If only people knew how many grades of steel there are, perhaps they wouldn’t take nearly every piece of metal for granted. There is a lot going on with a few numbers and letters that people don’t know about. So what do these numbers mean and who comes up with these grades?
While most every metal alloy has different grades, we’ll start with stainless steel because it’s most likely to be found in your average household due to its resistance to corrosion and relatively low cost. The most common stainless steel alloy is 302 stainless steel. This steel is used for nearly everything from household products such as kitchenware, pressure containers, cryogenic containers, washers, springs, to the pinnacle of the Chrysler Building in New York City.
If ever there was a universal man-made metal, this is it.
At its most basic level, stainless steel is simply a steel alloy that has at least a 10.5% Chromium. But beyond the Chromium, there can be a litany of other materials within stainless steel. As for Type 302 stainless steel, it consists of 70% iron, 18% chromium, 8% nickel, and 2% manganese.
Stainless Steel History
The history of stainless steel goes all the way back to the 1821 when French metallurgist Pierre Berthier noted stainless steel’s resistance to oxidation (rust). However, back in the early days, Berthier and his early successors fiddled with the amount of carbon and chromium in their alloy – making it too brittle for general use. However, as metallurgy techniques improved over the years, metallurgists have been able to steadily remove the carbon from the alloy, achieving Berthier’s dream of pairing corrosion resistance with cracking resistance.
So how do you get all of those materials from the number 302? Well, 300 series steel connotes general use. As you can see from the list of items, 300 definitely places the ‘general’ in general use. Going down the line, here are the types: 100 is for Special Steels; 200 alloy steels are Tool Steels; 300 is for miscellaneous, 400 is for heat resistance steels, and 500 through 800 series are for pressure vessels and engineering steels.
Memorizing all of the types of stainless steel would be quite an undertaking – plus there are even other metals that are categorized in the same way. Much like a complex family tree, types of metals can be specially made for all types of applications.
As you can see, it’s a wide, wide world of metals – built for a specific purpose and we have it all at CFI. If you want any type of component, made from any and every type of alloy, call us at 847-918-0333 and one of our experienced engineers will be happy to speak with you.