Effect of Different Fluoride on Weld Formation and Organization with A-TIG Welding of Titanium Alloy

Abstract:

Nine kinds of fluoride were used for A-TIG welding of titanium alloy. Welding arc shape and electrical signals were collected by the high-speed cameras and Hannover analyser in the process. After welding, organization of welded joint was observed and analysised. The results show that: MgF₂ had the apparent effect in increasing the weld penetration, it was 2 times the depth of weld without flux. KF was in the second place. LiF could decrease the weld penetration; Compared with MgF₂, KF had a small weld width , narrow HAZ width and total joint width. NaF obtained the minimum HAZ width; The angle of NaF, KF, MgF₂ and AlF₃ between columnar crystal growth direction and weld center axis was bigger than the other fluoride. The length of the column crystal size was determined by the size of penetration, the width variation law was for AlF₃＞KF＞MgF₂＞NaF; the grain size of coarse grain area in HAZ was for MgF₂ > NaF > AlF₃ > KF.

Key words:titanium alloy;A-TIG welding; fluoride; penetration; grain