316 vs 321 Stainless Steel: What’s the Difference?
Stainless steel is a type of metal that is used almost in every application. It has various grades, and each grade has a different composition of elements which makes it suitable for particular applications.
316 and 321 stainless steel are commonly opted and have different characteristics. The guide below features in detail a comparison of 316 vs 321 stainless steel– helping you choose a relevant option for your application. So, let's read below.
What is 316 Stainless Steel?
Stainless steel 316 is a grade of steel that is highly corrosion-resistant and easy to form. It has molybdenum, which adds to its resistance against corrosion.
The pros and cons of 316 stainless steel are as follows:
Advantages:
- 316 stainless steel performs very well at high temperatures, it doesn't lose its stability nor deforms easily.
- 316 stainless steel is also compatible with rigorous cold working and can easily be formed into different components.
- 316 is available easily which makes it possible to achieve the projects quickly.
Disadvantages:
- 316 stainless steel is not weldable enough, and components that require welding may find using it a bit challenging.
- It is a heavy material, and applications that have weight constraints may not find it suitable.
- The cost of 316 stainless steel is very high in comparison to the other grades of stainless steel.
What is 321 Stainless Steel?
Stainless steel 321 has a high content of titanium. It has high corrosion resistance and also offers high weldability. 321 stainless steel, however, is not formable when subjected to high temperatures.
Advantages:
- 321 has a high weldability as it has titanium, which boosts weldability.
- 321 stainless steel is suitable for use at high temperatures and can be used for manufacturing heat exchangers and furnaces.
- It is affordable and can be chosen for projects with tight budgets.
Disadvantages:
- Stainless steel 321 can overcome high temperatures but loses its strength.
- If subjected to strain hardening, stainless steel 321 has a decreased ductility.
- It is not easily available and sourcing it causes delays to projects.
Comparing 316 and 321 Stainless Steel
A detailed comparison of 316 and 321 acier inoxydable is given below.
Chemical Composition
316 Stainless Steel: Stainless steel 316 has 16 to 18% of chrome, 2-3% of molybdenum, 10 to 14% of nickel, 2% manganese, 0.1% nitrogen, 0.045% phosphorus, 0.08% carbon, 0.03% sulfur, 0.75% silicon.
321 Stainless Steel: 321 stainless steel has 0.08% carbon, 0.045% phosphorus, 1% silicon, 9 to 12% nickel, 17 to 19% chromium, and 0.030% sulfur.
Résistance à la corrosion
316 Stainless Steel: 316 stainless steel has a high resistance against corrosion.
321 Stainless Steel: It offers good corrosion resistance in an intergranular state but less in environments that are high in salt or acidic.
La force
316 Stainless Steel: It is strong, but at high temperatures, it has less strength.
321 Stainless Steel: It performs with strength in high-temperature applications.
Solidité
316 Stainless Steel: It offers excellent toughness in environments that are low-temperature.
321 Stainless Steel: It has excellent toughness at all temperatures.
Résistance à la chaleur
316 Stainless Steel: It can withstand a maximum temperature of 870 degrees centigrade but cannot withstand it for a longer span.
321 Stainless Steel: It is suitable for continuous exposure to 870 to 925 degrees centigrade.
Fabrication and Welding
316 Stainless Steel: 316 stainless steel has high weldability and can withstand corrosion after welding.
321 Stainless Steel: Stainless steel 321 also has good weldability, but care is needed for the heat zones.
Magnétisme
316 Stainless Steel: It is non-magnetic but becomes a little magnetic when subjected to cold working.
321 Stainless Steel: It is non-magnetic even when subjected to cold working.
Cost Comparison
316 Stainless Steel: 316 is an expensive grade of stainless steel.
321 Stainless Steel: It is affordable and can work with budgeted applications.
Quick Chart of 316 vs 321 Stainless Steel
The chart below offers an insight into a comparison between stainless steel 316 and 321.
| Propriété | Acier inoxydable 316 | Acier inoxydable 321 |
| Dilatation thermique | 16.5 | 16.5 |
| Modulus of Elasticity (GPa) | 740 | 720 |
| Density (g/cm3) | 7.98 | 7.92 |
| Point de fusion (°C) | 1398-1420 | 1398-1420 |
| Specific Heat (J/kg·K) | 500 | 500 |
| Conductivité thermique | 16.2 | 16.3 |
316 Stainless Steel and 321 Stainless Steel: Which One is Right for You?
The selection between 321 stainless steel and 316 stainless steel is based on assessing the nature of applications and the environment to which it will be subjected.
If you need to have weldability and heat resistance, then 321 stainless steel is a better choice. However, if you are using the component in marine environments, then 316 is a better option.
Applications of 316 vs 321 Stainless Steel
The applications of 316 and 321 stainless steel are as follows:
Acier inoxydable 316
- In marine environments, it can withstand corrosive environments.
- 316 stainless steel has high biocompatibility and is used for making medical device components.
- Chemical industries import it to deal with corrosive chemicals.
- The food and beverage industry opts for 316 stainless steel due to its cleaning ease and corrosion resistance.
- The pharmaceutical Industry uses 316 stainless steel in many production equipment.
321 Stainless Steel
- Grade 321 stainless steel is suitable for high-temperature environments like furnace parts and exhaust systems.
- In heat exchangers, they are suitable for subjecting to high temperatures.
- In aerospace and jet engines, stainless steel 321 offers stability.
- Refinery equipment uses it for parts that are in contact with liquids and gases at high temperatures.
- The food processing industry uses 321 stainless steel in equipment with high-temperature exposure.
Conclusion
Using stainless steel in applications is a common practice; however, choosing the right grade is crucial. 316 and 321 stainless steel are two such grades that have different sets of properties, making them suitable for individual applications.
Nous, à DEK can help you make high-quality components using these grades. We also help you decide which grade is suitable for your application.
FAQ
What is 321 stainless steel equivalent to?
321 stainless steel is equivalent to grade 304 stainless steel.
Will 321 stainless steel rust?
No, it has good rust resistance, but it must not be exposed to marine environments.
Is 321 stainless better than 304?
321 stainless steel offers enhanced strength at high temperatures when compared to 304.
