Effects of Molybdenum Addition on Rolling Contact Fatigue of Locomotive Wheels under Rolling-Sliding Condition

Abstract

Rolling contact fatigue (RCF) damages often occur, sometimes even leading to shelling on locomotive wheel treads. In this work, the RCF damage behaviors of two locomotive wheel materials with different molybdenum (Mo) contents were studied, and the influence of depth of wheel material was explored as well. The result indicates that with the increase in the Mo content from 0.01 wt.% (wheel 1, i.e., a standard wheel) to 0.04 wt.% (wheel 2, i.e., an improved wheel), the proeutectoid ferrite content and the interlamellar spacing of pearlite decreased, the depth and length of the RCF cracks increased and the average RCF live of locomotive wheel steel improved by 34.06%. With the increase in the depth of material, the proeutectoid ferrite content and the interlamellar spacing of pearlite increased, the depth of RCF cracks increased, the length of RCF cracks of wheel 1 increased and then decreased whereas that of wheel 2 decreased, the RCF live showed a decrease trend for wheel 1, while the RCF life increased and then decreased for wheel 2. The processes of shelling can be divided into three patterns: cracks propagating back to the surface, crack connection and fragments of surface materials.

Review of laser cladding coating on wear and fatigue of railway wheels/rails

“…49 In addition, the experiments in this study were all conducted under dry conditions. However, railroad wheels inevitably encounter water (e.g., on rainy days), and cracks on the wheel surface can develop into peeling or even severe peeling due to the high pressure of the liquid trapped in the crack 50 . The large angle cracks on the cladding wheels may lead to more serious RCF damage than the untreated wheels.…”

Experimental study on wear properties of wheel and rail materials with different hardness values

“…The four rail steels show pearlite microstructure, which consists of alternating ferrite and cementite lamella [25].With the increase in the carbon content, the bulk hardness values of wheel and rail materials increase, whilst the proportion of proeutectoid ferrite in wheel steels decreases. The average pearlite lamellar spacing (Sp) was measured by the circular line method [26] In order to reduce the impact of sampling depth on hardness [27] and try to simulate the on-site contact condition, except for the ER8 wheel samples (because of the lack of new wheels, the sampling position of ER8 samples was about 20 mm deeper than other wheel samples), all samples were taken at the same depth of 5 mm below the wheel tread and the rail head. The hardness of ER8 is slightly lower than that of ER7 in this work (Table 1), while the hardness of the ER8 tread in field is generally slightly higher than that of ER7.…”