Recrystallization and Associated Twinning Evolution in Nickel-Based GH4141 Superalloy During Annealing
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JMEPEG (2020) 29:7940–7951 https://doi.org/10.1007/s11665-020-05315-6
Recrystallization and Associated Twinning Evolution in Nickel-Based GH4141 Superalloy During Annealing Hongliang Liu, Na Ta, Min Xu, Ye Meng, Guohua Xu, and Lei Zheng Submitted: 30 August 2020 / Revised: 14 October 2020 / Published online: 13 November 2020 The GH4141 superalloy with 20, 40 and 55% cold deformations is annealed at 1080, 1120 and 1180 °C for 3-25 min to study the recrystallization and twinning behavior. The migration rate of grain boundaries increases significantly as the temperature increases in the range of 1080-1180 °C. After recrystallization, the hardness of the alloy is obviously reduced, and the recrystallized grains are randomly oriented without preferred orientation. The orientation imaging microscopy maps indicate that large amounts of R3 twin boundaries caused by the stacking faults appear in recrystallized grains. On one hand, the fraction of R3 boundaries after short time annealing has increased with the increase of temperature, meaning that the higher temperature contributes to the faster migration rate of grain boundaries and thus promotes the formation of stacking faults and twin boundaries before full recrystallization. On the other hand, the density of R3 boundaries has gradually decreased with the increase of grain size due to the annihilation and rare formation of twin boundaries after full recrystallization. The twinning evolution can be explained using the classical growth accident model. Keywords
annealing, nickel-based superalloy, stacking faults, twinning, R3 boundaries
1. Introduction Owing to the excellent combinations of high temperature stability and mechanical properties, nickel-based superalloys have been widely used in aerospace industry (Ref 1-4). Cold deformation is an important processing method for superalloys, and the parts that processed at room temperature always possess good surface finish and dimensional accuracy (Ref 5, 6). Therefore, the cold-rolled strips and cold-drawn wires of nickel-based superalloys have been extensively used to manufacture the critical high-temperature components (Ref 7, 8). In order to obtain the excellent performances, the microstructure of superalloys should be controlled precisely during processing. It is believed that the properties of superalloy parts are strongly dependent on their final microstructures, and fine uniform grain sizes are especially helpful to improve the mechanical strength. In general, cold deformation and subsequent annealing treatment are effective methods to obtain the fine equiaxed microstructure (Ref 9). Besides, the matrix of cold deformed superalloys is unstable due to the existence of high stored strain energy and dense micro-defects. Therefore, a suitable annealing treatment is often performed after cold deformation to improve
Hongliang Liu, Na Ta, Min Xu, and Lei Zheng, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China; Ye Meng, Institute of Advanced Materials and Technolo
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