Curious why ferritic stainless steel is the most used type of stainless steel in many industries, like in the automotive industry?
Few reasons are its high ductility, durability, and strong resistance to oxidation.
Whether you want to gain more understanding about ferritic stainless steel applications, properties, and composition, this guide is for you.
Let’s now proceed!
The Definition of Ferritic Stainless Steel
Ferritic stainless steel is known to have high chromium percentage. It also has low carbon content and a non-hardenable, ferrite structure.
Additionally, ferritic-type is known for their good weldability and mechanical properties. That makes it an attractive option for various applications, especially in fabricating steel components.
Composition
Considering the stainless steel composition is very essential before you purchase them.
Take a look at the ferritic stainless steel composition listed below.
| Iron (Fe) | 65-72% |
| Chromium (Cr) | 16 – 24% |
| Carbon (C) | < 0.08% |
| Nickel (Ni) | < 2.0% |
| Manganese (Mn) | < 1.0% |
| Silicon (Si) | < 1.0% |
| Phosphorus (P) | < 0.04% |
| Sulfur (S) | < 0.03% |
| Nitrogen (N) | < 0.1% |
| Molybdenum (Mo) | < 2.0% |
| Titanium (Ti) | < 0.1% |
| Copper (Cu) | < 0.5% |
| Selenium (Se) | < 0.5% |
| Aluminum (Al) | < 0.5% |
| Vanadium (V) | < 0.2% |
Advantages of Using Ferritic SS
If you choose ferritic stainless steel, it will surely benefit your fabrication projects and applications.
Let’s learn its advantages in detail:
- High Strength: Ferritic material is known for its high strength. It makes the material suitable for applications that require superior strength and durability.
- Oxidation Resistance: Another advantage is its highly resistant to oxidation. Therefore it is perfect for applications that require strong protection against environmental conditions.
- Cost-Effective: When compared to other stainless steel grades, ferritic is a cost-effective solution due to its lower price point.
- Low Maintenance: Ferritic stainless steel is also low-maintenance and requires minimal cleaning and maintenance. So if the upkeep is an important factor for your applications, ferritic is very ideal.
- Temperature Tolerance: Widely known for its excellent temperature tolerance. For applications that require extreme temperatures, you can find it very useful.
- Easy to Machine: Due to easy-to-machine properties, meaning it can be produced quickly. As result, it became a great choice for applications that demands a quick turnaround.
DISADVANTAGES
Regardless of its many advantages, ferritic steel has some disadvantages.
One of the main disadvantages is that it cannot be hardened by heat treatment. This means that any parts or components made from this steel will remain relatively soft. It will not be able to withstand high levels of wear and tear or heavy loads.
Another disadvantage is that it has a lower resistance to high temperatures compared to austenitic. This means that it is not suitable for applications where it will be exposed to high temperatures for extended periods.
Finally, ferritic is susceptible to stress corrosion cracking. This is a type of corrosion that occurs when a material is exposed to a combination of tensile stress and a corrosive environment. This can cause components made from ferritic stainless steel to fail prematurely.
Where to Use Ferritic SS
Knowing its intended uses will help you determine how the material can benefit your specific application.
We will now discuss each ferritic stainless steel uses in detail.
Automotive Exhaust System
Ferritic SS is an important material used in automotive exhaust systems.
It offers better fatigue strength and wearing resistance, which helps to extend the life of the exhaust system. Also, its ductile properties make it easier to form complex shapes. It allows it to be used in various exhaust system components.
Industrial Piping
Ferritic stainless steels are used in industrial piping applications due to superior temperature resistance and strength.
They are less expensive and are easier to weld. Works well for fabricating cryogenic storage tanks and piping.
Marine Applications
The ferritic type of stainless steel is highly resistant to rust, making it ideal for marine applications.
You can use the material for boat hulls, propellers, and other components that are exposed to the harsh saltwater environment.
Heat Exchangers
The ferritic material is used in heat exchangers due to its higher temperature strength.
In heat exchangers, it is used in tubes and other components. As well as in the shell or housing. The tubes are usually welded together and the shell is usually welded or bolted. The tubes are designed to maximize heat transfer. While the shell provides structural support and helps protect the tubes from mechanical damage.
You can also use the stainless steel type for heat exchanger components including gaskets, flanges, and valves.
Food Processing Equipment
The ferritic type of stainless steel is an ideal material for food processing equipment. This is due to its non-toxic nature.
