Characterisation on impact-toughness in Al-bearing hot-rolled TRIP steel produced through dynamic-partitioning

In this study, an energy-efficient processing route involving hot rolling and on-line heat treatment was proposed, which was applied to Al-containing hot-rolled TRIP steel. The experiments were carried out involving hot rolling and on-line heat treatment, where the samples were subjected to different processing routes. The results showed that the cooling temperature determined the microstructural type of experimental steels, while the cooling pattern determined the decomposition state of retained austenite. The introduction of polygonal ferrite in martensitic matrix, and decomposition of retained austenite in ferritic and bainitic matrix were harmful to impact toughness. The fracture mode in ferritic matrix through air cooling was ductile fracture containing dimples and the fracture morphology reflected the best impact toughness of 134 J in selected steels.