Hot Working Behavior in Multiphase Steel with Ti and V

Area of Science:

• Materials Science
• Metallurgy
• Mechanical Engineering

Background:

• Advanced multiphase steels with Ti and V microadditions are crucial for modern engineering applications.
• Understanding the influence of hot working on steel properties is essential for optimizing manufacturing processes.

Purpose of the Study:

• To investigate the effects of hot working parameters on yield stress and softening in a novel Ti- and V-microalloyed multiphase steel.
• To analyze the dynamic recrystallization behavior and austenite grain evolution under various thermomechanical conditions.

Main Methods:

• Continuous compression tests were conducted using a GLEEBLE 3800 thermomechanical simulator.
• Samples were deformed at temperatures ranging from 900 °C to 1100 °C and strain rates of 0.1 s⁻¹, 1 s⁻¹, and 10 s⁻¹.
• Two-stage compression with isothermal holding was employed to study recrystallization kinetics.

Main Results:

• The activation energy for plastic deformation was determined to be 375 kJ·mol⁻¹.
• Continuous dynamic recrystallization was identified as the primary mechanism reducing strain hardening.
• Increasing strain rate from 0.1 s⁻¹ to 10 s⁻¹ decreased primary austenite grain size from ~16 µm to ~6 µm.
• Recrystallization times (t₀.₅ and tR) were quantified and shown to be temperature-dependent.

Conclusions:

• Hot working conditions, particularly temperature and strain rate, critically control dynamic recrystallization and austenite grain refinement in this multiphase steel.
• The findings provide a basis for developing optimized thermomechanical treatment strategies for producing high-performance steel forgings.