256 Prakt. Met. Sonderband 46 (2014) 
Starting from 35% of thickness reduction, the reagent highlighted some recurring structural ferrite pe 
modifications inside the austenitic regions, which tended to expand inside the y-grains as strong ir 
the deformation proceeded (Fig. 2). However, these regions cannot be strictly related to deforma 
SIM because cold working has been found that render a deformed area more anodic [8] phases 
and, therefore, different responses to chemical etching can occur inside the same phase. reductio 
In Lean DSS, the increased presence of faulted regions at low thickness reductions can be 
addressed to their more proneness to SIM formation [B=T], because austenite is less 
stable than in the other grades. On the contrary, the absence of structural modifications in 3.4. MA: 
SAF 2507 highlighted its great stability if compared to the other DSS. 
After del 
and 220 
3.2. HARDNESS level of - 
able to £ 
In all DSS, similar trends in hardness were observed. The presence of austenite gave rise the high 
to an HV increment conditioned by the high strain-hardening rate of the FCC phase, The rest 
especially in the first stages of deformation (Fig. 3). Respect to the other grades, a greater transforr 
(relative) increasing in hardness was observed in Lean DSS. 
In SAF 2101, the different curve slope after 15% of thickness reduction can be addressed 
to the unbalanced phase ratio characterizing this steel. In this grade, the ferrite was 
thinned in a minor extent respect to the other DSS — in which the presence of a 
considerable amount of strain-hardened austenite caused a greater thinning of the ferritic 
bands — and rolling mainly affected austenite. which was more refined and fragmented. 
—e— 2101 1 2304 
~~ 2304 
08-4 —=—2205 
or —1— 2507 
$ 06 - 
8 05] ao 
01 x A progre 
nr = SEE deforma 
thickness reduction (%) va riation 
the satur 
Figure 3 — Hardness curves (LH) and diffraction spectra (RH) of the deformed DSS that cold 
can be a 
thicknes: 
3.3. X-RAYS DIFFRACTION owing to 
saturatio 
The AR diffraction spectra were characterized by narrow peaks, owing to solubilisation inhomoc 
(Fig. 3), and the height of a(110) and y(111) principal peaks in SAF 2304 and 2507 
suggested a nearly-random grains orientation in both phases. On the other hand, the 
signal from a(200) and y(220) reflections in SAF 2101 and 2205 respect to the principal 
peaks revealed the presence of a strong initial texture in the AR-materials and the heights 4. SUM 
of y-peaks in SAF 2101 again underlined its unbalanced microstructure. Cold deformation 
caused a rearrangement of the grains and the peak broadening at the highest thickness In the pr 
reduction denoted the heavy grains of the phases (Fig. 3). were inv 
XRD measurements are widely employed to detect SIM in austenitic stainless steels, since various 
it can be easily revealed: however. if the martensitic transformation occurred. SIM and features 
210° ; 
250