Laser Powder Bed Fusion of SS316L Stainless Steel for Strut Based Lattice Structures in Biomedical Implant Applications: A Comprehensive Review

Authors:

Akarsh Mishra^a1, Tanmay Gupta^a , Vikram Singh Rajput^a and Yash Chandra^a

^aDepartment of Mechanical Engineering Ajay Kumar Garg Engineering College Ghaziabad, Uttar Pradesh, India

Abstract: Additive manufacturing through laser powder bed fusion (LPBF), commonly known as selective laser melting (SLM), has rapidly evolved into a robust route for fabricating geometrically complex metallic components for biomedical implants. Among candidate alloys, austenitic stainless steel SS316L combines biocompatibility, corrosion resistance, and low cost, making it attractive for orthopedic and craniofacial implants where titanium remains unaffordable. This review consolidates findings from more than 80 peer reviewed studies on SLM of SS316L, with deliberate emphasis on strut based lattice topologies and their suitability for bone analogue implants. Process fundamentals, melt pool dynamics, the role of volumetric energy density, and the conduction, keyhole, and balling regimes are summarized first. Reported mechanical responses for as built SS316L (yield 420 to 590 MPa, ultimate tensile 565 to 720 MPa, elongation 30 to 55 percent, hardness 210 to 280 HV) are then linked to cellular substructure, Hall Petch behaviour, and build orientation. The study next examines strut based unit cells (BCC, FCC, BCC Z, FCC Z, octet truss, diamond) and triply periodic minimal surfaces (gyroid, primitive, diamond, Neovius), interpreted through Maxwell stability and the Gibson Ashby scaling laws. Stress shielding, the optimum pore window of 300 to 600 micrometres, and in vitro and in vivo evidence on porous SS316L scaffolds are critically reviewed. Process parameter optimization studies based on Taguchi, response surface methodology, Box Behnken design, and machine learning are compared. Persistent gaps are identified, including scarcity of integrated process structure property biology studies for SS316L lattices, weak quantitative mapping of strut size to compressive strength, and lack of unified surface and microstructure control protocols. The paper closes with a road map for future work bridging SLM parameter optimization, lattice design, and biological validation.

Keywords: Selective laser melting, SS316L, lattice structure, biomedical implant, stress shielding, Gibson Ashby model, process optimization.