An investigation on rotatory bending fretting fatigue damage of railway axles

Abstract

Fretting damage failure analysis of a Chinese carbon railway axle RD2 was carried out. The wheel hub was in situ cut to expose the damaged surface of the wheel seat to avoid additional damage. A small‐scale axle test rig was developed, and simulation tests were performed at different rotator speeds of 1800 and 2100 rpm. The wear mechanism of fretting damage areas was a combination of abrasive wear, oxidative wear and delamination. The fracture surfaces exhibited characterization of multisource and step‐profile. The fretting fatigue crack initiated at the subsurface and propagated along an inclined angle at the first stage. The fretting damage at the higher speed was more severe compared with the lower speed, which lead to a relatively shorter fatigue life. The damage morphologies of the axle in the simulation tests were in good agreement with that observed in the failure analysis on real axle.

Fatigue limit of induction hardened railway axles

“…For the press-fitted shaft/flange joint at 1:3 scale, the maximum stress in the area of the critical wheel seat/axle body transition point was up to 2.5 times higher in the surface induction-hardened specimens than in the standard specimens with no surface heat treatment when subjected to the same number of cycles (Table 5). This result is in accordance with the results published by Makino et al 3 which show induction hardened S38C steel axles tempered at 200°C (used in Shinkansen trains) attaining fatigue limits in the range 270-300 MPa in the area of the press-fitted joint for 10 7 cycles.…”

“…Demands for higher reliability and safety of railway vehicles have brought intensive research of degradation processes in railway wheelsets and new approaches to wheelset design . Extremely high repeated contact stresses between wheels and rails cause rolling contact fatigue .…”

“…Extremely high repeated contact stresses between wheels and rails cause rolling contact fatigue . A very serious form of damage to wheel seats is fretting fatigue, caused by small‐amplitude oscillatory movement of wheels in press‐fitted seat/axle joints …”

“…1,2 A very serious form of damage to wheel seats is fretting fatigue, caused by small-amplitude oscillatory movement of wheels in press-fitted seat/axle joints. 3 Fatigue damage of railway wheelset axles is also one of the limiting factors in rail transport safety. [5][6][7][8][9] This is the main reason for the development of new axle design concepts giving higher resistance to fatigue crack initiation and propagation.…”

Effect of Cooling Condition on Fatigue Behavior of the Forged EA4T Steel

“…[4,5] Fatigue fracture impaired the security of the high-speed railway. [6][7][8][9] Moreover, previous studies showed that the forging process affected the grain size, second-phase particle size, and mechanical properties. [10][11][12][13] Song et al [9] indicated that the inclusions at the subsurface were most harmful to fatigue performance.…”