U71Mn钢轨表面激光熔覆Fe基合金组织与性能研究

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摘要研究目的：随着列车运行速度的大幅提高,对钢轨的耐磨性能及滚动接触疲劳性能提出了更高的要求。为提高钢轨的耐用性,本文利用激光宽带熔覆技术对U71Mn钢轨表面进行强化,采用同步送粉方式进行自熔性Fe基粉末的激光熔覆,目的是获得厚度1 mm左右无裂纹、气孔等缺陷,且与钢轨冶金结合的高性能激光熔覆层。

研究结论：通过测试分析和试验结果表明,在CO2激光功率4 200W、扫描速度为300 mm /min、送粉速率18 g /min等工艺条件下,可获得厚度1 mm的优质涂层,其显微硬度平均值可达HV780,高于熔合区及基体的硬度,在过渡区处存在硬度拐点,但经静载抗压实验看出,涂层在453 kN静载荷下无开裂现象。激光熔覆涂层的组织主要由C-Fe、Cr0. 19Fe0. 7Ni0. 11、NiCrFe、FeCr等物相组成,但是在熔合区靠近基体处有马氏体组织形成,是由于激光快速加热及快速冷却造成的。

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	杨胶溪
	刘华东

关键词 ：激光熔覆, 钢轨, 铁基合金, 组织与性能

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.

Key words： laser cladding rail surface Fe -based alloy microstructure and property

收稿日期: 2009-08-13

PACS:	TG665
	TG174. 4
	TG155. 5

基金资助:北京市09科技创新平台(1010005366901);北京市自然科学基金(3092008);北京市教委科研计划(KM200910005022)

作者简介: 杨胶溪, 1971年出生,男,副研究员;刘华东, 1984年出生,男,硕士研究生。

引用本文:

杨胶溪，刘华东. U71Mn钢轨表面激光熔覆Fe基合金组织与性能研究[J]. 铁道工程学报, 2010, 27(7): 34-37.
YANG Jiao—xi，LIU Hua—dong. Research on the Microstructure and Properties of Laser Cladding Fe—base Alloy on U71 MU Rail Surface. 铁道工程学报, 2010, 27(7): 34-37.

链接本文:

http://tdgcxb.crec.cn/CN/ 或 http://tdgcxb.crec.cn/CN/Y2010/V27/I7/34

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