Research progress of K438 by electron beam additive manufacturing

K438, Nickel-based superalloy, has excellent heat-corrosion resistance and high-temperature oxidation resistance, and is widely used in hot components of aero-engines such as turbine blades under working conditions of 900 ℃. Different from traditional preparation process, Additive Manufacturing (AM) technology has become an ideal process for "non-weldable" K438 superalloy due to its advantages of short production process, homogeneous microstructure and good high-temperature mechanical properties of components. Laser Source Additive Manufacturing (LSAM) in AM technology is prone to thermal stress accumulation and thus has a high susceptibility to cracking. Selective Electron Beam Melting (SEBM) technology is based on vacuum environmental conditions and powder bed preheating procedures, which can precisely control temperature changes and significantly reduce the residual thermal stress inside the workpiece, thereby reducing the number of cracks. In this paper, the current research status of K438 superalloy prepared by SEBM is reviewed, including the influence of working environment, process parameters and post-treatment technology on the quality of K438 superalloy, and the microstructure evolution trend of K438 superalloy under different process conditions, as well as the evolution of the phase organization of K438 superalloy under different process conditions.