Towards Managing Advanced Steel Surface Chemistries in Continuous Annealing and Galvanizing
The world-wide cost of corrosion estimated at approximately $2.5 trillion USD per year, a significant portion of which can be assigned to the corrosion of ferrous materials. This cost is significantly mitigated, however, through galvanizing, in which a thin layer of Zn applied to the steel surface such that it sacrificially protects the underlying steel from aqueous corrosion. Globally, almost 350 Mt/year of sheet steel are galvanized, making it one of the most important technologies deployed to manage the costs of corrosion. In addition, the extension of product and infrastructure lifetimes provided by the corrosion prevention of steel through galvanizing has kept millions of tons of carbon dioxide from being emitted in replacement steel production.
More recently, significant vehicle mass reductions have been realized through the increased deployment of Zn-coated advanced high strength steels (AHSSs) in advanced automotive architectures. This dramatic change has led to significant safety and fuel efficiency improvements in conventional vehicles and is a key enabler to the deployment of the next generation of electric vehicles. Increases in AHSS properties have typically come through more highly alloyed steel chemistries coupled with sophisticated thermal processing routes and part geometries employing thinner material cross-sections – for which robust corrosion protection provided through galvanizing is essential to maintain vehicle safety.
However, the increased levels of alloying elements have resulted in complex surface chemistries and significant challenges with respect to the production of high-quality Zn-based coatings. This paper will discuss the fundamental challenges of deploying Zn-coated advanced steels into automotive structures, with a focus on gas/metal reaction thermodynamics and kinetics, the resultant surface chemistries and how these can be beneficially altered through various processing strategies ensuring that the required reactions with the zinc alloy bath take place.
Professor Joe McDermid earned his bachelor’s degree in Metallurgical and Materials Engineering at Queen’s University in 1985 and his Ph.D. in Metallurgical Engineering from Mcgill University in 1992. Joe McDermid is presently Professor at McMaster University, in the Department of Materials Science and Engineering. He has been working at McMaster for over 16 years. He previously worked at Noranda Technology Centre from 1992-2003 as a Senior Scientist.
As the NSERC/Stelco Industrial Research Chair in Advanced Coated Steels from 2003 to present, McDermid has focused on integrating and developing new grades of advanced high strength steels for automotive weight reduction and safety enhancement with the continuous galvanizing process, the most widely practiced and cost-effective means of protecting steels against corrosion.
His expertise is in Physical Metallurgy of Advanced High Strength Steels, Microstructure-Property Relationships, High-Temperature Oxidation, Continuous Galvanizing of Advanced Steels, Reactive Wetting, Electron Microscopy.
Prof. McDermid was Editor-in-Chief of the Canadian Metallurgical Quarterly from 2013 to 2021. During his term, he increased the Impact Factor of the journal from 0.6 to above 1.2. He also contributed to several special edition volumes of the Canadian Metallurgical Quarterly.