Many know 316 stainless steel as the go-to metal for heavy-duty applications. It’s tough, corrosion-resistant, and … expensive.
Do you need 316’s resistance properties for your part, or can you skate by with a cheaper product? It depends on your application.
To give you an idea of how 316’s protective properties (and price) compare, let’s put it up against other metals as well as other types of stainless steel.
316 Stainless Steel Vs. Other Metals
Many consider 316 to be the ultimate grade in corrosion protection. That’s why some call it “marine grade” -- it can even withstand consistent saltwater immersion and splashing. That’s why it’s also one of the most expensive stainless steels. Let’s compare:
316 Vs. Itself (Sorta)
There’s a type 316 variant called 316L. Performance-wise, 316L is better than any other stainless steel for extreme-temperature, high-corrosion applications. Yes, even better than its cousin, though the margin’s slight. It’s widely popular for construction and infrastructure jobs.
(Don’t forget there’s another simple-but-notable difference between 316 and 316L stainless steel.)
Vs. Carbon Steel
The added chromium in stainless steel makes it more corrosion resistant than carbon steels. Although if you’re considering ugly, ol’ carbon steel in the first place, you may not care if your part looks like vomit. The rough surface that rusting leaves, however, may be another story.
Carbon steel is far cheaper than stainless steel, so weigh that against your need for protection.
Click here for a chart of carbon steel grades, including their characteristics and best uses.
Vs. Galvanized Steel
For some cost-conscious engineers and buyers, galvanized carbon steel is the most economical process for protecting a part from corrosion. Its zinc coating is an on-the-cheap way to imitate stainless steel. It can actually outperform many stainless steels in salty environments because the zinc layer prevents the carbon from reacting with chloride.
Aluminum has high oxidation and corrosion resistance thanks to its passivation layer. When aluminum oxidizes, its surface will turn white and sometimes pit.
In some extremely acidic or base environments, aluminum may corrode in a hurry, leaving you with a mess.
On the plus side, aluminum is almost always cheaper than stainless steel.
316 Vs. Other Stainless Steels
All stainless steel is naturally corrosion-resistant -- that’s what it’s famous for, right? But even stainless steel can corrode if the wrong grade is used in the wrong place.
In numerical order, here are the most common ones that specialize in fighting corrosion:
3CR12 resists mild corrosion, particularly in wet abrasion environments. It’s common in:
- Rail wagons
301’s corrosion resistance is notable, though not as strong as 304’s. It has uses in:
- Automotive components
- Rail cars
302 boasts corrosion resistance comparable to grade 301. It’s great for applications such as:
- Food and drink
Type 304 makes up about 50% of all stainless produced, so it’s readily available. The price is lower than 316’s and is often the basis for comparing the prices of other grades.
The 304 grade has wonderful corrosion resistance, but it’s susceptible to pitting in warm chloride environments. (Think projects near the coast or heavily salted roads.) Still, it’s got excellent toughness.
- Food processing
Worried about oxidation? 309S is resistant to it. It’s also more resistant than 304 to temperature changes. It’s used in heating and furnace parts.
The 317 grade actually offers better wear resistance than 316. It’s going to cost you a few more bucks, though. It’s useful for:
- Paper machinery
- Ink and dying processes
- Acetic acid distillation
The 409 grade resists atmospheric and automotive exhaust corrosion. Notably, it’s about as cheap as stainless steel gets. The aluminized version of 409 adds salt and cosmetic wear resistance. Uses of these grades include:
- Auto exhaust systems
- Heat exchangers
- Furnace liners
Type 430 balances good corrosion resistance with other qualities. (Warning: The 430F variation is inferior in wear protection.) It’s far cheaper than 304 ($0.94/lb. vs. $1.63/lb., the last we checked) due to lower nickel content. Common applications include:
- Automotive trim
- Refrigerator doors
- Cold-headed fasteners
If you want better pitting resistance than what you get from 430, try 434 and its added molybdenum. The price of 434 is also lower than 304’s.
Type 440 ups the chromium and carbon even more to improve toughness and corrosion resistance. Typical applications include instruments.
But Wait! There’s More (if You Can Find It)
There are loads of stainless steel grades that are lesser known. Click here for a more exhaustive list of grades, including their traits and ideal uses.
The metal on your mind not on this list? That’s probably for one of two reasons:
- It’s more decorative or machinable than it is corrosion-resistant.
- It’s not widely available.
Availability matters -- grades that manufacturers don’t use often may take extra time and money to obtain. Remember that if you try to go cheaper than 316.