The effect of porosity content on the high-temperature mechanical properties of DZ409 superalloy

Abstract

DZ409 alloy is a new type of directional solidification nickel-based high-temperature alloy, which has excellent comprehensive performance. It can become a candidate alloy for the new generation of heavy-duty gas turbine blade materials that consider multiple properties. However, in the actual production process, shrinkage porosity often occurs in the castings, which seriously affects the mechanical properties. To investigate the effect of shrinkage porosity on the typical mechanical properties of DZ409 alloy in near service conditions (650 °C and 950 °C), Additionally, the tolerance limits of porosity for the basic mechanical properties of the DZ409 superalloy were determined, tensile experiments were designed on DZ409 specimens with different porosity amounts at 650 °C and 950 °C. The results indicate that the influence of micropores on tensile properties is non-monotonic. Furthermore, this non-monotonic influence law was verified through numerical simulation. This result indicates that when the pore content is within a limited range, its impact on the mechanical properties of directional castings is limited. The correlation between shrinkage porosity defects, mechanical properties, and microcracks has been studied, and the corresponding mechanisms have also been discussed.