Microstructural Characterization of a Prototype Titanium Alloy Structure Processed via Direct Laser Deposition (DLD)
- PDF / 848,820 Bytes
- 9 Pages / 593.972 x 792 pts Page_size
- 35 Downloads / 218 Views
ODUCTION
THE high strength-to-weight ratio and damage tolerance characteristics of titanium alloys makes these systems attractive for applications such as large structural casing components, struts, and vanes in the compressor sections of gas turbine engines (Figure 1). Typically, such structures have integrated functionality, combining the needs to resist pressure loading with the requirement to provide local stiffening for attachment features while minimizing excess mass. Creating loadcarrying sections as webs, flanges, and hollow features is possible using subtractive manufacturing and fabrication or via casting with the use of cores; however, these methods show increasing cost and technological complexity[1] as the complexity of the geometry increases together with the requirements for precision on finelength scales. Using an additive manufacturing technique changes the balance point of these relationships,[2] allowing potentially greater design sophistication[3] in shorter lead-time components. Moreover, the flexibility of the approach allows opportunities for economic savings through reduced processing operations, reduced component count, or the use of simpler, lower cost preforms. In particular, additive processing can reduce the number of joints within complex structures. This can enable designs with increased stiffness while reducing the associated mass and feature cost of the joint regions. DANIEL CLARK, Specialist Welding Engineer, is with Rolls-Royce plc, Derby DE24 8BJ, United Kingdom. MARK T. WHITTAKER, RCUK Research Fellow, and MARTIN R. BACHE, Professor, are with the Materials Research Centre, College of Engineering, Swansea University, Singleton Park, Swansea SA2 8PP, United Kingdom. Contact e-mail: [email protected] Manuscript submitted July 12, 2011. Article published online November 10, 2011. 388—VOLUME 43B, APRIL 2012
Near-net-shape fabrication is a desirable outcome both through the substantial reduction of time spent in material removal, especially for complex forms, relative to machining intensive routes and also through the efficiency in material usage, particularly for high-cost alloys. Castings can offer similar opportunities although still requiring mold making and core removal. However, the key differences are in the requirements for the development of associated tooling such as patterns and metal running systems, particularly for intricate forms. Many different types of additive processes are available that employ a variety of consumable and fusion techniques that display varying characteristics with respect to forming complexity, surface control, volumetric deposition rate, heat accumulation, and feature resolution scale. Zheng et al.[4] conducted a comparative evaluation of microstructures resulting from welding using tungsten inert gas (TIG), plasma, and laser-welded Ti 6Al 4V. All the processes produced weld beads without visual evidence of oxygen contamination when using local shielding arrangements. The titanium alloy showed differences in microstructure and hardness when welded u
Data Loading...
