Stainless steel is an alloy primarily composed of Chromium (Cr) and Nickel (Ni), which together form a protective oxide layer that resists corrosion. Among the hundreds of stainless steel grades available, 304 and 316 are the most commonly used in commercial applications. Both belong to the Austenitic family, known for their durability, corrosion resistance and versatility.
What Makes 304 and 316 Stainless Steel Similar?
304 and 316 stainless steel grades share a number of core characteristics that make them suitable for a wide range of applications:
- Are classified as “18-8” stainless steel, containing ~18% Chromium and ~8% Nickel.
- Both belong to the austenitic family of stainless steels
- Are non-magnetic after annealing and cannot be hardened by heat treatment.
- Share similar mechanical properties and can be finished identically for aesthetic consistency.
They exhibit similar mechanical properties, with 316 offering slightly better performance in areas such as hardness, thermal expansion, heat transfer coefficient, tensile strength, electrical resistivity, weldability, formability, and machinability.
Chemical Composition Comparison
| Element | 304 | 316 |
| Chromium | 18% – 20% | 16% – 18% |
| Nickel | 8% – 10.5% | 10% – 14% |
| Molybenum | 0% | 2% – 3% |
| Carbon | 0.08% max. | 0.08% max. |
| Silicon | 1.0% max. | 1.0% max. |
| Manganese | 2.0% max. | 2.0% max. |
| Phosphorus | 0.045% max. | 0.045% max. |
| Sulphur | 0.03% max. | 0.03% max. |
| Nitrogen | 0.1% max. | 0.1% max. |
Stainless steels owe their corrosion resistance to a thin chromium oxide film on the surface, but other elements, such as molybdenum and nitrogen, can improve corrosion resistance.
What is the chemical difference between 304 and 316 grades of Stainless Steel?
While the chemical difference between 304 and 316 stainless steel may seem minor, it has a significant impact on corrosion resistance—particularly in environments containing chloride ions such as saltwater or coastal air.
The key distinction lies in the presence of Molybdenum (Mo) in 316 grade stainless steel. This element enhances resistance to pitting corrosion, making 316 more suitable for harsh environments.
To compare corrosion resistance, we use the Pitting Resistance Equivalent (PRE) formula:
PRE = % Chromium + 3.3 × % Molybdenum + 16 × % Nitrogen
- 304 Grade PRE ≈ 18
- 316 Grade PRE ≈ 24
A higher PRE value indicates stronger resistance to corrosion, especially in chloride-rich conditions. While both grades can be finished identically for a consistent appearance, improving the surface finish can further enhance corrosion resistance without altering the underlying grade.
Stainless Steel 304 Grade
Stainless Steel 304 grade is corrosion resistance against “freshwater environments”. These environments are typically neutral in pH, don’t have chloride irons and are regularly cleaned. 304 widely used in the food and beverage industry, where hygiene and corrosion resistance are critical.
Grade 304 typically contains 18.5% Chromium and 8.5% Nickel and is commonly used for in indoor applications that are required to remain clean and hygienic such as sinks, benchtops, ovens, fridges, and cooking utensils. Historically known as 18/10 stainless, 304 was first developed in Sheffield, UK, for the production of cutlery and kitchenware.
Stainless Steel 316 Grade
316 stainless steel, like its little sibling 304, offers excellent corrosion resistance, however with a crucial advantage: it performs reliably in environments containing chloride ions, such as coastal areas or industrial zones with salt exposure.
In addition to 17% Chromium and 11% Nickel, 316 includes approximately 2% Molybdenum, which significantly improves its resistance to pitting corrosion. 316 is ideal for outdoor architectural features, beachside fencing, and gabion cages where exposure to salt air and moisture is unavoidable.
However, while 316 is highly resistant, it is not suitable for being submerged in salt water,. Its strength lies in offering a low-maintenance, long-lasting solution for structural applications in harsh environments.
What are the Mechanical & Physical differences between 304 and 316 grades of Stainless Steel?
The differences between the two grades are the following:
- Slight difference in the Electrode potential with 304 being slightly lower than 316. This is not enough to see corrosion of 304 when in contact with grade 316 in a sea water solution but have it at elevated temperature, high flowrates with high concentrations then there may be a low level of corrosion of the 304.
