PSI - Issue 3

Raffaella Sesana et al. / Procedia Structural Integrity 3 (2017) 459–467 Author name / Structural Integrity Procedia 00 (2017) 000–000

463

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rare traces of pre-euctectoid ferrite at prior austenitic grain boundaries. The tensile and fatigue samples were obtained from the sampling positions specified in EN 13674-1 (2010), i.e. their loading axis was parallel to the longitudinal axis of the rail, and it was located 10 mm below the surface of the fillet between the running surface and the side of the rail head. Specimens were obtained by means of turning and grinding. In Figure 2 the fatigue specimen geometry is reported. The geometry, different from EN 13674-1 (2010), was required for the testing machine gripping system. Surface finish requirement are compliant with EN 13674-1 (2010).

Table 1. Sample chemical composition. C Si Mn

P

S

Cr

Al

V %

N %

%

%

%

%

%

%

%

min max med. dev. med. dev. med. dev. med. dev. med. dev. med. dev. med. dev.

0.6

0.13

0.65 1.25

0

0

0

0

0

0

R260 (EN 13674 tab 5)

0.82

0.6

0.03

0.03

0.15

0.004 0.002

0.03

0.01

0.732 0.018 0.676 0.014 0.724 0.017 0.726 0.016 0.021 0.716 0.018 0.708 0.006 0.73

0.275 0.007 0.276 0.003 0.288 0.004 0.298 0.002 0.251 0.003 0.282 0.004 0.271 0.003

1.098 0.006 1.072 0.004 1.078 0.004 1.079 0.004 1.071 0.005 1.081 0.003 1.083 0.005

0.021 0.001 0.015 0.001

0.012 0.002 0.019 0.003 0.015 0.003 0.018 0.001 0.014 0.002 0.016

0.041

0.001

0.0062 0.0004 0.0064 0.0002 0.0066 0.0004 0.0062 0.0003 0.0069 0.0003 0.0066 0.0006 0.0062 0.0002

A

0

0

0

0.043

0.001

0.001

B

0

0

0

0.02

0.041

<0.001

0.002

C

0.001

0

0

0

0.02

0.039

0.001

0.001

D

0.001 0.019 0.001 0.016 0.001 0.022 0.001

0

0

0

0.043

0.002

0.001

E

0

0

0

0.03

0.001

0.001

F

0

0

0

0

0.013 0.002

0.037

0.001

0.002

G

0

0

0

Fig. 3. Microstructures of rails B (left) and C (right). Pearlite, traces of pre-euctectoid ferrite. Optical microscopy after Nital etching, 700 x.

Monotonic tensile testing specimens were obtained according to EN 13674-1 (2010) for what concerns geometry