Issue 18

V. Di Cocco et alii, Frattura ed Integrità Strutturale, 18 (2011) 45-53; DOI: 10.3221/IGF-ESIS.18.05 51  [120] for 43.55°;  [112] for 54.39°;  [030] for 59.90°;  [003] for 78.72°;  [113] for 80.80°. Figure 9 : X-Ray spectra obtained from monotonic loading up to  g =5%. Figure 10 : X-Ray spectra obtained from monotonic loading up to  g =10%. When unloading from  g =10% to  g =5% martensite peaks [112] and [030] are not clearly evident, while [011] and [022] austenitic peaks grows which demonstrates the presence of both phases with a greater quantity of martensite as shown in Fig. 11. It is worth noting that the X-Ray spectra obtained during the monotonic loading stage under the same value of applied deformation is completely different, as shown in Fig. 9, where the main phase was the austenite. This is a direct consequence of the marked hysteretic behavior of the material, as shown in Fig. 3.b. The final step of the mechanical cycle consists in complete unloading, i.e. the applied load is removed and a final diffraction test was carried out; the corresponding spectra was compared with the initial one, as illustrated in Fig. 12, in order to observe possible irreversible effects during loading unloading cycles. The figure shows good agreement between 35 45 55 65 75 85 95 Counts [u. a.] 2 · θ [°] A ‐ [011] A ‐ [022] 35 45 55 65 75 85 95 Counts [u. a.] 2 · θ [°] M ‐ [120] M ‐ [112] M ‐ [030] M ‐ [003] M ‐ [113]