V含量对超级双相不锈钢的组织及耐点蚀性能的影响

In this paper, the effect of V on the pitting corrosion resistance of super duplex stainless steels was investigated. Thermo-Calc software was used for calculations of equilibrium precipitation phases in super duplex stainless steels with different V contents, and the effects of V content on the microstructure, duplex ratio, alloying element distribution and pitting resistance of super duplex stainless steels were analyzed by optical microscopy, scanning electron microscopy and immersion corrosion experiments. The results showed that: with the increase of V mass fraction from 0.20% to 0.49%, the volume fraction of ferrite phase increased from 46.12% to 51.96%; the decrease of Cr, Mo and N content in the duplex microstructure led to the decrease of duplex pitting resistance equivalent value (PREN), in which the austenitic PREN decreased from 37.71 to 33.74; all three experimental steels experienced significant pitting corrosion. The increase in V content promotes the formation of pitting pits and accelerates the corrosion of the experimental steel matrix, which eventually leads to a decrease in pitting resistance.