Improving strength-ductility synchronously of Electron beam welded Ti600/Ti2AlNb joint through isothermal forging

Abstract

Different alloys can be flexibly combined to meet the performance needs of different parts of the compressor disc by welding process. However, achieving a good combination of dissimilar alloys with different mechanical properties has always been a research difficulty. In this work, a Ti600/Ti₂AlNb joint was fabricated through electron beam welding and an isothermal forging was used to optimized its microstructure and mechanical performance. The isothermal forging process increases the ultimate tensile strength (UST) and yield strength (YS) of the Ti600/Ti₂AlNb joint by ∼18 ​%, while ∼2.5 times the ductility. It is indicated that before forging, the Ti600/Ti₂AlNb joint exhibits a much lower strength than that of Ti600 matrix, whereas the opposite is true after isothermal forging. The isothermal forging broken the coarse columnar grains of Ti600/Ti₂AlNb joint and render to an equiaxed B2 structure in which the acicular α₂ and O phase are precipitated, resulting a synchronous enhancement of strength and ductility. This work may pave an effective routine for improving the comprehensive mechanical properties of dissimilar metal welding joint.