J. N. Wolk, C. E. Davis, Naval Surface Warfare Center, Carderock Division, Bethesda, MD; L. Salamanca-Riba, University of Maryland, College Park, MD
The Navy after next is exploring smaller, faster, lightweight ships for more rapid response. As weight critical platforms become increasingly important for future combatants, titanium alloys are potential candidates for naval applications because of the high strength to density ratio. Titanium alloys are currently joined through conventional welding with strict shielding gas requirements to prevent contamination. Friction stir welding (FSW) is a possible alternative to conventional joining of titanium. FSW uses a non-consumable tool to generate frictional heat to plastically deform and mix metal to form a consolidated joint. Because FSW does not reach melting temperatures, this also provides reduced distortion from residual stresses and heat due to melting during traditional gas metal arc welding (GMAW). This study examines the microstructural evolution of FSW of Ti-5111. Ti-5111 was developed as a lower cost alternative to Ti-621/0.8Mo. A near alpha alloy, Ti-5111 has a composition of 5%Al-1%Sn-1%Zr-1V-0.8% Mo, and specified UTS of 100ksi with 10% elongation. Friction stir welds of Ti-5111 were successfully fabricated and examined in three orientations through the use of optical microscopy and transmission electron microscopy. Thermomechanical simulations of the friction stir welds were also performed.
Summary: This study examines the microstructural evolution of FSW of Ti-5111, a near alpha alloy with a composition of 5%Al-1%Sn-1%Zr-1V-0.8% Mo. Friction stir welds of Ti-5111 were successfully fabricated and examined in three orientations through the use of microscopy.
