Additive Manufacturing of Metals: Ultrasonic and Other Solid State Additive Manufacturing
Sponsored by: MS&T Organization
Program Organizers: Ian D. Harris, EWI; Ulf Ackelid, Arcam AB; Ola Harrysson, North Carolina State University; Sudarsanam Babu, The Ohio State University; Brent Stucker, University of Louisville
Tuesday 2:00 PM
October 18, 2011
Room: D130
Location: Greater Columbus Convention Center
Session Chair: Brent Stucker, University of Louisville
2:00 PM
Standards for the Additive Manufacturing Industry: Brent Stucker1; 1University of Louisville
For two years, participants in the ASTM F42 Committee on Additive Manufacturing Technologies have worked to develop industry standards for materials, processes, design, terminology and testing. Significant terminology, testing, process and file format standards have been balloted and approved for the additive manufacturing community. An overview of these efforts and an update on the latest standardization activities will be presented in the talk.
2:40 PM
Characterization of Microstructure in Al-3003 Alloy Builds Fabricated by Very High Power Ultrasonic Additive Manufacturing: Hiromichi Fujii1; Sriraman Ramanujam2; Sudarsanam Babu2; 1Tohoku University; 2The Ohio State University
Ultrasonically consolidated 3003 aluminum alloy builds were prepared with constituent tapes by using very high power ultrasonic additive manufacturing process. The process was performed under the conditions of 20 kHz frequency, 26 µm oscillation amplitude, 5.6 kN applied normal force and 35.6 mm/s sonotrode velocity. Microstructures of interface and bulk regions were quantitatively characterized using electron backscattered diffraction technique. The interface microstructure consists of fine equiaxed grains. The {111} planes of these grains lay on the welding plane and <011> directions were aligned with vibrating direction, confirming a shear deformation mode at these regions. Furthermore the density of low angle grain boundaries significantly decreased owing to recrystallization. In contrast, original elongated grains and recrystallized grains were observed in the bulk region of tape. These elongated grains correspond to rolling texture components of face centered cubic materials. The microstructural gradients are also rationalized based on the accumulated thermomechanical cycles during processing.
3:00 PM
Dislocation Density Based Finite Element Modeling of Face Centered Cubic Materials Undergoing Ultrasonic Consolidation: Deepankar Pal1; Brent Stucker1; 1University of Louisville
A dislocation density based constitutive model has been developed and implemented into a crystal plasticity quasi-static finite element framework. This approach captures the statistical evolution of dislocation structures and grain fragmentation at the bonding interface during Ultrasonic Consolidation (UC) as a function of normal pressure, sinosuidal simple shear loading, weld speed, mating surface texture profiles and initial conditions such as microstructural morphology, chemical and material information. Hardening is incorporated using statistically stored and geometrically necessary dislocation densities (SSDs and GNDs). The model also incorporates various local and global effects such as friction, thermal softening, acoustic softening, surface texture of the sonotrode and initial mating surfaces and presence of oxide-scale at the mating surfaces. A parallel MPI platform and homogenization approach are being implemented to improve CPU time and space efficiency. The model has been shown to predict key features of microstructural evolution and bond formation during UC.
3:20 PM
Solid State Additive Manufacturing of Metals: Mark Norfolk1; Matt Short1; 1EWI
Ultrasonic Additive Manufacturing(UAM) is a relatively new process with the ability to build fully dense metal parts in a variety of relevant metals using solid state joining. From this core capability, three unique opportunities arise, namely the ability to; 1) Embed one metal into a matrix of another for sensing or property optimization 2) Create complex 3D internal channels, which is an enabler for molds, thermal management, and chemical processing 3)Join dissimilar materials, which is an enabler for metal matrix composites and cladding. Central to these capabilities is that UAM is a solid state process with bonding occurring without melting, thus avoiding the significant property loss of current AM technologies. Several applications of the technology will be reviewed including solid metal parts with embedded channels for thermal management, metal matrix composites (MMC) for structural materials, embedded shape memory alloys (SMA) for active stiffness control and solid-state cladding for petro-chemical applications.
3:40 PM Break
4:00 PM Student
Elastic Constants of Ultrasonic Additive Manufactured Al 3003-H18: Daniel Foster1; Sudarsanam Babu1; Marcelo Dapino2; 1Welding Engineering OSU; 2Mechanical Engineering OSU
Ultrasonic Additive Manufacturing (UAM), also known as Ultrasonic Consolidation (UC), is a layered manufacturing process in which thin metal foils are ultrasonically bonded to a previously bonded foil substrate to create a net part. This work pertains to the evaluation of bonds in UAM builds through ultrasonic testing of build’s elastic constants. Results from UAM parts indicate anisotropic elastic constants and also a reduction of up 48% in elastic constant compared to that of a control sample. In addition UAM parts are approximately transversely isotropic, with elastic constants in the plane of the Al foils having nearly the same value, while properties normal to foil direction have much lower values. The above reduction was attributed to interfacial voids. In contrast, the measurements from builds made with very high power ultrasonic additive manufacturing (VHP-UAM) showed a drastic improvement in elastic properties and approaching the values similar to that of bulk aluminum.
4:20 PM Student
Thermal Stability of Al3003 Builds Made by Very High Power Ultrasonic Additive Manufacturing: Kittichai Sojiphan1; Sudarsanam Babu1; 1Ohio State University
Very High Power Ultrasonic Additive Manufacturing (VHP-UAM) is a solid-state joining process used to fabricate solid parts from thin foils. The process improves higher bonding ratios and capable of fabricating high temperatures and harder alloys due to its higher normal force and vibration amplitude compared to traditional UAM process. In the current work, three VHP-UAM builds made of 150 μm thick Al3003-H18 foils were made with process parameters varied from 26-36 μm vibration amplitude, 4-8 kN normal force, at constant 35.6 mm/s weld speed and 20 kHz frequency. Microhardness and electron backscatter diffraction (EBSD) techniques were used to examine hardness distribution, grain structures, and texture distributions of as-processed and heat-treated VHP-UAM builds compared to as-received foils. The results indicate that the gradients in microstructures and textures exist within layers from top to bottom of the builds in both as-processed and heat-treated conditions. Possible mechanisms based accumulated plastic deformation are discussed.
4:40 PM
Characterization of 304L Stainless Steel Builds Produced by Very High Power Ultrasonic Additive Manufacturing: Sriraman Ramanujam1; Hiromichi Fujii1; Suresh Babu Sudarsanam1; Matt Short2; 1The Ohio State University; 2The Edison Welding Institute
Builds of 304L stainless steel were made by Very High Power Ultrasonic Additive Manufacturing using foils (100 μm thick/ 25.4 mm wide) in the annealed condition. Processing was carried out at different vibration amplitudes, normal force levels, and travel speed at 20 kHz frequency without any external heating. Hardening of layers (up to 64%) was noted from the original foil hardness of 171 HV. Electron backscattered diffraction analysis suggests the formation of a narrow (5 μm) bond region comprising of fine equiaxed recrystallized grains (0.2-2.8 μm) from a larger initial grain size distribution (0.2-16 μm). Although dynamic recrystallization during bonding of materials has been observed earlier, the occurrence of this phenomenon from an initial annealed microstructure is of significance. It appears the annealed material of low stacking fault energy has undergone strong interfacial work hardening at high shear strain/ strain rate conditions and then dynamically recrystallized due to adiabatic heating.