Effect of overheating on the strength of single crystal superalloy DD6: Mechanism, simulation and prediction

DX Pan and XG Wang and RY Cui and C Jiang and XM Shan and D Mi and ZC Liu, MATERIALS CHARACTERIZATION, 229, 115577 (2025).

DOI: 10.1016/j.matchar.2025.115577

Aero-engines may face the risk of One-Engine-Inoperative (OEI) during service, which typically leads to overheating lasting tens of seconds. This very short overheating process may have a significant impact on the mechanical properties of the material used in safety-critical components of aero-engines, such as turbine blades. This paper aims to understand the effect of overheating on the yield strength of nickel-based single crystal superalloy DD6 through a comprehensive investigation. A first surprising experimental finding is that the overheating under some typical OEI conditions may increase rather than decrease the yield strength of the DD6 superalloy. And the highest increase can reach 20 % to 30 %. The underlying micromechanical mechanisms supporting this counterintuitive finding are revealed in this work. It shows that the overheating enables directional coarsening of the primary gamma' precipitates and simultaneous precipitation of the finer secondary gamma' precipitates, which thereby imposes a complex impact on hindering dislocation behavior. In particular, the secondary gamma' precipitation plays an important role in this deformation mechanism. This is supported by molecular dynamics simulation conducted at the atomic scale. Finally, a yield strength prediction model that enables taking into account the overheating effect is proposed. The experimental verification shows that the proposed model enables predicting the yield strength of DD6 alloy after experiencing a given OEI, with an acceptable error level of less than 5 %.

Return to Publications page