Microstructure evolution dependence of work-hardening characteristic in cold deformation of a difficult-to-deform nickel-based superalloy

Abstract

The work-hardening characteristic of nickel-based GH4141 superalloy was investigated using uniaxial compression tests with different cold deformations. Prior to compression, the solution treatment was optimized using the dissolving temperature of precipitations, the mean size of grains, and the microhardness of the samples. The typical true strain-stress curve included elastic deformation (ε ≤ 0.03), elastoplastic transition (0.03 ≤ ε ≤ 0.05), and plastic deformation (ε ≥ 0.05) stages. The true strain-stress relationship was formulated on the basis of Tian-Zhang model. During the plastic deformation stage, the true stress gradually increased due to the increase in dislocation slip resistance caused by the formation of dislocation tangles and different boundaries. The hardening rate gradually decreased because of the tardy dynamic recovery, and the decreasing dislocation density increment caused by the formation of grain boundaries.