BS/EN 14726-2019 pdf download.Aluminium and aluminium alloys – Determination of the chemical composition of aluminium and aluminium alloys by spark optical emission spectrometry.
— cleaning brushes for the counter—clecti-ode, If needed (the filaments should not contaminate the elect rode):
— particle trap for filtering the metal condensate out of the waste-gas stream;
— spare and expendable parts [or the spark optical emission spectrometer in accordance with the manufacturer’s instructions (e.g. counter electrode, insert br sample table, etc.).
7.2 Reference materials and recalibration samples
The certified reference materials, the reference materials (see ISO Cuide 301 and the recahibration samples should he listed amid documiwnted in a laboratory procedure:
— certified reference materials for calibration (see Clause 10)
— blank sample: high-purity aluminium or aluminium alloy prepared from high-purity constituents (e.g. Al Sn30) (see Cbiise 10)
— binary samples (if required e.g. for line interlerence correction (see Clauce 10))
— control samples for checking the accuracy of the calibration; they shall not be included in the calibration functions (see Clmisec 10 and Ii);
— samples for the control of the spectrometer drift (see Clause 12):
— recalihration samples for drift correction (see Clause 10).
8 Samples
8.1 Generalcase
Sampling plays an essential i-ole in the accuracy of the analytical results. Sampling allows obtaining laboratory samples whose dimensions are suitable for the preparation of test samples for S—OES and whose chemical composition shall represent that of the material to he tested.
Sampling of molten metal shall be carried out accor(ling to EN 14361.
Test samples, shall l)FCse11t a defined area which represents their average chemical composition. This area shall he sufficiently homogeneous across the test section. The position and size of tIm representative sample area varies with tlw sampling conditions, as well as with 11w type of alloy and tlw analytes.
NOTE I The test result only refers to the effective lest area which is the vaporised fraction of the sample. For the simultaneous multi-element analysis of different alloys, a mean analysis zone should be defined.
For S-OFS. there is an additional requirement: as far as possible. the metallographic structure in the test sample and in reference materials should he similar.
NOTI 2 Cylindrical samples with 040 mm x 30 mm (0 55 mm 3() mm) and disc samples with a central sprue, e.g. 0 50 mm x 10 mm or 0 55 mm 4,5 mm (also called plate or mushroom sample) are frequently used.
8.2 Sampling of linished and semi-finished products
A piece, suitable for use on the spark stand, is mechanically separated (e.g. by sawing) from the part to
he analysed (see NOTFj. Such piece shall have a minimum thickness of approximately 1 mm, cut in such
a way that allows the plane surface to be machined or otherwise prepared. Additionally, it should be
large enough for a sealing edge to protrude over the opening of the sample table (exception: air stand).
When using small samples, care should be taken to ensure that no overheating occurs due to sparking.
NOTl A small piece of any Ii nished or semi-timi ished product can miever ruly represent the whole and a sample of this tYpe cannot be used to certify a cast.
To check the homogeneity of a sample using spark spectrometry, the piece of metal or ingot can be analysed at various locations (e.g. along the diagonal through the part): special attention should therefore be given to areas susceptible to segregation.
Attention should be given to possible systematic deviations due to structural differences to the reference materials during evaluation.
A compromise for samples of sufficient size is to re-melt them in a suitable furnace under inert gas to produce a sample similar to those normally used for S-OFS. However, volatile elements, such as sodium, magnesiu in can be partially lost dun ng a re-melt i iig operation.
8.3 Sample preparation
For spark optical emission spectral analysis, a plane, flat surface in the representative area is produced on the sample by machining. Lathes and milling machines are used.
During final machining, the cutting speed, cutting angle and cutting tool should be chosen in such a way that no sample material Is raised above the machined surfaces and that no single hard grains are torn from a soft microstructure. A certain residual roughness promotes the formation of electric sparks (see manufacturer’s instructions). The machined surface shall not be touched directly with the fingers or otherwise contaminated, especially for the determination of sodium, calcium amid phosphorous.
For the sample preparation of reference materials, check the homogeneity of a sample using the same technique with the same machining parameters shall be used SO that a similar surface condition is achieved.
A compromise for samples of sufficient size is to re-melt them in a suitable furnace under inert gas to produce a sample similar to those normally.BS/EN 14726-2019 pdf download.