Microstructure and Texture Evolution during Superplastic Deformation of SP700 Titanium Alloy

Abstract

The superplastic tensile test was carried out on SP700 (Ti-4.5Al-3V-2Mo-2Fe) titanium alloy sheet at 760 °C by the method of maximum m value, and the microstructure characteristics were investigated to understand the deformation mechanism. The results indicated that the examined alloy showed an extremely fine grain size of ~1.3 μm and an excellent superplasticity with fracture elongation of up to 3000%. The grain size and the volume fraction of the β phase increased as the strain increased, accompanied by the elements’ diffusion. The β-stabilizing elements (Mo, Fe, and V) were mainly dissolved within the β phase and diffused from α to β phase furthermore during deformation. The increase in strain leads to the accumulation of dislocations, which results in the increase in the proportion of low angle grain boundaries by 15%. As the deformation process, the crystal of α grains rotated, and the texture changed, accompanied by the accumulation of dislocations. The phase boundary (α/β) sliding accommodated by dislocation slip was the predominant mechanism for SP700 alloy during superplastic deformation.

Quality, Microstructure, and Properties of Metal Alloys

“…The work presented in this Special Issue [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] demonstrates the possibilities of further improving the microstructure quality and mechanical properties of metal alloys.…”

“…Microstructure and texture evolution tests during superplastic deformation of SP700 titanium alloy were carried out on SP700 (Ti-4.5Al-3V-2Mo-2Fe) titanium alloy sheets at 760 • C [3]. The microstructure characteristics were investigated to understand the deformation mechanism.…”