D. Arrell

Bio: D. Arrell is an academic researcher. The author has contributed to research in topics: Filler metal & Heat-affected zone. The author has an hindex of 1, co-authored 1 publications receiving 295 citations.

Nickel based superalloy welding practices for industrial gas turbine applications

Abstract: The continued drive for increased efficiency, performance and reduced costs for industrial gas turbine engines demands extended use of high strength-high temperature capability materials, such as nickel based superalloys. To satisfy the requirements of the component design and manufacturing engineers, these materials must be capable of being welded in a satisfactory manner. The present paper describes the characteristic defects found as a result of welding the more difficult, highly alloyed materials and reviews a number of welding processes used in the manufacture and repair of nickel alloy components. These include gas tungsten arc (GTA) and electron beam (EB) welding, laser powder deposition and friction welding. Many of the more dilute nickel based alloys are readily weldable using conventional GTA processes; however, high strength, precipitation hardened materials are prone to heat affected zone and strain age cracking defect formation. A number of factors are found to affect the propensity f...

Aerospace applications of laser additive manufacturing

Abstract: Additive manufacturing (AM) has been used in aerospace applications from the beginning. It not only plays a role as a rapid prototyping technology for saving capital and time during the product development period but also brings profound influences on product design, direct part fabrication, assembly, and repair in the aerospace industry. Because of recent developments, AM has rapidly become a strategic technology that will generate revenues throughout the aerospace supply chain. In this chapter, we analyze the characteristics of aerospace components favoring AM, discuss different aerospace applications benefit from different AM processes, and describe the repair applications for aerospace components. Examples of aerospace applications both from commercial and academia areas are also analyzed. Finally, this chapter discusses the challenges of applying AM to the aerospace industry and potential future aerospace applications.

Additive manufacturing of Ni-based superalloys: The outstanding issues

Abstract: There is increasing interest in the use of additive manufacturing (AM) for Ni-based superalloys due to their various applications in the aerospace and power-generation sectors. Ni-based superalloys are known to have a complex chemistry, with over a dozen alloying elements in most alloys, enabling them to achieve outstanding high-temperature mechanical performance as well as oxidation resistance when processed using conventional routes (e.g., casting and forging). Nonetheless, this complex chemistry results in the formation of various phases that could affect their processability using AM, resulting in cracking. Furthermore, due to the directional solidification and rapid cooling associated with AM processes, the alloys experience significant anisotropy due to the epitaxially grown microstructure, as well as the residual stresses that can sometimes be difficult to mitigate using thermal postprocessing techniques. This article highlights the outstanding issues in Ni-based superalloys AM processing, with special emphasis on defect formation mechanisms, process optimization, and residual stress development.