It is often used for tanks, pipes, and other components.
Grades Lists of Ferritic SS
The stainless steel grades that are considered ferritic includes:
- 409-Grade Stainless Steel
- 430-Grade Stainless Steel
- 439-Grade Stainless Steel
- 441-Grade Stainless Steel
- 444-Grade Stainless Steel
Let us dig for more information about each grade and know their mechanical properties.
409 Stainless Steel
Since it contains a very low carbon amount, this makes the 409 stainless steel ferritic-grade. Then this results in a very low amount of chromium carbide formation.
| Mechanical Properties | Amount |
| Tensile Strength min. (MPa) | 520 |
| Yield Strength min. (MPa) | 205 |
| Elongation min. (%) | 40 |
430 Stainless Steel
Grade 430 SS is one of the most popular ferritic grades because it offers good formability and heat resistance. It also offers excellent properties such as the following:
| Mechanical Properties | Amount |
| Density | 8.0 g/cm3 |
| Melting Point | 1427°C (2600°F) |
| Yield Strength (0.2% Offset) | 205 Mpa (29700 psi) |
| Tensile Strength | 621 Mpa (90000 psi) |
| Elongation | 40% |
| Hardness | 180 HB |
| Impact Strength | 25 J |
| Modulus of Elasticity | 193 GPa (28000 ksi) |
| Thermal Conductivity | 16.2 W/m-K |
| Electrical Resistivity | 7.2 μΩm |
439 Stainless Steel
439 SS is a ferritic type of stainless steel because it contains a high chromium amount (11-18%) and very low nickel levels (0.75%). This combination of elements creates a hard martensitic structure that is highly corrosive resistant. It is also made with mechanical properties including:
| Mechanical Properties | Amount |
| Tensile Strength | ≥415 MPa |
| Yield Strength | ≥280 MPa |
| Elongation | >17% |
| Hardness | ≤HB 199 |
441 Stainless Steel
441 SS is a ferritic type because it contains a high chromium percentage (11.5-18%) and very little to no nickel. This combination of elements gives this material its high resistance to oxidation at elevated temperatures.
Grade 441 stainless steel is made up of excellent mechanical properties, such as:
| Mechanical Properties | Amount |
| Tensile Strength | 75-85 ksi |
| Yield Strength | 30 ksi |
| Elongation | 20-25% |
| Hardness | Rb 95 max |
| Impact Strength | 15-30 J |
444 Stainless Steel
The 444 SS is a ferritic type because it contains a higher percentage of chromium, around 18%. Additionally, grade 444 has a low carbon content which makes it more ductile. Plus! easier to form into shapes.
| Mechanical Properties | Amount |
| Tensile Strength | 790 MPa (115 ksi) |
| Yield Strength | 690 MPa (100 ksi) |
| Elongation | 25% |
| Modulus of Elasticity | 190 GPa (27×106 psi) |
| Shear Modulus | 81 GPa (11750 ksi) |
| Poisson’s Ratio | 0.27-0.30 |
| Hardness | Brinell 150-205, Rockwell B90-C30 |
Ferritic vs. Austenitic SS: Which is Better?
Ferritic SS and austenitic SS are two major stainless steel types.
Ferritic is composed of a ferrite matrix and has a body-centered-cubic (BCC) crystal structure. It is magnetic, has excellent ductility and formability properties.
However, austenitic stainless steel is made up of austenite. And it has a face-centered-cubic (FCC) crystal structure. Made with non-magnetic properties and has higher strength.
So how do they actually differ from each other?
Their main difference is their crystal structure and magnetic properties.
Another difference between them is each application.
Ferritic is typically used in applications that require strength and ductility. This include automotive parts, kitchen utensils, and pipelines.
However, the austenitic type is typically used in applications that need excellent corrosion safety and strength. Examples are chemical processing equipment, kitchen appliances, and surgical instruments.
In summary, even though they have differences, both types have their own unique applications and benefits.
Comparing Martensitic Over Ferritic Steel
When it comes to understanding the differences between ferritic and martensitic steel, it is important to know each strength and weakness.
To gain more understanding of their differences, please take a look at the tab below.
| STRENGTH | WEAKNESSES | |
| Ferritic SS |
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| Martensitic SS |
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Is Ferritic Stainless Steel Magnetic?
When it comes to that question, the answer is yes.
