Effect of yttrium on the cyclic oxidation behaviour of HP40 heat-resistant steel at 1373 K

The effect of rare earth elements on cyclic oxidation behaviour of HP40 at 1373 K has been investigated. The results demonstrate that 0.06 wt.% addition of Y effectively improves the cyclic oxidation resistance of such Si-containing alloy. By observing the cross-section of the scale, it is found that Y facilitates the formation of Si-rich internal oxide, which improves the spalling resistance of the scale. As a result, compared with the sample without Y addition, on which the spinel layer is discontinuous, a continuous duplex scale of chromia overlaid by manganese-rich spinel is kept at the outmost of the Y-modified alloy.

Research highlights
► Yttrium has a benefit effect on the cyclic oxidation resistance of HP40 alloy.
► Y facilitates the formation of internal oxide (silica) during cyclic oxidation.
► A continuous spinel layer is observed on Y doped alloy during cyclic oxidation.
► The internal oxide (silica) improves the adherence of the scale.