ISO 8049:2016 pdf free
ISO 8049:2016 pdf free.Ferronickel shot一Sampling for analysis
To be representative, a small ingot having a mass of 250 g to 1 000 g shall be obtained. This is obtained by blending and mass division of the intermediate sample made in accordance with 5.2 until the mass required for remelting is obtained.
Remelting shall be performed in conditions such that no variation in content (of either Ni or the impurities to be checked) occurs either during melting or casting of the final sample (slugs, rondelles,or small ingots).
In practice, the melting shall be done by induction heating in order to be carried out rapidly, it generally requires argon protection. The melted sample can be cooled and solidified in the melting pot itself, provided that argon protection is provided. However, it is much better to cast after melting by centrifuging. This ensures the following:
一an excellent homogeneity of the sample produced as a result of mixing the molten metal during its injection into the mould;
一a uniform crystalline structure which fosters a good repeatability of the measurements for physical analysis methods. The argon protection should preferably be maintained during centrifuging.
It is recommended that a reagent (such as aluminium chips in a proportion of 1 g/kg to 2 g/kg) be introduced to kill the shot to be remelted. Naturally, the dilution undergone by the sample can be taken into account to correct the nickel content found during final analysis.
If chips come from a single small ingot, due to the fact that cast small ingots are very homogeneous, it is not necessary to crush the chips.
NOTE This is all the more valid the finer the chips. Millings are finer than drillings.
If several small ingots have been cast it is useful, when possible, to crush the chips in order to achieve homogeneity between the chips from various small ingots.
In practice, crushability depends on the following:
一the nickel content, if it exceeds 35 %, the alloy becomes ductile and is difficult to crush;
一the impurity contents (above all carbon): high-carbon ferronickels can be crushed much finer than low-carbon ferronickels.
In the case of crushable ferronickels, a suitable crusher shall be used which does not introduce contamination with iron. Vibration mill laboratory crushers used for a duration of 10 s to 30 s are suitable. It is desirable that the crushing container be of tungsten carbide or, if this is not possible, of special anti-wear steel (ball-type or bar-type crushers are not permissible).ISO 8049 pdf download.
