Effect of Welding Parameters on the Liquation Cracking Behavior of High-Chromium Ni-Based Superalloy
- PDF / 2,131,275 Bytes
- 10 Pages / 593.972 x 792 pts Page_size
- 7 Downloads / 244 Views
ASM International 1059-9495/$19.00
Effect of Welding Parameters on the Liquation Cracking Behavior of High-Chromium Ni-Based Superalloy Amirhossein Mashhuriazar, Hamid Omidvar, C. Hakan Gur, and Zainuddin Sajuri Submitted: 28 March 2020 / Revised: 4 October 2020 / Accepted: 17 October 2020 Gas turbine blades working under extremely harsh operating conditions are made of superalloys. These superalloys are exposed to various damage mechanisms, which wear them out gradually. Welding is often preferred to repair the damaged components for cost minimization. This study aimed to investigate the effects of flexural load, heat input, and welding speed on the weldability and intergranular liquation cracking of high-chromium Ni-based superalloy. For this purpose, a series of Sigmajig tests designed based on the Taguchi method with L4 array, as well as microstructure investigations and residual stress measurements, were performed. The results showed that the microstructures of heat-affected zones (HAZs) were highly susceptible to cracking during the welding process, and all of these cracks appeared in the HAZ and grew perpendicular to the melting zone along grain boundaries. Flexural load contributed the most substantial impact (82%) on crack propagation compared with the 9.7 and 9.2% impacts of welding speed and welding heat input, respectively. We found that the lowest flexural load, welding speed, and heat input are the best welding parameters to reduce the total crack lengths at the welded area of high-chromium Nibased superalloy. Keywords
flexural load, heat input, Inconel 939, superalloy, welding, welding speed
1. Introduction Gas turbine blades are typically made of superalloys to provide a long service life with a satisfactory performance under high-temperature and high-stress operating conditions (Ref 1-3). High-chromium nickel-based superalloy, Inconel 939 (IN-939) is a popular choice in the manufacturing of the hightemperature components of a gas turbine. IN-939 is a precipitation-hardened Ni-based superalloy with excellent properties, such as high-temperature mechanical properties and high resistance to corrosion and oxidation (Ref 4). Extremely harsh operating conditions damage gas turbine blades through various mechanisms, such as surface erosion (Ref 5), hot corrosion (Ref 6), high-temperature fatigue cracking (Ref 7, 8), oxidation, and sulfidation (Ref 9). The manufacturing of superalloy components is costly and rather difficult; thus, the repair and reassembly of damaged parts might be more practical and cost-effective than replacing them (Ref 10). Moreover, the components have complex geometries, which are impossible to manufacture via casting or forging
Amirhossein Mashhuriazar and Hamid Omidvar, Department of Materials and Metallurgical Engineering, Amirkabir University of Technology, Tehran 1599637111, Iran; C. Hakan Gur, Department of Metallurgical and Materials Engineering, Middle East Technical University, Ankara 06800, Turkey; and Zainuddin Sajuri, Department of Mechanical and Manufacturing Engineerin
Data Loading...
