Page 48 - MSAM-3-2

Materials Science in

Additive Manufacturing

ORIGINAL RESEARCH ARTICLE
Effects of heat treatment on microstructure and

mechanical properties of 17-4PH/IN625 bimetallic
parts fabricated through extrusion-based

sintering-assisted additive manufacturing

Yulin Liu , Dayue Jiang , and Fuda Ning*
Department of Systems Science and Industrial Engineering, State University of New York at
Binghamton, Binghamton, New York, United States of America

Abstract

The mechanical properties of bimetallic composites are significantly influenced by
their interfacial morphologies. This study delves into the impact of various heat
treatment conditions on the microstructure and mechanical attributes of steel/
nickel bimetallic (17-4PH/IN625) components produced through extrusion-based
sintering-assisted additive manufacturing (ES-AM). The bimetallic composites were
annealed at 1150°C for 1, 4, and 8 h, followed by an aging treatment at 482°C for
samples annealed for 8 h. After annealing, microstructural heterogeneities, including
variations in grain size and elemental distribution within the transition zone close
to the interface, were observed. It was found that in the diffusion transition zone
*Corresponding author: between the two alloy layers, the diffusion of iron (Fe) and nickel (Ni) elements
Fuda Ning increased with longer holding times, as corroborated by microhardness tests and
(fning@binghamton.edu) quantified through theoretical parabolic diffusion law. The transition zone exhibited
Citation: Liu Y, Jiang D, Ning two distinct areas: an Fe-predominant zone and a Ni-predominant zone, with the
F. Effects of heat treatment on latter containing oxides and molybdenum (Mo)- and niobium (Nb)-rich precipitates.
microstructure and mechanical No new phases emerged post-heat treatment; however, shifts in peak due to
properties of 17-4PH/IN625
bimetallic parts fabricated through stress relaxation and the emergence of precipitates were identified through X-ray
extrusion-based sintering-assisted diffraction (XRD) observations. Microhardness within the transition zone increased
additive manufacturing. Mater Sci following heat treatment, peaking at 186 HV after a 4-h annealing. The optimal
Add Manuf. 2024;3(2):3281. 1.0
doi: 10.36922/msam.3281 heat treatment condition was identified as 1150°C for 4 h, which facilitated the
development of uniform microstructures and improved bonding strength. This
Received: March 27, 2024
study demonstrates an enhanced interfacial bonding strength in 17-4PH and IN625
Accepted: April 29, 2024 bimetallic parts manufactured through ES-AM, suggesting their wide-ranging
Published Online: May 24, 2024 potential applications in industry.
Copyright: © 2024 Author(s).
This is an Open-Access article Keywords: Bimetallic composites; Extrusion-based sintering-assisted additive
distributed under the terms of the
Creative Commons Attribution manufacturing; ES-AM; Heat treatment; Interface bonding; Diffusion zone
License, permitting distribution,
and reproduction in any medium,
provided the original work is
properly cited. 1. Introduction
Publisher’s Note: AccScience
Publishing remains neutral with The demand for hybrid structures containing a combination of varied metal materials
regard to jurisdictional claims in 1
published maps and institutional has increased to address the requirements of multiple industrial applications. Bimetallic
affiliations. structures offer several advantages, such as superior structural robustness, improved

Volume 3 Issue 2 (2024) 1 doi: 10.36922/msam.3281