Modeling of hot deformation behavior and processing map of ۱۳-۸Mo precipitation hardening steel

The objective of this research is to model the hot deformation behavior and draw processing map for ۱۳-۸Mo steel. For this purpose, hot compression tests were conducted on cylindrical samples with a diameter of ۵ mm and a height of ۱۰ mm within a temperature range of ۸۵۰ to ۱۱۵۰°C and strain rates from ۰.۰۰۱ to ۱s⁻¹. The microstructure of the deformed samples obtained from the hot compression tests was examined using optical microscopes.According to the results, as temperature increases and strain rate decreases, the flow stress decreases. Flow curves were plotted to estimate the constants of the fundamental power relationship at various strains. Based on fundamental calculations, the activation energy for this steel was determined to be ۲۸۸.۶۲ kJ/mol. Subsequently, processing map were drawn for strain rates ranging from ۰.۱ to ۰.۷. It was found that in the temperature range of ۱۰۷۰ to ۱۱۵۰°C and strain rates between ۰.۱ and ۰.۱۵s⁻¹, dynamic recrystallization occurs with an efficiency of Power dissipation between ۰.۲ and ۰.۵۲.Additionally, the results from the processing map indicated the presence of one unstable region and two stable regions for deformation; investigations revealed that there is kinking and shear band in the microstructure, which is attributed to the unstable region and dynamic recrystallization being the main factor for stability.

کلیدواژه ها:

۱۳-۸Mo precipitation hardening steel ، Dynamic recrystallization ، Hot compression test ، Processing map ، Characteristic equations.