducibility of the materials parameters determined with different machines. The macro and micro ranges are distinguished by the test forces in relation to the indentation depth. Attention is drawn to the fact that the micro range has an upper limit given by the test force (2 N) and a lower limit given by the indentation depth of 0,2 µm. The determination of hardness and other material parameters is given in Annex A. At high contact pressures, damage to the indenter is possible. For test pieces with very high hardness and modulus of elasticity, permanent indenter deformation can occur and can be detected using suitable reference materials. Indentations that result in damage or permanent deformation of the indenter are excluded from the scope of this test method. This test method can also be applied to thin metallic and non-metallic coatings and non-metallic materials. In this case, it is recommended that the specifications in the relevant standards be taken into account (see also 6.3 and ISO 14577-4). The analysis methods used in this standard do not take into account the effects of residual stress and indentation pile up or sink in the test piece material, both of which cause an offset to the indentation response that changes the calculated measured value.

ISO 14577-2:2015 specifies the method of verification and calibration of testing machines for carrying out the instrumented indentation test in accordance with ISO 14577‑1:2015. It describes a direct verification method for checking the main functions of the testing machine and an indirect verification method suitable for the determination of the repeatability of the testing machine. There is a requirement that the indirect method be used in addition to the direct method and for the periodic routine checking of the testing machine in service. It is a requirement that the indirect method of verification of the testing machine be carried out independently for each test method. ISO 14577-2:2015 is also applicable for transportable testing machines.

 This part of ISO 14577 specifies a method for the calibration of reference blocks to use for the indirect verification of testing machines for the instrumented indentation test as specified in ISO 14577-2.

This document specifies methods for testing metallic sheet materials to determine the stress-strain characteristics at high strain rates. This document covers the use of elastic-bar-type systems. The strain-rate range between 10−3 and 103 s−1 is considered to be the most relevant to vehicle crash events based on experimental and numerical calculations such as the finite element analysis (FEA) work for crashworthiness. In order to evaluate the crashworthiness of a vehicle with accuracy, reliable stress-strain characterization of metallic materials at strain rates higher than 10−3 s−1 is essential. This test method covers the strain-rate range above 102 s−1.

NOTE 1 At strain rates lower than 10−1 s−1, a quasi-static tensile testing machine that is specified in ISO 7500-1 and ISO 6892-1 can be applied.

NOTE 2 This testing method is also applicable to tensile test-piece geometries other than the flat test pieces considered here.