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While buying austenic stainless steel, 304 SS and 316 SS are the most popular variants. However, they differ in chemical, physical, and mechanical properties.
For a normal environment, grade 304 is a good and affordable choice. But in a harsh environment with high temperature, chemical, and chlorine content, 316 SS fits best. Let’s explore their differences and similarities in depth.
What Is 304 Stainless Steel?
304 stainless steel contains a high chromium content of 18% and a nickel content of 8%. For such a composition, 304 SS is also called 18/8 stainless steel. However, besides these two major elements, it contains other minor elements like:
- Iron
- Manganese
- Carbon
- Sulfur
- Silicon and
- Phosphorus
Based on carbon content, 304 stainless steel has two sub-grades:
- 304L stainless steel: It has low carbon and which is low carbon can handle higher temperatures.
- 304H stainless steel: The ‘H’ here stands for high carbon content. These stainless steel are resistant to extremely high temperatures.
304 stainless steel is popular because it is strong and resists corrosion well. You can also weld and mold them to give them a form structure.
What Is 316 Stainless Steel?
316 stainless steel has extended anti-corrosive properties. Besides chromium and nickel, it also contains 2–3% molybdenum, which makes 316 SS chloride tolerant. This makes it an ideal material for use in marine environments and other challenging conditions.
The sub-grades of 316 stainless steel are as follows:
| 316 SS Grade | Meaning | Feature |
|---|---|---|
| 316L | Low carbon | Increased weldability and resistance to intergranular corrosion. |
| 316H | High carbon | Resistance against creep and better thermal stability |
| 316Ti | Contains a small amount of titanium | High resistance to intergranular corrosion |
| 316N | The high amount of nitrogen | Increased tensile strength |
| 316LN | Low carbon but high nitrogen | Higher yield strength, tensile strength, and hardness than 316N |
304 Vs 316 Stainless Steel: Key Differences
Chemical Composition
Both 304 SS and 316 SS have high chromium and nickel content. The main difference between their chemical composition is in the presence of molybdenum in 316 SS. This inclusion of molybdenum strengthens the anti-corrosive features of 316 SS.
| Alloying Element | 316 Stainless Steel | 304 Stainless Steel |
|---|---|---|
| Chromium | 16.00% – 18.00% | 18.00% – 20.00% |
| Sulfur | 0.030% (max) | 0.030% (max) |
| Carbon | 0.08% (max) | 0.08% (max) |
| Phosphorus | 0.045% (max) | 0.045% (max) |
| Manganese | 2.00% (max) | 2.00% (max) |
| Silicon | 1.00% (max) | 1.00% (max) |
| Molybdenum | 2.00% – 3.00% | – |
| Nickel | 10.00% – 14.00% | 8.00% – 10.5% |
Physical Properties
304 SS and 316 SS have similar physical properties. However, the latter has a higher melting point than 304 SS. This increases the heat resistance of 316 SS. In contrast, 304 SS has better formability than 316 SS.
| Physical Property | 316 Stainless Steel | 304 Stainless Steel |
|---|---|---|
| Density | 7.87–8.07 g/cm^3 | 7.87–8.07 g/cm^3 |
| Melting Point | 1648℃ – 1673℃ | 1450℃ |
| Corrosion Resistance | Exceptional | Excellent |
| Chloride Resistance | High | Poor |
| Heat Resistance | Excellent up to ~925°C | Good up to ~870°C |
| Formability | Good | Very Good |
| Shear Modulus | 74.0 GPa | 77.0 GPa |
| Thermal Conductivity | 13–17 W/m.K | 16.2 W/m.K |
| Modulus of Elasticity | 193 GPa | 193 GPa |
| Thermal Expansion | 15–18 x 10^-6/K | 17.2 x 10^-6/K |
| Electrical Resistivity | 0.69–0.81 x 10^−6 Ω⋅m | 10.72 x 10^−6 Ω⋅m |
Mechanical Properties
316 SS is harder than 304 SS stainless steel. That is why 316 SS is more suitable for applications that require high tensile strength or robustness. However, 304 SS facilitates better bendability due to lower yield strength. So you can use them for critical metal shaping.
| Mechanical Properties | 316 Stainless Steel | 304 Stainless Steel |
|---|---|---|
| Hardness | High | Moderate |
| Tensile Strength | 400-620 Mpa | 500-700 Mpa |
| 0.2% Yield Strength | 240 MPa | 230 MPa |
| Elongation at Break | 60% | 70% |
| Elongation A50 mm | 45% min | 45 Min % |
| Machinability (annealed) | Fair | Fair, but better than 316 |
| Hardness (Brinell) | 149 max HB | 215 Max HB |
Corrosion Resistant
Comparing 304 SS and 316 SS, the latter has better cushion resistance than 304 SS. 316 SS contains about 2.00% – 3.00% of molybdenum that boosts anti-rusting. It also provides corrosion resistance against chlorine or seawater. This is the main reason for using 315 SS in marine applications. In constant, 304 SS doesn’t have molybdenum, so they are not chlorine resistant.
Besides, the nickel content in 316 SS is 10.00% – 14.00% in comparison to 8.00% – 10.5% of 304 SS. This increased amount of nickel in 316 SS also contributes to extending the corrosion resistance.
Heat Resistance
The melting point of 304 stainless steel is 1450℃. Meanwhile, the melting point of 316 SS ranges from 1648℃ – 1673℃. This difference of 198℃ to 223℃ makes 316 SS more heat resistant than 304 SS.
