Development of a new generation of quench and partitioning steels: Influence of processing parameters on texture, nanoindentation, and mechanical properties

Author(s)

Ariza-Echeverri, E. A. ; Masoumi, M. ; Nishikawa, A. S. ; Mesa, D. H. ; Marquez-Rossy, A. E. ; Tschiptschin, A. P.

• Document type: Journal article
• Source: MATERIALS & DESIGN; v. 186, p. 17-pg., 2020-01-15.

Abstract

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 {110}// 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)

• FAPESP's process: 14/11793-4 - Experimental and numerical analysis of high-strength structural steels during hot stamping and quenching and partitioning processes
• Grantee: Andre Paulo Tschiptschin
• Support Opportunities: Regular Research Grants