Duplex stainless steel

Double-phase steel requires heat treatment after welding! The values specified in ASTM standards correspond to the condition of the steel at the time of manufacture; strength and other properties vary significantly depending on the heat treatment applied.

S32760 is a highly alloyed super duplex stainless steel obtained by adding W and Cu to the base of super duplex steel S32750. Its microstructure in the as-used state consists of ferrite and austenite, with an optimal ratio of 1:1 between the two. Such a composition ratio enables the S32760 super duplex stainless steel to possess the dual characteristics of austenitic and ferritic stainless steels. It has a lower thermal expansion coefficient and a higher thermal conductivity than austenitic stainless steels. Its pitting resistance exponent (PREN) is greater than 40, granting it excellent resistance to stress corrosion cracking in environments containing chloride ions and acidic media. It also shows good resistance to chloride-induced pitting and crevice corrosion, as well as good resistance to erosion corrosion and corrosion fatigue. It boasts excellent mechanical properties and good weldability. It is primarily used in corrosive environments in industries such as oil, gas, chemicals, and shipbuilding, making it an ideal material for various corrosion-resistant industrial applications. Super duplex stainless steel presents welding issues in practical applications, and the microstructure of the welded joints as well as the phase proportions affect their mechanical and corrosion properties.

Speaking of things related to welding: before welding duplex steel, it is necessary to carry out preheating where required, as well as post-heating. The welding material also needs to be properly dried, and careful storage during use is essential. Any negligence at any stage can affect the final quality of the weld.