316L粉末选择性激光熔化成形工艺及力学性能研究

发布时间：2018-06-16 06:21

本文选题：选择激光熔化 + 工艺参数　；参考：《兰州理工大学》2017年硕士论文

【摘要】：选择激光熔化(SLM)技术可直接成形复杂结构的金属零件,成为了快速成形制造(RPM)技术中最有前景的技术。但SLM技术的发展时间尚短,国内基于该技术的基础研究还比较少。因此,本文以提高SLM成形零件质量为目的,对成形样件的致密度和力学性能进行了系统研究。研究的具体内容有:(1)单熔道成形规律的研究。以不同的线能量输入密度作为工艺参数,研究单熔道烧结表面质量。结果表明:按烧结表面质量可将其划分为四个区域(未熔化区、部分熔化区、充分熔化区、过熔区)。(2)工艺参数的优化。实验的工艺参数包括旋转角度(α )、铺粉厚度(h)、激光功率(P)、扫描速度(v)以及扫描间距(s)。优化结果为:α=600,h=0.04mm,P=310W,v=960mm/s,s=0.13mm,此时样件的致密度和力学性能最佳。(3)显微组织和断口形貌分析。观察SLM成形零件的表面微观形貌,其组织晶粒细小均匀,韧窝尺寸也均匀细小,这就表明样件力学性能相对较高。综合分析实验结果,能量输入密度φ=P/(vsh)可作为一个统一的参数来研究各工艺参数对样件致密度和力学性能的影响,φ存在一个最优值,此时,样件的致密度和力学性能最佳,当能量输入密度低于或高于该值,样件的致密度、抗拉强度、屈服强度都有所下降,相应的延伸率会小幅度提升。(4) SLM成形零件中冶金缺陷的研究。SLM成形零件内部的冶金缺陷降低其致密度和力学性能。冶金缺陷的形式有孔隙、裂纹、氧化物夹杂以及残余应力等。优化工艺参数,可改善成形零件中存在的冶金缺陷。综合而言,本文的研究结果,为进一步研究SLM成形零件的致密度和力学性能提供理论基础。
[Abstract]:Laser melting technique (SLM) has become the most promising technology in rapid prototyping (RPM) because it can be directly used to form metal parts with complex structures. However, the development time of SLM technology is still short, and the basic research based on SLM technology is relatively few. Therefore, in order to improve the quality of SLM forming parts, the density and mechanical properties of the formed samples are studied systematically in this paper. The specific content of the study is the study of the forming law of the single melt channel. The surface quality of single channel sintering was studied with different input density of linear energy. The results show that it can be divided into four regions according to the quality of sintered surface (unmelted zone, partial melting zone, full melting zone, overmelting zone, etc.). The technological parameters of the experiment include rotation angle (伪), thickness of powder coating, laser power, scanning speed (v) and scanning spacing. The optimized results are as follows: (a) the density and mechanical properties of the samples are the best, and the microstructure and fracture morphology of the samples are analyzed. The microstructure and dimple size of SLM formed parts are fine and uniform, which indicates that the mechanical properties of the samples are relatively high. Synthetically analyzing the experimental results, the energy input density 蠁 P / v 路h) can be used as a unified parameter to study the effect of each process parameter on the density and mechanical properties of the sample. There is an optimum value 蠁, and the sample has the best density and mechanical properties. When the energy input density is below or above this value, the densification, tensile strength and yield strength of the sample are all decreased. The study of Metallurgical defects in the formed parts of SLM. The Metallurgical defects in the formed parts of SLM can reduce the density and mechanical properties of the formed parts. Metallurgical defects take the form of pores, cracks, oxide inclusions and residual stresses. The metallurgical defects in forming parts can be improved by optimizing process parameters. In general, the results of this paper provide a theoretical basis for further study of density and mechanical properties of SLM forming parts.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG665

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