Prakt. Met. Sonderband 30 (1999) 363 
Na Higher strength of high temperature phase indicates that B-type specimens not only are more stable 
Natel 10 and possess higher reversible deformation, but also are able to generate greater forces if compared 
ied to the A-type samples. In the case of martensite deformation (testing at room temperature), the B 
specimens are typified by lower forces necessary to the martensite reorientation or for stress 
Went “har . . . . Lo . 
Lo induced martensite formation. To obtain the same strains in A and B specimens, a lower force 
Ted vag (energy) i for the B i def tion if d he A Thi b 
gy) is necessary for the B specimens deformation if compared to the A ones. This can be 
explained on the basis of a summary effect of internal stresses generated in the matrix during 
training sequences and the external stresses applied during the bending test. The second reason is 
the easier growth of preferentially oriented martensite variants in material B in which the sweeping 
effect is more pronounced during training if compared to A (14). The observed results of 
mechanical tests were correlated with the substructure observations. The substructure of the 
material in as received conditions is shown in Fig. 3. It is evident that the substructure is 
predominantly formed of martensite B19' at room temperature. The martensite is internally twinned 
and this character of martensite is conserved even after the “soft training” procedure as follows 
from Fig. 4 (specimen A after 20 training sequences). 
1%) ranged 
ascribed to 
hese results 
ons (12, 13) 
ations and | | | | 
Jf tained B Figure 3: Substructure in as-received state. Figure 4: Specimen A after “soft training 
erties. The | . . 2 
ed at on The substructure of “hard trained” specimens B changes dramatically after 20 training sequences, as 
can be seen from Fig. 5. 
Figure 5: Substructure of specimen B after 20 training sequences (“hard training”). 
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