选区激光熔化GH4169成形件表面质量和致密度研究

发布时间：2018-05-14 08:21

  本文选题：选区激光熔化 + GH4169合金　； 参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：选区激光熔化(SLM)属于增材制造领域中的一种先进技术,在汽车航空等领域应用前景广泛。它可以制造近终端、终端成形件,但是其成形件表面质量和致密度一直很难达到理想状态。本课题以GH4169合金为成形材料,以改善SLM成形件表面质量和致密度为目标,系统的研究了工艺参数对于它们的影响。通过设计正交实验方案,首先分别研究各个工艺参数对于样品表面质量和致密度的影响,进而将各工艺参数结合在一起,研究能量输入对于结果的影响,最后对成形件上表面粗糙度和致密度的相互影响关系进行分析。同时对于粉末未熔、过熔、粘附、球化等表面缺陷以及孔洞、未熔合、裂纹等内部缺陷进行了研究。对于SLM成形件上表面质量和致密度的研究结果表明,成形件上表面质量和其致密度主要受到激光功率、扫描速度和扫描间距的影响,而扫描方式对其影响较小。最优工艺参数组合为激光功率大小为320~340 w,扫描速度大小为1000~1200mm/s,扫描间距大小为60μm,铺粉层厚大小为40μm,扫描方式旋转角大小为67°。此时表面粗糙度较小,致密度较高。综合考虑各个影响因素可以得出体能量密度在130 J/mm3~150 J/mm3,搭接率在30~40%时,试样上表面质量较好,致密度较高。对于侧表面的研究结果表明,侧表面主要受到激光功率的影响,在激光功率为300 w时成形件侧表面质量较好。侧表面质量随着侧面倾斜角度的减小而变差,当倾斜角为30°时,侧面出现无法熔合的现象。且同一工艺参数下,成形件上表面质量要普遍好于侧表面质量,侧表面Ra值要比上面Ra值平均高出2.97μm。对比分析上表面质量和致密度,从体能量密度和搭接率两个角度进行研究,发现成形件上表面质量和致密度相互影响,且表面粗糙度Ra值和致密度呈现负相关的规律。
[Abstract]:Selective Laser melting (SLM) is an advanced technology in the field of material augmentation, which has a wide application prospect in automotive aviation and other fields. It can produce near-end and end-shaped parts, but the surface quality and density of the forming parts are always difficult to reach the ideal state. Taking GH4169 alloy as forming material and improving surface quality and density of SLM forming parts, the influence of process parameters on them is systematically studied in this paper. Through the design of orthogonal experiment scheme, the effects of each process parameter on the surface quality and density of the sample were studied respectively, and then the influence of energy input on the result was studied by combining the process parameters together. Finally, the relationship between surface roughness and density is analyzed. At the same time, the surface defects, such as non-melting, overmelting, adhesion and spheroidization, as well as internal defects such as cavity, unfused, crack and so on, were studied. The results show that the surface quality and density of SLM are mainly affected by laser power, scanning speed and scanning distance, but the scanning mode has little effect on it. The optimum technological parameters are as follows: laser power is 320,340 ws, scanning speed is 1000 ~ 1200mm / s, scanning distance is 60 渭 m, thickness of powder layer is 40 渭 m, rotation angle of scanning mode is 67 掳. The surface roughness is smaller and the density is higher. When the bulk energy density is 130 J/mm3~150 J / mm 3 and the lap ratio is 30 ~ 40 mm, the surface quality of the sample is better and the density is higher. The results show that the side surface is mainly affected by laser power and the surface quality is good when the laser power is 300 w. The surface quality of the side becomes worse with the decrease of the angle of the side slope. When the angle of inclination is 30 掳, the side surface will not fuse. Under the same process parameters, the surface quality of the formed part is generally better than that of the side surface, and the Ra value of the side surface is 2.97 渭 m higher than that of the upper surface. By comparing and analyzing the upper surface quality and density, from the aspects of bulk energy density and lap ratio, it is found that the surface quality and density of the formed parts interact with each other, and there is a negative correlation between the surface roughness Ra value and the density.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG665
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本文编号：1887097