Application of 2205 (S31803 S32205 1.4462) Duplex Stainless Steel
Introduction
2205 (S31803 S32205 1.4462) is a ferrite-austenite duplex stainless steel developed as an alternative to Grade 316L and 317L austenitic stainless steels. It has good welding performance, corrosion resistance and high strength, and has been increasingly used in many fields. The properties of 2205 duplex stainless steel make it much better than the mono-grade stainless steel materials. It is widely used in the oil and gas, marine, pressure vessel and chemical industries due to its high corrosion resistance, increased stress corrosion and crack resistance, pitting resistance, crevice corrosion resistance and wear resistance.
Composition and Classification of 2205 Duplex Stainless Steel
2205 (S31803 S32205 1.4462) is a two-phase ferrite-austenite duplex stainless steel composed of 22–23% chromium, 3–3.5% molybdenum, 5–6% nickel and other alloying elements. Its microstructure is composed of austenitic and ferritic phases. This structure is 50% austenitic and 50% ferritic. The corrosion resistance of the duplex stainless steel is twice that of the general austenitic stainless steel.
Development and History of Duplex Stainless Steel
Duplex stainless steels have existed for many years, but it was not until the mid-20th century that technological advances in metallurgy made them suitable for mass production. The earliest development of duplex stainless steels began in 1905 with the invention of “Austenitic-Ferritic” steels, also known as “Ferritic Martensitic Stainless Steels”. The original 2205 alloy was developed in 1936, but due to its sensitivity to water pitting corrosion and its higher cost, its use was limited. However, two years later, a fully austenitic stainless steel was developed with a higher corrosion resistance, and this led to the development of other austenitic-ferritic alloy combinations, i.e. “duplex stainless steel”. In 1950, the first duplex stainless steels were commercially produced.
Mechanical Properties of 2205 Duplex Stainless Steel
2205 duplex stainless steel has been increasingly used in applications due to its excellent mechanical properties. It has a minimum tensile strength of 485MPa, a minimum yield strength of 275MPa, and a minimum elongation of 25%. The tensile strength is two times that of ordinary austenitic stainless steel, and its elongation percentage is much higher. Furthermore, due to its two phases, the yield strength is dramatically increased and the susceptibility to stress corrosion cracking is greatly reduced.
Corrosion Resistance of 2205 Duplex Stainless Steel
2205 duplex stainless steel has excellent corrosion resistance compared to other stainless steel grades. The resistance to chloride stress corrosion cracking of 2205 duplex is much greater than that of type 316 stainless steel. The duplex microstructure of 2205 duplex stainless steel provides superior resistance to pitting, crevice corrosion and general corrosion compared to austenitic stainless steel grades. In addition, 2205 duplex stainless steel has excellent resistance to erosion corrosion, erosion-corrosion cracking, and embrittlement due to high-velocity water erosion.
Weldability of 2205 Duplex Stainless Steel
2205 duplex stainless steel has good weldability, but the welding operation should use the appropriate welding parameters. Generally, 2205 duplex stainless steel can be welded with pre-heating, inter-run and post-weld heat treatment, but additional crack and corrosion points must be pay attention when welding.
Conclusion
2205 (S31803 S32205 1.4462) duplex stainless steel has superior mechanical properties, good weldability, excellent corrosion resistance and stress corrosion resistance, making it more suitable for some high-end applications. With the development of science and technology, duplex stainless steel will become the mainstream of low-alloy stainless steel and be widely used in various industries as an excellent material.
