Effects of Solution Treatment Temperature on Microstructure and Properties of 00Cr25Ni7Mo4N duplex stainless steel for Water Conservancy Engineering

The effects of solution temperature on the microstructure, mechanical properties and corrosion resistance of 00Cr25Ni7Mo4N duplex stainless steel were studied by means of metallographic microscopy, scanning electron microscopy, tensile testing and electrochemical testing. The results show that the microstructure was dual phase structure of ferrite (α phase) and austenite (γ phase) for hot-rolled duplex stainless steel and duplex stainless steel after solution treatment at temperatures of 1 025-1 200℃. With the increase of solution treatment temperature, the content of α phase increased and the content of γ phase decreased, at solution treatment temperature of 1 175℃, the content ratio of α phase to γ phase was close to 1:1 in duplex stainless steel. After solution treatment at different temperatures, the tensile strength, yield strength and Rockwell hardness of the steel decreased in varying degrees, while elongation, percentage reduction of area and impact energy increased in varying degrees, compared with those of the hot-rolled duplex stainless steel. At solution treatment temperature of 1 175℃, the tensile strength and yield strength of the duplex stainless steel were high, while elongation, percentage reduction of area and impact energy all reached their maximum. When the solution treatment temperature was 1 175℃, the duplex stainless steel had the best corrosion resistance, exhibiting the most positive free corrosion potential, the smallest free corrosion current density, the largest capacitive arc radius and passive film resistance, and the dispersion coefficient closest to 1.