Corrosion properties of laser melting-deposited corrosion-resistant ultrahigh strength steel AerMet100

The corrosion electrochemical behavior and pitting corrosion characteristics of laser melting-deposited corrosion-resistant ultrahigh strength steel AerMet100 was studied in 3.5% NaCl solution by potentiodynamic polarization curves and electrochemical impendence spectroscopy (EIS) and acid ferric choloride solution by weight loss method and scanning electron microscopy (SEM) separately. The results show that electrochemical corrosion resistance of as-deposited AerMet100 (AD) steel is improved by eliminating dendritic segregation and heterogeneous structure through heat-treatment, which is slightly superior than that of the forged one. Meanwhile, there are different corrosion properties in different directions. And the results also show that preferential pitting corrosion prefers to occur at the selective dendrite cores where depletion of Cr, Mo, Ni compared to dendrite boundaries and "district corrosion battery" set up by heterogeneous structure between inter-layer heat-affected zone and adjacent zone make AD AerMet100 steel poor pitting corrosion resistance, after heat-treatment, the pitting resistance is improved, and the pitting mass loss rate decreases to be similar to that of the forged steel.