ISO 4499-4-2016 pdf free download.Hardmetals – Metallographic determination of microstructure – Part 4: Characterisation of porosity, carbon defects and eta-phase content.
5 Principle
This part of ISO 4499 handles the following key issues:
— description of methods for sample preparation;
— description of how to identify and measure the relevant feature.
In some cases, the approach adopted in Iso 4499-2 and Iso 4499-3 can be useful, whereby the intercept method is used on microphotographs of the structure for relevant quantification of feature size, such as eta-phase or graphite rosettes.
6 Apparatus
6.1 Metallographic optical microscope, or other suitable equipment permitting observations and measurements on a screen up to the required magnification.
6.2 Scanning electron microscope (SEM), permitting observations and measurements of features too small to be resolved with an optical microscope.
6.3 Equipment for preparation of test-piece sections.
7 Calibration of measurement apparatus
For reliable quantitative measurements, images shall be calibrated against a stage micrometre or scale traceable to a National Reference Standard. The most commonly used stage micrometres for SEMs are the SIRA grids. These are ruled lines which form a grid and are available with 19,7 lines/mm and 2 160 lines/mm. However, these shall also be calibrated and certified as being traceable to a National Reference Standard.
For images obtained from an optical microscope, an image of the calibration graticule shall also be obtained using the same objectives (and internal magnification step changers or zoom position) and illuminating technique. The microscope shall be set up for Köhler illumination to obtain the maximum resolution, see Reference [4].
For images obtained from a scanning electron microscope, images of the graticule should be obtained under the same conditions (accelerating kV, working distance, illumination aperture) as those used for the hardmetal.
8 Preparation of test samples
8.1 Methods of preparation
There are several methods for the preparation of hardmetal surfaces for metallographic examination. For example, a detailed description is given in ISO 4499-1. Firstly, careful coarse grinding is carried out to remove sufficient material to ensure that the true structure is revealed. After grinding with fine diamond grit wheels, polishing is effected by using diamond paste or diamond powders of progressively finer grain size down to 1 urn on rigidly supported laps of, for example, thin plastic, thin felt or paper.ISO 4499-4 pdf free download.