Small punch investigation of the dynamic strain aging behaviour and intermediate temperature embrittlement of Inconel 625

Abstract

In this study, the deformation behaviour and mechanical property evolution of Inconel 625 were studied at different temperatures and deformation rates by using small punch test (SPT). With the increase in the temperature, small punch characteristic parameters decreased, and an approximate platform was found in the temperature range of 300–600 ℃. The dynamic strain aging (DSA) characteristics were observed in the load-displacement curves over a similar temperature range. To analyse the small punch DSA behaviour, the serration types, critical displacement, and maximum load drop were examined. The serration types changed from Type A to Type C when the temperature increased or the deformation rate decreased. The abnormal DSA was proven at around 600 ℃. Then, the influence of the strain rate was analysed and the intermediate temperature embrittlement was found at 600–700 ℃ as the strain rates decreased. Considering the difference between the SPT and the uniaxial tensile test, the influence of stress triaxiality on DSA was discussed. The similar change rule of serration types was presented. SPT was proven to be a reasonable method to evaluate the DSA behaviour which could replace uniaxial tensile test.