Effect of laser focus shift on surface quality and density of Inconel 718 parts produced via selective laser melting

Bean, Glenn E.; Witkin, David B.; McLouth, Tait D.; Patel, Dhruvil; Zaldivar, Rafael J.

doi:10.1016/j.addma.2018.04.024

Cited by 58 publications

(34 citation statements)

References 21 publications

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“…One way to improve the build rate of the SLM process is increasing the laser power, which allows for higher scanning speed, larger laser spot size and hatch spacing, and greater layer thickness [ 14 , 15 , 16 ]. Among the SLM process parameters, the spot size of the laser is an effective variable in controlling the laser energy density, so as to adequately melt the powder and build parts of acceptable quality [ 17 ]. The appropriate laser spot size should provide sufficient energy density to melt the current powder layer and fuse to the previously melted one, but also to be small enough to meet requirements of the dimensional precision and surface roughness [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

Effects of Laser Spot Size on the Mechanical Properties of AISI 420 Stainless Steel Fabricated by Selective Laser Melting

Yang

Jiang

et al. 2021

Materials

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The purpose of this study is to investigate the effects of laser spot size on the mechanical properties of AISI 420 stainless steel, fabricated by selective laser melting (SLM), process. Tensile specimens were built directly via the SLM process, using various laser spot diameters, namely 0.1, 0.2, 0.3, and 0.4 mm. The corresponding volumetric energy density (EV) is 80, 40, 26.7, and 20 J/mm3, respectively. Experimental results indicates that laser spot size is an important process parameter and has significant effects on the surface roughness, hardness, density, tensile strength, and microstructure of the SLM AISI 420 builds. A large laser spot with low volumetric energy density results in balling, un-overlapped defects, a large re-heated zone, and a large sub-grain size. As a result, SLM specimens fabricated by the largest laser spot diameter of 0.4 mm exhibit the roughest surface, lowest densification, and lowest ultimate tensile strength. To ensure complete melting of the powder and melt pool stability, EV of 80 J/mm3 proves to be a suitable laser energy density value for the given SLM processing and material system.

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Section: Introductionmentioning

confidence: 99%

Effects of Laser Spot Size on the Mechanical Properties of AISI 420 Stainless Steel Fabricated by Selective Laser Melting

Yang

Jiang

et al. 2021

Materials

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“…The AM-parameters and the defect-growth laws are used as input data, to evaluate the reliability and the parameter sensitivity study, as described in Section 2.2. The results allow the definition of a new set of AM-parameters, the improvement of the inspections methods (to include the X-Ray computed tomography [5,9,10] and ultrasonic testing (UT) [8]), and the modification of the manufacturing route (to include Hot Isostatic Pressure (HYP) [57,58], annealed [10]). The new AM-parameters can be used as feedback to replay the first loop or to redefine the inspection schedule.…”

Section: Methodsmentioning

confidence: 99%

A Methodology to Evaluate the Reliability Impact of the Replacement of Welded Components by Additive Manufacturing Spare Parts

Coro

Macareno

Aguirrebeitia

et al. 2019

Metals

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This article shows a method for inspection scheduling of structures made by additive manufacturing, derived from reliability function evaluations and overhaul inspection findings. The routine was an adaption of an existing method developed by the authors for welded components; in this latter case, the routine used a stochastic defect-propagation analysis for pores and lack of fusion defects of additive manufacturing process, instead of the weld liquation crack. In addition, the authors modified the specific stress-intensity factor for welded components to consider additive manufacturing-related material property variability, defect distributions, flaw-inspection capabilities, and component geometry. The proposed routine evaluated the failure rate and inspection intervals using the first-order reliability method (FORM + Fracture) to alleviate the computational cost of probabilistic defect-propagation analysis. The proposed method is one of the first applying reliability concepts to additive manufacturing (AM) components. This is an important milestone, since in 10 years, additive manufacturing is to be used for 30% of the components in aeroengines. This paper presents an example comparing the reliability and cost of a jet engine, with components either made by additive manufacturing or welded parts; in the process, the reliability AM-key features are found, and overhaul schedules of an airplane fleet made with AM components are defined. The simplicity and performance demonstrated in the comparison make the proposed method a powerful engineering tool for additive manufacturing assessment in aeronautics.

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“…Studies commonly review the effects of varying parameters such as powder particle size (Balbaa et al, 2020), laser scanning velocity, scanning strategy, laser power and total energy density . Other articles look at processspecific relationships, such as the effects of shielding gas flow (Bean et al, 2018). (Oter et al, 2020) As shown in Table 2, studies have produced contradictory results.…”

Section: Build Parameter Studiesmentioning

confidence: 99%

Surface Roughness Considerations in Design for Additive Manufacturing - A Literature Review

2021

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One often-cited benefit of using metal additive manufacturing (AM) is the possibility to design and produce complex geometries that suit the required function and performance of end-use parts. In this context, laser powder bed fusion (LPBF) is one suitable AM process. Due to accessibility issues and cost-reduction potentials, such ‘complex’ LPBF parts should utilise net-shape manufacturing with minimal use of post-process machining. The inherent surface roughness of LPBF could, however, impede part performance, especially from a structural perspective and in particular regarding fatigue. Engineers must therefore understand the influence of surface roughness on part performance and how to consider it during design. This paper presents a systematic literature review of research related to LPBF surface roughness. In general, research focuses on the relationship between surface roughness and LPBF build parameters, material properties, or post-processing. Research on design support on how to consider surface roughness during design for AM is however scarce. Future research on such supports is therefore important given the effects of surface roughness highlighted in other research fields.

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Effect of laser focus shift on surface quality and density of Inconel 718 parts produced via selective laser melting

Cited by 58 publications

References 21 publications

Effects of Laser Spot Size on the Mechanical Properties of AISI 420 Stainless Steel Fabricated by Selective Laser Melting

Effects of Laser Spot Size on the Mechanical Properties of AISI 420 Stainless Steel Fabricated by Selective Laser Melting

A Methodology to Evaluate the Reliability Impact of the Replacement of Welded Components by Additive Manufacturing Spare Parts

Surface Roughness Considerations in Design for Additive Manufacturing - A Literature Review

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