Corrosion behavior of 9Cr heat-resistant steel deposited metal with different Si contents in lead-bismuth

In order to investigate the effect of Si content on the corrosion behavior of 9Cr ferritic-martensitic heat-resistant steel deposited metal in liquid lead-bismuth alloy, corrosion experiments were performed on 9Cr ferritic-martensitic steel deposited metal with different Si contents in saturated oxygen and controlled oxygen (oxygen concentration: 1 ×10⁻⁶ ~ 5 × 10⁻⁶ wt.%) static lead-bismuth at 550 ℃, respectively. The results show that the double-layered oxide scale forms on the surface of deposited metal in saturated oxygen lead-bismuth at 550 ℃, and the discontinuous passivation layer and the double-layered oxide scale with uneven thickness form on deposited metal in oxygen-controlled lead-bismuth at 550 ℃. The passivation layer will fail in some areas during the corrosion process through penetration mechanism and film breakdown mechanism, where oxidation aggravates to form the double-layered oxide scale. With the increase of Si content in the deposited metal, the thickness of the oxide layer in the saturated oxygen lead-bismuth decreases, the continuity of the passivation layer in the controlled oxygen lead-bismuth increases, and the corrosion resistance of the deposited metal in the lead-bismuth increases.