Effect of electrical pulse on dynamic recrystallization of ferrite and properties of High-Carbon Chromium steel

By taking the traditional Gleeble method as a reference, this paper studies the influence of electrical pulse (1x10³-2x10³A/cm²) on the High-Carbon Chromium steel 9Cr18 (specimens: φl0*20mm) in three heating temperatures (500°C,600°C,700°C) and three deformation amounts (10%,25%,40%). Compared with Gleeble tests in the same conditions, stress-strain curves show that the electrical pulse significantly reduces the maximum deformation resistance with the maximum decreasing amplitude 24.5% at 600°C; TEM results demonstrate that electrical pulse not only refines grain size, but also reduces the dynamic re-crystallization temperature (decreasing amplitude is about 100°C). In steel processing with pulse current in ferrite temperature range, dynamic recrystallization will occur in a lower temperature, which will reduce the deformation resistance greatly. What is more, the dynamically recrystallized grain size in this lower temperature range is smaller due to pulse current and the grain grows slowly and can be easily controlled. As a result, 1μm ultrafine grain microstructure can be obtained.