Effect of Short Heat Treatment Routes on the Tribological Properties of Ti- 6Al-4V Alloy

In this research, the effect of annealing and aging temperature as well as the effect of quenching media on the microstructure, hardness and dry sliding wear behavior of11-6Al-4Valluy hos been studied. Cylindrical samples with the diameter of 10 mm and the height of20mm were solutionized at 930 ·cand 1060"Cfor 600 seconds and then were quenched in the cold water and in the air. The samples were aged at different temperature of480"C, 55o·c and 610 ·cfor 360 s to increase the hardness. Heat treated samples were tested using standard pin-on-disc test machine at the applied loads of 100, 150 and 200 N. Microst1Uctural investigations using scanning electron microscope revealed thatfor the samples solutionized at 930 ·cand quenched in the water, the microst1Ucture is composed ofprimary a and high volume fraction of martensitic a' phase with fine precipitated of P between martensitic lathes. In the case of air cooled samples, transformed P has also been appeared in the vicinity of primary a. For the samples solutionized at 1060 ·c and quenched in the water, fully martensitic microst1Ucture with fine p precipitates was observed. For the sample solutionized at 1060"C and air quenched, plate like a and lamellar grain boundary P were detected. The maximum hardness value relates to the sample solutionized at 1060"C and quenched in water which is equal to 433 Hv. Different wear mechanisms, including oxidative wear, scratch, and delamination occurred at the worn surfaces at different applied loads. For the samples quenched in the water, the oxidative wear mechanism governing at low applied load and oxide debris was observed as separate or compacted particles which formed in the contact between pin and steel counter face detached from the sample. At higher applied loads, delamination and scratch mechanism was al&o observed and metallic plate like debris was detached from the sample. Mechanically mixed layer (MML) wasformed on the surface of the pin at high applied loads andfor the samples with low hardness value adhesion marks were alBa revealed on the steel disc. The minimum weight loss in the wear test is related to the sample quenchedfrom the 1060"C in the cold water and aged at 550 "C.