Deformation mechanisms and microstructure evolution in multi-pass hot spinning of Inconel825/Q345 explosive clad composite cylinders

Explosive clad plates combining dissimilar metals are promising for aerospace components, yet their forming behavior remains challenging due to property mismatches between constituent layers. This study investigates the multi-pass hot spinning of Inconel825/Q345 explosive clad composite cylinders through integrated finite element simulation and experimental characterization. A thermo-mechanical model is established to simulate the 7-pass process, and the deformation mechanisms are analyzed based on stress triaxiality and microstructural evolution. Results show that the outer Inconel825 layer undergoes coupled axial-circumferential deformation while the inner Q345 layer exhibits constrained passive deformation with enhanced radial compression. The stress state transitions axially from tensile-dominated near the tailstock to compressive-dominated toward the flange. Microstructurally, the recrystallized fraction in Inconel825 decreases sharply from 99.8% in the raw material, the interface becomes subgrain-dominated with a peak subgrain fraction of 70.7%, and the Q345 layer shows stress-state-dependent evolution with recrystallization of 96.8% and grain coarsening to 26.7 μm in high-triaxiality regions but fine equiaxed grains in low-triaxiality regions. Compared with the 7-pass path, the 16-pass path produces a more diversified texture distribution and achieves improved mechanical performance, including an ultimate tensile strength of 714.75 MPa, a yield strength of 463.77 MPa, as well as 23.9% higher reverse bending strength, 10.0% higher lateral bending strength, and a peak tensile-shear strength of 168.40 MPa. Residual-stress tests further show that the tensile residual stress at point Z in the Inconel825 layer increases by 50.0% and that in the Q345 layer increases by 37.9%.