Fe-Cr-based stainless steels are commonly used in commercial and domestic applications. The most popular of these are Fe-Cr-Ni (300 series) steels, which are a single face centered cubic austenite phase. With the recent volatility in the market price of Ni, however, there is increasing interest in alternatives to 300 series steels.
One low-cost alternative is 400 series steels, which contain little to no Ni, have higher Cr content, and are a single body centered cubic ferrite phase. They have great workability, but at elevated temperatures (500-800°C), the brittle sigma (σ) phase emerges, thus limiting their application to room temperature uses and requiring specific production protocol and heat treatment.
We developed a range of Fe-Cr-Mn-Al alloys that have the cost benefit of ferritic stainless steels but do not form the brittle sigma phase! Addition of a small amount of Al in the presence of Mn prevents its formation.
Just before HMC students presented their experimental work on this alloy system at the 2020 TMS conference, we filed a provisional patent on the alloys. This became an international patent filing in 2021.
The experimental results inspired a student in the group to computationally explore how aluminum prevents sigma formation, and her work led to several physics senior thesis projects and a Best undergraduate poster prize at the (virtual) TMS conference in 2021
We are working on a journal paper that will also include work done by UNSW students following the success of HMC students' work, and we are working on finding an industry partner to pursue commercialization.
Laspa Fellows: Stephanie Blankley '20 (engineering), Doug Raigosa '20 (engineering), 'Holly Frank '20 (physics), 'Natalie Krieger '21 (engineering), Jackson Baker '21 (engineering), Kaitlyn Paulsen '22 (engineering), Anna Soper '22 (physics/math), Savanah Diaz '22 (physics/math), Alexandra Loumidis '22 (engineering)