Phase Transformation and Microstructural Behavior of New Steel Grades for Hot Sheet Stamping

Abstract:

Since the last few years several researches have focused in proposing new approaches to decrease the energy impact of the hot sheet stamping process. Among them, one possibility is to use steel grades characterized by a lower austenitization temperature in order to reduce the heating energy required for the process, but still maintaining the steel quenchability under the investigated process conditions. In the paper, the behaviour of two new steel grades developed by ArcelorMittal and devoted to hot stamping is investigated in terms of transformation kinetics and microstructural behaviour. An extensive dilatometric analysis, performed by using a modified axial extensometer, permitted to evaluate the steel kinetics of phase transformation as a function of the applied cooling rate, amount of strain and strain rate. The micro-hardness of water and die quenched samples of the investigated steel grades was measured and their microstructure analyzed by means of optical and scanning electron microscopy to evaluate the characteristics of the formed martensite and the possible phenomenon of autotempering.

• Periodical: Key Engineering Materials (Volumes 611-612)
• Pages: 1054-1061
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.611-612.1054
• Online since: May 2014
• Authors: Stefania Bruschi*, Andrea Ghiotti, Beatrice Valoppi, Juan David Puerta-Velasquez, Pascal Drillet, Maribel Arribas, Iñigo Aranguren, Joerg Clobes
• Keywords: Auto-Tempering, High Strength Steel (HSS), Hot Stamping, Martensite, Phase Transformation Kinetics

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