Experimental study on the mechanical strength and dynamic strain aging of Inconel 617 using small punch test

In the present work, the mechanical strength and deformation characteristics of Inconel 617 were studied using small punch test at different temperatures and deformation rates. As temperature increases, small punch characteristic parameters decreases and three temperature intervals are defined. An important conclusion here is that dynamic strain aging phenomenon can be found at a high-temperature small punch deformation of Inconel 617 in a multi-axial stress state. Due to serration plastic flow, small punch characteristic parameters of Inconel 617 appear no significant changes in the temperature range from 300 °C to 700 °C. To describe dynamic strain aging behaviour, serration type, critical displacement, and maximum load drop are discussed. As the temperature increases or deformation rate decreases, the serration type of the load–displacement curve gradually changes from Type A to Type C, and maximum load drop increases. Meanwhile, critical displacement displays normal and inverse behaviour at different temperature ranges. Based on the deformation characteristics analysis, the mechanical strength of Inconel 617 in different aging states was analysed. Finally, the relationship between the mechanical strength, small punch characteristic parameters and hardness was established. The results show that small punch test is an effective method for reasonably estimating the mechanical strength and dynamic-strain aging behaviour of Inconel 617.