Abstract
The laser scanning strategy has an important influence on the surface quality, residual stress, and deformation of the molten metal (deformation behavior). A divisional scanning strategy is an effective means used to reduce the internal stress of the selective laser melting (SLM) metal part. In order to understand and optimize the divisional scanning strategy, three divisional scanning strategies and an S-shaped orthogonal scanning strategy are used to produce 316L steel parts in this study. The influence of scanning strategy on the produced parts is verified from the aspects of densification, residual stress distribution and deformation. Experiments show that the 316L steel alloy parts adopted spiral divisional scanning strategy can not only obtain the densification of 99.37%, but they also effectively improve the distribution of residual stress and control the deformation degree of the produced parts. Among them, the spiral divisional scanning sample has the smallest residual stress in plane direction, and its σx and σy stress are controlled within 204 MPa and 103 MPa. The above results show that the spiral divisional scanning is the most conducive strategy to obtain higher residual stress performance of SLM 316L steel parts.
Highlights
Selective laser melting technology adopts single-point high-energy laser beam to melt metal powder layer by layer along the filling path of three-dimensional discrete profile
It was found that by using the normal partition strategy, the selective laser melting (SLM) parts had a large amount of residual stress in the overlap area, which was not conducive to residual stress distribution in the fabricated plane
Using an oblique line and layer-staggered divisional strategy forms micro-pores and affects the surface quality of parts, but the overlap regions in the adjacent layers are not located in the same vertical plane, so that the residual stress distribution of the components is more uniform, and the value is smaller
Summary
Selective laser melting technology adopts single-point high-energy laser beam to melt metal powder layer by layer along the filling path of three-dimensional discrete profile. Kruth et al [14] designed a “bridge curvature method” to study the influence of the scanning line’s length, scanning line direction and island scanning strategy on residual stress. Studied the influence of the size of island shape on the densification, microstructure, and mechanical properties and residual stress of the part, and the optimum width of the region was found to be within 5 mm to 7 mm. Many scholars above have studied the influence of the scanning strategy on the quality of SLM parts based on Z-shaped scan, S-shaped scan and divisional scan, and put forward several kinds of divisional scanning methods according to specific problems. On the basis of the aforementioned researchers, three kinds of divisional scanning strategies are developed to study the influence on the densification, surface quality, residual stress distribution and deformation of SLM parts in this paper
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