Session: 03-04-02: Advanced Machining and Finishing Processes
Paper Number: 112918
112918 - Effect of Layering Sequence on the Characteristics of Wire Arc Additive Manufactured Parts
Wire arc additive manufacturing (WAAM) is gaining popularity among other additive
manufacturing processes for the manufacture of large-scale components. Wire arc additive
manufacturing allows for rapid deposition rates, greater productivity, and reduced material
waste. The energy source used by WAAM to melt wire and deposit additive layers is an
electrical arc. The microstructural evolution of the solidification process in WAAM depends on
the amount of heat input and the layering sequence. For all additive manufacturing deposits, the
creation of anisotropic characteristics was a common challenge. Many post-processing
techniques, including shot peening, interpass rolling, and quick cooling, were employed in order
to achieve isotropic characteristics. Nonetheless, these processes increase production time and
expense, thus it is required to get isotropic characteristics in the as-built deposited parts in order
to increase productivity. To examine the effect of layering sequences on grain development,
microstructure, and mechanical properties, Inconel 825 alloy was deposited in various sequences
for layering by wire arc additive manufacturing in this work. The WAAM deposits were
fabricated using GMAW welding in a distinct layering sequence.
In wire arc additive manufacturing, oscillation beads are favored for increasing the wall width;
nevertheless, this method results in columnar grain formation for some alloys. However, despite
the use of oscillating beads, it is necessary to apply repeated passes for walls with a wide width.
Several layering sequences were developed to prevent columnar grain production from
oscillation beads and many passes in a single layer. The microstructure of the deposits was
formed with varied properties based on the layering patterns. During the deposition of many
layers, heat conduction predominates from the top to the bottom of the deposited heights. Thus,
the direction of heat conduction promotes the growth of grains in that direction from bottom to
top by linking grains at fusion boundaries. This phenomenon occurs frequently in WAAM as a
result of the remelting of prior layers. At the fusion border between the previously solidified
bead and liquid metal, nucleation and epitaxial grain growth likely to develop. Hence, the
transverse columnar grains are determined by the grain size of the previous layer. Traditional
stacking sequence in one direction yields columnar grains, however zigzag layering sequence
refined the grain growth. The zigzag layering sequence mostly disrupted the direction of heat
conduction and grain development. The smaller size of fragmented grains improves the isotropic
characteristics. The anisotropic behavior of additively manufactured deposits has been shown to
depend on grain growth direction and size, which are affected by the layering sequence.
Hardness and tensile strength of WAAM deposits with zig-zag layering sequence were found to
be superior to standard layering sequence methods. Moreover, the zigzag layering sequence
improves the resolution of deposited walls having a linear shape.
Presenting Author: Muralimohan Cheepu STARWELDS Inc.
Presenting Author Biography: Dr. Murali Mohan Cheepu is a research manager at STARWELDS Inc. He has over ten years of
experience in the manufacturing and research industries. His research focuses on welding and
joining, additive manufacturing, automation, digitalization and artificial intelligence. In addition,
he is doing research on a novel TIG welding process with C-type filler to increase productivity.
Cheepu has won a number of awards, such as best researcher from KWJS, trusted reviewer from
the Institute of Physics in the UK, and best paper from materials and welding conferences. He
serves on the editorial board, reviewer, conference chair and technical committee member.
Cheepu has written more than 100 peer-reviewed articles including conference papers, patents
and welding research supplement articles in the American Welding Society. Cheepu has a
master's degree in welding engineering from the NIT Tiruchirappalli and a doctorate in
mechatronics engineering from Kyungsung University.
Authors:
Muralimohan Cheepu STARWELDS Inc.Ragavanantham Shanmugam Fairmont State University
Mohanavel Vinayagam Bharath Institute of higher Education and Research
Seth Dennison Navajo Technical University
Effect of Layering Sequence on the Characteristics of Wire Arc Additive Manufactured Parts
Paper Type
Technical Paper Publication