Abstract: Key influencing factors of the heat treatment properties of AerMet100 ultra-high strength steel were systematically investigated using various detection methods such as optical microscope (OM), transmission electron microscope (TEM), energy dispersive spectroscopy (EDS), universal testing machine, pendulum impact testing machine, and Rockwell hardness tester. The results indicate that adding a normalizing process step before the formal heat treatment of large-diameter variable cross-section bars can effectively refine the grain structure of forgings, thereby ensuring a more stable and reliable final heat treatment quality. In addition, the sampling position of furnace specimen on the circular section of large-diameter AerMet100 steel forgings has a significant impact on the measured values of impact properties, although its influence on the mechanical properties such as tensile strength, yield strength, elongation, and reduction of area of the material after heat treatment is relatively small. According to the recommended heat treatment system, the heat treatment tests on small specimens show that extending the quenching and tempering holding time has little effect on the tensile properties of the specimens.

Key words: AerMet100 steel, ultra-high strength steel, grain refinement, heat treatment process, mechanical properties