Effects of Ti and Y on resistance to corrosion in Fe–Cr-X Alloys

The effect of Ti and Y on the corrosion behavior of the FeCr alloy was investigated in a 3.5% NaCl solution. Ti was found to inhibit the formation of the σ phase, significantly reducing the presence of pitting in the material. In addition, Ti acted indirectly on the oxide layer, increasing the concentrations of Cr and Fe, consequently generating a probable enrichment of Cr 2 O 3 and FeOOH, which enabled the formation of a more stable passive film resistant to attack by chloride ions. On the other hand, Y caused the precipitation of a phase identified as Fe 17 Y 2 , which was accompanied by an elongated σ phase, both located at the grain boundaries, besides the formation of Cr 23 C 6 and Y 2 O 3. Its addition resulted in an improvement in the corrosion resistance of the FeCr alloy by reducing the precipitation of the σ phase. However, its effect was much less important than that of Ti, since the results showed that the FeCrY alloy was still highly susceptible to localized forms of corrosion.