The Microstructure, Mechanical Properties, and Corrosion Resistance of a Novel Extruded Titanium Alloy

Abstract

Titanium alloys are widely used in marine engineering and other industries. To broaden their application, a novel (α + β) titanium alloy Ti−6Al−3Mo−2Zr−2Fe was studied in this work. A tube with an outer diameter of 60mm, inner diameter of 38 mm, and length of 500 mm was produced by ingot metallurgy and hot extrusion. The microstructure, mechanical properties, and corrosion resistance of the tube were systematically analyzed. The as−extruded Ti−6Al−3Mo−2Zr−2Fe alloy exhibited a typical duplex microstructure. EBSD observation showed that a strong <10 1¯0>//RD fiber texture of an α phase with a close−packed hexagonal structure was formed in the radial direction. The transformation temperature Tβ was determined to be 880–890 °C. A duplex microstructure with fine α platelets was obtained when the alloy was solution−treated at 850 °C for 1 h and underwent an aging treatment at 550 °C for 6 h. The room−temperature tensile strength and elongation of the aged alloy reached 1081.5 MPa and 6.5%, respectively. The corrosion resistance was tested by open circuit potential and a potentiodynamic polarization curve. The results show that the corrosion resistance of the Ti−6Al−3Mo−2Zr−2Fe alloy was better than that of the commonly used TC4 alloy in both a 3.5% NaCl solution and an acidic solution.