Additive Manufacturing: Alternative Processes (Beyond the Beam): Solid State Processes
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Additive Manufacturing Committee, TMS: Powder Materials Committee
Program Organizers: Paul Prichard, Kennametal Inc.; Matthew Dunstan, US Army Research Laboratory; Peeyush Nandwana, Oak Ridge National Laboratory; Nihan Tuncer, Desktop Metal; James Paramore, Texas A&M University
Wednesday 8:30 AM
February 26, 2020
Room: 7A
Location: San Diego Convention Ctr
Session Chair: Peeyush Nandwana, Oak Ridge National Laboratory
8:30 AM
Additive Friction Stir Deposition for Solid-state Additive Manufacturing of Metals and Metal Matrix Composites: Hang Yu1; 1Virginia Polytechnic Institute and State University
Additive friction stir deposition is an emerging solid-state additive process that combines the friction stir principle with a continuous material feeding mechanism to allow for site-specific deposition. It enables large-scale additive manufacturing and repair for a broad range of engineering alloys and metal matrix composites, including those traditionally classified as nonweldable alloys. While beam-based metal additive processes involve powder melting and rapid solidification, and suffer from problems like high residual stresses, porosity, and hot cracking, additive friction stir deposition fundamentally avoids these issues while resulting in equiaxed, fine microstructures with superior mechanical properties. In this talk, I will discuss the most recent advances in additive friction stir deposition of Al, Cu, as well as Al-Mo and Al-ZrO2 composites. Of particular interest are the novel dynamic phase and microstructure evolution phenomena enabled by the extreme thermomechanical conditions during deposition, which involve high strain rate, high peak temperature, and large shear strain.
8:50 AM
Additive Manufacturing of Aluminium Using Friction Stir Deposition: Mohamed Ahmed1; Ebtessam Elfishawy2; Mohamed Elsayed Seleman3; Abdelrahman Abdelmotagaly4; 1The British University in Egypt; 2The American University in Egypt; 3Suez University; 4Colorado School of Mines
In this work additive manufacturing using friction stir deposition from wrought AA2011 bar of 20 mm diameter against aluminum substrate was carried out. The effect of the spindle rotation rate (600-1200 rpm) and the feeding speed (3-9mm/min) on the deposition process, the microstructure and the hardness of the deposited parts were investigated. During the process after fixing the bar on the spindle shank and while rotating, the bar approaches the substrate at a constant feeding speed, the bar plastically deformed due to the friction between the rotating bar and the fixed substrate that causes the material to transfer from the bar to the substrate under the continuous feeding. The shape of the deposited parts varied by increasing the feeding speed with two diameters, small diameter of 20mm towards the substrate and large diameter of 40 mm at the top. The ratio between the two diameters varied with the feeding speed.
9:10 AM
Additive Friction Stir Deposition: Microstructural Control Sensitivity: Robert Griffiths1; David Garcia1; Hang Yu1; 1Virginia Polytechnic Institute
Additive Friction Stir Deposition (AFSD) is a solid-state additive manufacturing technology capable of processing a wide variety of alloys and composites. In general, materials processed via AFSD have been shown to have refined microstructures with equiaxed grains. Process input variables can be used to adjust thermomechanical conditions such as temperature, strain rate, and strain; however, the sensitivity of these conditions to the input variables changes with different material systems. Inherit material properties such as friction coefficients, stacking fault energy, and crystallography change how the material responds to process inputs and ultimately the degree of microstructural control that is achievable via AFSD. In addition, materials that rely on second-phase particles for strengthening have additional interactions with dynamic dissolving and precipitation occurring during the process. Microstructures and properties for a variety of material systems processed by AFSD are discussed, including systems that show high and low degrees of microstructural control.
9:30 AM
Impacts of Friction Stir Processing on Microstructure and Corrosion Properties of DMLS-AlSi10Mg: Mehran Rafieazad1; Mohsen Mohammadi2; Adrian Gerlich3; Ali Nasiri1; 1Memorial University of Newfoundland; 2Marine Additive Manufacturing Centre of Excellence (MAMCE), University of New Brunswick; 3Centre for Advanced Materials Joining, Department of Mechanical and Mechatronics Engineering, University of Waterloo
Despite the already existing advantages of additively manufactured AlSi10Mg, there are still process-induced imperfections associated with the direct metal laser sintering process, such as microstructural inhomogeneity and high level of porosity. The post-printing thermal treatments have been shown to be an effective method to reduce the microstructural inhomogeneity, but unable to diminish the porosity level of the part. In this study, Friction Stir Processing (FSP) is introduced as a practical post-printing process capable of reducing both the porosity level and microstructural inhomogeneity of the DMLS-AlSi10Mg alloy. A detailed microstructural analysis of the as-printed DMLS-AlSi10Mg alloy before and after FSP treatment utilizing optical microscopy, scanning electron microscopy, and electron backscatter diffraction were performed. To further investigate the impact of the FSP-induced microstructural modifications and porosity reduction on the corrosion performance of the alloy, anodic polarization testing was conducted on both as-printed and FSPed DMLS-AlSi10Mg alloy.
