铁碳合金强流脉冲电子束表面合金化研究

发布时间：2018-06-08 06:26

本文选题：强流脉冲电子束 + 表面合金化　；参考：《江苏大学》2017年硕士论文

【摘要】：钢铁材料是目前使用极为广泛的工程材料之一,运用先进的表面处理技术来提高钢铁表面性能、延长使用寿命对世界工业的发展有着十分重要的作用。本文利用近些年来深受学者青睐的表面处理技术—强流脉冲电子束(HCPEB)装置,选用碳钢(20#钢、45#钢)和灰铸铁为基体材料进行表面Cr元素合金化处理。采用X射线衍射(XRD)对样品辐照前后的物相变化进行检测,使用光学显微镜(OM)、扫描电子显微镜(SEM)及透射电子显微镜(TEM)对合金化处理前后样品的表面形貌以及表层显微结构变化进行分析。使用维氏硬度计测试合金化处理前后样品的表面及截面硬度变化,并使用电化学工作站测试合金化处理前后样品的耐腐蚀性能变化。通过分析碳钢及铸铁材料在不同脉冲次数下,其试样表层组织结构以及表层硬度等性能的改变情况,建立脉冲次数—含碳量—表面合金化之间的影响机制。结果表明:20#钢和45#钢HCPEB辐照合金化后,两种材料样品表面都有熔坑出现。20#钢样品HCPEB辐照处理后,材料表面熔坑较45#钢样品浅,表面形貌看起来更均匀、平坦。两种样品表面都形成了合金化改性层,其厚度范围约为4~9μm之间,合金化层由重熔层和Cr扩散层组成。Cr在样品表面发生扩散,并在基体内与C元素结合生成颗粒细小的Cr23C6增强相。显微硬度测试结果表明,两种材料经HCPEB辐照合金化后,其表面明显得到强化,并且随着脉冲次数的升高,表面显微硬度值呈上升趋势,45#钢表面显微硬度提高幅度高于20#钢样品。电化学实验结果表明,HCPEB辐照合金化处理可显著改善20#钢和45#钢样品表面的耐蚀性能,其中,20#钢表面耐腐蚀性效果提高更为明显。利用HCPEB技术对灰铸铁材料进行Cr元素表面合金化,经过HCPEB辐照合金化后,样品表面有熔坑出现,同时表面石墨发生明显裂解、溶解现象。其表层均形成了厚度约为5~11μm的合金化层,合金化层由重熔层和Cr扩散层组成;Cr在样品表面发生扩散,基体内析出颗粒细小的Cr23C6增强相。显微硬度测试结果表明,合金化后的铸铁样品其表面强度得到明显优化,其效果随脉冲次数提高而愈加明显。电化学实验结果表明,铸铁材料合金化后其耐腐蚀性能改善不大,仅在高次数脉冲辐照合金化下略有增加。表面粗糙度、表层组织均匀性,Cr元素的固溶作用等因素共同决定了样品表层的耐腐蚀性。
[Abstract]:Iron and steel material is one of the most widely used engineering materials at present. It is very important for the development of the world industry to use advanced surface treatment technology to improve the surface properties of iron and steel and prolong its service life. In this paper, the high current pulsed electron beam (HCPEB) device, a surface treatment technology favored by scholars in recent years, was used to alloying Cr elements on the surface of carbon steel 20 # steel 4) and gray cast iron. X-ray diffraction (XRD) was used to detect the phase changes of the samples before and after irradiation. The surface morphology and microstructure of the samples before and after alloying were analyzed by means of optical microscope, scanning electron microscope (SEM) and transmission electron microscope (TEM). Vickers hardness meter was used to measure the surface and cross section hardness of the samples before and after alloying, and electrochemical workstation was used to test the corrosion resistance of the samples before and after alloying. The influence mechanism of pulse times, carbon content and surface alloying was established by analyzing the changes of surface microstructure and hardness of carbon steel and cast iron under different pulse times. The results show that after HCPEB irradiation alloying, there are melting pits on the surface of both kinds of samples. After HCPEB irradiation treatment, the surface melting pit is lighter than that of 4steel, and the surface appearance is more uniform and flat. The alloying modification layer was formed on both surfaces, and the thickness range was about 49 渭 m. The alloying layer consisted of a remelting layer and a Cr diffusion layer, which diffused on the surface of the sample, and combined with C element in the base to form a fine Cr23C6 reinforcement phase. The results of microhardness test show that the surface of the two materials is obviously strengthened after HCPEB irradiation alloying, and with the increase of pulse number, the increase of surface microhardness of 4steel is higher than that of steel 20#. The results of electrochemical experiments show that HCPEB irradiation alloying treatment can improve the corrosion resistance of 20 # steel and 4 # steel, especially the corrosion resistance of 20 # steel. The surface alloying of Cr element in gray cast iron was carried out by HCPEB technology. After HCPEB irradiation alloying, the surface of the sample appeared melting pits, and the graphite on the surface of the sample was obviously cracked and dissolved. The alloying layer is about 5 渭 m thick. The alloying layer consists of a remelting layer and a Cr diffusion layer, which diffuses Cr on the surface of the sample and precipitates a fine Cr23C6 reinforcement phase in the substrate. The results of microhardness test show that the surface strength of alloyed cast iron samples is obviously optimized and the effect is more obvious with the increase of pulse number. The results of electrochemical experiments showed that the corrosion resistance of cast iron was not improved after alloying, but only slightly increased under high frequency pulse irradiation alloying. The corrosion resistance of the surface layer is determined by the surface roughness and the surface structure homogeneity and the solid solution action of Cr element.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.445

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