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Metallurgical and Materials Transactions A

, Volume 45, Issue 10, pp 4499–4509 | Cite as

Microstructural Evolution of the 55 Wt Pct Al-Zn Coating During Press Hardening

  • Chang Wook Lee
  • Bruno Charles De CoomanEmail author
Article

Abstract

Press hardening is increasingly being used to produce ultra-high strength steel parts for passenger cars. Al-Si, Zn, and Zn-alloy coatings have been used to provide corrosion protection to press hardening steel grades. The use of coatings has drawbacks such as coating delamination or liquid metal-induced embrittlement. In the present work, the microstructural evolution of Al-Zn coating during press hardening was studied. The 55 wt pct Al-Zn coating can in principle provide both Al barrier protection and Zn cathodic protection to press hardened steel. During the heat treatment associated with the press hardening, the 55 wt pct Al-Zn alloy coating is converted to an intermetallic surface layer of Fe2Al5 and a FeAl intermetallic diffusion layer. The Zn is separated from both intermetallic compounds and accumulates at grain boundaries and at the surface. This Zn separation process is beneficial in terms of providing cathodic protection to Al-Zn coated press hardening steel.

Keywords

Diffusion Layer Alloy Layer Cathodic Protection Press Hardening FeAl Intermetallic Compound 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgments

The authors gratefully acknowledge the support of Dr. Yeol Rae CHO of the POSCO Technical Research Laboratories in Gwangyang, South Korea.

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Copyright information

© The Minerals, Metals & Materials Society and ASM International 2014

Authors and Affiliations

  1. 1.Graduate Institute of Ferrous TechnologyPohang University of Science and TechnologyPohangSouth Korea
  2. 2.Materials Design LaboratoryPohang University of Science and TechnologyPohangSouth Korea

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