Optimization of Thermal and Energy Efficiency in Multi-Stage Hot Forming of AISI 1060 Steel Hollow Components Using Deform-3D and NSGA-II

This study investigates the thermal and energy efficiency of a multi-stage hot forming process for producing high-aspect-ratio hollow cylindrical components from AISI 1060 steel. The process integrates hot backward extrusion and subsequent ironing, simulated using Deform-3D under thermo-mechanical coupling conditions. Three key forming parameters—initial billet temperature, deformation degree (i.e., reduction in area/strain), and punch speed were systematically varied according to a Box–Behnken Design (BBD). The responses considered were the heat loss ratio after extrusion (HLRextr), total heat loss ratio over the complete forming sequence (HLRtotal), and total forming energy consumption (Utotal). Reduced regression models were developed and validated using ANOVA, achieving high predictive accuracy (R2 > 0.98). Multi-objective optimization using the Non-dominated Sorting Genetic Algorithm II (NSGA-II) was performed to minimize all three objectives under the constraint that the final average billet temperature remained within 850–900°C. The resulting Pareto front revealed clear trade-offs between thermal retention and energy demand, with selected solutions offering either minimal energy consumption or minimal total heat loss. The findings highlight the dominant influence of billet temperature and punch speed on both heat retention and energy efficiency, providing practical guidelines for parameter selection in industrial multi-stage hot forming of medium-carbon steels.