321 stainless steel, also widely known in the industry as ER312, is one of those stainless steel types you’ll often hear across different industries. But, do you know what it is exactly? Do you know what 321 stainless steel is, where they’re used, and how people choose to use them?
If you don’t and you want to know more about it, then you’re in the perfect page. Our article for today will solely be focused in making sure you understand 321 stainless steel better than anyone else!
By the end of this article, you will know 321 stainless steel by heart!
What is 321 Stainless Steel Grade?
Source: Smiths Advanced Metals
In the easiest way to describe it, 321 stainless steel is an acier inoxydable austénitique made for applications that involve heat and welding. It contains chromium and nickel, with added titanium to help the material stay stable when exposed to high temperatures.
321 stainless steel is easy to form and weld and stays tough even at very low temperatures. You can’t harden it through heat treatment and it’s naturally non-magnetic.
En savoir plus: Maîtriser la précision avec l'usinage CNC de l'acier inoxydable
321 Stainless Steel Composition and Properties
Source: Angang Steel
One of the most important things to know about these alloys would be its properties. Like many alloys, 321 stainless steel has its own fair share of advantages and benefits, making it easy to determine if it’s a good fit or not.
Résistance et durabilité
321 stainless steel offers solid strength for most industrial uses, especially “heat” type situations. It holds its mechanical properties better than other typical grades when exposed to higher temperatures, helping prevent early material damage.
Résistance chimique
This grade handles many organic and inorganic chemicals well at moderate temperatures. It’s commonly used in environments where exposure to acids or reactive substances is expected, as long as conditions are controlled and not overly aggressive.
Résistance à la corrosion
Typically, 321 performs much like 304; it stands out after welding or heat exposure. Thanks to the titanium content, corrosion is greatly reduced making it more reliable in applications that stay within higher temperature ranges.
Résistance à la température
321 stainless steel is built for heat; we’ll leave it at that. It performs in its best in intermittent service up to around 900°C and non-stop processing close to 925°C. Therefore, it’s a strong option for parts that face repeated heating and cooling cycles.
Soudabilité
Welding 321 stainless steel is pretty straightforward. The titanium in its chemical makeup helps prevent carbide buildup during welding, lowering the risk of corrosion in the heat-affected zone. In most cases, you wouldn’t need post-weld heat treatments.
Usinabilité
Like most austenitic stainless steels, 321 can be more challenging to machine than carbon steel. Still, with proper tooling, speeds, and cooling, you can well enough manufacture and use it for most fabrication and custom part requirements.
Applications
Because of its heat stability and weld performance, 321 stainless steel is widely used in heat exchangers, exhaust systems, furnace parts, chemical processing equipment, and aerospace components where high temperatures are part of daily operation.
Also Read: Acier inoxydable 303 vs 304 : sont-ils identiques ?
Stainless Steel 321 vs. 304
Source: KongFang Metal
Stainless steel 321 and 304 are both austenitic stainless steels used in many everyday and industrial applications. At a glance, they look and behave similarly. However, they’re made for different conditions and situations, especially when heat or welding is involved. So, here’s a breakdown of how they’re different:
| Fonctionnalité | Acier inoxydable 304 | Acier inoxydable 321 |
| Type d'acier inoxydable | Acier inoxydable austénitique | Austenitic stainless steel (titanium stabilized) |
| Composition chimique | Chromium, nickel | Chromium, nickel, titanium |
| Résistance à la chaleur | Good for general use | Better for sustained or repeated high heat |
| Weld Performance | Good, but may need low-carbon filler | Excellent stability after welding |
| Strength at Room Temperature | Same | Same |
| Strength at High Temperature | Drops faster with heat exposure | Maintains strength better over time |
| Applications | Food equipment, tanks, trim, piping | Heat exchangers, exhausts, aerospace parts |
| Coût et disponibilité | Lower cost, widely available | Higher cost, slightly less common |
Overall, the difference between 321 and 304 all boils down to how the material will be used over time, not just how it performs during installation.
If the application stays at normal temperatures and cost matters, 304 is often the more practical choice. When welding is involved and the part will see repeated heat exposure, 321 offers added peace of mind by reducing long-term corrosion risks.
321 Stainless Steel Equivalent
Source: Metal Strip Solutions
Now that we know that 312 is an alloy that’s just based off of 304, we can therefore say that it’s equivalent to EN 1.4541, AISI 321, and UNS S32100.
If we’re talking about alternative grades, the following have been deemed the best and fittest:
- Stainless Steel Grade 304 H
- 347
- Grade 304 L
Will Stainless Steel Rust?
Contrary to popular belief, just because it’s stainless steel doesn’t mean it can’t rust. Although stainless steel has high levels of corrosion resistance, it will, eventually rust under specific situations and circumstances. After all, it’s called “stainless” and not “stain-free.”
321 Stainless Steel Suppliers: Why HDC’s 321s are the Most Trusted
Many people, especially business owners understand that there’s nothing better than feedback, product quality, and speed in the steel industry. And we at HDC possess all those characteristics, all with flying colors.
Organizations and companies from all around the world trust us with what they need. Whether they need the typical stainless steel, titanium steel, copper, or even plastic, or if they need CNC machining and metal fabrication services, our team will be your best bet.
HDC’s expertise, mastery, and overall dedication will be the best business you will ever experience. Reach out to us and get a free quotation!
