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.Compare 304 stainless steel with other grades in our expert guides:
304 vs 430 stainless steel. 304 vs 303 stainless steel.
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
Find out more about the role of stainless steel in healthcare.
304 stainless steel is also used in different types of small components. Just some examples include:
T-handle – 304 stainless steel cam
Paddle latch – 304 stainless steel screws
Torque hinge – 304 stainless steel pins & nuts
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.
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 flavors or odors 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, so can be used in some marine applications, 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:
Elematic 2-Lock™ cable tie – 316 stainless steel teeth
Quarter-turn spring latch
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.
This table shows the key differences between the two grades, including their density, melting point (or melting range for 316 grade), modulus of elasticity, electrical resistibity, thermal conductivity and shear modulus.
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 Sulfur 0.015 0.015 Nitrogen 0.10 0.10 Molybdenum - 2.0 – 2.5
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 73200 psi 79800 psi Tensile Yield Strength 31200 psi 34800 psi Hardness (Rockwell B) 70 80 Elongation at break 70% 60%
In summary, these are the primary characteristics of each stainless steel.
316 stainless steel has superior corrosion resistance properties but both are used for pharmaceutical and medical applications, including medical surgical instruments. Whilst the two grades both have high tensile strength, 316 is superior. However, 304 stainless steel has excellent welding qualities and is the most widely used of the austenitic stainless steels for such applications.
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 1562°F 1562°F
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