About this Abstract |
| Meeting |
MS&T26: Materials Science & Technology
|
| Symposium
|
Advances in Zinc-Coated Sheet Steel Processing and Properties
|
| Presentation Title |
Effect of Austenitizing Parameters on Microstructural Stability of Galvannealed (GA) Coating and Liquid Metal Embrittlement (LME) Suppression in Hot-Stamped Boron Steels |
| Author(s) |
Henrique Lacerda Eleuterio, Joao Luiz Costa Carvalho, Juliana Cristina de Paula |
| On-Site Speaker (Planned) |
Henrique Lacerda Eleuterio |
| Abstract Scope |
Galvanized coatings are commonly applied to boron steels for hot stamping because they provide superior surface quality compared to alternative coatings. Despite this advantage, degradation of Zn coatings and occurrence of liquid metal embrittlement (LME) at austenitization temperatures remain significant challenges. This study evaluates Zn galvannealed (GA) coating modified by increasing heat input in galvannealing process applied in hot stamping with different autenitizing temperatures. Increased Fe content reduces Zn activity and liquid fraction at elevated temperatures, promoting formation of Fe–Zn solid solutions and significantly decreasing Zn diffusivity along prior austenite grain boundaries, which is the primary mechanism for LME. Microstructural evolution, Fe–Zn phase transformations, and diffusion profiles were characterized using scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS), X-ray diffraction (XRD), and Hydrogen uptake. The results demonstrate that GA coatings maintain microstructural stability under the evaluated austenitizing conditions, exhibiting uniform phase distributions, preserving substrate integrity throughout the forming process. |