Regular Article

Hot workability of V-Ti microalloyed steel for forging

¹ School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, PR China
² Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, PR China
³ Xining Special Steel Co. Ltd, Qinghai Special Steel Engineering Technology Research Center, Xining 810005, PR China

^* e-mail: lyzh@ustb.edu.cn

Received: 12 March 2018
Accepted: 2 July 2018

Abstract

The hot compression and the hot tensile experiments were carried out on a Gleeble3800 thermal-mechanical simulator at different deformation conditions. The relationship between the flow stress and Zener-Hollomon parameter was established by the hyperbolic sine function. The hot deformation apparent activation energy is about 371 kJ/mol. There are two peak regions of m-value in the m maps with true strain of 0.2. One peak corresponds to the temperature of 1050 °C and the strain rate of 0.01 s⁻¹, the other one corresponds to the temperature of 1200 °C and the strain rates within range of 0.1 s⁻¹ ∼ 1 s⁻¹. There is only one peak region (1150 °C ∼ 1200 °C, 0.1 s⁻¹ ∼ 1 s⁻¹) of m-value, when true strain is 0.4 or 0.9. The reduction of area increases from 65% to 98% with the temperature increases from 800 °C to 1200 °C. In temperature range of 1000 °C ∼ 1200 °C, the reduction of area is always over 90%, which means that the plasticity of the steel is fine. According to the results of the research, it can be proved that the optimal deformation conditions with different strain correspond to the peak regions of m-value. The optimum deformation conditions is the temperature of 1200 °C and the strain rates within range of 0.1 s⁻¹ ∼ 1 s⁻¹, which were suitable for the true strain with 0.2, 0.4 and 0.9 at the same time.