Prakt. Met. Sonderband 52 (2018) 217 
Ndi 
along is W 23.2 SIMULATION OF STRESS AND STRAIN DISTRIBUTIONS IN THE 
U MICROSTRUCTURE 
Displacement controlled simulations of tensile loading was performed on the FE model 
until average macroscopic strain of 1.2 % was reached. In Fig. 6 the distributions of von 
Mises stress (a-c) and equivalent plastic strain (d-f) in models with and without cracks at 
the last deformation step are depicted. 
0. —=] 2400 MPa 
3, Feferite, 
icrostructural | 20% 
1:30 diaorgr u 8 ; 
Fig. 6: Simulated distributions of (a-c) von Mises stress, (d-f) equivalent plastic strain in the 
FE model. (a, d) intact model, (b, e) crack in ferrite, (c, f) crack in martensite 
The simulation results of stress and strain patterns in the intact microstructure (a, d) and 
for comparison in the microstructure with cracks, located in the ferrite (b, e) or in the 
martensite (c, f) are presented in Fig. 6. In the microstructure without cracks, von Mises 
stress and equivalent plastic strain reached moderate values at the last loading step (a, d). 
High values of von Mises stresses concentrate at the crack tips in the “hard” martensite 
(marked with two arrows in Fig. 6c). In contrast to that, high strain concentrations, greater 
than 20 % are formed at the crack tips in the “soft” ferrite (marked with two arrows in 
Fig. 6e). 
3. RESULTS AND DISCUSSION 
se distributions . 
Si The microstructure of ferritic-bainitic steels like 22NiMocr3-7 is fine and very complex, 
consisting of hard and soft constituents, which are arranged locally in different patterns 
depending on the manufacturing history. The combination of chosen characterization 
methods — optical microscopy, EBSD and EDX — has been used to describe the 
microstructure of 22NiMoCr3-7 with segregation areas. Based on the experimental data