Effects of Temporary Alloying and Severe Plastic Deformation on Microstructure Evolution and Mechanical Properties of Ti-Alloys: A Comparative Study
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Near-α (VT 20) and α + β (Ti–6Al–4V) Ti alloys having similar initial grain morphology with equiaxed α in transformed β were subjected to microstructure refinement processes by thermohydrogen processing (THP) and caliber rolling (CR), respectively. The microstructure analysis after THP and CR of the alloys revealed the change in morphology and refinement of microstructure. The microstructure analysis after initial constant strain rate tests at 850 °C exhibited needle-like morphology for THP alloy, whereas it was equiaxed for as-received VT 20 and CR 750 alloy. An additional attempt was made on the CR alloy towards determining the magnitudes of strain rate sensitivity index (m) through differential strain rate test conducted over a number of strain rate change cycles at 850 °C and 927 °C. Both THP and CR processes resulted in grain refinement and the change in morphology of microstructure.
KeywordsThermohydrogen processing Caliber rolling VT20 Ti–6Al–4V Grain refinement