Mechanical behaviour of third-generation steel subjected to strain path changes

The development of new steel grades is essential to meet the evolving demands of vehicle manufacturing and to understand their mechanical behaviour under complex loading paths is critical to ensuring reliable and effective forming operations. This study investigates the response of a third-generation advanced high-strength steel subjected to reverse shear loading and two-step uniaxial tension tests, with reloading at 0°, 45°, 55° and 90° relative to the initial prestrain direction. Under reverse shear loading, the material exhibits a pronounced transient Bauschinger effect that stabilizes after approximately 20 % prestrain. No hardening stagnation is observed, and permanent softening occurs at higher prestrain levels. In the two-step tension tests, a transient Bauschinger effect is observed at 90° from the rolling direction, with no latent hardening present for cross-loading. A dislocation-based crystal plasticity model is employed to simulate the material response under non-proportional loading, and its predictions are compared with experimental results to assess the model’s accuracy in capturing strain-path sensitivity in third-generation steel.