Improving Tension/Compression Asymmetry of a Hot‐Extruded Mg–Zn–Y–Zr Alloy via Yttrium Addition

Abstract

In this study, effects of different yttrium (Y) contents ranging from 0 to 2.5 wt% on the microstructure and tension/compression asymmetry of as‐extruded Mg–5.5Zn–0.6Zr alloys are investigated. The influence of Y on improving the tension/compression yield strength is been studied. The results show that the volume fractions of the microscale I (Mg3YZn6) and W (Mg3Zn3Y2) phases remarkably increase with Y addition. Simultaneously, the nanoscale MgZn and Mg–Zn–Y phases uniformly precipitate during extrusion. Benefiting from the pinning of second phases, the microstructure is strikingly refined from 16.3 to 5.5 μm. Among them, the Y element promotes grain refinement most effectively when the Y content is 2.0 wt%. Second phase strengthening and fine‐grain strengthening enhance the hardening rate and suppress twinning, which leads to the improvement of the tension/compression asymmetry. Specifically, yield strength of 231 MPa and ultimate tensile strength of 312 MPa are achieved with 2.5 wt% Y addition. The relative increment is about 33.0% and 65.3% compared to the unmodified alloy, respectively. In addition, the tensile yield strength to compressive yield strength ratio (TYS/CYS) is reduced from 1.30 to 1.09.

Effects of non‐proportionality and tension–compression asymmetry on the fatigue life prediction of equivalent stress criteria

“…It should be noted that a tension–compression asymmetry is found for a large variety of polymers 38–42 and other materials 43,44 . Therefore, this effect is not unique to the adhesive investigated in this work.…”

“…It should be noted that a tension-compression asymmetry is found for a large variety of polymers [38][39][40][41][42] and other materials. 43,44 Therefore, this effect is not unique to the adhesive investigated in this work. In literature, however, implications of the asymmetry on the (equivalent) stress-based fatigue life prediction are hardly considered.…”

Effects of non-proportionality and tension-compression asymmetry on the fatigue life prediction of equivalent stress criteria

“…Table 1. It should be noted that a tension-compression asymmetry is found for a large variety of polymers [37][38][39][40][41] and other materials 42,43 . Therefore, this effect is not unique to the adhesive investigated in this work.…”

A Strain Rate‐Dependent Constitutive Model for Asymmetric Hardening Behavior of TB9 Titanium Alloy

“…Next, Equation ( 15) and ( 16) are substituted into Equation ( 13) to obtain the stress increment dσ ij , as expressed in Equation (17).…”

“…However, a phenomenon is often observed that some materials have different flow stresses between tension and compression, and it is defined as the strength differential effect or asymmetric yielding. [15][16][17] Concerning the constitutive modeling of the different metals and alloys, most attention has been devoted to the asymmetric yielding and hardening type. [18,19] Stoughton and Yoon [20] described the strength differential effect of sheet metal forming The TB9 titanium alloy is one of the most promising materials for engineering application due to high strength, high toughness, and corrosion resistance.…”