Austenitic and ferritic stainless steels have different benefits that make them well-suited to different projects. However, both types also have weaknesses that can cause difficulties in the production, maintenance, or cost of stainless steel products. Duplex stainless steel helps to solve these problems by combining austenitic and ferritic stainless steels to balance their strengths and weaknesses.
Stress Corrosion Cracking Resistance
One of the major downfalls of austenitic steel is its weakness to stress corrosion cracking. Stress corrosion cracking damage typically occurs at high temperatures when the steel is under high tensile stress. Duplex stainless steel is extremely resistant to stress corrosion cracking due to its high chromium content. This makes duplex steel useful in hot water tanks, swimming pools, or subsea connections manufacturing.
A drawback of using ferritic stainless steel is its poor weldability in thick sections. Small amounts of martensite can form in ferritic steel, making it less ductile. High temperatures can also cause rapid grain growth, leading to a loss in ductility and toughness. Duplex steel, while not as weldable as austenitic steel, can be welded with care in thick sections.
Both austenitic and ferritic steels have relatively low strength. Austenitic steel breaks at around 200 MPa 0.2% PS, while ferritic steel breaks at 250 MPa 0.2% PS. Duplex stainless steel is much stronger due to the combination of austenite and ferrite. Though different types of duplex steel have different tensile strengths, most varieties break at between 400 and 550 MPa 0.2% PS. Duplex steel’s strength makes it suited for use in custom pressure vessel connections and in structural applications such as bridges.
Do You Need a Forged Pressure Vessel Manufacturer?
Duplex stainless steel’s combination of corrosion resistance, high strength, and moderate weldability makes it a great choice for industrial flanges, forged vessel components, and custom pressure vessel connections. For more information on our ANSI industrial flanges, call us at (281) 441-4088 or contact us online.