Minimizing Distortion During High Pressure Gas Quenching Processes

Steel components, such as gears for rotorcraft transmissions, are quench hardened to improve the hardness, strength, and fatigue performance. During a quench hardening process, components are heated to form austenite, followed by quenching (either gas or liquid) to transform to hard martensite. With High Pressure Gas Quenching (HPGQ), parts are rapidly cooled by using a pressurized gas such as Nitrogen or Helium. Hardening is a highly nonlinear process due to the plastic deformation caused by thermal stresses and phase transformations, both of which lead to distortion. Reducing distortion caused by hardening has always been pursued by heat treaters for the purposes of improving part quality and reducing cost. A new gas quenching method to minimize distortion of Ferrium C64 gear steel was developed by DANTE Solutions as part of an effort with the US Army's Aviation Development Directorate (ADD). This method utilizes a new state-of-the-art gas quench chamber to control the temperature uniformity of parts using a recipe developed through computer modeling.