The effect of oxide scale and microstructural changes during cyclic hot corrosion on high-temperature tensile properties of Rene-80 superalloy

ABSTRACT

The effect of oxide scale and microstructural changes during 10, 20, and 40 hot corrosion cycles on the high-temperature tensile properties of Rene-80 superalloy at 950 ^°C was investigated. Due to the formation of micro-cracks and micro-voids, compressive stresses produced from Cr₂O₃ and NiO growth, and tensile stresses stemming from NiMoO₄ transformation and Al internal oxidation, the oxide scale spalled. By increasing the hot corrosion cycles, UTS (Ultimate Tensile Strength) and El.% (Elongation) first decreased and then increased due to the propagation of intergranular vertical cracks from the oxide scale to the Rene-80 after 20 cycles. During hot corrosion cycles, YS increased due to a rise in the density of near-surface intergranular cracks close to the Rene-80/oxide scale interface resulting from micro-void linkage and γ′-depleted zone. Due to the high area fraction and the small average size of secondary γ′, UTS and YS were the highest and lowest after ten cycles, respectively.

Graphical abstract

KEYWORDS:

• Rene-80 superalloy
• hot corrosion
• oxide scale
• tensile properties
• fracture surface
• γ' precipitate

Disclosure statement

No potential conflict of interest was reported by the author(s).