A validated finite element model for designing a multistage forming process to enhance annealing-induced shape change in AISI 420 sheet

• Validated AISI 420 model predicts annealing-induced shape change over 300–760 °C. • Creep equation captures residual-stress relaxation below 760 °C annealing. • New forming route increases shape change (4 to 47 µm) for reliable measurement. • Staged simulation workflow enables efficient tooling optimization. Heat treatment of metallic components, while crucial for achieving desired material properties, often induces shape changes that compromise dimensional accuracy. For components manufactured from AISI 420 sheet, this shape change is minor yet critical, presenting significant challenges for experimental measurement and parametric investigation. This work develops and validates a finite element-based constitutive model suite to not only predict this phenomenon but also to design a novel multistage forming process that deliberately amplifies the shape change for measurability. The model, which incorporates mechanical and thermal effects, was implemented in a staged workflow preserving state variables across simulations. Validation against an existing process demonstrated excellent agreement in predicting both earing and annealing-induced shape change. Subsequently, this validated model was employed to design a new process. Among five tooling variants assessed, the optimized design successfully amplifies the shape change to 47.3 µm, a tenfold increase over an existing process. Our analysis reveals that shape change is governed by the magnitude and components of residual stress in conjunction with product geometry. This study contributes a validated constitutive model suite, a systematic workflow for FEM-based process design, and a novel multistage forming process engineered to amplify annealing-induced shape change and enhance measurability.