As we know, stainless steel can be divided into martensitic stainless steel, ferritic stainless steel, austenitic stainless steel, ferritic-austenitic duplex stainless steel, and precipitation-hardening stainless steel.
Now let’s talk about Ferritic stainless steel.
Basic information
Basic Type: 430 (1 .4016).
Cannot be hardened by heat treatment.
Magnetic: Yes.
Moderate to good corrosion resistance.
Weldability is reasonable in thinner sections but poor in thicker sections (over 2.5mm).
Good deep-drawing properties.
Generally a flat product specification.
Not used at low temperatures.
Features (composition)
Ferritic stainless steel generally does not contain nickel.
The main alloying element is chromium, and the chromium content is generally 12% to 30%. Ferritic stainless steels are roughly divided into three categories: Cr 11%~15%, Cr 16%~20%, and Cr 21%~30% according to the chromium content in the steel.
This steel contains fairly low levels of carbon, mostly below 0.12%.
It often contains ferrite-forming elements such as aluminum, which can ensure that the structure of the steel is mainly ferrite.
Physical properties
AISI / ASTM
Density (g/cm3)
Electrical resistance (μΩ·m)
Thermal conductivity at 20 °C (W/(m·K))
Specific heat 0 – 100 °C (J/(kg·K))
Thermal expansion 0 – 600 °C (10−6/K)
Young’s modulus (GPa)
409 / 410
7.7
0.58
25
460
12
220
430
7.7
0.6
25
460
11.5
220
430Ti / 439 / 441
7.7
0.6
25
460
11.5
220
434 / 436 / 444
7.7
0.6
23
460
11.5
220
447
7.7
0.62
17
460
11
220
Advantage
High strength,
Chloride Stress Corrosion Resistant,
Resistant to localized corrosion such as pitting and crevice corrosion.
Disadvantage
Poor toughness at room temperature and low temperature，
High-notch sensitivity，
Sensitive to intergranular corrosion.
About the notch sensitivity
Ordinary ferritic stainless steels with more than 15% chromium (after normal heat treatment) are very sensitive to notches. The brittle transition temperature is generally higher than room temperature, but there will be room temperature brittleness if there is a gap.
If the chromium content increases, the sharpness of the notch increases, and the brittle transition temperature also increase. At 870°C, the incision sensitivity completely disappeared.
About the sensitivity to intergranular corrosion
Common high-chromium ferritic stainless steels not only cause embrittlement, but also susceptibility to intergranular corrosion. Especially when the temperature exceeds 900 ~ 950 ° C and then rapidly cooled, it has a very sensitive intergranular corrosion tendency.
Intergranular corrosion susceptibility can be eliminated by heating to about 700~850°C, then holding for a certain period of time and rapid cooling.
Welding or high-temperature quenching generally does not experience embrittlement because of the short time through its corresponding embrittlement temperature zone.
Steel structure bridge – 4003/410 color-coated stainless steel, SASSDA, South Africa (the service life of the bridge is more than 8 years)
Inner wall of tunnel – 1.4016/430 Prepainted Stainless Steel, Monte Mario Tunnel, Centro Inox, Italy
Inner wall of tunnel – 1.4016/430 painted stainless steel, Monte Mario tunnel, Centro Inox, Italy
Wind protection fence – SUS445J2 stainless steel, JSSA, Japan
Platform screen door – 4510/439 stainless steel, microwired, KOSA, Korea
Electric pole – 1.4003 stainless steel (originally applied in 1982, along coastline – 10m from waves, no rust), South Africa
Power station – 1.4003/ 410 Stainless Steel, Cooling Tower, X-Grid Fill, South Africa
Curtain wall
Building facade curtain wall – SUS445M2 stainless steel, low reflectivity matte finish, ASSDA, Australia
Building facade curtain wall – 1.4521/444 Stainless Steel No. 4 Frosted Panel (horizontal panel), Vivo Building, Rio De Janeiro, Nucleo Inox, Brazil (coastal environment)
Building facade curtain wall – SUS445J2 stainless steel, Future Science Museum, JSSA, Japan
Building facade curtain wall – 4526/436 Stainless Steel, Ugine & Alz Steel Service Center, Assel-Mittal Stainless, Katowice, Poland
Elevator
Escalator steps – SUS430LX – (1.4016/430) Stainless Steel, Japan
Media center roof – SUS445J2 stainless steel, Kitakyushu Media Center. Fukuoka Prefecture) 1998, Japan
School roof – 430Ti stainless steel (vertical seam technology), Ugine & Alz, Austria
City Facilities
Street Light – 1.4510/439 Stainless Steel, Electropolished Welded Pipe, KOSA, Korea, Seoul
Post Office Box – 1.4003/410 Stainless Steel, Color Coated, SASSDA, South Africa, Ferritic stainless steel is often color coated when aesthetics are the main consideration.
Railway platform ticket machine – 1.4003/410 stainless steel, painted (15 years of service), SASSDA, UK
Electrical enclosure – 1.4003/410 stainless steel, color coated (15 years of service), SASSDA, South Africa
In order: bread oven, gas kitchen utensils, large coffee machine, heating vending machine
In order: Continuous Toaster, Microwave Oven, Side-by-Side Gas Oven, Cold Storage
In order: Coffee Machines, Restaurant Carts, Display Counters, Wall Cabinets
Home & Office
Ferritic stainless steels (400 series) have been widely accepted in the following application areas.
This is because of its unique aesthetics, corrosion resistance to cleaning and disinfecting agents, low thermal expansion coefficient and magnetic properties (suitable for induction cooktops), and considerable cost advantages compared to other materials.
In Order: gas stove, combi, microwave oven, gas stove
Container – 1.4003/410 Stainless Steel (frame and panels), POSCO, Korea
Container – 1.4003/410 stainless steel, Prepainted (frame and door panels)
Coal truck – 1.4003/410 stainless steel (panel), Columbus, South Africa. Served for more than 20 years.
Coal Truck – 1.4003/410 Stainless Steel (Panel), Columbus, South Africa. Served for more than 15 years.
Coal Truck – 1.4003 Stainless Steel (Interior & Front), SASSDA, South Africa
Coal Truck – 1.4003/410 Stainless Steel, Color Coated, Europe
Coal truck – 409/410, painted, TISCO, China
Coal Truck – 1.4003 Stainless Steel, SASSDA, South Africa
Streetcar – 1.4003/410 stainless steel (body frame and colored panels), Europe
Frequently asked questions
Are ferritic stainless steels magnetic
Yes. It’s Always Magnetic.
Does ferritic stainless steel rust
No. In addition to rust resistance and local corrosion resistance, ferritic stainless steel has excellent local corrosion resistance such as chloride stress corrosion resistance, pitting corrosion resistance, and crevice corrosion resistance.
What is Ferritic stainless steel best known for?
It’s AISI405.
AISI405 stainless steel’s uses: For the manufacture of corrosion parts, equipment, and liners resistant to water vapor, ammonium bicarbonate mother liquor, and hot sulfurous petroleum.Production of parts that require high toughness and impact load, such as turbine blades, structural parts, bolts, nuts, etc.
What is the difference between austenitic and ferritic stainless steel?
Ferritic stainless steel is magnetic, austenitic stainless steel is non-magnetic.
Ferritic stainless steel has higher hardness and resistance to localized corrosion and chloride stress corrosion than austenitic stainless steel.
Unlike austenitic stainless steel, ferritic stainless steel is sensitive to intergranular corrosion and has high-notch sensitivity. This is the reason for the limited use of ferritic stainless steel.
