The Effect of Microstructure on Mechanical Behaviour for Titanium Alloy (Ti-6Al-4V)

Abstract

The characteristics of mechanical behavior are investigated for Ti-6Al-4V alloy. Four kinds of specimens are prepared under different heat treatments in order to produce different microstructures. In the present investigations, impact, tensile and fatigue crack growth tests are performed for each test specimen. The results obtained through the investigations are compared. Additionally, fractal dimensions of crack path are obtained using the box counting method. The results are: 1) the microstructures show as equiaxed, bimodal and lamellar microstructures respectively, 2) the impact energy and elongation are superior for the bimodal microstructure, and the hardness and tensile strength are superior for the lamellar microstructure, 3) the fatigue crack growth rate is similar for all microstructures in the low ΔK region while that of equiaxed microstructure is the largest, and that of lamellar microstructure is the lowest in the high ΔK region respectively, 4) the fractal dimension, D of lamellar microstructure shows higher value than that of the equiaxed and bimodal microstructures under 200 magnification view of the SEM micrographs.