Research on precise control of microstructure and mechanical properties of Ni-based superalloy cylindrical parts during hot backward flow spinning

Ni-based superalloy cylindrical parts widely used in the fields of aviation and aerospace have high requirements for the microstructure and mechanical properties. Hot flow spinning is an effective forming technology for manufacturing cylindrical parts with thin walls. The high-temperature plane strain compression test was put forward as the physical simulation test of hot backward flow spinning (HBFS) of cylindrical parts, and a new method for controlling the microstructure and mechanical properties of spun parts precisely based on hot processing map was proposed as the basis of selecting the reasonable processing parameters of HBSF. The results show that the relationships between the large true strains and stresses of Haynes 230 alloy during HBFS can be obtained effectively by the high-temperature plane strain compression test; the reasonable processing parameters which are beneficial for dynamic recrystallization and hot plastic deformation can be selected directly on the basis of the hot processing map. The influence of the processing parameters of HBSF on the microstructure of Haynes 230 cylindrical spun workpiece was also investigated, the results show that the influence of thinning ratio and forming temperature on the microstructure of the spun workpiece is remarkable, while the average grain size of spun workpiece decreases slightly with the increasing of feed rate. The yield strength and tensile strength of the Haynes 230 cylindrical spun part at the temperature of 800°C are both increased obviously compared with the original cylindrical blank, and the elongation is also slightly increased, which is particularly helpful in the high-temperature service of the Ni-based superalloys.