The Effect of ECAP Processing Conditions on Microstructural Evolution and Mechanical Properties of Pure Magnesium—Experimental, Mathematical Empirical and Response Surface Approach

Abstract

In this study, a quantitative evaluation approach was used to investigate how certain ECAP processing parameters affect the microstructural evolution, Vicker’s microhardness values and tensile properties of pure Mg. The ECAP processing parameters were number of passes, ECAP die channel angle and processing route type. The response surface methodology (RSM) technique was used to design 16 runs of the experiment using Stat-Ease design expert software. Billets of pure Mg were processed up to four passes of routes Bc, A and C at 225 °C. Two ECAP dies were used with internal channel angles of 90° and 120°. Experimental findings were used to establish empirical models to assess the influence of the ECAP processing parameters on grain size and mechanical properties of ECAPed billets. The established relationships were examined and validated for their adequacy and significance using ANOVA as well as several statistical criteria. Response surface plots and contour graphs were established to offer better understanding of the intended relationships. In addition, the optimum processing parameters for grain size, hardness values and tensile properties were defined. Both experimental results and the theoretical model revealed that route Bc is the most effective route in grain refining. The experimental findings showed that four passes of route Bc through the die channel angle 90° revealed a significant reduction in the grain size by 86% compared to the as-annealed counterparts. Similar to the grain size refining, four-passes processing through the ECAP die with an internal channel angle of 90° leads to improved Vicker’s microhardness values. Additionally, four passes of route Bc using the 90° die angle recorded a significant HV increase at the edge and central areas by 112% and 78%, respectively, compared to the as-annealed counterpart. On the other hand, according to the optimization findings, two passes of route Bc using a die angle of 120° resulted in the best ultimate tensile strength for pure Mg, whereas four passes of route Bc revealed the optimum ductility at fracture.

Effect of ECAP Route Type on the Microstructural Evolution, Crystallographic Texture, Electrochemical Behavior and Mechanical Properties of ZK30 Biodegradable Magnesium Alloy

“…They outlined that the starting basal slip clutches the great majority of the deformation, while the subsequent passes involved the activation of non-basal slip systems and so required a lower amount of deformation energy [ 47 ]. Alateyah et al [ 84 ] generated a comprehensive statistical analysis of the effect of ECAP parameters on the grain size and mechanical properties of pure Mg. They reported that 2-Bc using an ECAP die with a channel angle of 120° was the optimum processing condition for increasing σu, whereas 4-C using an ECAP die with a channel angle of 120° was the optimum processing condition for improving the ductility.…”

Influence of Ultrafine-Grained Microstructure and Texture Evolution of ECAPed ZK30 Magnesium Alloy on the Corrosion Behavior in Different Corrosive Agents

“…Meyer et al [ 96 ] and Agnew et al [ 97 ] reported similar improvement in the ductility of AZ31B, whereas they noticed a decrease in the YS while the UTS kept constant. Alateyah et al [ 98 ] generated a comprehensive statistical analysis for the effect of ECAP parameters on the tensile properties of pure Mg. Mostaed et al [ 24 ] achieved improvement in the EL by 30% of ZK60 alloy after ECAP processing through 4-passes at 150 °C. Naik et al [ 85 ] reported a similar trend for AM80 alloys.…”

Optimizing the ECAP Parameters of Biodegradable Mg-Zn-Zr Alloy Based on Experimental, Mathematical Empirical, and Response Surface Methodology

“…Moreover, increasing the die angle up to 120° in both regions resulted in decreasing the hardness, which could be attributed to the decrease in the plastic strain [ 35 ]. Furthermore, increasing the number of passes resulted in hardness improvement, which could be argued to be the result of strain hardening [ 57 , 73 ].…”

“…The obtained optimum values for channel angle and corner angles were 93.64° and 0°, respectively. Alateyah et al [ 57 ] used RSM, ANOVA, GA, and RSM-GA to optimize the ECAP parameters of pure Mg, and they reported that ECAP processing using a die with ϕ = 90° through 4-passes of route Bc was the most significant parameters in grain reining and Vicker’s microhardness values. Furthermore, ECAP processing using an ECAP die with ϕ = 120° through two passes of route Bc displayed the highest TS, while 4-passes of route C using the 120°-die showed the best D% at fracture.…”