Dynamic Recrystallization and Flow Behavior in Low Carbon Nb–Ti Microalloyed Steel

Abstract

Single-pass hot compression tests are performed to study the hot deformation behavior of a low carbon microalloyed steel at temperatures in the range of 950-1050 C and strain rate from 0.01 to 0.5 s-1. Based on true stressstrain data, the effect of strain rate and temperature on the flow behavior of this steel is analyzed and peak stress is determined as well. The partial derivative of the strain hardening rate to stress is used to determine the critical stress. The value of activation energy and the ratio of critical stress (strain) to peak stress (strain) are estimated. The relationship between characteristic points and Zener-Hollomon parameter is established. The kinetic model for the calculation of volume fraction of dynamic recrystallization is also established. The strain dependence of material constants are determined from fifth-order polynomials and the flow stresses under different deformation conditions are predicted, consistent with the experimental results. Figure 7. Comparisons between measured and predicted flow stress at different strains. www.advancedsciencenews.com www.steel-research.de steel research int. 2018, 89, 1700395

Evolution of Dynamic Recrystallization in 5CrNiMoV Steel during Hot Forming

“…However, at the strain rate of 0.1, 1, and 10 s -1 , DRX behavior stayed incomplete and the unrecrystallization grains are illustrated in Figure 10 by the white arrows. It was for that higher strain rates, to some extent, brought less time for the movements of grain boundaries and dislocations, which restrained the growth of DRX nuclei [38,39]. Figure 11 illustrate the new recrystallized DRX grains and un-recrystallized grains, respectively.…”

Rapid Visualization of Microstructural Evolution during Hot Strip Rolling Using Phenomenological Models and the Laguerre–Voronoi Diagram

“…Unfortunately, the basic assumption that microstructure after deformation should be homogeneous and fully composed of equiaxed recrystallized grains regardless of recrystallization occurring or not inconsistent with the actual mixed microstructure consisting of both equiaxed recrystallized and elongated nonrecrystallized grains, [11][12][13][14] indicating that the austenite microstructural heterogeneity caused by partial recrystallization is not taken into consideration in the conventional methods. Furthermore, the macroscale microstructural states revealed in Sellars's work cannot provide a direct view of their evolutions due to lack of details; [15][16][17][18] therefore, other microscale microstructural features, such as the sizes and their distributions of both equiaxial and elongated grains, and the mixed fraction of microstructure must be employed to describe the microstructural state more precisely.…”

Effect of Zr on Dynamic Recrystallization Behavior of Ti‐Microalloyed Low Carbon Steels

“…Meanwhile, the effective content of Ti was reduced, and the precipitation strengthening of TiC was weakened. [5,6] To solve the adverse effects, Zr can be added to Ti-microalloyed steel to preferentially combine with O and S to form ZrO 2 and ZrS. [7,8] Previous studies have shown that the addition of Zr was able to prevent the growth of austenite grains at reheating temperatures.…”