PSI - Issue 37

Junpeng Li et al. / Procedia Structural Integrity 37 (2022) 582–589 Junpeng Li/ Structural Integrity Procedia 00 (2021) 000 – 000

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composition of wheel steel and U71Mn rail steel is shown in Table 1. The original microstructure of U71Mn rail steel is displayed in Fig.3.

Table 1. Chemical compositions of rail and wheel materials (wt %) and hardness. Specimens C Mn Si P

S

Hardness/HV0.5

ER7

0.52

0.80

0.40

≤0.035 ≤0.03

≤0.035 ≤0.03

277 298

U71Mn

0.65~0.77

1.00~1.40

0.15~0.35

pearlite

Fig.3. microstructures of rail materials before testing.

3. Results 3.1. Surface macro morphology analysis (1) Surface crack length analysis

When the specimen experiences different contact load cycles (N), the morphology of the contact surface and the corresponding surface crack size when the contact surface is magnified by 30 times are shown in Fig. 4. The surface crack length and frequency distribution of the main specimen under different load cycles is shown in Fig. 5.