Effects of solution treatment on mechanical properties and corrosion resistance of 4A duplex stainless steel

Abstract

Abstract In this study, 4A duplex stainless steels were prepared via remelting in an intermediate frequency furnace and subsequently solution treated at different temperatures. The effects of solution treatment on the mechanical properties and corrosion resistance of 4A duplex stainless steel were investigated. Microstructures were characterized via optical microscopy and scanning electron microscopy. The mechanical properties were evaluated via hardness test, tensile test, and impact test experiments. The point corrosion resistance was studied via chemical immersion and potentiodynamic anodic polarization. The results showed that with increasing solution temperature in the range of 1 223 – 1 423 K, the tensile strength and hardness first decreased and then increased, and minimum values were obtained at 1 323 K. The σ phase precipitated at the boundaries of the α/γ phases in samples solution treated at 1 223 K, decreasing both impact energy and pitting potential of the experimental steels. When experimental steels were solution treated at 1 373 K for 2 h, a suitable volume fraction of α/γ was uniformly distributed throughout the microstructure, and the steels exhibited optimal mechanical properties and pitting corrosion resistance.