Preheating Influence on the Precipitation Microstructure, Mechanical and Corrosive Properties of Additively Built Al–Cu–Li Alloy Contrasted with Conventional (T83) Alloy

Materials, vol. 16, pp. 4916

Abstract

In this paper, the high strength and lightweight Al–Cu–Li alloy (AA2099) is considered in as-built and preheated conditions (440 °C, 460 °C, 480 °C, 500 °C, and 520 °C). The purpose of this study is to investigate the influence of laser powder bed fusion (LPBF) in situ preheating on precipitation microstructure, mechanical and corrosive properties of LPBF-printed AA2099 alloy compared to the conventionally processed and heat-treated (T83) alloy. It is shown that precipitations evolve with increasing preheating temperatures from predominantly globular Cu-rich phases at lower temperatures (as-built, 440 °C) to more plate and rod-like precipitates (460 °C, 480 °C, 500 °C and 520 °C). Attendant increase with increasing preheating temperatures are the amount of low melting Cu-rich phases and precipitation-free zones (PFZ). Hardness of preheated LPBF samples peaks at 480 °C (93.6 HV0.1), and declines afterwards, although inferior to the T83 alloy (168.6 HV0.1). Preheated sample (500 °C) shows superior elongation (14.1%) compared to the T83 (11.3%) but falls short in tensile and yield strength properties. Potentiodynamic polarization results also show that increasing preheating temperature increases the corrosion current density (Icorr) and corrosion rate. Indicated by the lower oxide resistance (Rox), the Cu-rich phases compromise the integrity of the oxide layer.

Authors 8

1. Frank Adjei-Kyeremeh corresponding Aachen Foundry Institute

   RWTH Aachen University

   Affiliation as printed

   Foundry Institute, RWTH Aachen University, Intzestraße 5, 52072 Aachen, Germany

2. Yudha Pratesa Aachen Chair of Corrosion and Corrosion Protection Foundry Institute

   RWTH Aachen University

   Affiliation as printed

   Chair of Corrosion and Corrosion Protection, Foundry Institute, RWTH Aachen University, Intzestraße 5, 52072 Aachen, Germany

3. Xiao Huan Shen Aachen Steel Institute

   RWTH Aachen University

   Affiliation as printed

   Steel Institute, RWTH Aachen University, Intzestraße 1, 52072 Aachen, Germany

4. Wenwen Song Aachen Steel Institute

   University of Kassel · RWTH Aachen University

   Affiliation as printed

   Institute of Materials Engineering (IfW), University of Kassel, Moencheberg Str. 3, 34125 Kassel, Germany

   Steel Institute, RWTH Aachen University, Intzestraße 1, 52072 Aachen, Germany

5. Iris Raffeis Aachen Foundry Institute

   RWTH Aachen University

   Affiliation as printed

   Foundry Institute, RWTH Aachen University, Intzestraße 5, 52072 Aachen, Germany

6. Uwe Vroomen Aachen Foundry Institute

   RWTH Aachen University

   Affiliation as printed

   Foundry Institute, RWTH Aachen University, Intzestraße 5, 52072 Aachen, Germany

7. Daniela Zander Aachen Chair of Corrosion and Corrosion Protection Foundry Institute

   RWTH Aachen University

   Affiliation as printed

   Chair of Corrosion and Corrosion Protection, Foundry Institute, RWTH Aachen University, Intzestraße 5, 52072 Aachen, Germany

8. Andreas Bührig–Polaczek Aachen Foundry Institute

   RWTH Aachen University

   Affiliation as printed

   Foundry Institute, RWTH Aachen University, Intzestraße 5, 52072 Aachen, Germany