Oak Ridge Natl Lab, Deposit Sci & Technol Grp, Oak Ridge, TN 37830 - USA
Total Affiliations: 5
MATERIALS & DESIGN;
JAN 15 2020.
Web of Science Citations:
A novel quenching and partitioning process (Q\&P) including the hot stamping (HS) process was studied, using two stamping temperatures (750 degrees C and 800 degrees C) and two quenching temperatures (318 degrees C and 328 degrees C). This combination is here called Hot Stamping and Quenching and Partitioning process (HSQ\&P). The partitioning step was performed at 400 degrees C for 100 s in all cycles. Microstructural features were comprehensively studied using electron backscattered diffraction and nanoindentation techniques. HSQ\&P samples showed a good combination of ductility and high-strength due to the presence of: retained austenite, inter-critical ferrite with low stored internal strain energy, grain refinement via DIFT-effect (deformation induced ferrite transformation), martensite, and bainite. Significant internal stress relief was caused by carbon partitioning, which was induced by the DIFT-effect and the partitioning stage. This also led to a considerable stored energy, which was characterized by the Kernel average dislocation and geometrically necessary dislocation analysis. In addition, predominant // strain direction crystallographic texture was identified, which promotes slip deformation and enhances the mechanical properties. Moreover, remarkable amounts of fine film-like retained austenite oriented along compact crystallographic directions (i.e., < 111 > and < 112 >) were observed. Finally, subsize tensile test verified the optimum mechanical behavior of HSQ\&P specimens. (c) 2019 Published by Elsevier Ltd. (AU)