Study on Balling Phenomena in Selective Laser Melting

Abstract

Balling phenomena is a common defect in selective laser melting (SLM) process, it is the main reason causing high surface roughness、pores、tilt delamination and other defects, seriously affect the density and mechanical properties of parts. The classification and formation process of balls、 influencing factors and hazards of balling phenomena at home and abroad are summarized systematacially. Results show that different metal balls have different formation mechanisms. The formation process of balling phenomena is complex, and many factors during fabricating affect the formation of ball reaction. But the current researches at home and abroad of balling phenomena are not systematic, comprehensive and thorough enough. It will be useful for restraining and eliminating balling phenomena during SLM process to research on the influence of technological parameters, physical and chemical features of powders on balling.

Defect Formation Mechanisms in Selective Laser Melting: A Review

“…The SLM process consists of complicated physics, such as absorption and transmission of laser energy [16], rapid melting and solidification of material, microstructure evolution [17,18], flow in a molten pool [19], and materials evaporation [20]. The process is thus affected by the aforementioned factors to form defects of porosities, incomplete fusion holes, cracks, and impurities, etc.…”

The Characteristic Microstructures and Properties of Steel-Based Alloy via Additive Manufacturing

“…SLM production sample quality is influenced by many factors, for instance, laser scanning speed, powder and shape, energy input, and so on. The SLM production process involves complex physical processes, such as fast melting and solidification [ 67 , 68 ], absorption and transmission of laser energy [ 69 ], as well as material flow in the molten pool [ 70 ].…”

Influence of oxygen content on selective laser melting leading to the formation of spheroidization in additive manufacturing technology

“…[15][16][17][18] Among the few studies, Li et al 19 suggested that the reason for the spheroidization problem is a wetting problem between the liquid metal and the solid surface but did not indicate whether this was related to the oxygen content. Zhang et al, 20 when studying the SLM spheroidization problem, found that the size of the metal balls in the melt pool was related to the oxygen content and that the size of the metal balls in the melt pool increased with increasing the oxygen content. Kruth et al 21,22 found that the spheroidization phenomenon was inextricably linked to surface oxidation and that the formation of spheroidization was inseparable from surface oxidation, and also that the generated oxide lm could be broken with a higher energy laser or by adding a deoxidizer to the liquid metal to stop the occurrence of spheroidization.…”