Effect of Mn element on microstructure evolution of galvanized coating of hot stamping steel

doi:10.13251/j.issn.0254-6051.2022.04.015

Abstract

Abstract: Surface morphology and cross-sectional microstructure of the galvanized coating of hot stamping steel after holding at 800 ℃for different time were characterized by means of SEM and XRD, and the influence of Mn element on microstructure evolution of the coating during the interdiffusion of elements was analyzed by means of EPMA、WDX、EDS and GDOES. The results show that with the extension of holding time from 3 min to 7 min, the surface morphology of coating evolves from “hill” to “crater”, then gradually spheroidizes. The “crater” morphology on coating surface leads to uneven coating thickness and large fluctuation after holding for 5 min. The coating phase changes with the prolongation of holding time. The coating is mainly composed of Fe₄Zn₉ and δ phases after holding for 3 min. When prolonging the holding time to 5 min, the coating is mainly composed of Fe₄Zn₉ and α-Fe(Zn) phases, and Mn is enriched in the α-Fe(Zn) phase near the substrate to form a manganese-rich sublayer. After holding for 7 min, the area of Mn enrichment decreases and moves towards the coating surface due to the continuous diffusion of Mn element from the substrate to the surface of the coating.

Key words: Mn element, 22MnB5 steel, hot-dip galvanizing, microstructure evolution

CLC Number:

TG156.1

Liu Liyan, Bi Wenzhen, Wei Xicheng. Effect of Mn element on microstructure evolution of galvanized coating of hot stamping steel[J]. Heat Treatment of Metals, 2022, 47(4): 93-99.

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