Difference between Stainless Steel Ferrite and Austenite Steel
Understanding Stainless Steel Microstructures in Industrial Applications
One of the most commonly used materials in construction, infrastructure, manufacturing, and architectural works is stainless steel. For industry players such as construction heads, architects, and contractors, it is only important to know the Difference between ferritic and austenitic stainless steel when choosing the material, in terms of durability, corrosion resistance, and structural performance.
Stainless steel is not a material, but a family of alloys, which can be classified according to the microstructure. Some of the most common types of stainless steel (austenitic vs ferritic) find a wide application in industry and construction. The properties of these two types are very different in terms of chemical, magnetic properties, corrosion resistance, strength, and cost.
When deciding on the type of material to use, the difference between stainless steel ferrite vs austenite always comes into play, as they have their own advantages. Although ferritic stainless steel is appreciated due to its magnetic characteristics as well as its cost-effectiveness, austenitic stainless steel is reputed to have great resistance to corrosion as well as formability. Knowledge of these differences assists decision-makers in selecting the most suitable grade of steel to be used in particular environmental and structural conditions.
Types of Stainless Steel (Austenitic vs Ferritic)
To clearly see the difference between ferritic and austenitic stainless steel, it is vital to take a look at their structural properties and composition.
Austenitic Stainless Steel
The most widely used type of stainless steel all over the world is austenitic stainless steel.
Key characteristics include:
- Minor content of high chromium and nickel.
- Very high corrosion resistance.
- Most conditions are Non-magnetic structure.
- Excellent ductility and formability.
- Excellent performance in extreme temperatures.
Typical austenitic and ferritic grades of stainless steels, respectively, are:
- 304 stainless steel
- 316 stainless steel
- 321 stainless steel
These grades are popular in architectural buildings, chemical factories, pipelines and facades of buildings.
Ferritic Stainless Steel
Ferritic stainless steel is a compound that is composed of chromium and small amounts of nickel. Its design provides it with alternative mechanical and magnetic characteristics.
Main characteristics include:
- Magnetic stainless steel building.
- Average corrosion resistance.
- Low cost relative to austenitic grades.
- Increased stress corrosion cracking resistance.
- Low formability in comparison to austenitic steel.
Ferritic grades used are common and include:
- 409 stainless steel
- 430 stainless steel
- 434 stainless steel
They are usually applied in automotive parts, industrial equipment, and architectural trims.
Key Differences Between Ferritic vs Austenitic Stainless Steel
A simplified comparison is given below to gain a better understanding of the difference between the ferritic and the austenitic stainless steel:
Composition
- Austenitic: Chromium + Nickel
- Ferritic: It contains a majority of Chromium with a small amount or no Nickel.
Magnetic Properties
- Austenitic: Non-magnetic
- Ferritic: Magnetic
Corrosion Resistance
- Austenitic: Excellent
- Ferritic: Moderate
Cost
- Austenitic: Higher cost
- Ferritic: More economical
Applications
- Austenitic: Construction, pipelines, chemical plants.
- Ferritic: motor vehicle, electrical equipment, machinery.
Chemical composition table of Austenitic stainless steel
| GRADE | COMPOSITION | MICROSTRUCTURE | |||||||
|---|---|---|---|---|---|---|---|---|---|
| SI | C | MN | OTHERS | NI | CR | MO | AUSTENITE FERRITE |
||
| 304L | 0.75 | 0.035 | 2.0 | – | 8/11 | 18/20 | – | A + 2/8%F | |
| 304 | 0.75 | 0.08 | 2.0 | – | 8/11 | 18/20 | – | A+2/8%F | |
| 304N | 0.75 | 0.08 | 2.0 | 0.1/0.16N | 8/11 | 18/20 | – | A + 2/8%F | |
| 304H | 0.75 | 0.04 – 0.10 | 2.0 | – | 8/11 | 18/20 | – | A + 2/8%F | |
| 347 | 0.75 | 0.08 | 2.0 | Nb : 10xC | 9/13 | 17/20 | – | A + 4/12%F | |
| 316 | 0.75 | 0.08 | 2.0 | – | 11/14 | 16/18 | 2/3 | A + 3/10%F | |
| 308L (generally filler metal only) | 1.0 | 0.03 | 2.0 | 10/12 | 19/21 | A + 4/12%F | |||
| 310 | 0.75 | 0.15 | 2.0 | – | 19/22 | 24/26 | – | 100% A | |
| 321 | 0.75 | 0.08 | 2.0 | Ti: 5xC | 9/12 | 17/19 | – | A + 4/12%F | |
| 309 | 1.0 | 0.08 | 2.0 | – | 12/15 | 22/24 | – | A + 8/15%F | |
Physical properties of Ferrite stainless steel
Property |
Ferritic |
Density Value (kg/m3) |
7700 |
Thermal conductivity (20°C, W/m.°C) |
25 |
Thermal expansion (0-100°C μm/m/°C) |
10.5 |
Electrical resisivity (nΩ.m) |
600 |
Specific heat range (0-100°C, J/kg.°C) |
430-460 |
Conclusion
To sum up, it is important to know the distinction between ferritic and austenitic stainless steel among leaders in the industry that deals with the construction, engineering and infrastructure development. The two materials are in the larger category of stainless steel (austenitic vs ferritic), although they vary in composition, magnetic properties, corrosion strength, and price.
Austenitic stainless steels are the best in corrosion resistance, high flexibility and are non-magnetic, hence suitable in harsh environments. Instead, ferritic stainless steels provide a cost-effective alternative material, have high wear life, and are magnetic. Knowing how to compare ferritic and austenitic stainless steel, building architects, contractors, and construction professionals are able to make well-informed choices about the materials used in their projects that enhance life and performance.
FAQs
Q1. What is the main difference between ferritic and austenitic stainless steel?
The main variation between ferritic and austenitic stainless steel is their content and crystal structure. Nickel is found in austenitic stainless steel and is generally non-magnetic and has greater corrosion resistance, whereas ferritic stainless steel contains predominantly chromium, is magnetic and is often more cost-effective.
Q2. Which is better: ferritic vs austenitic stainless steel for construction?
The decision to use ferritic or austenitic stainless steel is relative to the surroundings. The austenitic grades are used in corrosive or coastal environments, whereas the ferritic grades are used in the economical projects and moderate exposure conditions.
Q3. Why is austenitic stainless steel non-magnetic compared to ferritic stainless steel?
The magnetic or non-magnetic stainless steel characteristics can be attributed to their crystal structures. The structure of austenitic steel is face-centred cubic, which does not allow magnetism, whereas the structure of ferritic steel is body-centered cubic, which permits magnetism.
Looking for expert guidance on the difference between ferritic and austenitic stainless steel for your construction or industrial project? Connect with our material specialists today to choose the right stainless steel grade for your application. Contact us now or email us at export@hansmetalindia.com to discuss your requirements.