Mechanical properties and microstructure evolution during dynamic compression and cutting of nickel-based superalloys

Abstract

Superalloy GH4169 has been widely used on account of its excellent property. However, the microstructure characteristics of the machined surface will be changed significantly because of mechanical-thermal coupling effect after the cutting process, which affects the fatigue performance of key components. To clearly understand the microstructure development of surface layer during machining process, the mechanical behavior and microstructure evolution of GH4169 under high strain rate and high temperature conditions are studied in detail by dynamic compression tests. The peak stress can be improved by rising strain rate and decreasing temperature. Cutting experiments show that the depth of low angle grain boundaries distribution and plastic deformation in the machined surface layer are improved by rising cutting parameters. The degree of twin boundaries deviation from the ideal misorientation increases by improving cutting parameters. In addition, the geometrically necessary dislocation density increases first and then decreases by increasing distance from the machined surface. Furthermore, the cutting simulation model based on dynamic compression tests are established.