94  Prakt. Met. Sonderband 38 (2006) 
Additionally hardness indentations, made to mark the places for corresponding LOM and t 
SEM pictures, are removed from the analysis. Grain boundaries between ferrite grains are 
identified by the relation of contour length of the segment and area of the segment. Us 
Figure 7 shows the result of image processing and analysis after comination, be 
segmentation and classification. The martensite and ferrite are detected as separate pr: 
phases, ferrite grain boundaries can also be identified, thus the aim of the classification is us 
obtained. lig 
a 
nc 
us 
Ferrite the 
Ferrite grain boundaries be 
ba 
qu 
Martensite W 
Si 
m 
gr 
fe 
Figure 7: Final result of classification step te 
ar 
cl 
5. RESULTS T! 
m 
In Figure 8, the area content of ferrite and martensite for one investigated dual phase steel Gi 
is shown. 104 LOM and 104 SEM images and the combined images of LOM and SEM te 
images are used for the quantification. The average value of martensite content is about Fo 
41%. 
: os _ . ” mr ar 
After identification of martensite islands and ferrite grains additional characteristics can be Si 
determined, i.e. particle sizes and form parameters. a 
Cc 
0 ..... Phase content ferrite 
. ro | 
u Ar : 
04 
oo 5 
u [4 
Phase content martensite 
04 es 
. ; ; ; I= 
=» 40 ® 8 00 120 
Image number 
Figure 8: Phase content of ferrite and martensite in a dual phase steel