Effects of preheating and carbon dilution on material characteristics of laser-cladded hypereutectoid rail steels
Effects of preheating and carbon dilution on material characteristics of laser-cladded hypereutectoid rail steels
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DOI：
10.1016/j.msea.2017.12.003
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发表时间：
2018-01-18
期刊：
影响因子：
6.4
通讯作者：
Wu, Xinhua
中科院分区：
文献类型：
--
作者：
Lai, Quan;Abrahams, Ralph;Wu, Xinhua
对于通常在重载条件下使用的过共析钢种，研究了预热条件和碳稀释对使用单熔覆层和双熔覆层的激光熔覆钢轨的微观结构和机械性能的影响。热影响区的显微组织表明，通过使用 350°C 的预热温度增加预热区域的长度，成功地抑制了对轮轨接触行为产生不利影响的马氏体形成。观察了过共析基体中碳的稀释情况，并研究了其对 410L 铁素体不锈钢沉积物显微组织的影响。 410L熔覆层中铁素体的形成归因于极低的碳含量，并且在铁素体晶粒边界上没有观察到碳化物形成。稀释带的厚度被确定为大约等于第一包覆层的厚度。由于在稀释带中形成马氏体，EBSD 获得的织构测量显示出随机趋势。为双重沉积开发了强凝固纤维结构，特别是在第二次沉积中。根据维氏显微硬度、剪切和拉伸屈服强度以及极限拉伸和剪切强度对 410L 沉积物进行机械表征，并与观察到的微观结构形态相关。
The impacts of preheating conditions and carbon dilution on the microstructural and mechanical properties of laser cladded rails using single and double cladding layers have been investigated for a hypereutectoid steel grades typically used under heavy haul conditions. The microstructures in the HAZ showed that formation of martensite, which has a detrimental effect on behaviour in wheel-rail contact, was successfully inhibited by increasing the length of the preheated region using a preheating temperature of 350 degrees C. Dilution of carbon from the hypereutectoid substrate was observed and its effect on the microstructures of the 410L ferritic stainless-steel deposits was investigated. The formation of ferrite in the 410L cladding layers was attributed to the very low carbon content, and no carbide formation was observed on boundaries of the ferritic grains. The thickness of dilution band was determined to be approximately equal to the thickness of the first cladding layer. Texture measurement obtained by EBSD showed a random trend owing to the formation of martensite in diluted bands. Strong solidification fibre texture was developed for double deposition, particularly in the second deposit. Mechanical characterization of the 410L deposits undertaken in terms of Vickers microhardness, shear and tensile yield strengths, and ultimate tensile and shear strengths were correlated with the observed micro structural morphologies.