Citation: Gao, J.; Yang, S.; Zhao, P.; Yang, S.; Li, J.; Liu, W.; Zhang, C. Optimization of Process Parameters for ESR Waspaloy Superalloy by Numerical Simulation. Materials 2022, 15, 7483. https://doi.org/10.3390/ ma15217483 Academic Editor: Alexander Yu Churyumov Received: 19 September 2022 Accepted: 22 October 2022 Published: 25 October 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). materials Article Optimization of Process Parameters for ESR Waspaloy Superalloy by Numerical Simulation Jinguo Gao 1,2 , Shulei Yang 1,2 , Peng Zhao 1,2 , Shufeng Yang 1,2 , Jingshe Li 1,2 , Wei Liu 1,2, * and Changle Zhang 1,2 1 School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China 2 State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China * Correspondence: liuwei@ustb.edu.cn Abstract: A transient numerical simulation method is used to investigate the temperature field, velocity field, and solidified field of large-size Waspaloy superalloy during the electroslag remelting (ESR) process. The effects of melting rate, filling rate, and thickness of the slag layer on the molten pool shape and dendrite arm spacing evolution have been discussed. The temperature in the slag pool is high and relatively uniformly distributed, the temperature range is 1690–1830 K. The highest temperature of the melt pool appears in the center of the slag–metal interface, 1686 K. There are two pairs of circulating vortices in the slag pool, the side vortices are caused by the density difference caused by the buoyancy of the slag, the center vortices are the result of the combined action of electromagnetic force and the momentum of the falling metal droplets. The molten pool depth and dendrite arm spacing increase with the increase of melting rate, but the slag layer thickness and electrode filling rate have little effect on the molten pool morphology and dendrite arm spacing if the droplet effect is not taken into account. Considering the morphology and depth of the molten pool as well as the size and distribution uniformity of the dendrite arm spacing, it is appropriate to maintain the melting rate at 5.8 kg/min for the industrial scale ESR process with the ingot diameter of 580 mm. Keywords: numerical simulation; electroslag remelting; waspaloy superalloy; molten pool; dendrite arm spacing 1. Introduction Waspaloy superalloy is a γ ′ phase precipitation reinforced nickel-based wrought superalloy [1,2]. The alloy has high strength and sufficient toughness at 650 ◦ C~700 ◦ C simultaneously, and is widely used in aerospace, petrochemical and other fields. In recent years, with the development of the performance stability of turbine discs for advanced aero- engines, the purity, grain size and strength of Waspaloy alloys are gradually demanding [3]. The melting process of Waspaloy has gradually changed from VIM (vacuum induction melting) to VIM + VAR (vacuum arc remelting), and then to VIM + ESR + VAR [4–7]. Among them, ESR provides high purity and high uniformity of electrode ingots for VAR, which is a vital part of metallurgical quality improvement [8,9]. It is essential to optimize ESR process parameters to achieve metallurgical quality improvement of Waspaloy. However, a series of complex and coupled physical phenomena are involved in the process of ESR [10,11]. Moreover, the equipment, process and test measurement methods used in the whole smelting process are more complex. For large-scale industrial electroslag ingot production, the traditional trial and error method not only costs very much, but also many important internal operation parameters are difficult to obtain [12]. With the rapid development of computer application technology and the continuous progress of numerical simulation methods, the mathematical model simulation method can be used Materials 2022, 15, 7483. https://doi.org/10.3390/ma15217483 https://www.mdpi.com/journal/materials