Study on the microstructure, mechanical property and residual stress of SLM Inconel-718 alloy manufactured by differing island scanning strategy. (December 2015)

• Record Type: Journal Article
• Authors: Lu, Yanjin; Wu, Songquan; Gan, Yiliang; Huang, Tingting; Yang, Chuanguang; Junjie, Lin; Lin, Jinxin
• Is Part Of: Optics & laser technology. Volume 75(2015)
• Page Start: 197
• Page End: 206
• Publication Date: 2015-12
• Subjects: Island scanning strategy -- Inconnel-718 -- Selective laser melting -- Residual stress -- Mechanical property; Optics -- Periodicals; Lasers -- Periodicals; Electronic journals; 621.366
• DOI: 10.1016/j.optlastec.2015.07.009
• Languages: English
• ISSNs: 0030-3992

Abstract

Abstract: Inconel-718 has received an extensive using in mold industry. The selective laser melting (SLM) is providing an ideal means for manufacturing mold insert with complex geometrical features and internal architecture. During the manufacturing of high quality mold inserts with conformal cooling channel, the parameters play a vital role in the SLM process. In the study, the Inconel-718 alloys were manufactured by SLM with 2×2 mm 2, 3×3 mm 2, 5×5 mm 2, and 7×7 mm 2 island scanning strategies. The microstructure, mechanical property, and residual stress were investigated by optical microscope, tensile test and Vickers micro-indentation, respectively. It can be found that the relative density increased with enlarging the island size; the results on the microstructure indicated that the cracks and more pores were detected in the 22-specimen; whilst the microstructures of all specimens were composed of fine dendritic grains, cellular, and columnar structures; the tensile testing suggested that the ultimate tensile strength and yield strength of all samples was similar; while the outcome of the residual stress showed that the value of residual stress was ranked in the following sequence: 22-specimen<55-specimen<77-specimen<33-specimen. Although the 22-specimen had lower residual stress compared with the other groups, the occurrence of cracks limited its processing application in SLM. Through integrated into account, the 55-scanning strategy is a promising candidate for manufacturing of mold inserts. Highlights: Laser scanning strategies in selective laser melted Inconel-718 were studied. The analysis of mechanical property and residual stress were proposed. The island scanning strategy affected the formation of pores and cracks.