Issue 30

J. Toribio et alii, Frattura ed Integrità Strutturale, 30 (2014) 424-430; DOI: 10.3221/IGF-ESIS.30.51

(a) (b) Figure 2 : Scanning electron micrographs: (a) air-cooled steel, (b) steel cooled inside the closed furnace.

Steel

PA

PS 15

PF 19

d C

(μm) (μm)

12

s 0 0.26 Table 1 : Microstructural parameters. 0.16 0.23

1200

1000

800

600

 (MPa)

400

PA PS PF

200

0

0.00 0.02 0.04 0.06 0.08 0.10  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.

E (GPa)

σ Y (MPa)

σ R (MPa)

ε R

RA (%)

Steel

PA PS PF

202 200 203

650 560 441

1105 0.067 33 1055 0.072 20

965

0.092 14

Table 2 : Mechanical properties.

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