Advanced High Strength Steels: Improved Properties by Design of Textures and Microstructures

38th Risø International Symposium on Materials Science

Kestens, Leo A.I.^1,2 ; De Knijf, Dorien^1,3 ; Cerda, Felipe Castro^1,4 ; Petrov, Roumen H.^1,2

Ghent University, EEMMeCS Dept, Technologiepark 903, Gent

9052, Belgium^1

Delft University of Technology, Materials Science and Engineering Dept, Mekelweg 2, Delft

2628 CD, Netherlands^2

ArcelorMittal - Gent, John F. Kennedylaan 51, Gent

9042, Belgium^3

Universidad de Santiago de Chile, Department of Metallurgical Engineering, Estación Central, Av. Lib. Bdo. O'Higgins 3363, Santiago de Chile, Chile^4

关键词: Advanced high strength steel;    Austenite transformations;    Cold rolling textures;    Crystallographic textures;    Ferrite grain diameter;    Quenching and partitioning;    Strength and ductilities;    Texture and microstructures;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/219/1/012004/pdf
DOI  :  10.1088/1757-899X/219/1/012004

来源: IOP

【 摘 要 】

Texture and microstructure formation during annealing of a 75% cold rolled AHS steel, reheated at a rate of 10°C/s to ∼3000°C/s were studied with the purpose to investigate the interaction between the recrystallization and the austenite formation as well as the possibility of grain refinement. It was found that at ultra-high heating rates, the bcc-fcc phase transformation starts before the completion of recrystallization and the deformation texture is partially retained in the samples after annealing. The crystallographic texture observed in the martensitic phase, which is the product of intercritical austenite transformation in as-quenched samples, i.e., after the double α-γ-α' transformation, is similar to the initial cold rolling texture, which is an indication for the texture memory effect. After ultra-fast reheating with average reheating rates of 1000°C/s and higher, a significant grain refinement was observed with an average calculated ferrite grain diameter of ∼2 μm. The obtained final ferrite grain size depends significantly on both the reheating temperature and the heating rate. The same effect is observed in 75% cold rolled quenching and partitioning steels for heating rates of 400°C/s, 800°C/s and 1000°C/s. In both cases the combination of fine grains, and weak RD/ND-fiber textures produce an increase of strength and ductility compared to material annealed using a conventional heating rate of ∼10°C/s.