Ferritic stainless steel
Ferritic steel is known as direct chromium stainless steel, as its chromium content ranges between 10.5% and 30%. In this case, the carbon content decreases.
Ferritic steels have a ferritic structure at any temperature, as they do not display any transformation of ferrite into austenite during heating, or a martensitic transformation while cooling. For this reason, phase changes are not possible and ferritic steels cannot be changed by heat treatment.
Basic features of ferritic steels
Their level of weldability and corrosion resistance is higher than those of martensitic steels, but lower than those of austenitic steels. Chromium makes it a resistant material, but the absence of nickel decreases resistance and weakens the material in some mediums, such as H2S, NH4Cl, NH4NO3, etc. In the case of steels with a higher chromium ratio (25-30%), the resistance level in heated sulphurous environments is higher.
The size of the grain of ferritic stainless steels tends to increase in high temperatures. In long periods at 450-500ºC they become more brittle.
Compared to austenitic steels, ferritic grades also display high resistance to corrosion under SCC stress (induced by means of nickel amounts of up to 1.5%), particularly in chlorides at high temperatures. They are also resistant to pitting.
By comparison to austenitic grades, ferritic steels are less ductile and resilient. Malleability is also lower, but high enough to enable easy cold working. Ferritic steels achieve greater ductility and resistance in annealing.
Most frequent uses:
- Oil or natural gas processing plants
- Car exhausts
- Ornaments and nitric acid tanks
- Hot water tanks
- Furnace, nozzle, and combustion chamber parts
Sectors and Parts in which ferritic steel is relevant:
At Castinox, ferritic steel is a basic material for manufacturing parts in the chemistry industry, water processing industry and the paper industry. At Castinox, we manufacture ferritic steel components for:
Ferritic steel valves
- Rotary valves
- Ball valves
- Male valves
- Butterfly valves
- Guillotine valves
Fluid pump pieces
- Pump bodies
Ferritic stainless steels