Features of Permanent Joints of Titanium (α+β)-Alloys Obtained by Friction Stir Welding Using a Nickel Superalloy Tool

Abstract

Titanium alloys are widely used in industry, especially (α+β)-alloys, among which Ti-6Al-4V alloy is the most popular one. Another common alloy that often appears in patents for titanium products is Ti-4Al-3Mo-1V. Here, we investigate welded joints of (α+β)-alloy Ti-4Al-3Mo-1V obtained by friction stir welding (FSW) using a working tool made of nickel-based heat-resistant alloy ZhS6U. In addition, welded joints of Ti-6Al-4V and Ti-4Al-3Mo-1V alloys with similar mechanical characteristics were considered. Mechanical tests showed that the obtained joints had a tensile strength greater than that of the base metal. This result was achieved in the welding mode where the axial load was varied during the welding process. X-ray diffraction analysis revealed a change in the phase structure of the welded joint.

Keywords

• friction stir welding
• titanium alloys
• weld strength
• fatigue
• microhardness
• X-ray structure analysis