2023 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2023): Materials: Metals-Graded Compositions
Program Organizers: Joseph Beaman, University of Texas at Austin
Wednesday 1:10 PM
August 16, 2023
Room: 416 AB
Location: Hilton Austin
Session Chair: Anthony Stair, Carnegie Mellon University
1:10 PM
Compositionally Graded Transition from Tungsten to Ferritic-martensitic Steels via Directed Energy Deposition: Deniz Ebeperi1; Tim Graening2; Ying Yang2; Yutai Katoh2; Ibrahim Karaman1; 1Texas A&M University; 2Oak Ridge National Laboratory
Nuclear fusion reactors utilize W and W-based alloys as plasma facing components, which require joining into steel cooling structures based on the state-of-art divertor designs. Direct joining between W and steels lead to formation of brittle intermetallics. Joining with filler alloys are not compatible for high temperature applications as the microstructure may degrade and promote a critical failure. Directed energy deposition technique enables deposition of multiple pre-alloy or elemental powders simultaneously, in a layer-by-layer fashion, with a precise control of the composition to avoid formation of intermetallic or detrimental phases. In addition, its ability to fabricate compositionally graded transitions reduces the coefficient of thermal expansion mismatch between adjacent interlayer alloys. In this study, we demonstrated a framework to optimize the processing parameters for each alloy, generated processability maps and successfully fabricated a dense, multilayered, linear compositional gradient fromW to Gr91 steel, using V-based and Fe-based alloys as transition elements.
1:30 PM
Directed Energy Deposition of Stainless Steel 304L to Inconel 625 Gradients: Print Strategies and Defects: Anthony Stair1; Jack Beuth1; Bryan Webler1; Maarten de Boer1; 1Carnegie Mellon University
The bonding of dissimilar metals via additive manufacturing can create structures with different properties based on the location withing the geometry of the component. Bonding of dissimilar metals is difficult due to formation of unintended intermetallic phases and mismatches in thermal properties like thermal conductivity, melting temperature, and coefficient of thermal expansion. By using process parameters to control the dilution of the stainless steel 304L build plate into the melt pool in single layer builds, we have avoided gross defects such as large voids, cracks, or deleterious phases. Tensile testing of specimens printed with a defect free parameter set showed that the gradient between the two materials was stronger than stainless steel 304L. Some unsuccessful experiments contained cracking. The compositions and build parameters of experiments which resulted in cracking are compared to those of experiments that did not crack to determine what the cause of the cracking is.
1:50 PM
Microstructural Investigations on SS316L-Cu Graded Deposition Prepared using Wire Arc Additive Manufacturing: Bunty Tomar1; Shiva S.1; 1Indian Institute of Technology Jammu
Fabrication of steel and copper-based functionally graded material (FGM) through cold metal transfer-based wire arc additive manufacturing is a novel exploration. Components combining Cu and steel show significant usage in many industrial applications as they combine high corrosion resistance, ductility, thermal conductivity, and wear resistance to excellent mechanical properties. Joining steel and copper is challenging due to the mismatch in their thermo-mechanical properties. In this experiment, a functionally graded material (FGM) structure of pure copper (Cu) and 316L stainless steel (SS) was successfully developed using cold metal transfer-based wire arc additive manufacturing (CMT-WAAM). The interface of the fabricated samples was characterized under optical microscopy, field emission scanning electron microscopy, and X-ray diffraction techniques. Detailed EBSD and TEM analysis was performed to analyze the grain orientation, strain distribution, grain boundary misorientations, and formation of metastable and intermetallic phases. This works paves the way to use CMT-WAAM to fabricate steel/copper FGMs.
2:10 PM Break