**Constitutive Equation of GH4169 Superalloy and Microstructure Evolution Simulation of Double-Open Multidirectional Forging**

**Yongbo Jin 1,2, Hao Xue 1, Zheyi Yang 1, Lili Zhang 3, Chunxiang Zhang 2, Sirui Wang 1 and Junting Luo 1,2,\***


Received: 4 September 2019; Accepted: 24 October 2019; Published: 25 October 2019

**Abstract:** This paper presented a double-open multidirectional forging with relatively few deformation passes and a uniform deformation. The constitutive equation and dynamic recrystallization model of the GH4169 superalloy were identified based on a thermal compression test and imported into Deform simulation software. The microstructure evolution law of GH4169 superalloy undergoing double-open multidirectional forging was simulated. The evolution of the recrystallization volume fraction and recrystallized grain size of the GH4169 superalloy during double-open multidirectional forging was obtained. Both higher temperatures and more passes were found to produce more complete recrystallization and smaller recrystallization grain size. At the maximum temperature studied, 1000 ◦C, with nine passes, the recrystallization volume fraction exceeded 95%, and the recrystallized grain size reached 3–5.5 μm.

**Keywords:** constitutive equation; GH4169 superalloy; microstructure evolution simulation; multidirectional forging
