Issue 30

J. Toribio et alii, Frattura ed Integrità Strutturale, 30 (2014) 424-430; DOI: 10.3221/IGF-ESIS.30.51 426 (a) (b) Figure 2 : Scanning electron micrographs: (a) air-cooled steel, (b) steel cooled inside the closed furnace. Steel PA PS PF d C (μm) 12 15 19 s 0 (μm) 0.16 0.23 0.26 Table 1 : Microstructural parameters. 0 200 400 600 800 1000 1200 0.00 0.02 0.04 0.06 0.08 0.10 PA PS PF  (MPa)  Figure 3 : Stress-strain curves (standard tension tests). The conventional mechanical properties obtained from the standard tension tests are shown in Tab. 2, beside the ductility measured by the reduction in area percentage ( RA ). The three pearlitic steels (PA, PS and PF) have the same Young modulus ( E ~ 200 GPa), but while the yield strength σ Y , the ultimate tensile strength (UTS) σ R and the reduction in area percentage RA increase with the increase of the cooling rate used for the thermal treatment of the material, the strain at UTS ε R decreases. Steel E (GPa) σ Y (MPa) σ R (MPa) ε R RA (%) PA 202 650 1105 0.067 33 PS 200 560 1055 0.072 20 PF 203 441 965 0.092 14 Table 2 : Mechanical properties.