INVESTIGATION RESULTS 
THERMALLY- INDUCED DEFORMATION 
SI After cyclic heat treatment in the temperature range between room temperature and 1050;C, a posi- 
tive change of length was determined at all investigated cooling rates. The plastic linear deformation 
de ray dependent on the number of cycles increased in an approximately linear way in the first range (F ig. 
0 fe ter N 1). After approximately 25 thermo cycles, the irreversible deformation behaviour of the material 
men rc showed saturation effects. The measurement at a reduced cooling rate showed a significantly reduced 
el : deformation amount. 
Ne influence of 
forge duplex. alloy./ water... AR 2 
meer mei tv! Toiige duples alloy / air 
ont of the i UA el 
been put into a = | : 
ll. The tempera- jy ie N 
T curve tosether ’ 20 25 30 
hss determined cycle no. [1] 
Fig. 1: plastic linear deformation after cyclic heat treatment 
THERMALLY-INDUCED MICROSTRUCTURAL CHANGES 
Compared to the initial state of the microstructure, a significant microstructural change was to be 
MC NE detected after heat treatment at 1050;C. Fig. 2 - 3 show this difference with magnification being the 
€ dectrolytich- same in both figures. The initial state was characterised by a strongly anisotropic rolling structure. 
Te omy The relevant phase domains coagulated due to the repeated cyclic heat treatment between room 
ital bee temperature and the temperature of solution heat treatment. The rolling direction, which had clearly 
’ been identified initially, was to be identified only faintly after cyclic heat treatment. In the figures, 
ferrite is represented by dark colours and austenite by bright colours. In order to describe and quan- 
tify the coagulation effect, the directional development of the phase size in ferrite and austenite was 
described 
+ gourse of X-ray 
urpose diffracto- 
{ the x-ray inten- 
procedure. The 
Fig. 2: Light-microscopic image of the initial Fig. 3: Light-microscopic image of the 
state material cycled at 1050;C 
305