Preparing hot-rolled steels for the future

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Breakthrough metallurgies are opening the path to next-generation hot-rolled high-strength steels with exceptional properties.

Aniruddha Dutta & Koenraad Theuwissen

Preparing hot-rolled steels for the future

As the current first generation of advanced high-strength steels – such as micro-alloyed or quench and tempered steels – reaches the limits of what can be achieved with conventional metallurgical solutions, new horizons need to be explored.

In the quest for stronger materials with good ductility and good in-use properties aiming at weight and cost reduction, one of the main working axes is the development of manganese hot-rolled steels. In recent years, manganese steels have become a research focus globally. Investigations from fundamental questions about the deformation mechanisms, to questions regarding manufacturability, along with investigations into the application potential are being looked into to develop a new methodological approach to the design of structural materials.

BREAKTHROUGH SOLUTIONS

Therefore, breakthrough solutions are currently being developed by OCAS researchers for next-generation hot-rolled high-strength steels. The second generation of advanced high-strength steels includes high-manganese concepts. By activating different deformation mechanisms, a wide range of mechanical properties can be obtained with such high-manganese concepts, specifically providing excellent ductility and good strength, as compared to the first generation advanced high-strength steels. Low-density high-manganese highaluminium concepts are also being investigated, from the fundamental metallurgy point of view as well as from the manufacturing perspective.

3RD GENERATION

Apart from these, the 3rd generation of advanced high-strength steels with complex martensitic-based microstructures containing controlled amounts of austenite are also being investigated by OCAS’s metallurgy team. The microstructural characteristics are key to determining the material properties, which can be tuned by composition and processing adjustments. Medium-manganese concepts have been used to reach extreme strength levels in heavy-gauge hot-rolled strip products while maintaining good ductility, which is typically required for structural applications. The lower manganese contents make these steels easier to manufacture in the steel shop, as well as during downstream processing, while also reducing the alloying costs and providing attractive properties.

DIFFERENT MARKET SEGMENTS CALL FOR DIFFERENT PROCESSING

Similar compositions can be processed differently to obtain higher austenite contents, which contribute to outstanding (low temperature) toughness and elongation in lower-strength materials, meeting the property demands of other applications. The metallurgical designs have good property robustness with respect to processing variations, which are inherent to the production environment. This contributes to the overall cost-effectiveness of these products. After laboratory investigations, our efforts are now being focused on the industrialisation of such concepts in hotstrip mills.