Session: 17-01-01: Research Posters

Paper Number: 150293

150293 - Understanding the Joining Mechanisms of Grcop42 - Inconel 625 Fabricated via Laser Directed Energy Deposition 

Fabrication of robust dissimilar metal joints is essential for creating multi-material components. However, multi-material additive manufacturing (AM) involves in-process changes in composition and temperature. In liquid-state AM processes, buoyancy, remelting, and Marangoni mixing between dissimilar metals lead to the formation of new alloys. These resultant alloys often exhibit a wider liquidus-solidus temperature range, increasing susceptibility to solidification cracking. Understanding the impact of process-induced mixing on solidification rate and microstructure at dissimilar interfaces is key to understanding the joining mechanisms in dissimilar metals.

This research aims to comprehensively investigate how AM process physics affects dissimilar joining mechanisms by depositing Inconel 625 onto GRCop. The Inconel 625-GRCop system is selected due to the thermal management capabilities offered by GRCop alloys, which are crucial for high-temperature structural applications where Inconel alloys are used. Cracking is observed when depositing Inconel 625 onto GRCop, necessitating investigating the causes and mechanisms of such failures in dissimilar metal AM.

A multi-physics modeling framework combined with experimental fabrication and characterization is proposed to address current barriers. This approach will explore the role of dissimilar interfaces and AM process physics on thermal history and fluid flow and, subsequently, on process-induced mixing and joining mechanisms. CALPHAD initially predicts phases as a function of composition and temperature in the dissimilar system. Based on the predicted mixed alloys, thermo-physical properties will be predicted at different temperatures and compositions using the combined CALPHAD database and the density functional theory (DFT).

Conventional alloying or arc-melting will fabricate mixed alloys across the compositional spectrum. Experimental thermo-physical property measurements of these alloys will be conducted.

A coaxial wire-fed powder-fed laser-directed energy deposition (WP-LDED) process will fabricate dissimilar metal components, offering combined benefits of high deposition rates and fine resolution. This coaxial configuration allows for multi-material, direction-independent manufacturing by using an axial wire-feed and a circumferential powder-feed capability all integrated into one deposition head. Dissimilar joints will be fabricated using varied LDED parameters, including bimetallic and compositionally graded joints and transition layers. A customized computational fluid dynamics model (CFD) will predict thermal fluid flow at dissimilar interfaces during WP-LDED. This model will simulate transient thermal history, bead dimensions, and alloy composition, providing insights into the effects of thermal fluid flow and history on process-induced mixing.

Consequently, AM process strategies can be optimized to establish parameters that produce robust dissimilar joints. This study will provide a fundamental understanding of the physics involved in joining/failure mechanisms in dissimilar metal AM.

Presenting Author: Nahal Ghanadi Oregon state University

Presenting Author Biography: Nahal Ghanadi is a graduate research assistant in advanced manufacturing at the School of Mechanical Engineering at Oregon State University. She completed her master's studies in mechanical engineering at Sapienza University of Rome. Her research primarily focuses on metal additive manufacturing, and she is currently working on projects to understand the joining mechanisms in dissimilar metal additive manufacturing and to design open pore structures for catalytic applications.

Authors:

Nahal Ghanadi Oregon state University
Somayeh Pasebani Oregon state University