The fatigue performance of titanium alloys joined via the powder interlayer bonding method

Abstract

AbstractThis study investigated the fatigue performance of two forged variations of α + β titanium alloys, namely Ti-6Al-4V (Ti-6-4) and Ti-6Al-2Sn-4Zr-6Mo (Ti-6-2-4-6) joined via the powder interlayer bonding (PIB) process. Both alloys were bonded at relevant temperatures in the specific alloy’s α + β region. Modifications to the microstructure during the bonding process where it recrystalised into a bi-modal structure, resulted in improved low cycle fatigue (LCF) response for the Ti-6-4 alloy. This improvement is seen throughout the fatigue curve when compared to the LCF performance of the as received Ti-6-4 material. The improvement in LCF performance resulting from the microstructure transformation overcomes any reduction in performance that can be attributed to retained porosity after the bonding cycle. While the HCF performance of the Ti-6-2-4-6 alloy joined via the PIB process fell below that of the as received β-forged billet material, the fatigue performance compares well with previous HCF results for welded material. Unlike the Ti-6-4 alloy, the β-forged Ti-6-2-4-6 alloy does not benefit from the transformation of its microstructure throughout the bond region.