Effect Of Heat Treatment On Microstructure And Tensile Property Of Ti-6al-6v-2sn Alloy

The microstructure and tensile properties of Ti-6Al-6V-2Sn alloy heat-treated at different solution and aging temperatures has been systematically investigated. Specimens were solution-treated at 970 degrees C (above the beta transus) and 920 degrees C (below the beta transus), respectively, followed by water quenching. When the alloy is quenched from 970 degrees C, alpha' (hcp) and alpha '' (orthorhombic) martensite phases co-exist in the microstructure. When it is quenched from 920 degrees C, alpha ' martensite phase does not form, while equiaxial primary alpha (alpha(p)) phase and alpha '' are found in the microstructure. The results also show that the strength of the alloy increases but the ductility deteriorates as the solution temperature becomes higher when the aging treatment is unchanged. This is because the volume fraction of equiaxial alpha(p) phase is lower but the volume fraction of the acicular secondary alpha (alpha(s)) phase is higher for higher solution temperature. When the alloy is aged at different temperatures after the solution treatment at 900 degrees C, the strength of the alloy decreases with the increase of aging temperature and the ductility shows the opposite trend as the size of the acicular alpha(s) becomes longer and its volume fraction is lower at higher aging temperature.