One of the most critical, yet invisible, challenges in manufacturing high-performance forged components lies deep within the material itself, at the microscopic scale of individual grains.
Achieving the right grain structure is everything: it determines strength, toughness, and fatigue life. But controlling it in complex, large-scale industrial forging processes has traditionally relied on costly trial-and-error.
Within the AID4GREENEST project, researchers at Fraunhofer IWM (Freiburg, Germany) have taken a decisive step towards changing this paradigm.
The team has developed and validated a physics-based, mean-field microstructure simulation framework capable of predicting steel grain evolution throughout the entire thermomechanical processing chain, from initial reheating through to the final forging phase.
The framework was tested against a demanding industrial benchmark: a large-scale turbine shaft made from high-performance low-alloy steel, forged by project partner Reinosa Forgings & Castings. The complex, multi-stage forging process creates extreme thermal and mechanical gradients that make microstructure control exceptionally challenging.
The results were exceptional. The model successfully predicted the grain structure evolution across the entire component, capturing both refined microstructures and the intricate spatial heterogeneity arising from complex thermomechanical histories.
Validation through metallographic analysis of the actual forged component confirmed the model’s ability to accurately represent real-world industrial forging physics.
This breakthrough delivers a transformative tool for the AID4GREENEST vision: enabling forging companies to de-risk the adoption of green steels by predicting how new, more variable materials will behave before they enter production.
The capability to simulate material behaviour with confidence unlocks tremendous potential for energy savings, waste reduction, and quality assurance from first production.
The next step: the rich output data, including predicted microstructure and thermomechanical fields, will serve as critical inputs for complementary full-field microstructure models currently being developed by the University of Oulu.
This collaborative effort is bringing the project one step closer to delivering a complete process-microstructure-property simulation chain for sustainable steel components.