The Effect Of Solution Treatment And Mn Si Re On Duplex Stainless Steels Of Microstructure And Performance

Tidal power devices immersed in sea water in the long-term and long-termimpact of the tides, which have serious corrosive effect on metal materials in thedevice structure, duplex stainless steel is suitable for tidal power equipment withgood corrosion resistance to sea water, but also hashigher strength metallicmaterials. Duplex stainless steel is obtained through the appropriate solutiontreatment and adjustment of alloy composition, Which have austenite and ferritehalf of each organization in order to get the best performance. This paper studisethe influence of solution treatment and alloying elements Mn, Si, RE on themiscrostructure, mechanical properties and electrochemical corrosion of duplexstainless steels.Acoording to comparition test,the study showed that the duplex stainlesssteel after different solution treatment temperature (950℃,1000℃,1050℃,1100℃,1150℃) for2h, the austenite in duplex stainless steel is reduced withincreasing temperature, mechanical properties and the pitting resistance was firstincreases and then decreases trend with increasing temperature, austenite phaseand ferrite phase ratio at1050℃closest to1:1, duplex stainless steel had thebest Comprehensive performance.The duplex stainless steel after different solution treatment time (1h,2h,3h,4h) at1050℃, the austenitic with the holding time is reduced, austenite phaseand ferrite phase ratio at1h closest to1:1, duplex stainless steel to achieve thebest performance. To determine the best solution treatment is1050℃insulation2h water-cooled, follow-up duplex stainless steel alloy composition studies usingthis solution treatment.Development components of duplex stainless steel is25Cr-5Ni-2Mo-3Cu- xMn-ySi-zRE (x=0.4,0.6,0.8,1.0,1.2; y=0.6,0.8,1.0,1.2; z=0.05,0.10,0.15,0.20). The study found that addition of Mn, the austenite was first increasesand then decreases trend with Mn content increased, mechanical properties andresistance to electrochemical corrosion performance was first increases and thendecreases trend with Mn content increased, When the Mn content is0.94%, theaustenite is the same as50%, duplex stainless steel had the best Comprehensiveperformance. The study found that addition of Si, austenitic phase is reducedwith increasing Si content, Strength increases with increasing Si content, but theductility, toughness decrease and corrosion drop. When the Si content is0.55%,the austenite is the same as50%, duplex stainless steel had the bestcomprehensive performance. The study found that addition of RE, RE makesthe microstructure of duplex stainless steel variable uniform austenite phasedecreased slightly, RE content is0.10%, duplex stainless steel of yield strength,elongation, impact energy and resistance to electrochemical corrosion wereincreased. Optimized the best ratio is25Cr-5Ni-2Mo-3Cu-0.94Mn-0.55Si-0.10RE. Tensile strength695MPa, yield strength is595MPa, elongation19%, theshrinkage rate is47%, the impact energy of36J, the hardness of Rockwellhardness is23, the corrosion current density is8.054E-9A, the corrosionpotential is-175.1mV.