Tribocorrosion Behavior of Inconel 718 Fabricated by Laser Powder Bed Fusion-Based Additive Manufacturing

Arpith Siddaiah,Javed Akram,Pankaj Kumar,Manoranjan Misra,Pradeep L Menezes,Ashish Kasar

doi:10.3390/coatings11020195

Arpith Siddaiah, Javed Akram + Show 4 more

Open Access

https://doi.org/10.3390/coatings11020195

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Abstract

Additive manufacturing (AM) by laser powder bed fusion (LPBF) has gained significant research attention to fabricate complex 3D Inconel alloy components for jet engines. The strategic advantages of LPBF-based AM to fabricate jet components for aerospace applications are well reported. The jet components are exposed to a high degree of vibration during the jet operation in a variable aqueous environment. The combined vibration and the aqueous environment create a tribological condition that can accelerate the failure mechanism. Therefore, it is critical to understand the tribocorrosion behavior of the Inconel alloy. In the present work, tribocorrosion behavior of the LPBF fabricated standalone coating of Inconel 718 in the 3.5% NaCl aqueous solution is presented. The LPBF fabricated samples are analyzed to determine the impact of porosity, generated as a result of LPBF, on the triobocorrosion behavior of AM Inconel 718. The study includes potentiodynamic tests, cathodic polarization, along with OCP measurements. The corrosive environment is found to increase the wear by 29.24% and 49.5% without the initiation of corrosion in the case of AM and wrought Inconel 718, respectively. A corrosion accelerated wear form of tribocorrosion is observed for Inconel 718. Additionally, the corrosive environment has a significant effect on wear even when the Inconel 718 surface is in equilibrium potential with the corrosive environment and no corrosion potential scan is applied. This study provides an insight into a critical aspect of the AM Inconel components.

Highlights

2025.8 mm2 surface area of Inconel 718 was in contact with the electrolyte throughout the tribocorrosion testing
It is expected that there is a small degree of electropolishing that occurs on the surface of the Additive manufacturing (AM) Inconel 718 in tribocorrosive environment, which can increase pitting corrosion resistance [23]. These results indicate that AM of Inconel 718 has a significant influence on the tribocorrosion performance as compared to the wrought counterpart
The described method of tribocorrosion testing enables the measurement of the galvanic current between the passive and the depassivated areas of the sample surface at OCP

Summary

Introduction

Due to its excellent high-temperature performance, it is widely used in aircraft turbojet engines as discs, blades, and casing for high-pressure sections of aircraft engine components. It finds application in rocket engines and cryogenic environments due to its good toughness at low temperatures, which protects the components from brittle fracture. The higher shear strength and low material removal rate of Inconel 718 create difficulty in machining, especially for complex parts where tight dimensional accuracy is required [1,2,3]. Additive manufacturing (AM) provides an excellent opportunity to overcome the difficulty of conventional machining to develop a complex structure of Inconel 718 [4,5]

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