Hot Deformation Behavior and Processing Maps of a 9Ni590B Steel

To increase the hot workability and provide proper hot forming parameters of a 9Ni590B steel for the simulation and production, the hot deformation behavior of the 9Ni590B steel is investigated through isothermal compression tests using a Gleeble-3180 thermal–mechanical simulator over a temperature range of 850-1200 °C with strain rates of 0.001-5 s⁻¹. The results indicate that as the deformation temperature increases and the strain rate decreases, the flow stress of the 9Ni590B steel decreases. The deformation–activation energy was calculated to be 364.99 kJ/mol based on the flow stress curve data. The dynamic material model (DMM) was used to establish the process map of the thermal deformation for the 9Ni590B steel. The results show that the optimal deformation conditions for the 9Ni590B steel hot working are with a temperature range of 1100-1200 °C and a strain rate range of 0.001-0.01 s⁻¹. The validity of the calculations was confirmed by observing the microstructure of the 9Ni590B steel sample under the optimal thermal process parameters.