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Effect of Prior Austenite Grain Size on Impact Toughness of Press Hardened Steel

Journal Article
2016-01-0359
ISSN: 1946-3979, e-ISSN: 1946-3987
Published April 05, 2016 by SAE International in United States
Effect of Prior Austenite Grain Size on Impact Toughness of Press Hardened Steel
Sector:
Citation: Wang, J., Enloe, C., Singh, J., and Horvath, C., "Effect of Prior Austenite Grain Size on Impact Toughness of Press Hardened Steel," SAE Int. J. Mater. Manf. 9(2):488-493, 2016, https://doi.org/10.4271/2016-01-0359.
Language: English

Abstract:

Impact toughness (or resistance to fracture) is a key material property for press hardened steel used in construction of the safety-critical elements of automotive body structures. Prior austenite grain size, as primarily controlled by the incoming microstructure and austenitization process, is a key microstructural feature that influences the impact toughness of press hardened steel. In this paper, a special Charpy V-notch impact test is developed to quantify the impact toughness of press hardened steel sheets with various prior austenite grain sizes, by stacking a number of thin sheets via mechanical riveting. Both the ductile-to-brittle transition temperature and upper shelf energy are analyzed in an effort to establish a correlation between impact toughness and prior austenite grain size. Within tested conditions, impact performance shows only a slight decrease as the prior austenitic grain size increases from 18 to 38 microns. On the other hand, grain refinement via micro-alloying in the new 1.8 GPa press hardening steel can significantly increase the impact toughness.