Influence of Sizes of Inclusions and Voids on Fracture Toughness of Ultra-High Strength Steel AerMet100 Original Research Article

Mechanical properties of the ultra-high strength steel AerMet100 aged at 454°C∼510°C were studied, and relationship between the critical crack tip opening displacement δIC and X0 (RV/RI)|R0 was calculated, where X0 was an average inclusion spacing and (RV/RI)|R0 was the void radius RV divided by the radius of the inclusion RI nucleating the void evaluated at the average inclusion size R0. The results showed that high fracture toughness could be reached after aging at 510 °C, and aging temperature affected fracture toughness apparently. δIC was in linear relationship with X0 (RV/RI)|R0 in the range of 8μm∼50μm. R0 was 0.53μm, X0 was 6.39μm for the tested steel, and the values of (RV/RI)|R0 were different for varied microstructures. The fracture toughness of AerMet100 steel was influenced by microstructures and inclusions greater than that of AF1410 steel.