Additive Manufacturing: Materials, Alloy Development, Microstructure and Properties: Additive Manufacturing of Fe-based Alloys
Program Organizers: Prashanth Konda Gokuldoss, Tallinn University of Technology; Zhi Wang, South China University of Technology; Jurgen Eckert, Erich Schmid Institute of Materials Science; Filippo Berto, Norwegian University of Science and Technology
Wednesday 2:00 PM
November 4, 2020
Room: Virtual Meeting Room 3
Location: MS&T Virtual
Session Chair: Amithesam Amerinatanzi, The University of Texas at Arlington
2:00 PM Invited
Structural Characterization of Wire and Arc Additive Manufactured (WAAM) Austenitic Stainless Steel: Sudhakar Vadiraja1; Ryan Foley1; 1Montana Technological University
This research focuses on the microstructural characterization of 308L stainless steel samples produced by a novel WAAM technique known as Plasma Arc Weld Print 3D (PP3D). PP3D consists of multiple plasma arc torches that can deposit material in two modes of deposition: a more conventional “continuous” deposition mode and a “dabber” deposition mode that produces relatively small and overlapping weld beads. Microstructural characterization of the specimens produced by these two modes was carried out by Leica DM750P optical microscopy. Dabber mode sub-grain microstructural features were significantly finer in size while being highly variable in terms of orientation and morphology. This is in contrast to coarser and more consistently oriented microstructural features of the continuous mode samples. At the macro-level, features of the dabber mode were observed to be consistently coarser with many columnar grain features when compared to the continuous deposition mode.
2:20 PM
Investigating the Mechanical, Microstructural, Corrosion and Impact Performances of a New Steel Composition, Produced by Tandem WAAM Mixing of Steel Wires: Osahon Ehigiator1; Supriyo Ganguly1; 1Cranfield University
It is an established knowledge that different alloying element play specific role in influencing the microstructure and properties of a materials. Material characteristics including; corrosion and impact performances can be optimised by designing new wire compositions or modifying existing ones. Wire mixing technique has been successfully applied in modifying the deposited material properties in functional graded parts and in modifying composition of aluminium alloy to eradicate solidification cracking. Utilisation of Tandem-GMAW process provides an opportunity of realising this technique; using off-the-shelf filler materials. This potentially provides a cost effective way of actualising the design of improved WAAM material compositions. This study investigates the mixing of 2.25Cr-1Mo and MoNiCr, with a view to harnessing their corrosion and low temperature toughness characteristics respectively, to achieve a composition with relatively improved performances.The modified composition achieved showed marked improvement in both corrosion and charpy performances, compared to the starting compositions.
2:40 PM
3D Characterization of Intrinsic Defects in Water- and Gas- Atomized 17-4 PH Stainless Steel Powder Precursors for Additive Manufacturing: Veeraraghavan Sundar1; Rachel Reed1; 1UES Inc.
Powder precursors have a critical effect on the outcome of AM processes. Two atomization routes (water- and gas- atomization) were used to create 17-4 PH stainless steel precursors for laser bed powder fusion processing at energy densities of ~ 100J/cc. Particle characteristics (size distribution, size width, apparent density, tap density), XRD, and mechanical testing (density, UTS, HRC and elongation %) were used to characterize the powders and AM parts. In addition, automated serial sectioning was used to characterize particle morphology and size distribution, as well as microstructure and defect distribution in the LPBF AM parts. A clear differentiation was demonstrated between the two processing techniques.
3:00 PM
Effect of Atomization and Processing Gas on Microstructures in Additively Manufactured 17-4PH Stainless Steel: Alexis Ernst1; Rainer Hebert1; Mark Aindow1; 1University of Connecticut
Powder bed fusion (PBF) techniques have the capability to produce complex near-net shaped components from a variety of different powders. For PBF of stainless steels it was suggested that the atomization gas and/or the background gas in the build chamber could have an important influence on the phase composition and microstructure in the as-built material. Since nitrogen is known to stabilize austenite, the use of nitrogen as the atomization gas or as the processing gas could affect the balance of the ferrite (⍺) and austenite (ɣ) phases. Here, we have built 17-4PH samples under identical conditions except for the use of N2 and Ar gas during the build process and we used commercial N2 and Ar gas-atomized powders. The effects of the gas on the microstructure, phase composition and final N2 contents have been assessed and the consequences of these observations can be a design variable in PBF of 17-4PH.