PSI - Issue 33

Jesús Toribio et al. / Procedia Structural Integrity 33 (2021) 1203–1208 Jesús Toribio / Porcedia Structural Integrity 00 (2021) 000–000

1205 3

2.0

1.5

1.0

0.0 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 A6 A5 A4 A3 A2 A1 A0 σ (GPa) ε 0.5

Fig. 2. Stress-strain curves of the progressively drawn pearlitic steels A0 to A6 (steel family A: from 0 to 6 cold-drawing steps).

3. Metallographic analysis

Different types of inclusion were found, namely: (i) manganese sulphur (MnS) inclusions with dark (non brilliant) appearance and irregular shape; (ii) silica (SiO 2 ) and aluminum (Al 2 O 3 ) oxides with clear brilliant appearance and more regular shape. Two of these types of inclusions (MnS and Al 2 O 3 ) are showed in Fig. 3.

Fig. 3. Second-phase particles in a hot rolled pearlitic steel.

Apart from the inclusions discussed above (those appearing more frequently), other types of inclusions were found (although more scarcely) used mainly to create new phases during the steel manufacturing. They were the following: (i) titanium oxides (probably in the form Ti 2 O 3 ), (ii) manganese silicates (possibly of the type 2MnO.SiO 2 , MnSiO 3 ), alumina silicates (SiO 2 /AlO 3 ), (iii) titanium nitride (TiN), (iv) vanadium nitride (VN). The main chemical elements appearing in an inclusion can be observed in the EDX spectrum given in Figure 4.