A comparison of experimental and computer-simulated isothermal upset forging of IMI685 titanium alloy

Abstract

The deformation characteristics of IMI685 titanium alloy in unlubricated-die upset forging under isothermal conditions have been investigated in both the β and (α + β) phase fields in the temperature ranges 1025–1075 °C and 950–1000 °C respectively and in the strain rate range 0.09 – 0.005 s −1. Finite-element methods were used with a finite-element code, ABAQUS, to simulate the deformation processes and analyse the deformation distribution of the specimens. The deformation distribution and microstructural features of the deformed specimens were also studied by optical and electron metallography. The deformation patterns obtained from finite-element analysis are in good agreement with those obtained from metallography. Undeformed grains and grains with little deformation were observed in areas coinciding with regions having lower values of the effective plastic strain in finite-element analysis. In areas in which higher values of the effective plastic strain were obtained, the structure featured elongated grains for β forged specimens and spheroidized α grains for (α + β) forged specimens. However, changing the strain rate did not appear to have a major influence on the deformation distribution in either of the phase fields studied. It was also concluded that the degree of inhomogeneous deformation in β forging is much lower than that in (α + β) forging.