AUSTANDING: Lean austenitic stainless steel composite microstructure with enhanced mechanical properties

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Lucía Morales Rivas holds since 2016 a PhD degree in Materials Science and Engineering, which got International Mention and was awarded the extraordinary prize by the Universidad Carlos III de Madrid.

Her research line involves the development of new steels and other metallic materials with improved mechanical properties through the study of mechanisms governing phase transformations, deformation, and failure, from both experimental and theoretical approaches.

She has co-authored more than 30 scientific publications and has supervised numerous graduate and postgraduate theses.

Between 2016 and 2022 she was affiliated with the Technische Universität Kaiserslautern (Germany), where she led as principal investigator a 3-year project on the fatigue behaviour of nanostructured steels.

In 2022 she joined the Centro Nacional de Investigaciones Metalúrgicas (CENIM, CSIC) in Madrid, where, since April 2023, she is conducting her project Austanding as a ComFuturo fellow.

El proyecto AUSTANDING propone el diseño y la fabricación aditiva de un nuevo acero inoxidable con características especiales que posea una combinación adecuada de resistencia, ductilidad y tenacidad y a la vez mantenga altos niveles de resistencia a la corrosión. Este innovador proceso de fabricación, basado en la impresión 3D capa a capa, permite la elaboración de piezas de acero con las altas prestaciones mencionadas y geometrías complejas que no han podido lograrse hasta ahora, lo cual se aplicará a la producción de intercambiadores de calor de próxima generación, unos dispositivos ampliamente usados y demandados por múltiples sectores industriales. La naturaleza de los procesos empleados en la fabricación de este acero contribuirá a avanzar hacia un modelo de industria siderúrgica con cero emisiones netas de carbono. Por otro lado, al ser una fabricación que busca materiales con una composición química lo más simple posible y que minimiza la utilización de metales escasos, el proyecto cumple con la misión de la economía circular.
The AUSTANDING project proposes the design and additive manufacturing of a new stainless steel with special characteristics that possesses the right combination of strength, ductility and toughness while maintaining high levels of corrosion resistance. This innovative manufacturing process, based on layer-by-layer 3D printing, enables the production of steel parts with the aforementioned high performance and complex geometries that could not be achieved until now, which will be applied to the production of next-generation heat exchangers, devices widely used and demanded by multiple industrial sectors. The nature of the processes used in the manufacture of this steel will contribute to moving towards a zero net carbon steel industry model. On the other hand, as it is a manufacturing process that seeks materials with the simplest possible chemical composition and minimises the use of scarce metals, the project fulfils the mission of the circular economy.

Extended project summary:

Additive manufacturing (AM), also known as 3D printing, based on layer-upon-layer building, is continuously proving itself to be a groundbreaking technology shaking metallurgists into the design of new alloys and complex microstructures, and, likewise, mechanical engineers into the conception of optimized parts. Heat exchangers are among the applications which most benefit from AM, as it enables the manufacturing of geometries otherwise impossible as a single part. The need of operation within a wide range of temperatures in corrosive environments might make the selection of austenitic stainless steels preferable over other alloys, owing to their superior stability. However, a disadvantage of stainless steels with respect to their competitors is the poor thermal conductivity of the former. Wall thickness reduction resulting in a better thermal transfer between fluids is limited by the strength-to-weight ratio of the corresponding material. Additionally, an appropriate ductility of AM-produced stainless steels is a clear prerequisite for high-pressure tubes and vessels.

With such a motivation, the AUSTANDING project aims to design a new AM-manufactured austenitic stainless steel, in particular using selective laser melting (SLM), following these strategies: high nitrogen content, and a mechanical composite behaviour conferred by an engineered sandwich-like microstructure. In this sense, the increase in content of critical chemical elements such as nickel will be avoided, resulting in an improvement in terms of sustainability. Computing tools based on thermodynamics and crystallography will be used for an optimum design.

Figure. Austenitic stainless steel