In-Situ Neutron Diffraction and Crystal Plasticity Finite Element Modeling to study the Kinematic Stability of Retained Austenite in Bearing Steels

摘要

This work integrates in-situ neutron diffraction and crystal plasticityfinite element modeling to study the kinematic stability of retained austenitein high carbon bearing steels. The presence of a kinematically metastableretained austenite in bearing steels can significantly affect themacro-mechanical and micro-mechanical material response. Mechanicalcharacterization of metastable austenite is a critical component in accuratelycapturing the micro-mechanical behavior under typical application loads.Traditional mechanical characterization techniques are unable to discretelyquantify the micro-mechanical response of the austenite, and as a result, thecomputational predictions rely heavily on trial and error or qualitativedescriptions of the austenite phase. In order to overcome this, in this presentwork, we use in-situ neutron diffraction of a uniaxial tension test of an A485Grade 1 bearing steel specimen. The mechanical response determined from theneutron diffraction analysis was incorporated into a hybrid crystal plasticityfinite element model that accounts for the martensite's crystal plasticity andthe stress-assisted transformation from austenite to martensite in bearingsteels. The modeling response was used to estimate the single crystal elasticconstants of the austenite and martensite phases. The results show that usingin-situ neutron diffraction coupled with a crystal plasticity model, cansuccessfully predict both the micro-mechanical and macro-mechanical responsesof bearing steels while accounting for the martensitic transformation of theretained austenite.