Softening Behavior of Two Ti Bearing Steels During Torsional Simulation of Rolling

An industrial controlled-rolling schedule was simulated in hot torsion for two Ti steels. The yield and the maximum stresses of each pass were determined from the recorded flow data. An approach resulting in a new softening parameter based on mechanical flow data is presented here.The evolution of austenite structure was determined from samples quenched after selected passes. The normalized times to 50% softening were determined from both the mechanical and metallographic data for each pass. The increase in Ti level from 0.03 to 0.12% in these steels led to austenite grain refinement in the simulated “as rolled” material. This improvement was ascribed mainly to TiC precipitation during rolling.