Heat treatment effect on microstructure and mechanical properties of TC21 titanium alloyAuthor(s): Mohamed El-Shennawy*
Effect of heat treatment on microstructure and mechanical properties of TC21 titanium alloy was investigated. TC21 in annealed condition with an equiaxed α+β structure was solution treated at temperature below β-transus (920?C, 15min) and temperature above β-transus (1020?C, 15min, WQ). Aging was applied for both groups of samples (600?C, 4h, AC). Treated samples below β-transus showed an equiaxed α+β structure. Samples treated above β-transus have been changed to a solely β-phase with little amount of secondary α-phase precipitated in the formed β-phase due to high cooling rate and aging process. Maximum hardness of 492HV30 was reported for samples treated at 1020?C due to precipitation of secondary lamellar alpha phase and small lathes of martensitic phase (α\\) in β-matrix. Maximum tensile strength of 1447MPa and ductility of 8% were reported for the samples treated at 920?C due to its structure that contained α, β and αs. Hence, treated samples at 920?C showed the best mechanical properties and the most reliable and repeatable characteristics.