- Because of its Molybdenum content, 316 is more resistant to pitting corrosion which means it can operate a higher temperature than 304 before it starts for most chemicals according to industry corrosion charts
- 316 has a slightly lower melting range (1375-1400) compared to 304 (1400-1450) but both are rated a having the Same Maximum service Temperature of 870 deg C
- 316 has a slightly lower elongation (55%) compared to 304 (57%)
- While both materials are non-magnetic after annealing, the more the 304 grade is cold worked compared to 316 the greater the Magnetic Permeability becomes.
When do I use 304 and when do I use 316?
Stainless Steel grades use alloying elements that are expensive when compared to traditional steel products. When deciding the grade to use, you must consider the following factors:
- The Environment in which the material is being used
- The Application in which the material is being used
- The Asset Life and Costs you are wanting to achieve
If you are replacing stainless steel how do you know which grade to replace with? Have a look at our blog post about How to Test if Your Stainless Steel is Grade 304 or Grade 316.
When to Use 304 Grade Stainless Steel
Applications:
- Food manufacturing: sinks, benchtops, ovens, fridges and utensils. Such as mesh for food processing mesh.
- Indoor environments: neutral pH, regularly cleaned and no chloride ions. Such as architectural mesh including balustrading and cabinetry mesh.
- External dry inland environments: where natural rainwater can regularly wash the surface, helping to prevent build-up of contaminants and reduce the risk of tea staining. Such as bird aviary mesh.
Advantages:
- Cost-effective for neutral environments.
- Slightly stronger and more wear-resistant than 316.
Limitations:
- Not suitable for coastal or high chloride environments.
- May show signs of tea staining over time if exposed to salt air.
When to Use 316 Grade Stainless Steel
Applications:
- Coastal environments: beach fencing, gabion cages and coastal structures.
- External environments: within 5km of surf coast or 1km of sheltered coastal waters.
- Polluted urban areas or high humidity zones: roof safety mesh.
Advantages:
- Contains Molybdenum (Mo) for enhanced resistance to pitting corrosion.
- Ideal for high chloride environments.
Limitations:
- Higher cost due to added alloying elements.
- Should not be used in submerged salt water.
Grade 304 & 316 Mechanical & Physical Differences
Property | 304 Grade | 316 Grade |
Melting Range | 1400–1450°C | 1375–1400°C |
Elongation | 57% | 55% |
Magnetic Permeability | Increases with cold work | Lower than 304 |
Maximum Service Temp | 870°C | 870°C |
Cleaning & Maintenance
- Regular cleaning is essential to prevent build-up of contaminants like salt and dirt.
- Pickling, passivation, and electropolishing are recommended for external applications to minimise tea staining.
Refer to our Care & Maintenance page for further information.
Quick Comparison: Key Questions to Help You Identify the most appropriate Grade of Stainless Steel 304 or 316?
Question | 304 Grade | 316 Grade |
Does it rust? | No | No |
Does it tarnish? | Rarely | Rarely |
Does it scratch? | Yes | Yes |
Is it safe? | Yes | Yes |
Is it magnetic? | No | No |
Can it be welded? | Yes | Yes |
Tensile Strength | ~515 MPa | ~485 MPa |
Suitable for coastal use? | No | Yes |
Contains molybdenum? | No | Yes (~2%) |
Suitable for food contact? | Yes | Yes |
Common indoor use? | Yes | Yes |
Common outdoor use? | Limited | Excellent |
Cost | Lower | Higher |
Resistance to chlorides? | Moderate | High |
Typical applications | Kitchens, appliances, food manufacturing | Coastal, industrial, polluted and architectural |
Variations Within Each Grade
Both grades can be customised with:
- Low or high carbon content
- Higher molybdenum levels (for 316)
- Additional alloying elements to enhance specific properties
Specification Made Easy
Navigating our extensive range of stainless steel products is simple with SSWM’s Product Selection Guides and Technical Data Sheets. These resources provide essential information on testing, standards, and product specifications, streamlining the selection process for every project.
Whether you’re sourcing Welded Mesh, Woven Mesh, Perforated Sheets or Coil Wire, we offer a wide variety of specifications in both 304 and 316 grades. Additional options are also available, including 316L, Duplex 2205, and Duplex 2507 to meet more specialised requirements.
Choosing the most appropriate stainless steel grade is critical to ensuring optimal performance and long-term durability. With SSWM’s expertise and comprehensive product range, finding the optimal solution for your application has never been easier.
Our Technical Sales Team is here to support you. Whether your needs are standard or highly specific, we’ll help you evaluate your options and select the most appropriate grade and specification for your project.
