The effect of additional silicon on the corrosion and erosion-corrosion of low chromium steels

The addition of 1wt.%Si to commercial steel containing 2.5wt.%Cr significantly lowered its erosion-corrosion metal wastage rate at 650 °C. The improved erosion resistance was largely a result of a modified corrosion behavior. Static oxidation studies showed that the normal silicon content 2.5Cr steel developed a duplex, spalling prone, iron-rich scale at 650 °C. However, with the addition of silicon, the scale was almost 50 times thinner, and was chromium-rich instead. Metal wastage was significantly reduced for static and dynamic corrosion as well as for erosion-corrosion. The thin scale that formed on the additional silicon steels cracked and chipped off at a low metal loss rate compared with the thick scale that formed on the normal silicon steels that spalled off at a higher metal loss rate.