Tensile Flow Behaviour and Fracture Studies of Beta Titanium Alloys at Elevated Temperatures

Tensile testing on metastable beta alloy with various microstructures was carried out in this study. Beta 21S is a metastable alloy that exhibits a wide range of material characteristics depending on the processing techniques used. Three different sheets that have been used in this paper which has the same substance but three different microstructures. At a strain rate of 0.001/s, the tensile test was done on a single sheet at five different temperatures. The sheet has developed varied microstructures, the tensile nature of the material varies the alloy’s characteristics. Mechanical characteristics for 400°C, 500°C, 600°C, and 7000°C are described for 21S sheets. The alpha phase sheet elongated at room temperature by 1-3 %, whereas the pure beta phase sheet elongated by 22-24 %. There is a significant improvement in the extension of the sheet with the variation in temperature for the alpha phase. The elongation of the pure beta phase does not alter as the temperature rises. The fracture surface was tested at all temperatures and the optimal temperature for forming the sheet has been determined

CARTECH Ti-3Al-8V-6Cr-4Mo-4Zr (BETA C)

CarTech Ti-3Al-8V-6Cr-4Mo-4Zr, also known as Ti-3-8-6-4-4 and Beta C, is a metastable beta alloy used in the solution heat treated or solution heat treated and aged condition. It is appropriate for applications where very high strength, minimum weight, and corrosion resistance are important. Ti-3Al-8V-6Cr-4Mo-4Zr has gained in popularity among beta alloys because it is easier to melt and process, exhibiting low segregation, good workability, and good heat-treating properties. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Ti-172. Producer or source: Carpenter Technology Corporation.

ATI 3-2.5

ATI 3-2.5 is a Titanium-3Aluminum-2.5Vanadium alloy that has higher strength than unalloyed titanium and is much more amenable to cold working than Ti-6Al-4V. This near-alpha, alpha-beta alloy is generally used in the annealed or cold-worked and stress-relieved conditions. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Ti-166. Producer or source: ATI.

Development of High Temperature Oxidation Resistant Titanium Alloy Arconic-THORTM

The aeroengine and airframe applications of titanium alloys are often limited by their insufficient oxidation resistance to the aggressive environment at higher temperatures. A high temperature oxidation resistant titanium alloy (Arconic-THORTM) has been developed. This alloy is an alpha-beta alloy with superior oxidation resistance and improved creep resistance. The oxidation weight gain of Arconic-THORTM is much lower than Ti-6242 and Beta 21s in the temperature range up to 750˚C. The room and elevated temperature properties of Arconic-THORTM are comparable to those for Ti-6242. Arconic-THORTM also shows superior, post-thermal-exposure tensile strength, ductility, and fatigue properties, and is capable of being cold formed, hot formed, and superplastic formed, welded and heat treated to different product geometries. The microstructures and mechanical properties for sheet manufactured from the production ingots are presented and discussed in this study.

Fatigue Life Enhancement of Titanium Alloy by the Development of Nano/Micron Surface Layer Using Laser Peening

Ti-15V-3Cr-3Al-3Sn (Ti-15-3) is a metastable beta alloy which is considered to be a potential alternative for Ti-6Al-4V alpha+beta alloy for aerospace applications, especially for sheet products. This paper describes the work carried out to enhance the fatigue life of Ti-15-3 in an economical way by means of laser peening without coating (LPwC) using Nd:YAG laser operating at a power density of 5 GW cm-2. In order to have a sufficient bulk hardness and high compressive stresses on the surface, as-received beta solution treated (ST) Ti-15-3 was subjected to aging (520 °C/10 h/Air-cooled) and then to LPwC. Laser peening induced a notable increase in Ra (arithmetic mean roughness), which was measured using MAHR GD-120 profilometer. The Electron Back Scatter Diffraction (EBSD) analysis of the aged sample (STA) revealed a significant increase in the alpha precipitation (20 vol%), and this led to a substantial increase in the hardness (~40%) and UTS (~50%). In addition to this, peening of aged (STA+LPwC) sample resulted in a considerable increase (~12%) in near-surface microhardness and compressive residual stress (maximum stress of -195 MPa at a depth of 150 μm). This increase in compressive stress and microhardness led to an enhancement in the fatigue life of the STA+LPwC sample by 210% when compared to STA sample. In spite of high surface roughness induced by the LPwC, fractography studies revealed that crack initiation was independent of surface roughness.

Corrosion behaviour of the titanium beta alloy nanotubular surface in the presence of fluoride ions

The titanium bioactivity could be increased by surface nanostructuring. Titanium alloys are using for dental implants manufacturing. It represents a specific problem because of using of the dental treatments with high concentration of fluoride ions and with acidic pH. The corrosion resistance of nanostructured surface of titanium beta alloy in environments with fluoride ions was examined by common electrochemical technique. The electrochemical impedance measurement showed high corrosion resistance in physiological solution. The fluoride ions have expected negative influence on corrosion behaviour of the layer. The nanotube bottom was preferentially attacked which resulted in layer undercoroding and its detachment.

Friction Stir Processing Trials of SP-700 (Ti-4.5Al-3V-2Fe-2Mo) Titanium Alloy

Superplastic titanium alloy (SP-700 with nominal composition of Ti-4.5Al-3V-2Fe-2Mo) an alpha-beta alloy, with a beta-rich fine microstructure and excellent superplastic formability has wide applications in aerospace components, metal wood heads, tools, automotive components. However, very little information is available regarding friction stir processing (FSP) characteristics of this alloy. This study discusses the trials of FSP of this highly formable titanium alloy. Results are discussed in terms of hardness and temperature measurements and microstructural observations.