What is dual-phase steel?
The so-called dual-phase steel we often refer to is dual-phase stainless steel.Dual-phase stainless steelMetallographicThe structure includes approximately50%Ferritic and50%Austenitic. To achieve this structure, the stable elements of the ferritic phase (Cr、Mo、Si、WStabilizing elements of the austenite (e.g., etc.)Ni、N、MnFerritic (etc.) offsets./The percentage of austenite not only depends on the alloy elements but also on the heat treatment process.
Two,Advantages of Duplex Steel
（1）Molybdenum-containing duplex stainless steel exhibits excellent resistance to chloride stress corrosion under low stress.
（2）Molybdenum-containing duplex stainless steel boasts excellent pitting corrosion resistance.
（3）Excellent corrosion fatigue and wear resistance properties.
（4）Excellent comprehensive mechanical properties，High strength and fatigue strength。
（5）Good weldability。
Section 3: Classification of Dual-Phase Steel
The classification of duplex stainless steel is based on its corrosion resistance, which depends on the alloy elements. Our usual practice is to determine the resistance to pitting corrosion equivalent number.PRENTo differentiate between duplex stainless steels. The pitting resistance equivalent number describes the stainless steel's resistance to localized corrosion in a chloride-containing environment.。
PRENThe calculation
PREN = Cr% + 3.3Mo% + 16N%, whereinCr、Mo、NChromium, molybdenum, and nitrogen content, expressed as weight percentages.
Lean duplex stainless steelTypical representativeUNS S32304-EN1.4362), Corrosion Resistance Equivalent Number22 - 27Mo-free or with a small amount of molybdenum, suitable for environments not too severe.
Standard Duplex Stainless SteelTypical RepresentativeS32205(EN1.4462), corrosion resistance equivalent number28 - 38Chrome content22%Molybdenum content3%Corrosion resistance falls within the middle range.
Super duplex stainless steel(Typical Representative)S32750(EN1.4410)), Corrosion Resistance Equivalent Number38 - 43， Chromium content25%Molybdenum content3.5%Nitrogen content0.22-0.3%。
Super Duplex Stainless SteelCorrosion resistance equivalent number greater than45，Suited for extremely harsh environments, commonly used in the oil and gas industry.