9:50 AM
Mechanical Property and Characterization of Anodized AA6061 After Additive Friction Stir-deposition: Ning Zhu1; Dustin Avery1; Brandon Phillips1; Ryan Kinser1; Paul Allison1; James Jordon1; Luke Brewer1; 1University of Alabama Tuscaloosa
This presentation discusses the role of surface oxides on the mechanical properties of AA6061 produced by additive friction stir-deposition (AFS-D). One application of AFS-D is to recycle scrap aluminum material by using solid-state additive manufacturing to produce new components. A potential concern is the solid-state mixing of surface oxides on the feedstock material into the additively produced component. Will these oxides reduce the ductility or strength of the material? To address this question, we produced large builds of AA6061 through AFS-D using strips of material with controlled oxide thickness. Oxide coatings with 33μm and 67μm thickness were hard anodized on 9.5mm thick feedstock. Characterization through scanning electron microscopy revealed that above 95% of aluminum oxides with radius less than 5μm were evenly distributed in the build. The change in tensile behavior is now being addressed. The connection between surface oxide thickness, deposit microstructure, and resultant mechanical properties will be discussed.
10:10 AM Break
10:30 AM
Effect of Counter-gravity 3D Printing on PLA Interlayer Fracture Energy: Hadi Noori1; Cole Lytle2; 1Oklahoma State University; 2Tinker Air Force Base
The multiaxial 3D printing process can reduce the manufacturing time, and open up the new way for the production of graded materials. It will also expand the application of sustainable additive manufacturing for repair and retrofit purposes. In this study, the effect of counter-gravity deposition on the tensile interlayer fracture energy of extruded PLA material was investigated. The tensile samples with one-layer thickness were 3D printed at three orientations of 0º, 90º, and 180º with respect to the direction of gravity force. Also, the effect of the nozzle orifice diameter was assessed in conjunction with the deposition orientation. The ratio of nozzle orifice diameter to deposition height was 1 for all samples that were made with different nozzle diameters of 0.6 and 0.8 mm. For both nozzle diameters, the statistical analysis of the interlayer fracture energies showed no significant difference for the samples that were 3D printed at different orientations.
10:50 AM
3D-printing via Binder Jetting and Consolidation of Nano Alumina Bone Scaffold Prototypes: Maricruz Carrillo1; Geuntak Lee1; Eugene Olevsky1; 1San Diego State University
There are two major limitations of current bone replacement techniques: inability to specify the shape of the graft and low mechanical properties. This often leads to a rejection of the implant, reoperation or removal. Current tissue engineering advances combined with recent advances in three–dimensional (3D) printing technologies have the potential to generate cell loaded bone grafts with specific architecture to increase implant success. In this study, a custom-built binder jetting printer was used to produce complex shape ceramic scaffolds strong enough to mimic bone. With this printer and the subsequent sintering, a cubic sample with a density of 70% and strength of 113 MPa was produced. Additionally, a complex scaffold shape with final porosity of 50% and strength of 30 MPa was also achieved. The results of this study show the potential of ceramic materials, processed via 3D printing and sintering, as a more effective bone substitute.
11:10 AM
Effects of Zener-Hollomon Parameter and Strain on the Heterogeneous Microstructual Evolution of Cold-sprayed Coatings: Yu Zou1; Hongze Wang1; Zhiying Liu1; Michel Hache1; Eric Irissou2; 1University of Toronto; 2National Research Council Canada (NRC)
Cold spray is being touted as a ‘near-net shape’ manufacturing technology that minimizes material waste by virtue of the high rate of deposition. During the cold spray process, metallic bulk components can be produced by spraying metal powders at high velocity, generating bonding through severe plastic deformation at temperatures well below the melting point of the powders. To fully understand the cold spray processing of metal powders, we systematically compare and study the microstructure evolution in Cu, Ni, Al, Ti, Ti-6Al-4V samples prepared using EBSD, TEM and nanoindentation. We show complex microstructure in these powder particles after cold spraying: nanocrystalline, nanotwins, annealing twins, gradient grains, deformation bands, dynamic/static recovery and recrystallization. The effects of gas temperature and powder velocity on the microstructure and mechanical properties in the cold sprayed samples are also discussed. Of particular interest are grain refinement, recrystallization and particle/particle bonding mechanisms of the cold sprayed powders.