Page 90 - MetalForming Magazine June/July 2022 80th Anniversary Issue

make are better suited for items such as rebar and beams. Minimills produc- ing sheet steels for stamped parts are more likely to add iron units to the melt, producing cleaner steels with improved properties. This iron could come from a blast furnace in the form of pig iron, or from products related to direct reduced iron (DRI).
Until recently, DRI production used either natural gas to create the H2 and CO gases required to reduce iron ore to iron, or coking coal as the carbon source for reduction. Although energy savings result as processing occurs below the melting temperature of iron, CO2 emis- sions are a byproduct of this approach.
New steel-production techniques rely on hydrogen instead of carbon to reduce iron oxide to iron. Green hydro- gen is the term given to hydrogen pro- duced from renewable-energy sources such as hydropower. DRI produced from green hydrogen results in minimal emis- sions, becoming one of the greatest potential decarbonization approaches
for the steelmaking industry. Green hydrogen is not yet commercially viable, but industry analysts project that some mills will reach commercialization in coming years. Other approaches are under investigation as well, but none appear to have near-term commercial- ization potential at a comparable scale.
In general, the BF-BOF approach to steelmaking results in more emissions than the EAF-CSP approach, but U.S. blast-furnace emissions are substan- tially below the world average, with much of the gaseous emissions captured and used to provide heat and energy for additional chemical reactions. Other companies use the carbon-based emis- sions from steelmaking as feedstock in the production of products such as ethanol, as well as building materials. Carbon capture, use and storage efforts at many steelmakers are a piece of the puzzle to attain net-zero emissions.
U.S steel mills offer steel produced using sustainable practices such as renewable energy, and automakers have
signed purchase agreements allowing them to offer a more environmentally friendly fleet. Some have even taken equi- ty shares in green-steel production start- ups. Furthermore, the closed-loop recy- cling strategies described for aluminum scrap are expanding to sustainable steels, reinforcing the importance of the circular economy on an industrial scale.
Energy and Emissions Reductions from New Grades
Vehicle safety demands sheet metals of the highest strength. Stamping of these highest-strength parts relies on warm and hot forming of steel and alu- minum alloys. Forming at elevated temperatures up to 900 C, requires the energy and emissions from the neces- sary furnaces. Steel and aluminum pro- ducers are creating formable cold- stamping alloys of nearly comparable strength to their counterparts formed at elevated temperatures to offer users additional options to create complex high-strength stampings. MF
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