Mechanisms and characteristics of spatter generation in SLM processing and its effect on the properties

• Published in: Materials & design 2017-03, Vol.117, p.121-130
• Main Authors: Wang, Di, Wu, Shibiao, Fu, Fan, Mai, Shuzhen, Yang, Yongqiang, Liu, Yang, Song, Changhui
• Format: Article
• Language: English
• Subjects: Energy input; Inclusion; Manufacturing stability; Metal additive manufacturing; Selective laser melting; Spatter
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2016.12.060

Selective Laser Melting (SLM) is a powder bed based technology to fabricate metal parts through laser melting, it provides excellent mechanical properties and freedom. The authors study the influence of laser energy on spattering, the investigation analyzed the formation principle, appearance and compositions of spattering. Results indicate that as the laser energy input increases from 0.32×105W/cm3 to 1.30×105W/cm3, the intensity and the quantity of spattering increases, the metal liquid jetted out even reach to the height of 11cm. Major sources of spattering included three types, which were mainly caused by recoil pressure, Marangoni effect and heat effect in molten pool, these three different sources of spattering leading to three types of spattering morphology correspondingly. The solidified spattering particles have an average size of approximately 162μm, much larger than the original powder size of 32μm, and these spatter particles present various appearances. The compositions of spattering powers are almost the same as the original powders, but the contents of O, Si and C increase dramatically. The spattering particles are embedded into the surface and interior of the SLM-fabricated parts. These results are helpful in controlling the intensity of spattering, improving stability and repeatability of the SLM fabrication process. Formation mechanisms of different types of spatter: (a) morphology of spherical splashing (type-I splashing); (c) morphology of coarse spherical morphology (type-II splashing); (d) morphology of irregular splashing (type-III splashing). [Display omitted] •As the laser energy input increases from 0.32×105W/cm3 to 1.30×105W/cm3, the intensity and the quantity of spattering increases, the metal liquid jetted out and reached to the height of 11cm.•Spattering included three types mainly caused by recoil pressure, Marangoni effect and heat effect in molten pool, these three different sources of spattering leading to three types of spattering morphology correspondingly. The compositions of spattering powers are almost the same as the original powders, but the contents of O, Si and C increase dramatically.•Spattering particles have an average size of approximately 162µm compared with the original powder size of 32µm. The spattering particles are embedded into the surface and interior of the SLM-fabricated parts to deteriorate the finial fabricated parts.