Technical Article
Green And Circular : The Future of Stainless Steel Production
In the past three years , the dash to green steel , both carbon and stainless , has accelerated . Stainless steel is intrinsically more sustainable than carbon steel because it is more durable , as well as being used extensively in green transition applications . In addition , 3D printing , recycling and electrification are helping to reduce carbon footprints still further .
By James Chater
It is an enormous challenge : how to reduce the carbon footprint of steel and stainless-steel mills ? Astonishingly , producing stainless steel on average generates seven times its weight in CO 2 emissions . What can be done ?
The last three years have seen a marked increase in decarbonization initiatives , mostly in Europe and Asia , both in carbon- and stainless-steel mills . European stainless steel producers and fabricators such as Alleima , Aperam , Mannesmann Stainless Tubes and Outokumpu are closely examining their carbon footprint , decarbonizing their energy supply and intensifying their recycling activities . Outokumpu and Aperam have launched sustainable products with near-zero footprint and have stepped up the re-use of scrap . Europe ’ s most active player is Outukumpu , which has undertaken to reach zero CO 2 emissions by 2050 , though it aims to get there much sooner . Stefan Erdmann , Outokumpu ’ s Chief Technology Officer , says the company generates 0.5 kg of CO 2 to make 1 kg of its Circle
Green stainless steel ( depending on the desired grade and alloy composition ) compared with a world average of 7 kg of
CO 2
( data provided by the CRU Group and worldstainless , for 2023 ).
Sustainable Stainless
Stainless steel has a head start over carbon steel in that it is longer-lasting . This durability is important as it means less metal is consumed , and because mining and refining have a large carbon footprint . Stainless is essentially a “ set and forget ” material , one moreover that does not need painting . Another sustainable feature is the favourable strength-to-weight ratio of many grades , especially duplex , which means less fuel is consumed when it is applied in ships or heavy vehicles , as well as in the handling and transportation of the materials . Stainless steel plays a crucial role in the green transition , as it finds multiple applications in low- and zero-carbon energy ( wind , wave , solar , geothermal , biomass , hydrogen , nuclear ) and decarbonization ( air-scrubbing systems in carbon capture and storage ). In water applications , stainless steel ’ s corrosion resistance and inert character make for greater hygiene and fewer leaks , conserving both materials and water . On buildings , stainless steel ’ s reflective capacity allows it to deflect and dissipate heat so that less air conditioning is needed .
3D Printing
New technologies are supporting sustainability not only in primary manufacture but also in fabrication . 3D printing , which is increasingly being used to make high-alloy components in aerospace , medicine and other industries , is less energy-consuming and wastes less material than subtractive manufacturing . The materials invented specifically for 3D printing have properties that cut CO 2 emissions . For instance , Sandia National Laboratories has just announced a new 3D-printed superalloy that is stronger at 800 ° C than others currently used in turbine parts . This translates into lower emissions for every watt of power output . Outokumpu entered the 3D-printing business a year ago by starting to produce low-carbon content metal powder at the company ’ s mill in Krefeld , Germany . The metal powder production further strengthens the circular economy by using steel scrap from local production .
Recycling
Stainless steel , like carbon steel , is 100 % recyclable – except here too stainless has an advantage , as it rusts less quickly if at all ! ( However , with certain specialty CRAs such as heat-resistant nickel alloys , 100 % recyclability cannot be achieved .) The most important alloying elements – chromium , molybdenum , aluminium , copper , nickel and titanium – are also recyclable . However , “ at a global level almost 50 % of the materials to produce stainless steel are scrap materials ( stainless steels and carbon steel scrap )” ( World Stainless
BUTTING , a producer of longitudinally welded tubes from coil and sheets , is working with Cronimet Envirotec to recycle materials , waste and cutting residue .
6 Stainless Steel World Americas - June 2024 | www . ssw-americas . com