Research and facilities – Faculty of Engineering
A person sifts through materials at CAMC.

Research and facilities

The Centre for Automotive Materials and Corrosion works alongside leading scientists and industry partners on cutting-edge science to test the mechanical and environmental degradation limits of materials.

CGL-Compatible 3G AHSS

Third Generation Advanced High Strength Steels (3G AHSS) are capable of attaining high strength and ductility with appropriate heat treatment. Dr. McDermid’s group focuses on optimizing the composition and heat treatment parameters of these steels to produce an ideally strong and ductile material capable of being processed on a continuous hot-dip galvanizing line.  Promising mechanical property results have ben obtained with 6 wt% Mn containing steels.  Current work is on the mechanisms that form the microstructure during heat treatment and the effect of steel chemistry on the resulting microstructure.

Successful galvanizing requires contact between Zn in the bath and Fe in the steel. Careful control of the CGL atmosphere can promote reduction of native surface oxides or create internal oxidation exposing more bare Fe to the Zn bath. Dr. McDermid’s group works to understand the thermodynamic and kinetic parameters that control oxide reduction and internal versus external oxidation. As a result, the CGL can be operated in a more cost-effective and environmentally friendly manner.

A section of steel is dipped in the zinc bath for approximately 4 seconds during continuous hot dip galvanizing. During that four seconds, a chemical reaction called reactive wetting takes place between the steel’s iron and the bath’s zinc and aluminum.  The intermetallic helps adhere the overlying zinc to the steel during further processing. By careful control of the atmosphere and holding times prior to dipping, the degree of reactive wetting can be varied, resulting in understanding of the kinetics of this process. This project is done by Dr. McDermid’s group using CAMC’s galvanizing simulator and meniscograph.

The Walter Smeltzer Corrosion Laboratory

Corrosion degrades materials and is a major cause of failure of structures and objects. In the Walter Smeltzer Corrosion Lab, the CAMC does both applied and fundamental research into corrosion and it’s prevention. Named for the founder of Corrosion Research at McMaster, the lab is in it’s third location at MARC

Steels require complex chemistries to attain their desired mechanical properties. Unfortunately, these complex chemistries can result in non-metallic inclusions (particles) in the steel that can collect hydrogen that would otherwise diffuse harmlessly through the steel. Collected hydrogen can eventually cause fracture of the steel, resulting in catastrophic failure of the part.

Dr. Kish’s group is working to understand which non-metallic inclusions in steel collect hydrogen and at what rate. Knowing the rate at which hydrogen collects allows an estimation of time to failure, while knowing which inclusions cause embrittlement allows development of alloys without those inclusions.  This will improve lifespan and reduce the number of failures of critical infrastructure.

Undersea pipelines are coated to prevent corrosion. To assemble the pipelines, a section at the end of each section of pipe is left uncoated when leaving the factory.  A coating is applied after welding at-sea to prevent corrosion around the welds.  In some situations, the factory applied coating may debond from the pipeline, allowing Hydrogen to build up between the steel pipe and the coating. This hydrogen can then cause hydrogen embrittlement of the steel and unexpected rupture of the pipe. Dr. Kish’s group is investigating the risks of the debondment and the possibility that the at-sea applied coating affects the debondment rate.

Magnesium is a light, strong metal that suffers from severe corrosion in aqueous environments. Coated magnesium can suffer from filamentary corrosion, where thin corrosion bands travel along the metal/coating interface, resulting in disbondment of the coating and failure of the coated component. In this work, Dr. Kish’s group seeks to determine the parameters that control filament corrosion in an attempt to reduce the amount of filamentary corrosion on coated parts, thereby increasing their lifespan.

In this research, we work in partnership with a coating manufacturer to compare the corrosion protection provided by different coatings in various on two magnesium alloys of interest to the automotive industry. After panels were coated, the coatings were scribed through to the base metal, then exposed to salt spray conditions for 1000h. The corroded panels were then sectioned and examined to determine the type and extent of corrosion.

Future work will examine the electrochemical stability of the coatings to determine optimum processing parameters for corrosion prevention.

Applying a layer of corrosion resistant steel on a substrate of traditional steel improves the lifespan of the component and reduces the material cost. Understanding how these multi-layered steels perform in a variety of conditions will increase their applicability. Thermal cycling may affect the robustness of the layered structure, while the atmospheric corrosion rate may be highly susceptible to the dewpoint.  This work, co-lead by Dr. Kish and Dr. Zurob seeks to determine the effect of high temperature and environmental dewpoint on the corrosion behavior of these steels.

Formability Testing

The 7000 series of aluminum alloys are high-strength alloys under investigation for automotive applications.  To attain the desired mechanical properties of the alloys, room temperature forming of these materials is not possible.  Dr. Jain‘s project focuses on determining the forming parameters required to successfully apply AA7XXX alloys to the automotive industry. Formability is controlled by the dominant deformation mechanism at each potential forming temperature. Experimental work determines the deformation mechanism, with the results used to develop constitutive material models that allow our industry partners to evaluate the ability to form specific components from AA7XXX alloys.

To make automotive parts from sheet material, the maximum amount the sheet can be stretched and strain must be known. After determining the ideal CGL-compatible processing parameters for 3G AHSS, Dr. McDermid’s group determines the formability limits of the resulting sheet.

Microstructure – Property Relationships

Third Generation Advanced High Strength Steels need to achieve high strength while maintaining acceptable levels of ductility, which make them promising for automotive applications. Understanding how these steels deform and break is critical to their application as it will promote alloy and heat treatment modifications to obtain optimal mechanical parameters.  Using micro-DIC (microscopic digital image correlation), a technique pioneered by Dr. Wilkinson, his group has mapped deformation and its effect on the microstructure of 3D steels in both 2D and 3D. Results to date indicate that cracking initiates in blocky retained austenite, then moves into the ferrite with the final stage of cracking occurring in the martensitic phase.  Coupling DIC with x-ray tomographic imaging of damage enables the development of robust models for fracture resistance and ductility enhancement.

Influence of Vanadium on Microstrain Partitioning and Evolution of Microstructural Damage in DP1300 Steel

This work by Dr. Wilkinson’s group uses X-ray tomography coupled with in-situ tensile testing to determine the mechanism that causes pure metals such as copper and magnesium to mechanically fail. The results show that damage is highly dependent materials class.  While face-centred cubic metal such as copper exhibit isotropic damage that can be modelled using continuum mechanics approaches magnesium, which is hexagonal close packed develops microcracks that form on twin interfaces and grain boundaries then spread through the materials. As a result, the continuum-based damage models do not work for HCP materials that undergo deformation twinning. A new approach based on crystal plasticity approaches is needed to fully understand ductile fracture in these materials.