You may recognize that the title sounds similar to something hot right now. Remember “The Federalist Papers” when Hamilton defended the constitution? Yeah, I just watch Hamilton on Disney+ (probably for like the third time now – my wife is obsessed)!
I've been inspired by Hamilton to do a bit more writing in my life and there still seems to be some confusion out there over the value of A4-80 stainless steel, so I'm going to tap my inner Hamilton and write my "defense" of it (yes, in other words, I'm suggesting that Hamilton was like a marketing/sales specialist for the constitution).
Before We Begin
In my A2 vs. A4 article series, I explore some of the differences and crossovers between the stainless steels and how they are named by their respective standardizing bodies.
Here are the links to the series:
Part 1 - Introduction: https://blog.eurolinkfss.com/a2-vs-a4-stainless-steel-part-1
Part 2 – Nomenclature https://blog.eurolinkfss.com/a2-vs-a4-stainless-steel-part-2 (probably the most useful reading as primer for this blog post)
Part 3 – Crossovers https://blog.eurolinkfss.com/a2-vs-a4-stainless-steel-part-3 (useful for taking the information in this blog post and applying it to stainless steel designations not discussed here)
If you haven’t already read through these blog articles, I suggest doing so, but let’s review slightly and then build from there to the value of A4-80 stainless steel specifically.
The Quick Review
Please allow me to take a moment to unpack this useful table with you.
As you can see in graph 1 “Differences between grades of stainless steel”, I did not specify fasteners for the basic information and there is no data about mechanical properties, only chemical compositions. This is because the key difference between these grades of stainless steel are the differences in their chemical compositions. I’d like to point your attention specifically to the differences between 304 (A2) stainless steel and 316 (A4) stainless steel.
Customers may find value in this extra corrosions resistance, especially if replacement or maintenance costs are relatively high, such as on roller coasters (especially those that may experience any sort of salt spray) or underwater applications, or simply for creating longer lasting lab or engineering equipment that may be subject to acidic or salty conditions.
Due to the addition of greater nickel, which is relatively expensive, and molybdenum, A4 stainless steel is more expensive than A2 stainless steel and may be more difficult to source for some product lines, therefore engineering and procurement teams will need to account for this.
So, now it should be obvious why A4 stainless steel is valuable. It pretty much boils down to corrosion resistance, but what if corrosion resistance isn’t the only concern.
What if mechanical properties are also a concern for the material?
The Meat and the Potatoes
That’s when this graph may be helpful:
Graph 2. "Differences Between Classes of Stainless Steel" (prepared by London Penland using Total Materia)
Notice that this graph is titled “Differences between CLASSES of stainless steel” rather than GRADES. (Again, I highly recommend taking a look at Part 2 of the A2 vs. A4 blog series, especially that nifty little flowchart breaking down all the stainless steel types)
Once you have determined the grade of stainless steel that is desired, engineering and procurement teams also need to account for the class of stainless steel that is desired. As you will notice, the higher the class (i.e. -80, -70, -50), the greater mechanical strength that the stainless steel possess.
Going back to my examples earlier, it can be very obvious why higher class stainless steels may be needed. For example, the roller coaster
Usually, whether a fastener is A4-70 or A4-50 stainless steel (from stock at least) depends on the type of fastener. Not all fasteners are available in A4-50 and A4-70 from stock, even in Europe. Some are only available in one or the other. Though usually, if a European company is going to stock a higher class version of a stainless steel fastener, then they’ll have the typical option (A4-50 or A4-70) and then an A4-80 option, with A4-80 providing the most robust mechanical properties of any austenitic stainless steel generally stocked (though there are some proprietary stainless steels out there that are even stronger, but also SIGNIFICANTLY more expensive).
For most applications, A4-80 stainless steel will provide both the corrosion and mechanical properties required for your customers’ MRO or OEM solutions. Though it may be more expensive than other standard options, like regular A2 or A4 stainless steel, it is significantly less expensive and more readily found in stock in a wider variety of product lines than the proprietary stainless steels.
Conclusion: A4-80 stainless steel is the total package!
About the author
London Penland, ex-teacher, tutor and educational non-profit leader and current business development director for
Here's a useful DIN/ISO conversion chart to download and/or print: