Grant: Alliance Grants

Railroad transport is essential to Canada. Since Canada's first railway in 1836, rail has expanded to almost 43,000 km of track transporting more than 100M people and 332M ton of goods worth $320B in 2019, including 91B in exports. Around 70% of all intercity surface freight and 50% of Canada's exports are moved by rail. One of the reasons for this is the low cost (3.5 cents per ton and kilometer vs. 13 cents for trucking) and fuel economy with 75% fewer greenhouse gas (GHG) emissions. This proposal advances the new concept of design and manufacture of multi-material railroad wheels using functionally graded materials (FGMs). Another goal is to repair of worn-out wheels using and additive manufacturing process, which will bring significant economic and environmental savings. Canadian railway companies operate some of the most challenging railroad systems in the world for wear and maintenance of the wheel-rail interface. Worn out wheels are repaired by machining down the damaged area ("reprofiling") until the machining allowance is reached, typically after 300,000 to 2,500,000 km and 2-5 reprofilings. Once the wheels are out of the dimensional bracket they are discarded, even if they are free of flaws. In 2006, this amounted to 350,000 wheel sets per year in the US alone, at an annual cost of USD $350 million. Wheels weigh between 400 kg (50-ton cars, 33 in) and 600 kg (100-ton cars, 36 in) and the steel can only be recycled through energy-intense re-melting which generates GHG of the order of 220 kg of CO2 per wheel in an electric arc furnace. The extended service life of wheels that can support a higher axle load will result in significant savings and reduction of greenhouse gas emissions, while the ability to use FGMs to achieve location-specific tailored mechanical and material properties will enable further applications in and beyond the sector.