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)!
(Photo Credit: Disneyplusorginals.disney.com)
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.
Graph 1. "Differences Between Grades of Stainless Steel" (prepared by London Penland using Total Materia)
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.
You may notice that unlike 304, 316 stainless steel has a higher nickel composition and contains a relatively high amount of molybdenum, whereas the 304 stainless steel does not contain molybdenum at all. This differences provides 316 stainless steel (or A4 stainless steel) a significantly greater corrosion resistance. This corrosion resistance specifically denotes A4 stainless steel with the ability to resist acids and salts, making it a great solution for research, chemical engineering and marine applications, amongst many others.
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 near the ocean: yes, corrosion resistance is probably necessary because of salt spray, but certainly being able to withstand high mechanical strain will also be a priority (if not more so). Or for example, the chemical engineering equipment: yes, resistance to acids may be pertinent in that chemical production process, but if that particular piece of equipment is moving or having to withstand significant mechanical strain, then having a higher class stainless steel will also improve the life of the fastener, thereby reducing MRO costs and possible down time.
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 Eurolink Fastener Supply Service and Social Chair/Educational Director for Young Fastener Professionals, empowers sales reps, purchasing agents and sourcing agents with researched industry-specific educational videos and articles. Click here https://eurolinkfss.com/vlog/ to see all of London’s VLOGs and gain access to download his lesson plans.
Here's a useful DIN/ISO conversion chart to download and/or print: