Prakt. Met. Sonderband 46 (2014) 127 
ı situ [5-11]. 3. RESULTS 
bserved up 
justment of 3.1 SETTING A DEFINED INITIAL MICROSTRUCTURE BY AUSTENITIZATION 
interactions 
lusions and The austenite grain size is one of the major influencing parameters for the formation of AF. 
es on the Therefore the setting of a defined austenite grain size before cooling the sample, in which 
sonventional the formation of AF occurs, and the determination of the austenite grain size are essential 
es are heat for a systematic investigation of the AF nucleation. 
n of the final A standardized method for the determination of the austenite grain size [16] exists, but 
5 paid to the within this study a computerized method is used in order to achieve optimized results with 
eters on the less time effort. Due to the small observed area in the HT-LSCM the analysis of austenite 
efits of the grain size is done best by optical microscopy after HT-LSCM treatment. For the grain size 
ited out. determination on the sample surface no chemical etching is necessary because of the 
thermal etching during the HT-LSCM treatment. The determination of austenite grain size 
inside the sample can be done after etching with picric acid. Fig. 2 illustrates the procedure 
of austenite grain size analysis, which is a combination of manual and computer based 
evaluation. Based on this computer aided method grain size distribution can be 
in Ti-alloyed determined, in contrast to the standardized methods [16] which just provide the amount of 
re done with grains per length or area unit. 
um induction 
the melt on 
was already 
e HT-LSCM. 
ind austenite 
w about the 
n the project Grain Size Tum 
Thermal etched Retraced austenite Computer based Grain size 
m sample surface => grain boundaries => evaluation => distributation 
fetallo- Fig. 2: Procedure of austenite grain size analysis 
yraphy / 
= In Fig. 3 the influence of austenitizing temperature on the austenite grain size is illustrated. 
It can be seen that the mean grain size increases with increasing treatment temperature. 
#0 po 00ST =1400°C 
JST T= 1300 °C Ty = 1200 °C 
Tan > 1200°C 
Analysis of 5 1000 
LSCM samples 2 
pe 5 
sy : a. 
Microscopy vs /250 “Cimin + = 4400°C 
f a 
/ 7 
200 400 600 5 200 400 600 
time {s] Austenite Grain Size [pm] 
Fig. 3: Tested austenitizing temperatures and the corresponding austenite grain size 
an distributions 
tion