Additive manufacturing (AM) technology is a rapid prototyping technology based on the discrete-accumulation principle. Driven by three-dimensional data of parts, solid parts are manufactured by stacking materials layer by layer. The biggest advantage of this molding method is that it can be molded without traditional tools, which reduces the working procedures and shortens the product manufacturing cycle, and is especially suitable for low-cost and small-batch product manufacturing. Moreover, the more raw materials with complex structure and high added value, the more obvious the advantages of rapid and efficient forming, and it has broad application prospects in aerospace, biomedicine, energy and chemical industry, micro-nano manufacturing and other fields.

Facing the requirements of low cost and high reliability of new aircraft, its parts and components are gradually developing towards large-scale and integration. Additive manufacturing technology can directly manufacture complex parts at low cost without using molds. It is expected to further optimize the existing aircraft parts structure, improve structural efficiency, and realize structural lightweight and high performance based on the advantages of additive manufacturing technology in configuration ability. Due to the simplification or omission of process preparation and mold design in traditional manufacturing, the digital design, manufacturing and analysis of products are highly integrated, which can significantly shorten the research and development cycle and cost.

Metal additive manufacturing technology can be divided into three types according to heat source types: laser, electron beam and arc. In the past 20 years, the powder-based metal additive manufacturing technology with laser and electron beam as heat sources has been mainly studied. By continuously melting or sintering metal powder, complex structural parts are continuously prepared layer by layer. Now it has been used in some key parts of high-tech fields such as aerospace, national defense and military industry, energy and electricity. However, due to the characteristics of raw materials and heat sources, metal powder-based laser and electron beam additive manufacturing technology can not be realized or even formed due to certain restrictions, and its raw materials and time costs are high, and there are many shortcomings: (1) for laser heat sources, its forming speed is slow, and the absorption rate of aluminum alloy to laser is low; (2) For electron beam heat source, the size of vacuum furnace body limits the volume of components; (3) Powder-based metal raw materials have high preparation cost, easy pollution and low utilization rate, which increases the raw material cost.

Based on the above reasons, the existing technology shows some limitations in forming large complex structural parts. In order to meet the requirements of large-scale and integration of aerospace structural parts, the low-cost and high-efficiency arc additive manufacturing technology developed based on surfacing technology has attracted the attention of some scholars. Waam (wire and arc additive manufacturing) uses electric arc as energy beam to manufacture metal solid parts by layer-by-layer surfacing. This technology is mainly developed on the basis of welding technologies such as TIG, MIG and SAW. The molded parts are fully welded, with uniform chemical composition and high density. The open forming environment has no restrictions on the size of the formed parts. The forming speed can reach several kg/h, but the surface of the parts manufactured by arc addition forming is undulating, and the surface quality of the formed parts is low, so it is generally necessary to carry out secondary surface machining. Compared with laser and electron beam additive manufacturing, the main application targets of arc additive manufacturing technology are low cost, high efficiency and near-net forming of large and complex parts.

Composite metal materials refer to composite metal materials produced by rolling method, explosive rolling method, explosive method and surfacing.