Manufacturing of Ni-based superalloy thin-walled components by complex strain-path spinning combined with solution heat treatment

Complex thin-walled components, such as conical-cylindrical parts, widely used in combustor shells, are generally made of Ni-based superalloy. However, it is difficult to manufacture the complex components with high dimensional accuracy by single process, and the formability of Ni-based superalloy is limited at room temperature due to the severe work hardening. A new spinning-heat treatment composite forming method of manufacturing the conical-cylindrical parts, consisting of shear spinning, solution heat treatment, and deep drawing spinning, was proposed. The feasibility of manufacturing the Ni-based superalloy complex component at room temperature was explored, and the spinning formability under complex strain path was analyzed. The results show that the limited thinning ratio of Ni-based superalloy is about 50% at room temperature under the strain state of pure shear deformation, and the work hardening of conical pre-formed blank can be completely eliminated by a 1200°C × 20 min solution heat treatment. Wrinkling occurs easily when single-pass deep drawing spinning was adopted to form the cylindrical section with the spinning coefficient of 0.78 under the linear strain path. Fracture along axial direction occurs easily at the opening area of the spun workpiece under the locally serrated strain path when multi-pass deep drawing spinning was adopted to form the cylindrical section without solution heat treatment. The spinning formability of the Ni-based superalloy of the multi-pass deep drawing spinning improves remarkably after solution heat treatment due to the improvement of deformation uniformity and the significant decrease of the tangential compressive stress at flange area. The experiments were carried out to verify the theoretical analysis results, and the Ni-based superalloy conical-cylindrical parts with high dimensional accuracy were manufactured successfully by the developed method combining of shear spinning followed by a solution heat treatment and multi-pass deep drawing spinning.