However, there is not much difference, and both can handle high heat well. The 304 steel works well up to 860. However, continuous use at 425°C-860 °C leads to corrosion in the steel.
In contrast, 316 has a high heat resistance and performs excellently up to 925°C. Nevertheless, continuous work at temperatures ranging from 454℃ – 843℃ can cause corrosion. Therefore, for optimal performance with 316SS, keep the temperature below 454℃ or above 843℃.
Application
304 SS is widely used in the food and medical industry due to the presence of cleaning elements like chromium. This grade further meets the sanitary regulations of the Food and Drug Administration.
Common Application of 304 Stainless Steel:
- Storage tanks
- Surgical tools
- Wheel covers
- Kitchen equipment
- Bathroom stalls
- Water piping
- Fryers
- Decorative trim
- Appliances
- Elevators
- Indoor electrical enclosures
The presence of molybdenum in 316 SS offers high chlorine resistance. Thus, you can use this steel in marine and applications dealing with chemicals and toxins.
Common Application of 316 Stainless Steel
- Boat fitting & marine components
- Chemical piping and equipment
- Medical implants & equipment
- Mining screens
- Pharmaceutical equipment
- Coastal region architectural paneling
- Commercial kitchen appliances
- Tubing
- Laboratory bench construction
- Paper mills
Price
The cost of 316 stainless steel is approximately 40% higher than that of 304 stainless steel. This is because nickel is an expensive lament, and 316 SS contains higher nickel content than 3014. Besides, it also includes additional molybdenum. This increases the price of 316 stainless steel.
However, the increased price is worth the deal as 316 SS brings greater heat and corrosive resistance than 304.
Advantages
304 Stainless Steel
- Higher tensile strength than 316
- Cost-effective
- Versatile use- from cookware to water piping
- More flexible
- Better Machinability
316 Stainless Steel
- Higher corrosion resistance
- Greater heat resistance than 304
- Suitable for heavy-duty application
- Food and medical-grade steel
- Ideal for marine uses
Disadvantages
304 Stainless Steel
- Less cushion resistant than 316 SS
- Not suitable for marine application
- Can’t tolerate extreme heat
- Softer and less scratch-resistant
316 Stainless Steel
- Expensive
- Hard to machine
- Less malleable than 304 SS
- Can rust on the welded spots
- Less flexible than 304 SS
304 & 316 Stainless Steel: Similarities
Appearance
Both 304 SS and 316SS have a shiny silver appearance. They look identical; you can’t differentiate them visually.
Austenitic Stainless Steel Grades
The 300 series of stainless steel is categorized as austenitic. Thus, both 304 and 316 grades are of this type. They are strong, durable, anti-corrosive, and high-temperature resistant.
Non-magnetic
304 SS and 316 SS are non-magnetic. The high chromium and nickel content in these two grades of stainless steel reduces magnetic susceptibility.
Same Density
They have the same density of 7.87–8.07 g/cm^3 despite the addition of molybdenum in 316.
Manufacturing Process
The manufacturing process of 304SS and 316SS are similar. They go through melting, alloying, casting, rolling, cutting and shaping.
304 vs 316 Stainless Steel: Which is Best For Your Application?
304 stainless steel resists corrosion well and is highly resistant to temperature. Besides, 304 SS has more bendability than 316 SS. These features make 304 SS suitable for applications like kitchen appliances, bathroom stalls, piping, etc.
However, choose 316 SS for heavy-duty applications requiring extended temperature and collision resistance. They are more robust and have high chloride resistance properties. So, if you need steel for mining, chemical treatment, and applications dealing with chloride, go with 316 SS.
Conclusion
To choose between 304 SS and 316 SS, you must consider your application needs. For general use and an affordable option, go for 304 SS. And application that deals with chlorine, chemicals, and high temperatures, choose 316 SS.
Nevertheless, RICHCONN is your go-to choice for machining structural components using any type of stainless steel. We offer CNC machining for a wide range of metals, including 304 and 316 stainless steel. So, contact us ASAP!
If you are interested in comparing stainless steel with other materials, we have prepared related articles for you：
- Stainless Steel vs Carbon Steel
- Tool Steel vs Stainless Steel
- Galvanized Steel vs. Stainless Steel
- Comparing 18/8, 18/10, and 18/0 Stainless Steels
- Alloy Steel vs. Stainless Steel
- Titanium vs Stainless Steel
FAQs
Is it possible to visually identify whether it’s a 316 or a 304 stainless steel?
You can’t visually differentiate 304 and 316 stainless steel. To do this, you will need to check the Material Test Report (MTR).
Which is more expensive: 316 SS or 304 SS?
The high content of nickel and the presence of molybdenum makes 316 SS more expensive than 304 SS.
Which is more suitable for industrial application: 304 or 316 stainless steel?
316 SS is more heat resistant and has higher tensile strength than 304 SS. So, for better strength and anti-collision properties, 316 SS is more suitable for industrial applications than 304 SS.
What are the weaknesses of 304 stainless steel?
304 stainless steel is soft and prone to scratching. Besides, they are susceptible to corrosion in the presence of chlorine.
Can 316 stainless steel go in the water?
Yes, you can use 316 stainless steel in water, even in seawater with chlorine. They have high nickel and molybdenum, making 316 SS extremely anti-corrosive.
