Ferrosilicon for stainless steel
Reducing costs for stainless steel production using specialty ferrosilicon
Ferrosilicon has a vital role to play in cost-effective production of stainless steel, thanks to its ability to recover the metallic chromium that would otherwise be oxidized during decarburization. At Elkem, we’re ready to help you streamline your alloying processes and boost the quality of your stainless steel, by identifying the best specialty ferrosilicon (FeSi) alloy for the task.
Stainless steel: Managing costs without compromising performance
With a global production of nearly 60 million tonnes in 2021, demand for stainless steel has never been higher, thanks to the ability to tailor its corrosion resistance, strength, hardness and aesthetics to the application.
The level of chromium is of course the main factor in determining these properties, with proportions of chromium being 16–20 wt% in the most popular grades, and above 30 wt% in specialty stainless steels.
But with high exposure to the very competitive consumer market, cost-effectiveness is always top of the agenda in stainless steel manufacture. In particular, the cost involved in incorporating chromium (and other alloying elements such as nickel and molybdenum) places great emphasis on minimizing wastage through slag – which is where ferrosilicon is vital.
Using ferrosilicon to recover chromium
The decarburization of stainless steel that takes place in the argon oxygen decarburization (AOD) converter is highly effective at eliminating carbon from the melt, but the process also oxidizes chromium, producing slag containing chromium oxide.
Adding ferrosilicon during the subsequent reduction step reverses this process, and re-forms chromium within the melt, reducing losses of chrome to the slag. A similar process can also be carried out on a smaller scale after melting of the scrap in the electric arc furnace (EAF), and ferrosilicon is also often used as a ‘trimming’ addition in the ladle furnace (LF) to ensure that the level of silicon is correct.
The substantial amount of ferrosilicon used across these processes means it’s worth paying close attention to ferrosilicon purity – something that at Elkem we’ve got several decades of experience with.
What’s the best ferrosilicon alloy for stainless steel?
Steel mills have long used standard (STD) ‘FeSi75’ ferrosilicon for the manufacture of stainless steel. But many steel mills are now requesting low-carbon ferrosilicon (and even ultra-low-carbon ferrosilicon), to ensure that no more carbon is re-introduced to the melt than absolutely necessary, and so produce a steel that’s within tight carbon level specifications at a lower cost than with standard ferrosilicon. Some customers also need tight control over aluminium and titanium, in order to avoid the formation of inclusions that reduce toughness, corrosion-resistance and polishability, as well as causing clogging of nozzles during continuous and ingot casting.
All these factors focus attention on the ferrosilicon used in stainless steel production, and we have grades of our STAINSIL™ ferrosilicon to cater for all requirements. We also offer grain refiners to enhance nucleation in the microstructure of austenitic and ferritic steels.
The Elkem advantage
For many decades, Elkem has been helping numerous manufacturers of stainless steel (large and small) with their ferrosilicon requirements. We pride ourselves on our attention to detail and our willingness to tailor our offering to the application in question – only the best is good enough for our customers.
And with cost, quality and sustainability increasingly on the mind of our customers, we don’t rest when it comes to our products and processes. From developing new formulations to ‘greening’ the energy supply to our ferrosilicon plants, we’re always on the lookout for ways to improve what we do, and what we can offer our customers.
Ferrosilicon for steel
The growing demand for higher-performance steels is placing ever-greater emphasis on the quality of ferrosilicon (FeSi) alloys used in steel manufacturing plants – and at Elkem, we’re ready to help you make the best decision for your business.