Tensile deformation behaviour of forged disc of IN 718 superalloy at 650 °C

The tensile properties of forged disc of IN 718 superalloy were evaluated in the strain rate regime between 10⁻⁴ and 10⁻² s⁻¹ at 650 °C. Flow oscillations were observed in stress–strain curves in the strain rate regime investigated. These flow oscillations were identified as strain increments attributed to twining mechanism at all the strain rates. However, presence of well defined serrations, temperature insensitivity of yield strength and increase in strain hardening exponent confirmed the occurrence of dynamic strain aging at 10⁻³–10⁻² s⁻¹ strain rates. Deformation behaviour was observed to be planer in nature. Fracture features remained same (transgranular) in the strain rate regime studied.