Deciding whether to choose 304 or 316 stainless steel can be challenging without the right information.
Looking at the two SS grades – from appearance, they look the same.
The main difference exists in their chemical composition. Actually, their chemical composition determines mechanical properties, chemical properties, and application.
Therefore, before discussing these austenitic stainless steels, let’s look at the chemical composition.
Comparing 304 vs 316 Stainless Steel Chemical Composition
As you will see from the table below, there are other variations of 316 and 304 stainless steels.
This variation is due to the unique chemical composition of each stainless steel grade.
Take for example:
- 316L – it has a low carbon content than the normal 316 SS
- 316Ti – titanium is present in small quantities for stabilization
- 316H – the SS has a high carbon quantity making it a perfect choice for high-temperature applications
- 304H – stainless steel grade has high carbon quantity with zero nitrogen content
- 304L – the SS grade has a low carbon content
|% of the element by weight||316||316L||316H||316Ti||304||304L||304H|
|Carbon (C)||0-0.07||0-0.03||0.04-0.08||0-0.08||0.08 max||0.03 max||0.04-0.1|
|Silicone (Si)||0-1||0-1||0-1||0-1||0.75 max||0.75 max||0.75 max|
|Manganese (Mn)||0-2||0-2||0-2||0-2||2.0 max||2.0 max||2.0 max|
|Phosphorus (P)||0-0.05||0-0.05||0-0.04||0-0.05||0.045 max||0.045 max||0.045 max|
|Sulfur (S)||0-0.02||0-0.02||0-0.02||0-0.03||0.03 max||0.03 max||0.03 max|
|Nitrogen (N)||–||–||–||–||0.10 max||0.10 max|
Note: These values are estimates – get the actual figures from your stainless steel manufacturer. They will provide you with their datasheet.
When evaluating the stainless steel 304 vs stainless 316 chemical composition, it is worth noting:
304 and 304L have Nitrogen
Theoretically, the maximum limit is about 0.1% in both cases. Generally, nitrogen in stainless steel is responsible for:
- Improved yield strength
- Improves pitting corrosion
316Ti has Titanium
The quantity varies from 0.4% to 0.7%. In stainless steel, titanium plays the following roles:
- 316Ti stabilization thereby improving welding properties
All 316 Stainless have Molybdenum
The amount present varies from 2% to 2.5%. Ideally, molybdenum is responsible for:
- Superior corrosion resistance in 316 stainless steel
- Makes 316 SS resistant to crevice and pitting corrosion
- Suitable for application involving chlorides and sulfur
Stainless Steel Composition – Source: Tuolian
Stainless Steel Grades – Source: Tuolian
Grade 316 SS – Source: Azo Materials
Grade 304 SS – Source: Azo Materials
304 vs 316 Stainless Steel Corrosion Resistance
In the two stainless steel grades, the magnitude of corrosion resistance depends on:
Look at some corrosion in SS grades, you realize that:
|Corrosion Type||304 SS||316 SS|
|Oxidation or rust under normal environmental conditions||Excellent||Excellent|
|Corrosion in chloride or saline conditions||Susceptible to corrosion||Excellent corrosion resistance properties|
|Pitting corrosion||Susceptible especially if there is chlorine||Superior corrosion resistance|
Note that 316 stainless steel offers excellent resistance even in presence of sulfuric acid, bromides, fatty acids, etc.
Forming Stainless Steel 316 vs 304
Forming stainless steel involves many procedures and practices where you transform the material to a suitable shape.
Between the two SS grades, 304 has excellent forming properties. In most cases, the molybdenum present in 316 SS negatively impacts the forming properties.
Stainless Steel 304 vs 316 Price
The type of alloying element influences SS grade prices.
Take for instance;
When there is a change in nickel, molybdenum chromium, or iron prices, it affects how much you pay for these alloy grades. Even with that in mind, 316 SS is pricier than 304 SS.
Therefore, you can choose 304 SS for applications where design and fabrication costs are a major concern.
304 vs 316 Stainless Steel Mechanical Properties
There are many variables determining SS grade strength and mechanical properties. The tables below give estimated values:
|SS Grade||Tensile Strength||Elongation A50mm||Hardness|
|316SS||400 to 620 Mpa||45% min||149 Max HB|
|304SS||500 to 700 Mpa||45%||215 Max HB|
Information courtesy of Kloeckner metals.
Again, when evaluating mechanical properties, these values may vary depending on the form stainless steel grades exist.
