Developing Fused Deposition Modeling Additive Manufacturing Processing Strategies for Aluminum Alloy 7075: Sample Preparation and Metallographic Characterization.

Huan Ding,Jonathan Raush,Congyuan Zeng,Kasra Momeni,Shengmin Guo

doi:10.3390/ma15041340

Abstract

Currently, no commercial aluminum 7000 series filaments are available for making aluminum parts using fused deposition modeling (FDM)-based additive manufacturing (AM). The key technical challenge associated with the FDM of aluminum alloy parts is consolidating the loosely packed alloy powders in the brown-body, separated by thin layers of surface oxides and polymer binders, into a dense structure. Classical pressing and sintering-based powder metallurgy (P/M) technologies are employed in this study to assist the development of FDM processing strategies for making strong Al7075 AM parts. Relevant FDM processing strategies, including green-body/brown-body formation and the sintering processes, are examined. The microstructures of the P/M-prepared, FDM-like Al7075 specimens are analyzed and compared with commercially available FDM 17-4 steel specimens. We explored the polymer removal and sintering strategies to minimize the pores of FDM-Al7075-sintered parts. Furthermore, the mechanisms that govern the sintering process are discussed.

Highlights

Due to their excellent mechanical properties, such as high strength [1], low density [2], and high stress-corrosion-cracking resistance [3], 7xxx series aluminum alloys are commonly employed by the aerospace industry
The fused deposition modeling (FDM)-based metallic part Additive manufacturing (AM) technology, referred to as bound metal deposition (BMD), has two main advantages, i.e., (i) the FDM equipment is low-cost and portable, as the operating temperature to make green bodies is about 190–250 ◦C [11,12,15], eliminating the need for expensive, high-energy heat sources such as a laser; and (ii) the printing materials are intrinsically safe because filament is less likely to cause safety concerns than powder-bed-based AM materials
After the wet mixing process, the polymer binder covers the surface of the aluminum 7075 (Al7075) powder evenly

Summary

Introduction

Due to their excellent mechanical properties, such as high strength [1], low density [2], and high stress-corrosion-cracking resistance [3], 7xxx series aluminum alloys are commonly employed by the aerospace industry. As an AM process, fused deposition modeling (FDM) has gained much attention in recent years for manufacturing customized polymer-based components rapidly Polymeric materials such as acrylonitrile butadiene styrene (ABS) [11], poly lactic acid (PLA) [12], and wax [13] are the most popular materials used by FDM. The FDM-based metallic part AM technology, referred to as bound metal deposition (BMD), has two main advantages, i.e., (i) the FDM equipment is low-cost and portable, as the operating temperature to make green bodies is about 190–250 ◦C [11,12,15], eliminating the need for expensive, high-energy heat sources such as a laser; and (ii) the printing materials are intrinsically safe because filament (powders bonded by polymer binder) is less likely to cause safety concerns than powder-bed-based AM materials

Methods

Results

Conclusion