The Effect of Post-weld Heat Treatment on the Corrosion Behavior of Different Weld Zones of Titanium Ti-6Al-4V Alloy by
- PDF / 1,900,484 Bytes
- 6 Pages / 593.972 x 792 pts Page_size
- 84 Downloads / 176 Views
JMEPEG https://doi.org/10.1007/s11665-020-05115-y
The Effect of Post-weld Heat Treatment on the Corrosion Behavior of Different Weld Zones of Titanium Ti-6Al-4V Alloy by Friction Stir Welding Alireza Nasresfahani, Abdol Reza Soltanipur, Khosro Farmanesh, and Ali Ghasemi (Submitted March 14, 2020; in revised form June 30, 2020) This study aims to investigate the effect of post-weld heat treatment on the corrosion behavior of different weld zones of titanium Ti-6Al-4V alloy by friction stir welding. Thus, the friction stir welding was used to join 3-mm-thick sheets of Ti-6Al-4V titanium alloy. Then, the welded sample from the optimal conditions underwent normalized heat treatment at 950 °C for 1 h in an argon inert gas environment. Next, the microstructures of different weld zones were examined using field emission scanning electron microscopy (FESEM), elemental analysis via EDS, phase analysis by XRD, and corrosion behavior through potentiostat equipment in HCl 5% solution. The results obtained from post-weld heat treatment also indicated that these operations significantly enhance the potential and converge the corrosion rate of different weld zones. Specifically, if the corrosion rate of the transition zone before heat operations is around 3.5 times that of the friction stir zone and 10 times that of the base metal, this difference will be less than 2.5 times that of the friction and 4 times that of the base metal following post-weld heat treatment. The post-weld heat treatment has reduced the difference in corrosion rate across various weld zones, but it has not made any changes in the corrosion rate of welds obtained at different traverse speeds. Keywords
frictions stir welding, heat treatment, microstructure, Ti-6Al-4V titanium alloy
1. Introduction One of the problems of fusion welding of Ti-6Al-4V titanium allow is the absorption of oxygen, nitrogen, and hydrogen gases as well as the formation of inappropriate compounds and microstructures which can affect the mechanical properties and corrosion behavior of this alloy. If friction stir welding is used, the absorption of gases can be prevented, and by controlling the microstructure, more suitable mechanical properties can be obtained. In the fusion welding of titanium Ti6Al-4V, a set of defects occur, including structural discontinuities, epitaxial growth and large beta grains, the absorption of oxygen, nitrogen, and hydrogen, as well as pitting, causing its replacement with friction stir welding. Since in the friction stir welding process, the material undergoes thermodynamic operations, the microstructure and integrity of the material change, considerably affecting its corrosion properties (Ref 1). The presence of a sticky, hard, stable, and inactive layer of titanium oxide (TiO2) on the titanium surface causes this alloy to be notable as an excellent candidate for corrosive environments. The alpha prime (a¢) phase of pure commercial titanium with a fine needle-like (acicular-like) appearance structures has a poor corrosion behavior (Ref 2). The extensive seg
Data Loading...
