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Published: 05/10/2018

Stainless Steel: 304 vs 316 Grade

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What's the difference between 304 and 316 grade Stainless Steel?

The main differences between the grades are as follows:

  1. 304-grade Stainless Steel is suitable for installations in environments which are kept hygienically clean such as in the food industry. Comparatively, for environments where exposure to particularly hazardous or corrosive substances is likely, such as the Offshore or Chemical industries, it is recommended that the more resistant 316-grade Stainless Steel is used.
  2. The addition of Molybdenum during the manufacturing process makes 316 Stainless Steel stronger and more durable, capable of withstanding higher levels of corrosion and the effects of chemicals such as chlorides and sulfuric acid.
  3. 304 stainless steel is made up of 18% chromium and 8% nickel, whereas 316 stainless steel consists of 16% chromium, 10% nickel, and 2% molybdenum.
  4. The Offshore industry would require the 316-grade of Stainless Steel as the acids found in salt water would attack 304, tarnishing the steel and potentially causing rusting.
  5. 316-grade Stainless Steel is often specified in Pharmaceutical installations in order to prevent excessive metallic contamination.
  6. 316-grade Stainless Steel is also significantly more resistant to heat in comparison to 304.

It is extremely difficult to visually differentiate between the two material types. Both 304 and 316 families of Stainless Steel are easy to clean, easy to weld and are renowned for their durability and sustainability. Both types also offer excellent levels of corrosion-resistance especially when compared to other steel types.

Material grades with 'L' in their AISI name (e.g. 316L) contain less carbon, but are visually otherwise identical to the grade without 'L' in their AISI name (e.g. 316). However the lower amount of carbon present means they are more corrosion-resistant and easier to weld.

Generally, material from the 304-grade family is suitable for most applications, with more demanding environments requiring the more corrosion-resistant 316-grade family of materials.

304 Stainless Steel Applications & Uses

304 family (304-1.4301, 304L-1.4306/7 etc.)
Suitable for most environments where a medium level of corrosion-resistance is required, where the material won't come into contact with harsh chemicals or airborne corrosive substances.

316 Stainless Steel Applications & Uses

316 family (316-1.4401, 316L-1.4404 etc.)
Suitable for all environments where 304 can be used, with additional corrosion-resistance properties - making it ideal for Offshore, Marine and Chemical Processing environments.

Choosing the right material

Make sure that you choose the right stainless steel for your electrical enclosures, trunking systems, conduit systems and cable tray systems, ensuring the grade is suitable for your installation environment and cleaning procedures.

We supply many of our Stainless Steel products in a choice of two different grades; the 304 family and the 316 family.

Comparison of the various Stainless Steel standards

There are many different standards for Stainless Steel recognised around the world. This table identifies and compares some of the most common standards.

Grade AISI ASTM SAE EN Standard German Standard Fasteners
304 Family 304 UNS S30400 30304 1.4301 V2A A2
304L UNS S30403 30304L 1.4306/7
316 Family 316 UNS S31600 30316 1.4401 V4A A4
316L UNS S31603 30316L 1.4404
- 316C16F
The above are just some of the most common Austenitic Stainless Steels (300 Series).

Chemical Composition Comparisons

% by mass
Number Name C
Si
Mn
P
S
Cr Mo Ni N
1.4301 X5CrNi18–10 0.07 1.0 2.0 0.045 0.015 17.5 to 19.5 - 8.0 to 10.5 0.1
AISI 304 / SAE 30304
UNS S30400 - ASTM A240/A240M
0.07 0.75 2.0 0.045 0.03 17.5 to 19.5 - 8.0 to 10.5 0.1
1.4307 X2CrNi18–9 0.03 1.0 2.0 0.045 0.015 17.5 to 19.5 - 8.0 to 10.5 0.1
AISI 304L / SAE 30304L
UNS S30403 - ASTM A240/A240M
0.03 0.75 2.0 0.045 0.03 17.5 to 19.5 - 8.0 to 12.0 0.1
1.4401 X5CrNiMo17–12–2 0.07 1.0 2.0 0.045 0.015 16.5 to 18.5 2.0 to 2.5 10.0 to 13.0 0.1
AISI 316 / SAE 30316
UNS S31600 - ASTM A240/A240M
0.08 0.75 2.0 0.045 0.03 16.0 to 18.0 2.0 to 3.0 10.0 to 14.0 0.1
1.4404 X2CrNiMo17–12–2 0.03 1.0 2.0 0.045 0.015 16.5 to 18.5 2.0 to 2.5 10.0 to 13.0 0.1
AISI 316L / SAE 30316L
UNS S31603 - ASTM A240/A240M
0.03 0.75 2.0 0.045 0.03 16.0 to 18.0 2.0 to 3.0 10.0 to 14.0 0.1

The above is for guidance only. Individual standards should always be referenced.

Chemical Key

  • C = Carbon
  • Si = Silicon
  • Mn = Manganese
  • P = Phosphorus
  • S = Sulfur
  • Cr = Chromium
  • Mo = Molybdenum
  • Ni = Nickel
  • N = Nitrogen

The remaining % in each case is made up of Fe (Iron).

Other Grades of Stainless Steel

There are many other grades of stainless steel available, all with slightly different properties.

For example, our cast stainless steel products are made from 316C16F Stainless Steel, which has very similar properties to 316-grade, but has additional properties which make it easier to cast and machine.

Need Help?

For more information or general advice on which grade is best for you, please don’t hesitate to contact us by calling +44 (0) 1388774455 or emailing info@electrixinternational.com.

Definitions

  • AISI
    American Iron and Steel Institute
  • ASTM
    American Society Testing and Materials
  • ASTM A240/A240M
    Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications
  • SAE
    Society of Automotive Engineers
  • UNS
    Unified Numbering System

References

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