Effects of Laser Cladding for Repairing and Improving Wear of Rails

다국어 초록 (Multilingual Abstract)

Laser cladding has been applied to reduce the wear on rails in a curved track. It is important to evaluate the wear and rolling contact fatigue (RCF) characteristics of laser cladding rails. This paper evaluated the wear characteristics of three types of laser cladding, i.e., Stellite 21, Inconel 625, and Hastelloy-C. The wear of Stellite 21 was reduced by 83% as compared to the untreated rail specimen, while those of Inconel 625 and Hastelloy C were decreased by 42% and 29%, respectively. Meanwhile, when laser cladding is applied, a cladding boundary between the rail and the laser cladding is created. The cladding boundary consists of the rail base material, the heat-affected zone, and laser cladding. At the cladding boundary, various types of microstructures are distributed, and as a result the hardness changes. The wear and RCF characteristics of the cladding boundary caused by rolling contact loads have been evaluated through twin-disc tests. Since Stellite 21 has low hardness at the cladding boundary, it suffered the most severe wear and damages in three types of laser cladding. If laser cladding is applied to reduce the wear of the curved track, the damage of the boundary, as opposed to the wear characteristics, should be taken into consideration. In this paper, Stellite 21 exhibits the best wear characteristics, but Hastelloy C is found to be the most appropriate when simultaneously considering both the wear and RCF of the cladding boundary.

참고문헌 (Reference)

1 Tyfour, W. R., "The steady state wear behavior of pearlitic rail steel under dry rolling-sliding contact condition" 180 : 79-89, 1995

2 Beynon, J. H., "Rolling contact fatigue of three pearlitic rail steels" 192 : 91-111, 1995

3 European Standard, "Railway applications – track –Rail. In EN 13674"

4 Grassie, S. L., "Rail corrugation : characteristics, causes and treatments" 223 : 1-18, 2009

5 Lewis, R., "Mapping rail wear regimes and transitions" 257 : 721-729, 2004

6 Simone Z., "Laser cladding with metallic powder" University of Trento 2015

7 Guo, Huo-ming, "Investigation on wear and damage performance of laser cladding Co-based alloy on single wheel or rail material" 328–329 : 329-337, 2015

8 Quan, L., "Investigation of a novel functionally graded material for the repair of premium hypereutectoid rails using laser cladding technology" 130 : 174-191, 2017

9 Lewis, S. R., "Improving rail wear and RCF performance using laser cladding" 366-367 : 268-278, 2016

10 Korean Standard, "Head Hardened Rails. In KS R 9110"

11 Jun, H. -K., "Fracture and fatigue crack growth analyses on a weldrepaired railway rail" 59 : 478-492, 2016

12 Workman, D., "Flash butt wedge repair of weld head defects" 1-7, 2011

13 Wang, W. J., "Eff ect of laser cladding on wear and damage behaviors of heavyhaul wheel/rail materials" 311 : 130-136, 2014

14 Seo, J. W., "Eff ect of friction modifi er on rolling contact fatigue and wear of wheel and rail materials" 61 (61): 19-30, 2018

15 Cuervo, P. A., "Correlations between wear mechanisms and rail grinding operations in a commercial railroad" 82 : 265-273, 2015

16 Lewis, S. R., "Assessment of laser cladding as an option for repairing/enhancing rails" 330–331 : 581-591, 2015

17 Seo, J. W., "Analysis of contact fatigue crack growth using twin-disc tests and numerical evaluations" 55 : 55-63, 2013

18 Saulot, A., "A tribological characterization of the damage mechanism of low rail corrugation on sharp curved track" 260 : 984-995, 2006