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| Research on the Microstructure and Properties of Laser Cladding Fe—base Alloy on U71 MU Rail Surface |
| YANG Jiao—xi，LIU Hua—dong |
| Beijing University of Technology，Beijing 100124，China |
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Abstract Research purposes: With much increase of train running speed，the higher properties of weal"一resistance and rolling contact fatigue—resistance are required to the rail．For increasing service life of the rail，the surface of U7 1 Mn rail Was strengthened by wide—band laser cladding technique．In order to obtain high—performance about 1 mm thick coating free of cracks and pores that metallurgically bonded with the rail matrix，the cladding process Was conducted by C02 laser with direct injection of the Fe—based powder into the molten p001．
Research conclusions: The results of experiments and analysis showed that high quality cladding coating with the thickness of about 1 mm can be obtained under the conditions of laser power being 4 200 watts，scanning speed being 300 mm／min and powder feeding velocity being 1 8 s／min etc．The coating had a higher hardness value of HV780 than that of the SUbstrate material，but there existed a hardness knee point between the coating and the substrate．The laser cladding coating did not appear cracks under the static load of 453 kN．The organsof the Fe -based coating weremainly composed of C-Fe, Cr0. 19Fe0. 7Ni0. 11, NiCrFe and FeCr etc. The martensite structure was formed in the fusion area adjacent to the substrate because of the rapid heating and rapid cooling.
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Received: 13 August 2009
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[1] I.A. Polonsky, T. P.Chang, L.M.Keer, An analysis of the effect of hard coating on near-surface rolling contact fatigue initiation induced by surface roughness [J]Wear, 1997 (1 -2) : 204 -219.
[2] Makoto Akama, Tadao Mor,i Boundary elem ent analysis of surface initiated rolling contact fatigue cracks in wheel/rail contact systems [J]Wear, 2002 (1 -2) : 35 -41.
[3] A. Saulot, S. Descartes, D. Desmyter, D.Levy, Y. Berthier, Atribological characterization of the "damage m echanism " of low rail corrugation on sharp curved track [J]. Wear, 2006 (9 -10) : 984 -995.
[4] A. Saulot, S. Descartes and Y. Berthier, Sharp curved track corrugation: From corrugation observed on -site, to corrugation reproduced on simulators[J]. Tribology International, 2009(11 -12): 1691 -1705.
[5] 胡家杰,王文健,钟雯,等.弯矩作用下钢轨疲劳裂纹扩 展行为研究[J].铁道工程学报, 2008(9): 26 -29.
Hu Jiajie, Wang Wenjian, Zhong Wen, etc. Research on the G rowth of Fatigue Crack of Rail Steel under Moment of Flexure Condition [J]. Journal of Railway Engineering Society, 2008(9): 26 -29.
[6] Jonas W. Ringsberg, Anders Skyttebol, B. Lennart Josefson, Investigation of the rolling contact fatigue resistance of laser cladded twin -discspecimens: FE simulation of laser cladding, grinding and a twin -disc test[J]. International Journal of Fatigue, 2005 (6) : 702 -714.
[7] F. J. Franklin, G. -J. W eeda, A. Kapoor, E. J.M. Hiensch, Rolling contact fatigue and wear behaviour of the infrastar two-material rail [J]. Wear, 2005 (7 - 8): 1048 -1054.
[8] Martin Hiensch, Per -Ol of Larsson, Ol of Nilsson, Didier Levy. Two -material rail development: field test results regarding rolling contact fatigue and squeal noise behavior[J]. W ear, 2005 (7 -8) : 964 -972.
[9] JonasW. R ingsberg, Francis J. Franklin, B Lennart Josefson. Fatigue evaluation of surface coated railway rails using shakedown theory, finite element calculations, and lab and field trials [J] International Journal of Fatigue, 2005(6): 680 -694.
[10 ]M. Hazra, A. K. M ondal, S. Kumar, C. Blawert, Laser surface cladding of MRI 153M magnesium alloy with ( A l + A l2O3) [ J ]. Surface & Coatings Technology, 2009 (16): 2292 -2299.
[11]Guovjian Xu, Munaharu Kutsuna, Zhongjie Liu. Characteristic behaviours of clad layer by amulti-layer laser cladding with powder mixture of Stellite -6 and tungsten carbide [J]. Surface & Coatings Technology, 2006 (6): 3385 -3392.
[12]John C. Betts. The direct laser deposition of AISI316 stainless steel and Cr3C2 powder [ J ] Journal of Materials Processing Technology, 2009 (11): 5229 - 5238.
[13]杨胶溪,闫婷,王喜兵,等.激光宽带熔覆碳化钨/钴基合 金的组织与性能[J].金属热处理, 2007(11): 26 -29.
Yang Jiaoxi, Yan Ting, Wang Xibing, etc. Microstructure and Properties of Laser Wide -strip Clad W C /Co -Base Alloy [J ]. Heat Treatment of Metals, 2007(11): 26 -29.
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2010, Vol. 27 
