Corrosion Behavior of Friction Stir-Processed and Gas Tungsten Arc-Welded Ti-6Al-4V
- PDF / 1,350,354 Bytes
- 10 Pages / 593.972 x 792 pts Page_size
- 50 Downloads / 189 Views
INTRODUCTION
TI- 6AL-4V is the most widely used a + b titanium alloy, accounting for more than 45 pct of the total titanium applications.[1,2] This alloy possesses a wide range of attractive properties including a high specific strength, an excellent fatigue strength, a good corrosion resistance, and an acceptable biological compatibility. These desirable properties have allowed its use for aerospace, chemical, and biomaterial applications. Welding is an important manufacturing process for the joining of large or complex shaped structural components in different applications. Fusion welding of wrought Ti-6Al-4V is associated with some disadvantages, such as a microstructural discontinuity; epitaxial growth and coarse beta grains[3]; adsorption of oxygen, nitrogen, and hydrogen[4]; and porosity.[5] These issues have motivated recent investigations to replace traditional fusion welding of Ti by solid-state joining processes such as friction stir (FS) welding. FS welding is a relatively new joining process[6] that has been applied successfully to aluminum alloys,[7–9] magnesium alloys,[10] and nickel-aluminum-bronze alloys.[11,12] More recently, the application of FS welding to titanium alloys has generated considerable interest.[13–15] However, the severe plastic deformation during thermomechanical processing associated with FS MASOUD ATAPOUR, formerly Visiting Scholar, Department of Materials Science and Engineering, Ohio State University, Columbus, OH 43210, is now Graduate Student, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran. ADAM L. PILCHAK, formerly Graduate Student, Department of Materials Science and Engineering, Ohio State University, is now Visiting Scientist, Air Force Research Laboratory, Materials and Manufacturing Directorate, RXLMP, Wright Patterson Air Force Base, OH 45433, and the Universal Technology Corporation, Dayton, OH 45432. G.S. FRANKEL and JAMES C. WILLIAMS, Professors, are with the Department of Materials Science and Engineering, Ohio State University, Columbus, OH 43210. Contact e-mail: [email protected] Manuscript submitted January 22, 2010. Article published online May 26, 2010 2318—VOLUME 41A, SEPTEMBER 2010
welding can result in considerable microstructure changes that significantly can affect the corrosion properties. The presence of a stable, hard, and adherent TiO2 passive film on the surface of titanium alloys makes them an attractive and feasible choice for many applications in corrosive environments.[16] However, the corrosion behavior of titanium alloys depends on the composition and the microstructural details. The presence of acicular structure was found to reduce the corrosion resistance of commercially pure Ti.[17] Similarly, the pitting potential of the Ti-6Al-2Sn-4Zr-2Mo0.1Si alloy in an NaBr solution was reduced by the presence of the Widmansta¨tten structure because of an increased alloying partitioning.[18] A Ti-5 pctTa1.8 pctNb alloy with nodular b in an equiaxed a matrix exhibited superior corrosion resistance compared
Data Loading...
