What is Duplex Stainless Steel Casting?
Duplex Stainless Steel Casting is the investment casting process using duplex stainless steel as the material. Duplex stainless steel is called “duplex” because they have a two-phase microstructure consisting of grains of ferritic and austenitic stainless steel. The picture shows the yellow austenitic phase as “islands” surrounded by the blue ferritic phase. When duplex stainless steel is melted it solidifies from the liquid phase to a completely ferritic structure. As the material cools to room temperature, about half of the ferritic grains transform to austenitic grains (“islands”). The result is a microstructure of roughly 50% austenite and 50% ferrite.
Duplex Stainless Steel Casting Grade-2205
Duplex 2205 Stainless Steel is a nitrogen-enhanced duplex used in stainless steel casting process for applications requiring high strength and excellent corrosion resistance. It is designed to combine improved resistance to stress corrosion cracking, pitting and crevice corrosion. Duplex 2205 provides nearly double the corrosion resistance typical in other austenitic stainless steels.
Chemical Composition of Duplex Stainless Steel 2205
|0.03 Max||2 Max||1 Max||0.03 Max||0.02Max||22.0-23.0||3.0-3.5||4.5-6.5||0.14-0.20|
Features of Duplex Stainless Steel Casting
Strength: Duplex stainless steel castings are about twice as strong as regular austenitic or ferritic stainless steel castings.
Toughness and ductility: Duplex stainless steel castings have significantly better toughness and ductility than ferritic stainless steel castings; however, they do not reach the excellent values of austenitic stainless steel castings.
Corrosion resistance: As with all stainless steels, corrosion resistance depends mostly on the composition of the stainless steel castings. For chloride pitting and crevice corrosion resistance, their chromium, molybdenum and nitrogen content are most important. Duplex stainless steel casting grades have a range of corrosion resistance, similar to the range for austenitic stainless steel castings, i.e from Type 304 or 316 to 6% molybdenum stainless steel castings.
Stress corrosion cracking resistance: Duplex stainless steels show very good stress corrosion cracking resistance, a property they have “inherited” from the ferritic side. Stress corrosion cracking can be a problem under certain circumstances (chlorides, humidity, elevated temperature) for standard austenitic castings such as Types 304 and 316 stainless steel castings.
Cost: Duplex stainless steel castings have lower nickel and molybdenum contents than their austenitic counterparts of similar corrosion resistance. Due to the lower alloying content, duplex stainless steels can be lower in cost, especially in times of high alloy surcharges. Additionally, it may often be possible to reduce the section thickness of duplex stainless steel, due to its increased yield strength compared to austenitic stainless steel. The combination can lead to significant cost and weight savings compared to a solution in austenitic stainless steels.
CFS Foundry for Duplex Stainless Steel Castings
CFS Foundry specializes in investment casting of duplex stainless steel. Our manufacturing capability of duplex stainless steel casting weight ranges from 1g to 50kgs. The minimum wall thickness is 2mm. We can supply 2205 duplex stainless steel castings for below applications:
- Chemical process vessels, heat exchangers and piping
- Oil field piping and heat exchangers
- Bleach washers, chip pre-steaming vessels and pulp mill digesters
- Flue gas desulfurization equipment
- Food processing equipment
We maintain positive communication with our customers to assure that we fully understand our customers’ requirements and manufacture products with the desired characteristics in the most cost effective manner. If you need a duplex stainless steel casting company for your project, pls get in touch with us right now!