Fatigue Resistant Martensitic Steel for Rotorcraft Drive Train Components

In Phase I of this SBIR program, QuesTek successfully demonstrated a novel thermomechanical processing technique to enhance the bending fatigue resistance of Ferrium C64 steel. A systems-engineering approach was followed to identify key microstructure attributes (e.g., nonmetallic inclusions) that control the mean and minimum fatigue resistance of the aforementioned steel. Through carefully devised experiments, QuesTek successfully optimized the thermomechanical process. Coupon scale fatigue testing was pursued to demonstrate enhancement in fatigue resistance.In Phase II, QuesTek proposes to build on the Phase I effort to scale up the thermomechanical process to actual test gears. Furthermore, QuesTek will attempt to optimize the thermomechanical processing for other steels of interest to ARMY such as AISI 9310, pyrowear X53, Ferrium C61 and Ferrium M54. Both single tooth bending fatigue and axial fatigue tests will be performed to demonstrate property enhancement. Additionally, mechanistic process modeling specifically targeting hot deformation such as forging and other thermomechanical processing will be identified and implemented; the model is envisioned to provide support to framing key processing parameters that maximizes fatigue resistance. The envisioned thermomechanical process will be complementary with other fatigue-enhancing processes such as peening.