PSI - Issue 56

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Author name / Structural Integrity Procedia 00 (2019) 000 – 000

Sai Kumar Balla et al. / Procedia Structural Integrity 56 (2024) 41–48

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This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the SIRAMM23 organizers Keywords: Laser powder bed fusion; Sand blasting,; Chemical anodizing; Wire EDM; Micro milling, Surface roughness

1. Introduction Additive manufacturing (AM), also known as 3D printing, is a revolutionary technology that has transformed how we design and produce objects (Diegel et al., 2019). This process allows for creation of complex geometries and unique shapes that are difficult to produce using traditional manufacturing methods. Additive manufacturing has entered many industries, including aerospace, medical, and automotive. The laser powder bed fusion (LPBF) process is one of the most promising metal AM processes, which offers a more efficient and cost-effective solution for producing complex geometries. LPBF uses a high-powered laser to selectively melt and fuse metal powders layer by layer to create a solid object. It allows for creating intricate designs with high accuracy, reducing the amount of material wasted in the production process (Thompson et al., 2016). Aluminium alloys are a popular material for additive manufacturing using LPBF because of their unique properties i.e., they are lightweight, have high strength, and exhibit excellent corrosion resistance. AlSi12 is a eutectic alloy with a small difference in melting and solidification temperatures, resulting in excellent thermal properties and good thermal resistance (Suzuki et al., 2021). AlSi12 is an ideal material for joining metal pieces together, such as welding and extrusion processes. The applications include fabricating thin-walled parts such as heat exchangers (Siddique et al., 2015) and other industrial-grade prototypes. Evidently, LPBF processed AlSi12 alloys reveals better strength than Evidently, LPBF processed AlSi12 alloys reveal better strength than conventionally manufactured alloys because solute Si in supersaturated solid solution inhibits work hardening strength (Takata et al., 2020). LPBF provides a better opportunity to fabricate these eutectic alloys even complicated shapes, with ease, but the surface quality is still a concern. Surface roughness in additively manufactured components is higher than conventionally manufactured components due to the staircasing effect formed by layer-by-layer manufacturing and partially melted particles. The surface roughness of the as-built components by the LPBF process is approximately 10-28 µm (Li et al., 2018; Spierings et al., 2011). Surface roughness is notably important and requires a smooth surface to eliminate premature failure from cracking in many applications. Surface roughness is an important factor for initiating fatigue failure, especially in LPBF processed components (Teimouri et al., 2022) and parts with poor surface quality effects the fatigue performance. To improve the surface quality, LPBF-processed alloys are subjected to various methods like process parameters optimization, adopting post-processing techniques such as polishing, machining, shot peening, sandblasting etc. Some authors have attempted to reduce the surface roughness by optimizing the process parameters such as laser power, scanning speed, hatch spacing, layer thickness, and scanning strategy (Cao et al., 2021; Liu et al., 2019). The other method to improve the surface quality of LPBF processed components is by adopting post processing techniques. Subramaniyan et al. have reduced the surface roughness of LPBF processed AlSi10Mg alloy by endorsing shot peening and with different heat treatments. They concluded that shot peening helps reduce surface roughness by 50% compared to as-built samples (Kumar et al., 2021). Lesyk et al. investigated the effect of shot peening on the surface quality of In718 alloy fabricated by the LPBF process (Lesyk et al., 2021), and it was concluded that shot peening helps in reducing surface roughness by approximately 48% due to new wavy surface formation due to severe plastic deformation. Further, another interesting study on pulsed electro-polishing of In718 alloy showed beneficial effects (Shrivastava et al., 2021). Polishing more reduces surface roughness compared to shot peening and shot blasting for AlSi10Mg alloy processed by LPBF (Sagbas et al., 2021). Since polishing is a material removal technique from the final component whereas shot peening is a cold plastic deformation process which produces compressive stresses resulting in plastic deformation which improves the surface quality and texture. Kaynak and Tascioglu tried to describe finish machining as an effective post-processing technique to reduce the surface roughness of LPBF-produced Inconel 718 alloy and achieved a reduction of 92% in surface roughness compared with as-built conditions (Kaynak & Tascioglu, 2023). Campos et al. investigated the effect of micro milling on the surface roughness of LPBF processed Ti6Al4V, producing better surface compared to initial conditions (de Oliveira Campos et al., 2020). Better surface quality is produced due to micro milling, lower ductility, and elevated hardness leads to less plastic flow during cutting. Varghese and Mujumdar studied the micro milled surface roughness and forces acting on surface during machining on LPBF processed Ti6Al4V alloy and concluded that surface roughness increased by increasing depth of cut due to increase in shear forces and chip