Influence of cyclic overheating on tensile strength and ductility of GH3230 alloy

In light of the application scenarios where the combustion chamber and turbine components of aeroengines are repeatedly subjected to short-term overheating， and reusable spacecraft endure cyclic high-temperature conditions， an experimental study is conducted to investigate the effects of cyclic overheating on the tensile properties of GH3230 alloy. Additionally， the oxidation-related microstructural and compositional changes are characterized.The results reveal that the cracking of internal oxides during plastic deformation reduces the actual load-bearing area of the oxidized sample. Grain coarsening also occurs during thermal exposure. These two factors jointly contribute to a continuous decline in room-temperature tensile strength as the number of overheating cycles increases. After removing the surface layer， the tensile strength is restored to a certain degree. The oxidative decarburization zone that forms near the sample surfaces exhibits improved plastic deformability. As a result， it effectively blunts oxide cracks and prevents them from penetrating into the matrix. Consequently， the tensile elongation of the oxidized sample after 10-40 cycles of over-temperature remains at relatively high levels due to the avoidance of the notch effect caused by surface cracks.