Microstructure and Phase Analysis of Pure Ti and Ti-6Al-4V GTAW Cladding Material

Abstract

The microstructure and phase configuration of pure Ti and Ti-6Al-4V GTAW cladding were studied. The cladding microstructures were divided into the base metal (BM) of the substrate, the heat affected zone (HAZ) and weld metal (WM). Depending on the location, the microstructure shape was observed to differ due to heat transfer effects, and the HAZ had a relatively fine structure due to fast cooling of the substrate contact. The lamellar spacing was 5㎛ for HAZ, which is smaller than the 10㎛ of WM. In the pure Ti, the microstructure compositions consisted of a lamellar structure with a pure Ti α phase and a rich Fe β phase, where Fe is an impurity segregated in the β phase. In the Ti-6Al-4V, the microstructure compositions consisted of a lamellar structure with a lean V content of α phase and a rich V content of β phase. The hardness values for pure Ti and Ti-6Al-4V were measured and found to be 425HV and 259HV, respectively. Key words: Pure Ti, Ti-6Al-4V, GTAW cladding, microstructure, HAZ, α and β phase