304 vs. 316 stainless steel: what’s the difference?
Both are part of the austenitic family of stainless steels, sharing a similar chemical composition. While this means many of their attributes are the same, there’s also a distinct difference. In this guide, we’ll look at the content of those two stainless steel grades and their unique properties – and how both express themselves in terms of characteristics: 304 vs. 316 stainless steel strength. 304 vs. 316 stainless steel uses. We’ll cover:
What is 304 stainless steel?
304 stainless steel alloys include a minimum of 18% chromium and 8% – 10.5% nickel with a maximum of 0.08% carbon.
As a general rule of thumb, austenitic stainless steels contain significant amounts of chromium and nickel, and that’s really what gives this family of steels their excellent corrosion resistance. Chromium provides a protective oxide layer. It does something else, too, with the addition of nickel – they enhance toughness and ductility, making the steel easy to work with. As austenitic stainless steel contains less iron than say, a ferritic stainless steel, this stainless-steel family is typically non-magnetic, though some have slight magnetic characteristics.
Specifically, 304 stainless steel is the most widely used of all stainless steels, which comes down to its properties.
You can learn more about stainless steel in our guide, Understanding stainless-steel grades.
What is 304 stainless steel used for?
Some of its common industrial applications include:
| Industry | Typical applications | Why |
|---|---|---|
| Food processing equipment | Tanks, pipes & containers | Resistance to corrosion, easy to clean |
| Consumer appliances | Sinks, refrigerators, dishwashers | Durability, resistance to corrosion, aesthetic appeal |
| Automotive | Exhaust systems, trim & grilles | Resistance to corrosion, aesthetic appeal |
| Medical equipment | Surgical instruments, dental instruments & implants | Biocompatibility, resistance to corrosion & withstands high-temperature cleaning processes |
| Chemical processing equipment | Reactors, tanks & pipelines | Resistance to corrosion, stands up to a range of chemicals |
| Aerospace components | Aircraft structures, engines | High strength-to-weight ratio, resistance to corrosion, thermal stability |
304 stainless steel is also used in different types of small components. Just some examples include:
What is 316 stainless steel?
Grade 316 is another austenitic stainless steel. As part of the 300 series of austenitic stainless steel, it also contains nickel, just as 304 does. Where 304 stainless steel alloys have a minimum of 18% chromium, 316 stainless steel has less with 16%. The nickel content in 316 is also higher, at 10%.
You would think this would give 304 stainless steel a higher resistance to corrosion, but 316 contains 2% molybdenum. The molybdenum helps resist corrosion caused by chlorides, such as sea water and de-icing salts. It also gives 316 greater resistance to chemical attacks.
While each offers excellent corrosion resistance, 316 stainless steel’s is actually higher than grade 304 stainless steel. Grade 316 often exhibits better strength at high temperatures, although both have excellent heat resistance.
Grade 304 vs. 316 stainless steel appearance is impossible to judge by the naked eye – they look the same, except when it comes to cost. Expect to pay more for 316, which is due to the higher nickel content and addition of molybdenum.
What is 316 stainless steel used for?
304 vs. 316 stainless steel uses often comes down to budget. Grade 316 can be used for the same applications as 304 – as you’ll see below – but 304 can’t always be used instead of 316. Here are just some of the industries and applications where 316 is put to work.
| Industry | Typical applications | Why |
|---|---|---|
| Food processing equipment | Tanks, pipes & containers | Non-reactive – does not impart any unwanted flavours or odours to food & easy to clean |
| Oil and gas | Pipelines, valves & fittings | Resistance to corrosive fluids and gases |
| Energy/power generation | Turbine blades | High-temperature strength & corrosion resistant |
| Medical equipment | Surgical instruments, dental instruments & implants | Biocompatibility, corrosion resistant & withstands high-temperature cleaning processes |
| Chemical processing equipment | Production of organic acids, storage tanks & reactors | Molybdenum enhances corrosion resistance, high-temperature strength |
| Marine | Boat fittings & seawater piping | Highly corrosion resistant in marine environments |
316 stainless steel is considered marine grade, but it’s not resistant to warmer sea water (304, even less so), which can cause chloride pitting. Still, its characteristics make it popular for use in small components too. Examples of common applications include:
304 vs. 316 stainless steel properties
As austenitic materials, their properties are similar. In the case of 304 vs. 316 stainless steel properties, they’re identical or nearly the same, which comes down to their similar chemical composition. For instance, their densities are often the same, despite the addition of molybdenum to 316. However, molybdenum has a relatively low atomic weight, so it doesn’t have much of an impact on density.
304 vs. 316 stainless steel: a comparison
Let’s compare their content. Again, note that they share much of the same content – except for molybdenum. Grade 316 also has more nickel, while 304 has more chromium.
| Element | 304 stainless steel % | 316 stainless steel % |
|---|---|---|
| Carbon | 0.07 | 0.07 |
| Chromium | 18.0 – 19.5 | 16.5 – 18.5 |
| Nickel | 8.0 – 10.5 | 10.0 – 13.0 |
| Silicon | 1.00 | 1.00 |
| Manganese | 2.00 | 2.00 |
| Phosphorous | 0.045 | 0.045 |
| Sulphur | 0.015 | 0.015 |
| Nitrogen | 0.10 | 0.10 |
| Molybdenum | - | 2.0 – 2.5 |
304 vs. 316 stainless steel strength
When it comes to mechanical strength, 316 stainless steel is generally considered stronger than 304. Again, this is attributed to 316’s molybdenum content. As a result, 316 stainless steel generally has better mechanical properties. The yield and tensile strength of each vary, depending on the manufacturing process and conditions involved – but in general, the tensile strength of 316 stainless steel is higher than that of 304 stainless steel.
Choosing between 304 and 316 stainless steel comes down to your application and its specific requirements for oxidation resistance, mechanical strength, and ultimately, cost. For example, if your application won’t be in a highly corrosive environment, go with grade 304. It’s still extremely resistant to corrosion, but it also costs less. At the same time, using 304 in applications that are better suited for 316 stainless steel can end up costing you more in the long run.
To understand the Rockwell B hardness test below, see our guide, What’s shore hardness and why should you care?
| Mechanical properties | 304 stainless steel | 316 stainless steel |
|---|---|---|
| Ultimate Tensile Strength | 505 MPa | 550 MPa |
| Tensile Yield Strength | 215 MPa | 240 MPa |
| Hardness (Rockwell B) | 70 | 80 |
| Elongation at break | 70% | 60% |
304 vs. 316 stainless steel differences
In summary, these are the primary characteristics of each stainless steel:
| Characteristics | 304 stainless steel | 316 stainless steel |
|---|---|---|
| Corrosion resistance | Excellent | Even better |
| Magnetic | No | No |
| Weldability | High | Good |
| Hardens during cold forming | Yes | Yes |
| Formability | Very good | Good |
| Machinability (annealed) | Fair, but better than 316 | Fair |
| Resists elevated temperatures | High | High |
| Maximum intermittent service temperature | 850°C | 850°C |
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