Abstract

To develop the commercial applicability of Wire-Arc Additive Manufacturing (WAAM), there is a crucial need to understand the corrosion behaviour of the fabricated materials for industry acceptance. It is well-known that WAAM process has a complex thermal process, resulting in unique microstructures and material surfaces. The current studies on corrosion resistance in the WAAM process are focused on Stainless Steels, Steels and Nickel-based alloys due to the potential industrial applications. Hence, a comprehensive review of the resulting microstructural evolution and corrosion resistance of the WAAM manufactured Stainless Steels, Steels and Nickel-based alloys has been presented.

It was found that the understanding of the corrosion resistance and corrosion testing needs further development for the mechanisms that the alloys are susceptible to. Development of various standardized corrosion testing for the metal alloys is necessary to optimize WAAM applications based on industrial requirements.

Introduction

Among the many additive manufacturing processes, Wire Arc Additive Manufacturing (WAAM) has recently been drawing interest due to its great and attractive prospect for fabrication of large parts, the possibility to process a vast range of materials in form of welding wires, and the addition of further details to semi-finished components [1]. However, most of the research have currently focused on optimization of the WAAM process parameters and analysis of the resulting thermal and residual stresses [2]. Unlike conventional manufacturing processes, WAAM process and post-processing treatments result in unique microstructures and material surfaces that alter the corrosion performance of the materials but are not fully studied or understood yet.

For instance, additively manufactured steels are subjected to very different time-temperature profiles and process parameters [3], consequently leading to strong differences in the microstructures. Overview of the microstructure of steels after conventional and additive manufacturing is depicted in Figure 1. Subsequently, the resulting microstructure also leads to variation in the corrosion resistance in the alloys.

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