Latest posts by Dan Williams (see all)
- Ten things you can do with MI:Workflow – send us your ideas! - 6th December 2016
- 100 Years of Stainless Steel - 16th October 2012
Granta’s recent trip to MS&T in Pittsburgh, the Steel City, reminded me that this year marks a hundred years since the invention of stainless steel, or at least since the first patents were granted to Strauss and Maurer in 1912 for the austenitic stainless steel they branded Nirosta. At about the same time in Sheffield, England, Harry Brearley discovered a corrosion resistant martensitic alloy which, although designed for gun barrels, first found fame as the new, shiny entrance canopy material for the Savoy Hotel.
From these beginnings, the idea that alloying iron with chromium and other elements could greatly enhance its corrosion resistance, appearance and strength took off, and today a search of the MI-21 “Materials information for the 21st Century” resource finds over four thousand grades and specifications of stainless steels worldwide.
As Granta’s product manager for a number of industry sectors I’ve come across this versatile material in countless applications—here I’m going to talk about a couple of the most extreme.
To the ends of the earth…
Few locations on the planet are more demanding than those encountered by oil & gas companies as they go deeper and deeper in their quest for new reserves. Rising oil prices mean that it’s now economical to drill to great depths, despite the high temperatures (over 300F) and pressures (typically around 15,000psi) this entails. Duplex and Super Duplex stainless steel ‘umbilicals’ plumb these depths, with stringent requirements to resist the chemical attack of hydrogen sulphide, carbon dioxide and sea water—as well as the pounding of vortex and wave induced vibration and impact.
When I talk to our GRANTA MI software users in this industry about why fast access to consistent, qualified materials information on their stainless steels is so critical to them, it always comes back to the same thing: reliability. Subsea developments are regularly expected to give ten years of productive life—and a failure could lose the oil companies $1m dollars a day in non-production time.
With that much at stake, who could afford to take chances with material selection?
…and closer to home
Alloying is not just about protecting the material from the environment. Sometimes it can be about protecting the environment from the material. A quick search of Granta and ASM International’s Materials for Medical Devices database for just one family of steels—the commonly used 316L variety—finds over 240 medical devices with FDA approval to use this material. The devices range from orthopaedic fixation systems to the stents and pacemaker leads used to treat artery and heart disease.
You can’t implant just any old material into the human body—device developers need to consider factors such as blood compatibility, soft tissue response, toxicity, carcinogenicity and a long list of other ways the material can interact with its environment to build up a picture of the steel’s “biocompatibility”. It’s this biocompatibility which makes stainless steel so useful in so many medical applications.
What’s next for stainless?
Iron is the least expensive and most widely used metal in the world, and in many applications very little can beat it for cost per unit of performance. So it’s safe to say that stainless steels will be with us for a while. But it would be wrong to think we’ve discovered all the secrets that alloying and heat treating different combinations of elements can bring. Projects such as President Obama’s Materials Genome Initiative seek to accelerate the pace through which new alloys are discovered and brought to market, so who knows what we’ll be saying on this blog about stainless steels in another hundred years’ time… stay tuned!