激光增材制造金属陶瓷材料热力本构与裂纹机制研究

发布时间：2018-04-14 23:27

本文选题：激光熔覆 + 热力本构　；参考：《天津工业大学》2017年硕士论文

【摘要】：本文采用激光增材制造技术中的激光熔覆技术在45#钢板上制备五种金属陶瓷涂层,对涂层构建了残余应力数值模型,并对两种涂层分别进行了残余应力的计算,采用金相显微镜、扫描电镜(SEM)、能谱仪(EDS)对五种金属陶瓷涂层的裂纹、金属与陶瓷间的界面结合进行分析,并利用电化学工作站以及硬度计对两种涂层的耐腐蚀性和硬度性能进行测试分析。结果如下:(1)建立了金属陶瓷涂层的残余应力计算数值模型,并对两种不同配比的金属陶瓷涂层残余应力进行了具体的计算;(2)在相同的激光工艺参数下,不同配比金属陶瓷粉末凝固后的熔覆层组织还是会表现出不同的组织形态、分布规律和密度分布。随着陶瓷成分配比的逐渐增加,FJ-3与FJ-17+WC30%所得到的熔覆层的截面形貌质量是不同的,在70%配比下,涂层出现了纵向贯穿性裂纹,涂层的质量降低;FJ-17与钴包碳化钨所得到的熔覆层的截面形貌质量是逐渐降低的,涂层中的气孔和裂纹出现概率逐渐增大;氧化钛和氧化铝陶瓷相的添加,得到的涂层在陶瓷相添加量40%以后开始出现裂纹现象;对于碳化钛陶瓷相的添加,得到的涂层整体形貌良好。(3)通过激光熔覆技术得到的金属陶瓷涂层的裂纹类型主要有剪切裂纹、显微缩孔裂纹、夹杂裂纹三种,导致金属陶瓷涂层中裂纹产生的原因主要是残余应力在涂层中通过气孔、夹杂、硬质相处产生聚集,由三种裂纹源诱发裂纹的生成而出现裂纹。
[Abstract]:In this paper, five kinds of cermet coatings were prepared on 4steel plate by laser cladding technology. The numerical model of residual stress was constructed, and the residual stresses of the two coatings were calculated.The cracks of five kinds of cermet coatings and the interfacial bonding between metal and ceramics were analyzed by metallographic microscope, scanning electron microscope (SEM) and energy dispersive spectrometer (EDS).The corrosion resistance and hardness of the two coatings were tested and analyzed by electrochemical workstation and hardness tester.The results are as follows: (1) A numerical model for calculating residual stress of cermet coatings is established, and the residual stresses of two kinds of cermet coatings with different ratios are calculated concretely.The microstructure of cladding layer after solidification of cermet powder with different ratio will still show different microstructure, distribution law and density distribution.With the increasing of ceramic composition ratio, the cross-section morphology of the cladding layer obtained by FJ-3 and FJ-17 WC30% is different. At 70% ratio, longitudinal penetration crack appears in the coating.The surface morphology of the cladding layer obtained by FJ-17 and cobalt coated tungsten carbide decreases gradually, the probability of porosity and crack in the coating increases gradually, the addition of titanium oxide and alumina ceramic phase,When the amount of ceramic phase was 40%, cracks began to appear in the coating, and for the addition of titanium carbide ceramic phase,There are three types of cracks in the cermet coating obtained by laser cladding: shear crack, microshrinkage crack, inclusion crack, etc.The main reason for the cracks in cermet coatings is that the residual stress in the coating accumulates through pores, inclusions and hard materials, and cracks are induced by three kinds of crack sources.
【学位授予单位】：天津工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.4;TG665

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