Ferritic does contain a certain amount of iron, which makes it magnetic. In fact, this material is one of the most magnetic types. This is due to its high iron content, which makes it more susceptible to magnetism.
The degree of magnetism will be based on the amount of ferrite present. Ferrite is a form of iron oxide. So the more ferrite present, the stronger the magnetic properties of the stainless steel will be.
Although ferritic steel is magnetic, it is not always considered suitable for applications that require strong magnetic fields, such as MRI scanners. In these situations, austenitic is used instead, as it is non-magnetic.
Can Ferritic-Type Stainless Steel be Welded?
Yes, it can be welded.
However, it can be more challenging than welding other types of stainless steel. This is because ferritic has higher carbon content and a lower melting point, making it more difficult to weld. In addition, this steel is also more prone to cracking during the welding process due to its low ductility.
To reduce the risk of cracking, it is important to use the correct welding technique. It is also important to use a filler material with low carbon content. You should preheat the workpiece as well to reduce the cracking risks.
Overall, while it is possible to weld ferritic steel, it is important to take the proper precautions to ensure a successful weld. Following the correct welding techniques, using the right filler material, and preheating the workpiece are all important steps. This will ensure a successful weld when working with this specific steel.
Does Ferritic SS Rust?
Ferritic type of stainless steel is known for its superior anti-corrosion properties, but is it rust proof?
The answer is both yes and no. Ferritic is not completely impervious to rusting. While it is more resistant than other types of stainless steel, ferritic steel can still rust under certain conditions.
The most common cause of rust is when the steel is exposed to high temperatures and moisture. As the metal heats up and is exposed to water or other moisture, corrosion can occur. This is especially true for ferritic stainless steel which is not properly sealed and does not contain any anti-corrosion coatings.
In addition to high temperatures and moisture, ferritic types can also be susceptible to rust if exposed to certain acids or other corrosive chemicals. In order to protect the steel from rusting, keep it clean, and free from any corrosive materials.
When properly cared for, ferritic will surely provide a long-lasting solution for many applications.
Regular Maintenance
To avoid rust on the steel, regular maintenance should be strictly done.
Here are step-by-step ideas to maintain the material. Do it regularly.
- First, clean the material regularly. You can use a mild detergent, warm water, and a soft cloth to remove any debris from the surface.
- Inspect the steel for signs of rust or corrosion. If you see any, address it immediately.
- Apply a lubricant, such as oil or wax, to the ferritic steel. This will help prevent rust from forming.
- Use a rust-inhibiting primer on the steel, if needed.
- If the steel is exposed to water, make sure to dry it off with a clean cloth after use.
- Store the ferritic stainless steel in a dry place, away from moisture and extreme temperatures.
- Regularly inspect the steel for any cracks, dents, or other damage. If any is found, repair it immediately.
Why Ferritic SS is Not Heat Treatable?
Ferritic SS are not heat treatable because of their high chromium content. The chromium content makes them resistant to hardening and tempering processes. Therefore, ferritic is usually used in its annealed form. It requires cold working processes to increase their strength and hardness.
Another reason is it contains less nickel and carbon, which makes them less amenable to heat treatment. The lower alloying elements make ferritic stainless steels quite soft and ductile in the annealed condition. But they can be strengthened and hardened through cold working or strain hardening.
As a result, ferritic steels are only used in applications where heat treatment is not necessary. Examples include kitchen sinks, automotive trim, and architectural facades.
Standard Price
Knowing the standard price of ferritic stainless steel is important. It will allow you to make informed decisions when purchasing the material.
Considering it also helps you to create a budget for the project. Also, it determines whether a certain material is a right fit for the job.
Knowing the estimated prices will allow you to compare prices with other materials. Therefore, you can find the most cost-effective option.
| Ferritic SS By Grades | Estimated Price per Foot |
| 409 Stainless Steel | $3 – $25 |
| 430 Stainless Steel | $2 – $50 |
| 439 Stainless Steel | $2 – $7 |
| 441 Stainless Steel | $3 – $19 |
| 444 Stainless Steel | $2 – $20 |
Conclusion
You finally understand how important ferritic stainless steel is. It plays a significant role in industries such as food processing, automotive, chemical, and more.
The knowledge you have gained now can help you make decisions about when and where to use ferritic stainless steel. At the same time, you are now familiar with how to maintain the material so can last longer.
If you still have concerns in mind, reach out immediately!