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Heat treatment effect on microstructure and mechanical properties of TC21 titanium alloy
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 (920â°C, 15min) and temperature above β-transus (1020â°C, 15min, WQ). Aging was applied for both groups of samples (600â°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 1020â°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 920â°C due to its structure that contained α, β and αs. Hence, treated samples at 920â°C showed the best mechanical properties and the most reliable and repeatable characteristics.