Analysis of work hardening mechanisms in Quenching and Partitioning steels combining experiments with a 3D micro-mechanical model

Analysis of work hardening mechanisms in Quenching and Partitioning steels combining experiments with a 3D micro-mechanical model

Celada-Casero, Carola (TU Delft Team Maria Santofimia Navarro; Spanish National Center for Metallurgical Research (CENIM-CSIC))
Vercruysse, Florian (Universiteit Gent)
Linke, Bernd (ThyssenKrupp Steel Europe AG)
Smith, Ali (Rina Consulting - Centro Sviluppo Materiali)
Kok, Piet (Universiteit Gent; Tata Steel)
Sietsma, J. (TU Delft Team Kevin Rossi)
Santofimia, Maria Jesus (TU Delft Team Maria Santofimia Navarro)

2022

Quenching & Partitioning (Q&P) steels owe their good strength-ductility combinations to the martensite/austenite (α’/γ) mechanical interactions and to the formation of mechanically-induced martensite (α′_mech) through the transformation-induced plasticity (TRIP) effect. An essential role is played by carbon, whose distribution among the phases can be modified through the Q&P route. This study presents a methodology to systematically and quantitatively examine the influence of the α’/γ mechanical interactions on the overall work hardening of the steel with respect to the role of carbon in the martensite. The methodology rests on the generation of a 3D micro-mechanical model that allows to derive, by crystal plasticity simulations, the overall response of a mechanically-stable α’/γ virtual microstructure. In combination with theoretical knowledge on hardening, the comparison between the experimental and simulated mechanical responses enables the quantification of the influence of the martensite carbon content and distribution on the overall TRIP strengthening contribution of the steel. The approach is applied to two low carbon Q&P-processed α’/γ microstructures of similar initial volume fractions of austenite and α′_mech formation kinetics with strain, but one containing a Nb-microaddition and displaying improved strength-ductility values. It is shown that the martensite strength and work hardening ability might additionally enhance or partially counteract the strengthening contribution from the austenite-to-α′_mech transformation during uniaxial loading. The results of this study highlight that the processing-dependent properties of the carbon-depleted martensite should be considered in the optimization of Q&P processed steels.

3D micromechanical modeling
Austenite
Crystal plasticity
Martensite
Q&P microstructures
RVE
TRIP effect
Work hardening

http://resolver.tudelft.nl/uuid:bdc28cce-b5ec-4dd7-a2d4-68c05edae039

https://doi.org/10.1016/j.msea.2022.143301

0921-5093

Materials Science and Engineering A: Structural Materials: Properties, Microstructures and Processing, 846

Institutional Repository

journal article

© 2022 Carola Celada-Casero, Florian Vercruysse, Bernd Linke, Ali Smith, Piet Kok, J. Sietsma, Maria Jesus Santofimia