Hot Deformation Behavior of Homogenized Mg-13.5Gd-3.2Y-2.3Zn-0.5Zr Alloy via Hot Compression Tests

Abstract

Mg-Gd-Y-Zn-Zr Mg alloys show excellent performance in high-end manufacturing due to its strength, hardness and corrosion resistance. However, the hot deformation and dynamic recrystallization (DRX) behaviors of Mg-13.5Gd-3.2Y-2.3Zn-0.5Zr were not studied. For this article, hot compression behavior of homogenized high rare-earth (RE) content Mg-13.5Gd-3.2Y-2.3Zn-0.5Zr (wt%) alloy was investigated by using the Gleeble-3500D thermo-simulation test machine under the temperature of 350–500 °C and the strain rate of 0.001–1 s−1. It was found that the high flow stress corresponded to the low temperature and high strain rate, which showed DRX steady state curve during the hot compression. The hot deformation average activation was 263.17 kJ/mol, which was obtained by the analysis of the hyperbolic constitutive equation and the Zener-Hollomon parameter. From observation of the microstructure, it was found that kink deformation of long period stacking ordered (LPSO) phase was one of the important coordination mechanisms of hot deformation at low temperature. The processing map with the strain of 0.5 was established under the basis of dynamic material model (DMM); it described two high power dissipation domains: one appearing in the temperature range of 370–440 °C and the strain rate range of 0.001–0.006 s−1, the other appearing in the temperature range of 465–500 °C and strain rate range of 0.001–0.05 s−1, in which dynamic recrystallization (DRX) mainly ocurred. The highest degree of DRX was 18% from the observation of the metallographic.

An Investigation on Microstructure, Texture and Mechanical Properties of AZ80 Mg Alloy Processed by Annular Channel Angular Extrusion

“…Magnesium (Mg) alloys, being among the lightest structural materials, have become a focus in the world due to their advantages [1,2], especially the high specific strength compared to other alloys [3,4]. In the past twenty years, Mg alloy structural components have been widely applied in automotive, aerospace, defense, and electronic industries, while more than 90% of them are in the as-cast state [5].…”

Controlling Grain Sizes of 42CrMo Steel by Pre-Stress Hardening Grinding

“…When the stress level is lower (ασ<0.8), substituting F (σ)=σn into Equation (2) and taking the nature logarithm on both sides. Then normaln=dlntrueε˙/dlnσ. According to the research in References [9,10,11], within a strain range from 0.08 mm to 0.18 mm for 42CrMo high-strength steel, the stresses increased almost linearly and the effect of temperature on the ratios was very small. Thus, in order to evaluate the constant n, true strain ε = 0.12 mm was chosen in this study.…”

“…By considering the effect of grain size on the degree of recrystallization, Zerilli and Armstrong [8] presented a constitutive relation into which the effects of strain hardening and high temperature softening based on true stress–strain analysis has been incorporated. The initiation and evolution of DRX were investigated through hot compression experiments [9,10,11], and systematic analysis coupling effect between dynamic recrystallization (DRX) behavior and flow stress. Li et al [12] established a Poliak–Jonas (P–J) model to calculate critical strain and kinetics of DRX through quantitative analysis of the regression of stress–strain data obtained in the experiment under different conditions.…”

Optimisation of Heat Treatment Process for Damping Properties of Mg-13Gd-4Y-2Zn-0.5Zr Magnesium Alloy Using Box–Behnken Design Method

“…However, the RE-rich compound could not be analysed by XRD due to its low-volume fractions [29]. Two granular phases (Figure 8a, Spot 2 and Spot 4 ) are considered to be the same phase due to their similar element content, and they may be Mg 5 Gd [30]. But, the content of Mg is high due to the selected part of the matrix phase.…”