Plastic deformation and microstructures of rail welds Supervisors:

A/Prof Wenyi Yan (http://users.monash.edu.au/~wyan/ ), Department of Mechanical & Aerospace Engineering,

Monash University, Australia

Mr Peter Mutton, Associate Director, Institute of Railway Technology, Monash University, Australia

Due to material inferior in the welding zone, the rail welds are the weakest links of rail tracks.

Figure 1 shows a few examples of rail weld fracture and damage. Rail weld failure is the result of

rolling contact fatigue, which depends on not only the increased dynamic wheel-rail contact loading

because of the railhead irregularity at the position of the weld resulting from welding but also the

plastic deformation and failure behaviour of rail welds. The latter is related to the microstructures at

rail welds and welding metallurgy process.

Figure 1. (a) Straight break failure in an aluminothermic weld, initiated from the weld foot; (b)

horizontal split web failure initiated from the mid-web on the weld collar surface (Salehi et al.,

2011); and (c) surface “squat” damage in the heat-affected zone at the surface of an rail weld

(Steenbergen, 2008).

We are looking for a PhD student to investigate the plastic deformation and failure behaviour of rail

welds in heavy haul railway systems for the transportation of mineral products. Uniaxial and biaxial

cyclic loading tests will be carried out to quantify the plastic deformation and failure behaviour of

rail weld samples under cyclic loading. The correlation between the macroscopic behaviour and the

microstructures of the rail steels will be investigated by characterizing the metallurgical

microstructures of the rail welds and the mechanical properties of these microstructures. The

metallurgical microstructures will be investigated by using scanning electronic microscope (SEM).

The mechanical properties will be measured by using nanoindentation tests. Additionally, the

numerical research by using the finite element method will be carried out to validate the measured

mechanical properties.

(c)

Applicants with a first class honours (or H1 equivalent) degree from the background of mechanical,

aerospace, materials or civil engineering are encouraged to apply. Further information can be

obtained by contacting Dr Yan (wenyi.yan@monash.edu).

Salehi, I., Kapoor A. and Mutton P. J. (2011). Multi-axial fatigue analysis of aluminothermic rail welds

under high axle load conditions. Int J Fatigue 33, pp. 1324-1336.

Steenbergen, M. J. M. M. (2008). Quantification of dynamic wheel–rail contact forces at short rail

irregularities and application to measured railwelds, J Sound Vib 312(2008) 606–629.