Effect of laser hatch style on densification behavior, microstructure, and tribological performance of aluminum alloys b
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Downloaded from https://www.cambridge.org/core. Tufts Univ, on 29 Jun 2018 at 14:09:13, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1557/jmr.2018.166
Effect of laser hatch style on densification behavior, microstructure, and tribological performance of aluminum alloys by selective laser melting Jie Liu,a) Yinglong Zhou, Yanbin Fan, and Xiangyang Chen College of Mechatronics Engineering, Foshan University, Foshan, Guangdong Province 528000, China (Received 25 January 2018; accepted 10 May 2018)
A systematic investigation of influence of the laser hatch style on densification behavior, microstructure, and tribological performance of aluminum parts’ preparation by selective laser melting (SLM) was implemented in this study. The scans with checker board (CB) style left better processing quality of surface morphology and few metallurgical defects to SLM parts in comparison with single fill and cross fill styles, hence leading to a relatively high densification level (99.42%). The CB style of shorter scan length left higher undercooling degree in small checker areas compared with other longer scan lengths, leading to finer equiaxed grains to the solidification microstructure. Accordingly, an enhanced mean microhardness of 129.7 HV0.1 was obtained in this hatch style, due to the grain refinement strengthening effect. The lowest coefficient of friction of 0.49 and wear rate of 2.43 104 mm3/(N m) were obtained. The improved densification level and formation of refined equiaxed grain and evenly distributed ring-shaped Si particles formed in CB parts changed the mechanism of material removal during sliding from the abrasion to adhesion of the tribolayer, significantly improving the wear resistance of SLM aluminum parts.
I. INTRODUCTION
Laser additive manufacturing (LAM) involves a group of advanced technologies used for preparing net-shaped intricate parts through the computer-aided design model.1–4 LAM processes were initially proposed for fabricating prototypes but in a few decades, their use changed and nowadays they are also exploited for preparation of structural or functional components for service in industrial and medical applications.5–7 One LAM technique that has attained considerably rising attention and engagement by industrial manufacturers is selective laser melting (SLM), which is based on local melting of a metal powder bed by using a high power laser beam.8–10 In comparison to the traditional manufacturing technologies, finer microstructures can be obtained in the SLM-processed parts due to the very high cooling rate of the melt pool.11 Excellent mechanical properties can be achieved derived from the significant grain refinement strengthening. Therefore, SLM shows a great potential in a broad range of industrial sectors, including aerospace, biomedical science, and automotive industries.12 Until now, SLM has been proved to be applicable in a number of alloy systems: 316L steel,13 CoCrMo,14 a)
Address all correspondence to this author. e-mail: jie.l
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