Fatigue Resistant Martensitic Steel for Rotorcraft Drive Train Components

Under this SBIR program, QuesTek proposes to develop novel thermo-mechanical processing techniques to enhance the bending and contact fatigue resistance of high strength secondary hardening matensitic steels such as Ferrium® C64 for rotorcraft drive train components. A systems-engineering approach will be followed to identify key microstructure attributes (e.g., nonmetallic inclusions) controlling the mean and minimum fatigue resistance of the aforementioned steels. From this analysis, QuesTek will optimize the thermomechanical processing of the alloy to reduce the fatigue potency of the microstructure features in service. As the leading alloy designer of advanced gear steels, QuesTek possesses in-depth knowledge of high strength martensitic steels and will leverage its in-house modeling schemes to devise and optimize the modified process route to achieve enhanced fatigue resistance without compromising on other critical properties such as fracture toughness and strength. In Phase I of this SBIR program, the goal will be to establish key property objectives and process parameters for the selected martensitic steels and demonstrate the feasibility of the novel thermo-mechanical processing technique to enhance fatigue resistance using coupon-scale bending fatigue tests on Ferrium® C64. The envisioned process will be complementary with other fatigue-enhancing processes such as peening.