Analysis of additive remanufacturing technology of nickel-based superalloy based on welding

Nickel-based superalloy with its high temperature resistance, corrosion resistance, resistance to complex stress and other properties, in the production of turbine engine working blades, guide blades, aircraft engines and industrial gas turbines and other high temperature parts have a wide range of applicability, and therefore known as the "heart of the engine". However, when these parts work at high temperature, complex stress, especially in the complex environment of seawater, it is easy to produce cracks, wear, fracture and corrosion, resulting in a large number of parts scrapped. Using additive remanufacturing technology to "remanufacture" used parts can bring their value into full play to a greater extent and obtain huge economic benefits.

Additive remanufacturing technology is the use of additive manufacturing technology to remanufacture and repair used parts:

Firstly, the 3D digital model of the parts is scanned by using some principles of digital processing.

Then, after the digital model is processed, the 3D digital model of the defective part is obtained.

The defective parts are directly and quickly processed by stacking layer by layer.

It is built on the basis of CNC CAD/CAE/CAM, welding, new materials and other existing mature technology, the core concept is "layer by layer superposition, layered forming". Since the beginning of the 20th century, the United States has carried out additive remanufacturing on military equipment such as B-52 bombers and M1 tanks, and has listed the replacement and remanufacturing technology of weapon systems as the research field of national defense science and technology. In China, additive remanufacturing technology has been successfully applied to various military equipment, which has produced huge economic benefits. Because additive remanufacturing technology itself is not mature enough, the research is still in the initial stage, so there are many problems to be solved. Therefore, the research status of additive remanufacturing technology based on welding is briefly introduced, and the research hotspots of future development are proposed by comparing different welding processes.

GasTungstenArcWelding(GTAW) is gas shielded arc welding with tungsten rod as one electrode. Its application is very flexible, especially compared to laser cladding, it can more easily handle the additive remanufacturing of non-ferrous metals such as copper, aluminum and magnesium. In addition, the arc length and arc stability are good, the lower limit of welding current is not restricted by the welding wire droplet transition and other factors, and the welding current can be used to 2A. However, it still has some shortcomings: on the one hand, the carrying capacity of the tungsten electrode is limited, and too much current is easy to burn the tungsten electrode, thus limiting the penetration depth; On the other hand, with the increase of current, the arc divergence of tungsten electrode becomes serious, causing the collapse of molten pool after forming, which seriously affects the forming quality.

The main factors affecting the GTAW process are welding current, tungsten electrode diameter, arc length, arc voltage and welding speed. Among them, the welding current is the key parameter to determine the GTAW weld formation. When other conditions remain unchanged, the increase of welding current can lead to the increase of arc pressure, heat input and arc column diameter, and increase the weld penetration depth and width. The arc length range is usually 0.5 ~ 3.0mm, when the shape is deformed, the arc length is the lower limit, otherwise the upper limit is taken; Welding speed is an important parameter to adjust the GTAW heat input and weld bead shape. After the welding current is determined, the welding speed has a corresponding value range. If the welding current exceeds the upper limit of the range, cracks, edge biting and other defects are easy to occur.