Hot workability and dynamic recrystallization mechanisms of pure nickel N6
(1. School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, China;
2. State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China;
3. School of Materials Engineering, Lanzhou Institute of Technology, Lanzhou 730050, China)
2. State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China;
3. School of Materials Engineering, Lanzhou Institute of Technology, Lanzhou 730050, China)
Abstract: The hot workability and dynamic recrystallization (DRX) mechanisms of pure nickel N6 were systematically investigated using hot compression tests. Based on hot compression data, the constitutive equation of N6 was developed and its reliability was verified. Its hot processing map was constructed, and combined with microstructural observations, a semi-quantitative response relationship between hot deformation parameters and microstructure was established. The DRX process of N6 is a thermally activated process and particularly sensitive to the strain rate. The optimal hot processing parameters for N6 were determined to be 950-1050 °C and 0.1-1 s-1. Furthermore, it was proven that the dominant nucleation mechanism is discontinuous DRX characterized by grain boundary bulging and twins assisting nucleation, while the continuous DRX characterized by subgrains combined with rotation is an inactive nucleation mechanism.
Key words: pure nickel N6; microstructure evolution; hot workability; processing map; dynamic recrystallization