Mechanical properties of advanced high-strength steels produced via quenching and partitioning

• Autores: María Irene De Diego Calderón
• Directores de la Tesis: Jon Mikel Molina Aldareguia (dir. tes.), Ilshat Sabirov (dir. tes.)
• Lectura: En la Universidad Carlos III de Madrid ( España ) en 2015
• Idioma: inglés
• Tribunal Calificador de la Tesis: José Manuel Torralba Castelló (presid.), José María Cabrera Marrero (secret.), Laura Moli Sanchez (voc.)
• Programa de doctorado: Programa de Doctorado en Ciencia e Ingeniería de Materiales por la Universidad Carlos III de Madrid
• Materias:
  • Física
    • Mecánica
      • Medida de propiedades mecánicas
  • Ciencias tecnológicas
    • Tecnología de materiales
      • Propiedades de materiales
      • Resistencia de materiales
    • Tecnología metalúrgica
      • Productos metalúrgicos (especiales)
• Enlaces
  • Tesis en acceso abierto en: e-Archivo
• Resumen

  • Advanced high-strength steel (AHSS) grades have been frequently used for applications that require a compromise between cost reduction, mechanical behavior and reliability of components that work under static and fatigue service loading conditions. Quenching and Partitioning (Q&P) is receiving increasing attention as a novel heat treatment to produce AHSSs containing martensite/retained austenite mixtures, with desirable combination of strength, ductility and toughness. However, despite the significant body of research on microstructure and mechanical properties of Q&P steels, there is still a significant lack of knowledge on the effect of microstructural architecture on their mechanical performance. Particularly, no research on fatigue and fracture behavior of Q&P steels has been carried out up-todate. Therefore, the main objective of this PhD thesis is to develop a concept of microstructural design in Q&P steels in order to improve a wide range of mechanical properties (uniaxial tensile, fatigue and fracture), as well as to gain fundamental understanding of their relationship with the microstructure and Q&P processing parameters. It is demonstrated that: (i) tensile mechanical behavior and strain partitioning between phases strongly depend on the microstructure of Q&P steels, which, in turn, can be tuned via manipulation of the Q&P parameters; (ii) matrix conditions play an important role in fracture behavior of Q&P steels and (iii) fatigue life of Q&P steels is also determined by their microstructure and can be enhanced via improvement of strength of interphase boundaries. Based on the analysis of the experimental results, it is shown that tailoring of the microstructure of Q&P processed steels can lead to further improvement of their mechanical performance.