SteelWhat is 304L stainless steel and what is it used for? Complete guide
304L stainless steel is one of the most widely used austenitic stainless steels in industry. It is the benchmark for almost everything: it resists corrosion very well, welds easily and is hygienic. In this guide we explain what 304L stainless steel is, its composition, its corrosion resistance, what it is used for and the sizes we stock.
What is 304L stainless steel?
Low-carbon austenitic stainless steel with excellent corrosion resistance and weldability. For the food and chemical industries and for structures.
It is an austenitic steel, that is, nonmagnetic and not hardenable by quenching; its corrosion resistance comes from chromium (18.00 – 20.00%), which forms a passive layer that protects the material, and from nickel (8.00 – 12.00%), which gives it its structure and toughness. The letter "L" means low carbon (0.030 % maximum), which prevents sensitization during welding and maintains corrosion resistance in welded joints.
Chemical composition of 304L stainless steel
This is the typical composition of 304L stainless steel (AISI 304L / EN-DIN 1.4306 / JIS SUS304L standard):
| Element | Contents | What for? |
|---|---|---|
| Carbon (C) | 0.030 % max. | Low ("L" grade): prevents sensitization when welding |
| Silicon (Si) | 1.00 % max. | Deoxidizer |
| Manganese (Mn) | 2.00 % max. | Stabilizes austenite |
| Phosphorus (P) | 0.045 % max. | Impurity, kept low |
| Sulfur (S) | 0.030 % max. | Impurity, kept low |
| Chromium (Cr) | 18.00 – 20.00 % | Provides corrosion resistance (passive layer) |
| Nickel (Ni) | 8.00 – 12.00 % | Provides the austenitic structure and toughness |
| Nitrogen (N) | 0.10 % max. | Adds mechanical strength |
Corrosion resistance and properties
304L is supplied annealed (solution treated) and does not harden by heat treatment because it is austenitic; its hardness increases only when cold worked. In the annealed condition its hardness is around 170 HB (approx. 88 HRB). What matters in this steel is not hardness but its excellent corrosion resistance and weldability.
If your process involves chlorides, salt or aggressive chemicals, it is worth moving up to 316L stainless steel, which adds molybdenum to better resist pitting.
What is it for? Applications of 304L
304L stainless steel is mainly used in:
- Sanitary tanks
- Process piping
- Food processing equipment
- Pharmaceutical equipment
- Chemical reactors
- Heat exchangers
- Valves and flanges
- Commercial kitchens
- Welded structures
Forms and sizes we carry
At NAT MAC we stock 304L stainless steel in these forms and sizes:
| Package size | Sizes |
|---|---|
| Plates | 3/16" – 4" (5 – 102 mm) |
| Round bars | Ø 7/8" – 12" (Ø 22 – 305 mm) |
| Flat bars | 1/8×1 – 1×6 in |
| Hex bars | 1/2" – 2" (13 – 51 mm) |
If you need a particular size, tell us which one and we will gladly source it for you.
304L equivalents and standards
304L stainless steel is also identified by these standards: AISI 304L / EN-DIN 1.4306 / JIS SUS304L. You can see how to read them in our article on steel standards.
In summary
- 304L is a low-carbon austenitic stainless steel ("L")
- Typical composition: Cr 18.00 – 20.00%, Ni 8.00 – 12.00%
- Does not harden by quenching; supplied annealed (~170 HB) and hardens only by cold working
- Excellent corrosion resistance and weldability
- We carry it in plates, round bars, flat bars, hex bars, cut to size
Why buy your 304L stainless steel at NAT MAC?
We have more than 54 years of experience as an industrial supplier and ISO 9001 certified quality. We carry quality stainless steel and help you choose the right grade for your application.
- Quality 304L Stainless Steel, backed and traceable
- Material cut to the size you need
- Advice on choosing between 304L and 316L for your process
- Plate, round bar, flat bar and hex bar
- On-time deliveries and competitive prices
Tell us what you are going to make and in what environment the part will work, and we will recommend the right grade and form. Request your free quote.
Sources: data sheet from our NAT MAC catalog (composition, sizes and applications) and public references from the stainless steel industry. Values are for reference and may vary by standard, heat and finish.
