Microstructure and mechanical properties of nickel-based superalloy GH4037 parts formed by thixoforming

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2020-04, Vol.780, p.139196, Article 139196
• Main Authors: Xiao, Guanfei, Jiang, Jufu, Wang, Ying, Liu, Yingze, Zhang, Ying
• Format: Article
• Language: English
• Subjects: Elongation; Extrusion; Forging; Grains; Liquid phases; Mechanical properties; Microstructure; Nickel; Nickel base alloys; Nickel-based superalloy; Recrystallization; Semi-solid processing; Superalloys; Surface properties; Temperature; Temperature effects; Tensile properties; Tensile strength; Thixoforming
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2020.139196

Semi-solid processing has unique advantages over traditional forging and casting routines. However, there is little research of semi-solid processing on nickel-based superalloys. In this paper, semi-solid thixoforming of nickel-based superalloy was carried out for the first time. Specimens of extruded GH4037 alloy were heated directly to a semi-solid temperature ranging from 1350 °C to 1390 °C and soaked for 30 min, and then transferred to a preheated die for thixoforming. GH4037 parts with complete filling status and good surface quality were thixoformed successfully at 1370 °C, 1380 °C and 1390 °C, respectively. The effect of temperature on microstructure evolution and mechanical properties of thixoformed GH4037 parts was investigated. The results indicated that fine recrystallized grains were obtained in the center of GH4037 parts formed at 1350 °C, while the microstructure was composed of large solid grains and partial liquid phases in the edge region. Homogeneous semi-solid microstructure consisting of solid grains and liquid phases was obtained at high temperatures. Excellent tensile properties were obtained at 1350 °C, but incomplete filling status affected the quality of GH4037 part. Both the tensile strength and elongation were poor at 1370 °C. The optimum forming temperature was 1380 °C, GH4037 part formed at this condition had complete filling status, good surface quality, uniform microstructure and good mechanical properties. This work has demonstrated the feasibility of thixoforming a nickel-based superalloy component with high performance. •Thixoforming of nickel-based superalloy GH4037 was carried out for the first time.•Parts with good surface quality were formed successfully at suitable temperatures.•Homogeneous semi-solid microstructure of GH4037 part was obtained at 1380 °C.•Some carbides were identified at grain boundaries and in the eutectic regions.•The optimum temperature for thixoforming of GH4037 alloy was 1380 °C.