High strength aluminum alloy has become one of the most commonly used metal materials for aerospace and automotive application parts due to its high strength, low density, excellent ductility, and corrosion resistance. The arc additive manufacturing technology has the ability to rapidly form complex structural components in situ, and is very suitable for the manufacturing of medium or large high-strength aluminum alloy aluminum parts. This article aims to comprehensively analyze the latest research progress and challenges faced by arc additive manufacturing technology for high-strength aluminum alloys.

Overview of Arc Additive Manufacturing Technology

Wire and Arc Additive Manufacturing (WAAM) combines the advantages of traditional welding techniques and additive manufacturing. It uses an arc as a heat source and filler wire as raw material for layer by layer deposition until the desired 3D shaped structural component is created. Compared to subtractive manufacturing and other additive manufacturing processes, WAAM has advantages such as high deposition efficiency, low equipment cost, high material utilization, the ability to manufacture large-sized components, high design freedom, wide material availability, and low environmental pollution. These characteristics make WAAM have broad development prospects in the field of metal intelligent manufacturing.

Inherent Properties and Defects of High Strength Aluminum Alloy Arc Additive Manufacturing

High strength aluminum alloys generally refer to 2 series aluminum alloys containing copper elements and 7 series aluminum alloys containing zinc elements that can be strengthened by heat treatment. They are mainly used in the aerospace field that requires high strength, high toughness, corrosion resistance, and high damage resistance. However, during the forming process of high-strength aluminum alloys in WAAM technology, the inherent characteristics of different forming methods and other aluminum alloys caused by layer by layer deposition heat input cannot be completely eliminated. These characteristics include interlayer bonding, melt pool zone (MPZ), melt pool boundary (MPB), and heat affected zone (HAZ).

Common defects in the WAAM process of high-strength aluminum alloys include cracks, porosity, uneven microstructure, residual stress, and deformation. These defects have a significant impact on the mechanical and structural properties of high-strength aluminum alloy components. For example, the tensile strength of high-strength aluminum alloy components deposited by simple welding deposition often does not exceed 300 MPa, far below expectations. Therefore, how to optimize the performance of high-strength aluminum alloy WAAM components by changing process parameters and post-treatment methods is one of the current research focuses.

Classification and principles of arc additive manufacturing technology

According to the different properties of the heat source, WAAM processes are usually divided into three types: gas metal arc welding (GMAW), gas tungsten arc welding (GTAW), and plasma arc welding (PAW).

Gas Metal Arc Welding (GMAW) is one of the most commonly used WAAM processes, which uses continuously fed filler wire as the electrode to melt the wire and substrate layer by layer under the protection of inert gas or active gas by arc. This process has the advantages of easy operation, high deposition rate, and relatively low cost, but faces challenges in controlling microstructure and reducing defects.

Gas tungsten arc welding (GTAW) uses a tungsten rod as the electrode, and an arc is generated between the tungsten rod and the workpiece. The filler wire is melted by the arc and deposited onto the substrate. The GTAW process has advantages in controlling heat input and arc stability, and is suitable for applications with high requirements for forming accuracy and microstructure. However, its sedimentation rate is relatively low, which limits its application in the manufacturing of large-sized components.

Plasma arc welding (PAW) forms a high-temperature, high-energy density plasma beam by compressing the arc, achieving rapid melting and precise control of the welding wire. The PAW process has the characteristics of high precision, high energy density, and low dilution rate in WAAM, and is suitable for manufacturing high-quality and high-performance aluminum alloy components. However, its high device complexity and cost limit its widespread application.

Researchers are exploring ways to improve the mechanical and structural properties of high-strength aluminum alloy WAAM components by optimizing process parameters, improving heat source design, and adopting advanced post-treatment techniques to address the defects present in the WAAM process. Future research will place greater emphasis on interdisciplinary collaboration, combining the latest achievements in materials science, mechanical engineering, and computer science to promote innovation and development in high-strength aluminum alloy arc additive manufacturing technology.