Effect of rotary swaging and annealing on mechanical properties and microstructure evolution of aeroengine high-temperature alloy steel tube.

Rotary swaging (RS) with mandrel was performed on aeroengine high-temperature alloy steel tubes at room temperature. Annealing experiments were conducted on both the non-RS and RS sections at various temperatures. The evolution of microstructure and mechanical properties was analyzed. Mechanical testing results revealed that RS resulted in a greater increase in yield strength compared to tensile strength, with a less pronounced recovery of yield strength enhancement after annealing. Annealing at 700 °C showed the most effective recovery of elongation. Microstructural observations showed shortening and coarsening of martensite packets and blocks after annealing, along with the evolution of precipitates. The higher dislocation density introduced by the RS process led to recovery during annealing and extensive recrystallization at 900 °C. Both annealing temperature and dislocations jointly influenced microstructure evolution and the work-hardening behavior. The thickness of shear layers induced by the RS process on the surface could be reduced after annealing and the elongated grains underwent recovery and recrystallization. This study provides a comprehensive investigation into the mechanisms of mechanical performance and microstructure evolution. It holds practical insights for applying the RS-annealing process to aeroengine high-temperature alloy steel tubes and for developing advanced processing routes for aeroengine shafts. [ABSTRACT FROM AUTHOR]