| 摘要: |
| 重熔次数对选择性激光熔化增材制造构件表面粗糙度及耐磨性能有重要影响，研究其影响机理及确定经济重熔次数对发展选择性激光熔化增材制造技术具有重要意义。采用选择性激光熔化增材制造设备制备 316L 样件，在样件制备过程中分组进行 0、1、2、3 次激光重熔，对不同激光重熔次数下的样件表面利用三维轮廓扫描仪、扫描电子显微镜等进行表征，利用高速往复摩擦磨损试验机对样件进行摩擦磨损试验，利用电子分析天平测定磨损前后的质量，对表征及磨损性能进行分析。 结果表明：SLM 增材制造样件表面粗糙度随重熔次数的增加而逐渐减小，重熔后的平均表面粗糙度 Sa、Sq、Sv、Sz 值分别从 0 次重熔（正常打印）的 8.437、11.88、82.68、252.2 μm 降低到三次重熔的 6.18、7.735、37.597、104.36 μm，分别降低 26.75%、34.89%、54.53%、58.62%；随重熔次数的增加，平均摩擦因数逐渐增大，质量磨损量逐步减小；2、3 次重熔样件在磨损试验的后半段瞬时最大摩擦因数出现了大于 1 的情况，这是由于在明显滑动之前出现“接点增长”，接点面积不断增大，致使摩擦力超过正压力。表面粗糙度及摩损性能出现上述变化的原因是，每次重熔会使表面吸附的粉末颗粒及熔接痕进一步融化融陷，直至消失，相邻熔道搭接处的“峰谷”现象得到抑制，孔隙和球化等缺陷逐渐被修复，表面变得更加平整。 研究发现不同重熔次数对表面粗糙度和磨损改变的程度不同；定义了经济重熔次数概念，1、2、3 次重熔次数对表面粗糙度和摩擦磨损性能综合改变率分别为ζ 1 =26.61%、ζ 2 =43.60%、ζ 3 =23.68%，确定了经济重熔次数为 2；根据研究成果，给出经济重熔次数在矿山机械上的应用实例。提出经济重熔次数概念，并给出经济重熔次数的应用实例，可为提高增材制造构件表面质量和耐磨性能提供新思路。 |
| 关键词: SLM 增材制造 316L 重熔次数 表面粗糙度 质量磨损 摩擦因数 |
| DOI：10.11933/j.issn.1007-9289.20230616001 |
| 分类号:TG249；TH117 |
| 基金项目:江苏省杰出青年基金（BK20211531）；安徽高校科学研究项目（KJ2021A1106，2022AH051378）；教育部产学合作协同育人项目（220604583025757）；安徽高校优秀青年教师培育重点项目（YQZD2023080） |
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| Effect of Number of Remelting Times on Surface Quality and Wear Performance of 316L Produced by Selective Laser Melting |
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LI Qiang1,2, LIU Songyong1, WANG Qingyang2
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1.School of Mechatronic Engineering, China University of Mining and Technology, Xuzhou 221116 , China;2.School of Mechanical and Electronic Engineering, Suzhou University, Suzhou 234000 , China
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| Abstract: |
| The number of remelting times (NRM) significantly influences the surface roughness and wear resistance of components used in selective laser-melting (SLM) additive manufacturing. Therefore, the investigation of its influencing mechanism and the determination of an economical NRM are crucial for applications of SLM additive manufacturing technology. In this paper, 316 L specimens were prepared using an SLM additive manufacturing device, during which they were grouped and remelted by a laser 0–3 times. Subsequently, the surfaces of the remelted specimens were characterized using a three-dimensional profile scanner and a scanning electron microscope. Furthermore, friction and wear experiments were conducted on the specimens using a high-speed reciprocating friction and wear testing machine, and the masses before and after wearing were measured using an electronic analytical balance. The following beneficial findings were observed. The surface roughness of the components in SLM additive manufacturing decreased with an increase in NRM. Specifically, the values of average surface roughness Sa, Sq, Sv, and Sz decreased from 8.437, 11.88, 82.68, and 252.2 μm (normal printing without remelting) to 6.18, 7.735, 37.597, and 104.36 μm (after remelting for three times) by 26.75%, 34.89%, 54.53%, and 58.62%, respectively. The average friction coefficient increased gradually, whereas the mass wear decreased with an increase in NRM. For the specimens remelted two and three times, the instantaneous maximum friction coefficient was greater than 1 in the later stage of the wear experiment. This is attributed to the fact that after multiple remelting times, the surface of each sample becomes very clean, resulting in very close contact between the friction pairs. Moreover, “contact growth” occurs prior to significant sliding, and the frictional force exceeds the positive pressure because of the constantly increasing contact area. These changes in surface roughness and wear performance can be explained as follows. Each remelting process further melts and sinks the welding marks and particles adsorbed on the surface until they disappear. Consequently, the “peak-valley” phenomenon at the overlap of adjacent melt channels is suppressed, and defects such as pores and balls are gradually repaired. Eventually, the surface flattens. Furthermore, different NRMs resulted in varying degrees of variation in surface roughness and wear. Accordingly, this study innovatively proposes the concept of an economical NRM. The comprehensive change rates of the surface roughness and wear performance after one, two, and three remelting cycles were 26.61%, 43.60%, and 23.68%, respectively, and the economical NRM was 2. Finally, application examples of the mining machinery of economical NRM based on the research results are presented. This study is expected to provide new clues for improving the surface quality and wear resistance of components in SLM additive manufacturing while reducing processing costs. Based on different requirements, NRM can be used for SLM additive manufacturing of parts on the surface or layer-by-layer inside. NRM can be used to improve the mechanical, metallurgical, and physical properties of additive manufacturing parts, thereby improving the properties of parts, such as wear resistance, corrosion resistance, and fatigue resistance. |
| Key words: SLM additive manufacturing 316L number of remelting times surface roughness quality wear friction factor |
