Effect of Glass Lubricant on the Hot Extrusion of Inconel 625 Alloy

A combination of numerical simulations and experiments was used to study the influence of glass lubricant on the hot extrusion of Inconel 625 alloy. The results showed that the glass lubricant left a large amount of abrasive debris and furrows on alloy surface, which produced different friction states. The use of a lubricant changed the alloy microstructure, decreasing the grain size, the high-angle grain boundaries (HAGBs), and the dynamic recrystallization volume fraction of the sample with lubricant. The temperature increase due to deformation and friction heat significantly affected the stress, strain, and flow rate of the billet during extrusion. The uneven friction states generated excessive local frictional heat, making the billet prone to overheating and crack initiation. The frictional heat caused local grain size and stress differences in the billet, causing further expansion of cracks.