Stainless Steel: Less Nickel, Same Strength?

As stainless steel has been around for well over a century, it's easy to imagine that we have learned all that there is to know about the useful alloy. But that certainly isn't true! Research teams from Tsinghua University in China and Tohoku University in Japan have collaborated to try and solve what is becoming an ever-more pressing issue...

That issue surrounds nickel, a key material in the production of some stainless steels; in fact, over 70% of the global supply of nickel goes into stainless steel production. The supply of this precious element is subject to constant fluctuation and demand grows all the time, especially as the production of electric vehicles continues to increase. This has led to 'significant challenges [in] maintaining stable production', according to the research teams.   

Run-Zi Wang is an Assistant Professor at the Advanced Institute for Materials Research at Tohoku University and led the recent study, which was published in the Additive Manufacturing journal. He pointed out that balancing the need to preserve stainless steel strength with the equally-important need to reduce nickel usage was a 'critical objective' in ensuring both structural integrity and sustainability. 

Attempting to address these concerns, Wang led his team in the development of a new stainless steel alloy. The study's aim was to develop a stainless steel that would reduce nickel dependence without affecting the alloy's strength. 

The 300 series of stainless steel (austenitic) is the most commonly used, accounting for over half of global stainless steel production. It also has the greatest nickel content of all stainless steel grades. Ferritic stainless steel, on the other hand, does not contain any nickel. The problem is that ferritic stainless steel has a lower hardening rate and fracture strength than austenitic stainless steel, placing notable limits on the applications for which it can be successfully used. 

The research teams created a composite structure using ferritic and austenitic stainless steels using an additive manufacturing technique similar to 3D printing. Metal layers were deposited via welding in a process known as 'wire arc directed energy deposition'.     

After the material was fabricated, the research teams analysed its mechanical properties. The analysis showed that 'the microstructure where the two metals interface revealed features associated with increased hardness and strength compared to either of the individual components alone'. The research teams concluded that the newly created bimetallic structure offers 'a promising solution, balancing material performance and nickel consumption'.

Once again, stainless steel has showed us that its journey is far from over. Here at BS Stainless, we are always excited about new developments and will continue to embrace the latest technologies and methodologies that drive stainless steel forward into the future. Find out more about our product range on the BS Stainless website.