Whether you are examining 304 or 316 stainless steel they exist as sheets, plates, pipes, tubes, bars, or strips.
In addition to the mechanical properties, let’s summarize the 304 vs 316 stainless steel physical properties in the table below:
|SS Grade||Melting point||Thermal conductivity||Thermal expansion||Density||Modulus of Elasticity|
|304 SS||1450℃||16.2 W/m.K||17.2 x10^-6/K||8.00 g/cm^3||193 GPa|
|316 SS||1400℃||16.3 W/m.K||15.9 x 10^-6||8.00 g/cm^3||193 GPa|
Information courtesy of Kloeckner metals.
304 vs 316 Stainless Steel Heat Resistance
Even though the two grades have the best heat resistance properties, there are some limits you should not exceed. Take for example:
- 304 Stainless Steel – It has superior thermal properties. Using this SS grade continuously within 425-860 °C may compromise corrosion resistance properties.
- 316 Stainless Steel – The SS grade works well within a broad temperature range. You can use it intermittently at 870°C.
Note: Always as the stainless steel grade supplier for accurate information based on their stainless steel.
Fabricating Stainless Steel 304 Vs 316
It is worth mentioning that 316 SS is not suitable for applications requiring high formability. Of course, this is due to molybdenum.
But, that is just one aspect.
However, you can easily fabricate the two stainless steel grades with standard tools and equipment.
Still, as you plan to fabricate 304 and 316 stainless steel, you should remember that:
Fabricating 316 SS
|Cold working 316 SS||· Suitable for roll forming, brake bending, stamping, and drawing
· Annealing after cold working is critical to eliminate internal stresses
|Hot working 316 SS||· Suitable for hot working however, don’t perform the process below 927°C
· Annealing after hot working is necessary for optimal corrosion resistance properties
|Heat treatment 316 SS||· Rapid cooling is recommended after annealing or solution treatment
· Never harden 316 stainless steel through heat treatment
|Machining 316 SS||· Good machining properties
· You can use standard metal cutting techniques such as milling, laser cutting, plasma cutter, etc.
· At times, cooling may be necessary since 316 stainless steel has a low thermal conductivity
|Welding 316 SS||· You can use the fusion welding technique
· Oxyacetylene welding is not recommended
· For heavy sections, post-annealing operations may be necessary
Fabricating 304 SS
|Heat Treating 304 SS||· Thermal hardening is not recommended
· Annealing or solution treatment is possible though between 1010 °C and 1120 °C
|Welding 304 SS||· Excellent welding properties
· You can use all fusion welding techniques
· Post-welding annealing is recommended for heavy sections
|Machining||· Easy to cut with standard tooling and operations such as laser cutter, plasma cutter, etc.|
|Forming properties||· Easy to form into complex shapes and parts – you can bend, spin, etc.|
Stainless Steel Grade 304 vs 316 Alloy Designation
Usually, there are varying names depending on specific standards such as:
|Stainless Steel Grade||EN||UNS||BS||Euronorm|
|316 Stainless Steel||58H||S31600||316S31||1.4401|
|304 Stainless Steel||58B||S30400||304S15||1.4301|
304 Stainless Steel Vs 316 Stainless Steel Applications
As earlier mentioned, the chemical composition plays an integral role when deciding where to use the stainless steel grade.
Some common applications include:
304 Stainless Steel Applications
- Home appliances such refrigerators, microwaves, etc.
- Tubes and pipes in heat exchangers, water systems, etc.
- Food processing equipment
- Kitchen equipment
316 Stainless Steel Applications
- Piping, or heat exchanger systems in saline or marine environments
- Chemical storage equipment
- Medical equipment and accessories
- Marine equipment and accessories
- Pharmaceutical industries, etc.
So, how do you choose any for any application?
|Application Requirements||316 Stainless Steel||304 Stainless Steel|
|Excellent formability||· Good||· Excellent|
|Cost a major factor||· Expensive||· Affordable – cheaper than 316|
|Highly corrosive environments including sulfur and chloride||· Best performance||· Not good – susceptible to corrosion|
|Parts submerged in water/frequently exposed to water||· Superior performance||· Performs well but not as 316|
|Greater strength||· Perfect alternative||· Can work but not as good as 316|
|Hardness is paramount||· Perfect alternative||· Can work but 316 stainless steel is superior|
As you can see from the chemical composition, it depends on the specific applications. At Tuolian, we will help you choose the best stainless steelgrade for all your applications – talk to experts now.