Hyo Tae Jeong

Texture development and its effect on mechanical properties of an AZ61 Mg alloy fabricated by equal channel angular pressing

Abstract Microstructure and texture development of an AZ61 Mg alloy during equal channel angular pressing (ECAP) was investigated and correlated with the mechanical properties. The microstructure was effectively refined by ECAP, and the original fiber texture of the extruded AZ61 alloy was disintegrated and a new texture was gradually developed by repetitive ECAP pressing. After 8 ECAP passes following route Bc, the yield stress is lower than for the as-extruded AZ61 alloy, indicating that the texture softening is dominant over the strengthening due to grain refinement. When route A was used, on the other hand, the yield stress slightly increased after 8 passes. This result is primarily due to a difference in texture. The dominant textures after 8 passes were ( 10 1 1 )[ 0 1 11 ] + ( 10 1 2 )[ 1 2 1 0 ] and ( 10 1 2 )[ 1 2 1 0 ] when processed by route Bc and route A, respectively. Tensile ductility increased after ECAP and the effect of ECAP on ductility is more remarkable when the initial grain size is large.

Grain Refinement and Texture Evolution in AZ31 Alloy during ECAP Process and Their Effects on Mechanical Properties

The softening of fine-grained ECAPed AZ31 Mg alloys could be ascribed to the texture modification during ECAP. Lower ECAP temperature is more effective in refining the microstructure. The strength of the ECAPed AZ 31 Mg alloys increased with decrease in grain size when they have similar texture.

Mechanical Properties and Texture Evolution of AZ31 Mg Alloy during Equal Channel Angular Pressing

Microstructure and texture evolution in the AZ31 Mg alloy subject to equal channel angular pressing (ECAP) have been investigated and correlated with the mechanical properties. When AZ31 Mg alloy was ECAPed up to 8 passes following the route Bc, grain refinement occurred effectively. Texture was also changed during ECAP. The original fiber texture of the extruded AZ31 Mg alloy changed to a new texture component of ] 1 3 2 5 )[ 1 1 01 ( , and the texture of ] 1 3 2 5 )[ 1 1 01 ( orientation was rotated to ] 0 2 5 7 )[ 6 4 13 ( orientation after 6-pass ECAP process. The variation of the strength with the pass number was explained by the texture and grain size. The strength data of AZ31 Mg alloys followed the standard Hall-Petch relationship when the similar texture was retained during the ECAP process. Otherwise the effect of texture on strength was dominant over the strengthening due to grain refinement.

Effect of Thermomechanical Treatment on the Texture Evolution and Superplasticity of a Zn-0.3wt.% Al Alloy

Texture evolution and superplastic deformation behavior of a quasi-single phase Zn-0.3wt%Al have been investigated. It was attempted to produce a stable and fine-grained microstructure in a dilute Zn-Al alloy through a proper thermomechanical treatment process (TMTP). The grain size of about 1 µm was obtained in the Zn-0.3 wt.% Al alloy and a relatively coarse grain size of 10 µm was also obtained through a subsequent aging treatment. The fine-grained material showed typical rolling texture with basal poles tilted about 30 degrees away from the ND toward RD, while the coarse-grained material showed a typical recrystallization texture with basal poles parallel to ND. A series of load relaxation and tensile tests were conducted at room temperature. According to the internal variable theory of structural superplasticity, the grain boundary characters of fine and coarse-grained materials were different from each other. A large elongation of about 1400% was obtained in fine-grained material at room temperature.