Comparison of the effect of ECAP and SSE on microstructure, texture, and mechanical properties of magnesium

• Microstructure, crystallographic texture, and mechanical properties of pure Mg, as a model hcp metal, were compared after processing by the two severe plastic deformation (SPD) techniques of equal channel angular pressing (ECAP) and simple shear extrusion (SSE). Both processes were performed on extruded bars at 250 degrees C for up to four passes, where the minimum grain sizes of 13.7 and 9.8 mu m were achieved in the ECAP and SSE processes, respectively. The fraction of dynamically recrystallized (DRX) grains, high angle grain boundaries (HAGBs), and the evolution of dislocation density with equivalent strain experienced the same trend in both processes with higher values after ECAP. The textural evolutions were completely different during ECAP and SSE despite their similar deformation modes. A conventional shear texture was developed after ECAP, while after SSE basal planes were aligned parallel to the processing direction. In the ECAP-processed material, texture softening and lower dislocation density counterbalanced the strengthening effect of grain refinement, resulting in a decrease in shear yield stress (SYS) and ultimate shear strength (USS), while in SSE the shear strength increased constantly with increasing number of passes. It can be deduced from the experimental results that SSE was more effective in achieving a fine-grained homogenous microstructure with high shear strengths as compared to ECAP.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Textil-, gummi- och polymermaterial (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Textile, Rubber and Polymeric Materials (hsv//eng)

Nyckelord

Magnesium

Equal channel angular pressing

Simple shear extrusion

Microstructure

Texture

Mechanical properties

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