What is ISO 23703 - Guidelines for misorientation analysis about?
ISO 23703 discusses microbeam analysis. A microbeam is a narrow beam of radiation, of micrometre or sub-micrometre dimensions. ISO 23703 describes the guidelines for misorientation analysis to assess mechanical damage such as fatigue and creep induced by plastic and/or creep deformation for metallic materials by using the electron backscatter diffraction (EBSD) technique.
ISO 23703 defines misorientation parameters and specifies measurement conditions for such mechanical damage assessment. ISO 23703 is recommended to evaluate mechanical damage of austenitic stainless steel, which is widely used for various components of power plants and other facilities. In ISO 23703, mechanical damage refers to the damage which causes the fracture of structural materials due to external overload, fatigue and creeps excepting the chemical and thermal damages themselves.
Who is ISO 23703 - Guidelines for misorientation analysis for?
ISO 23703 on the guidelines for misorientation analysis is useful for:
- Medical facilities
- Educational institutes
- Biomedical laboratories
- Research facilities
Why should you use ISO 23703 - Guidelines for misorientation analysis?
Mechanical damage such as creep or fatigue, in engineering materials, can be assessed by misorientation analysis using the electron backscatter diffraction technique. The electron backscatter diffraction technique measures the crystal orientation of the sample surface by indexing electron backscatter diffraction patterns which are acquired by scanning its surface with an electron beam in a scanning electron microscope (SEM). It can give orientation maps and misorientation maps. To determine the degree of damage induced in the materials, the misorientations calculated from the mapping data are qualified by various parameters such as the local misorientation, which is an averaged misorientation between neighbouring measurement points, and intra-grain misorientations, which is an averaged misorientation between the reference orientation assigned to each crystal grain and measurement points inside the grain. These misorientation parameters correlate well with the degree of mechanical damage caused by deformation, fatigue and/or creep. Therefore, the magnitude of the material damage can be estimated using the correlation curve which represents the relationship between the misorientation parameters and the degree of the damage (hereafter called the correlation curve).
In the electron backscatter diffraction measurement, the crystal orientation is identified through electron beam illumination to the material surface, acquisition of the electron backscatter diffraction pattern by an image detector, and then crystal orientation identification by indexing of the electron backscatter diffraction patterns. It is shown that the point-to-point accuracy of the crystal orientation measurement is about 0,05° to 0,5°. The misorientation parameters vary depending on SEM conditions, observation conditions, electron backscatter diffraction pattern acquisition conditions and crystal orientation identification conditions. Several measurement parameters are determined for calculating the misorientation parameters. In particular, the local misorientation greatly depends on the distance between the measurement points (step size). Furthermore, the accuracy of the crystal orientation measurement and the definition of the misorientation parameters may depend on the hardware and software used for the measurement and analysis. There are several vendors of commercial electron backscatter diffraction measurement and analysis systems. The correlation curve obtained for a certain condition using a certain measurement system is not always comparable with other master curves obtained with different conditions or systems. Therefore, it is necessary to have a standard to measure comparable master curves to show the degree of mechanical damage by using any electron backscatter diffraction system. ISO 23703 describes measurement procedures and conditions and definitions of misorientation parameters independent of the measurement system in order to assess the damage of austenitic stainless steel precisely. Using ISO 23703 you can define misorientation parameters and specifies measurement conditions for such mechanical damage assessment.
