Prakt. Met. Sonderband 46 (2014) 141
bserved on For several intensity classes (like the classes in Fig. 4) of a given type of inclusions, the
the number average mass is first calculated based on algorithmic results and other experimental
number of parameters (e.g. the results of the analysis in concentration). The average ESD
(Equivalent Spherical Diameter) corresponding to each intensity class is then calculated as
tive level or the diameter of a spherical inclusion of the given composition and mass, thus transforming
samples to intensity classes into size classes. Fig. 5 shows an example of quantitative size distribution
n. Although analysis for aluminum oxide inclusions.
cular when
xmical OES “PT TTT umm odes see dsr
steel casting me
nclusions at -
obular, less oo
clusions into one
AT methods ®
. Comparing
e. add more
ons of such
)n screening geo md
distribution Fig.5 Quantitative size distribution of AlOs inclusions in 3 low alloy steel samples.
quality than Note the horizontal axis expressed in um and the vertical axis in inclusions/mm?®.
y size. In the
d S tot) and
counting the 5.2 QUANTITATIVE OXYGEN DETERMINATION
sses “small”,
ficient in the In many steel products, the cleanness requirements impose a low oxygen level, typically
olled. <30ppm for wires, <15ppm for tire cords and <10 ppm for bearings [1], which is not
possible to analyze quantitatively by standard spectrochemical OES methods (i.e. based
on calibration of PMT signals), due to low sensitivity. Fortunately, the Spark-DAT methods
allow performing such an analysis, by recalculating the Total Oxygen Content (TOC) from
the quantitative results obtained in terms of composition, number and size of the various
oxide inclusions from the Spark-DAT analysis.
Fig. 5 Determination of oxygen with the indirect Spark-DAT method, in certified
IARM low alloy steel samples (left) and in samples from the continuous casting
mold (right - with permission of R. Dumarey, ArcelorMittal, Gent).
he inclusions This method is called “indirect”, because the oxygen channel is not needed for the
determination. As demonstrated in Fig. 5, this determination gives outstanding results at
