Bainite Kinetic Energy, Activation Energy, And Tribological Behavior Of Austempered Aisi4340 Steel

A study has been made of the effect of heat-treatment on the microstructures of commercial quality AISI4340 steel after austenitizing at 1128 K and austempering at temperatures ranging from 561 K to 644 K. The morphologies of the bainite structure were observed after etching using optical microscopy. The "Avrami " equation was used to determine the relationship between the transformed fraction and different austempering temperature. The activation energy was determined by using the "Arrhenius " equation. The results show the bainite sheaves and bainite width grow as the austempering temperature increases. High temperature results in fast bainite transformation and the bainite activation energy is 5.302 x 10(3) J/mol. The bainite microstructures highly enhanced tribological performance as compared to tempered martensite microstructures at the same hardness. (C) 2021 The Author(s). Published by Elsevier B.V.