Effect of impact processing on the structure and properties of nickel alloy ZhS6U produced by casting and electron beam additive manufacturing

Introduction. Nickel alloys are widely used in the aerospace industry, but their operational characteristics require improvement through surface modification. A relevant challenge is to conduct a comparative analysis of mechanical impulse processing methods for cast and additively manufactured ZhS6U alloy to optimize their properties. The purpose of this work is to investigate the influence of low-frequency (LF) and high-frequency (HF) impact processing on the structural-phase state and surface properties of nickel alloy ZhS6U, produced by electron beam additive manufacturing (EBAM) and casting. The research methods include microstructural analysis using optical microscopy, X-ray diffraction analysis of the phase composition, microhardness measurements, and tribological testing via scratch testing of ZhS6U alloy samples after various processing modes. Results and discussion. It is established that LF processing of the cast alloy increases the volume fraction of the strengthening γ' phase, while HF processing forms an additional Ti2O phase. The processing of the additive alloy demonstrates more significant changes: micro-strains in the crystal lattice are 1.71…2.18 times higher, micro-stresses in the surface layer are 2.09…2.73 times higher, and the microhardness of the processed surface of the additively manufactured ZhS6U alloy is 8…16% higher compared to the cast material. Optimal processing modes are identified to be: 40 seconds for LF and 20 minutes for HF, providing a minimum friction coefficient of 0.075. Conclusions. Mechanical impulse processing effectively hardens the surface of nickel alloy ZhS6U fabricated by different methods. The application of the developed approaches is recommended to improve the performance characteristics of parts in the aerospace and mechanical engineering industries. Further research is required on the cyclic stability of modified structures after mechanical impulse processing in various frequency ranges.