Effect of Annealing Temperature on Punching Shear Strength of Nb-A286 Superalloy
In the present research, effects of cold rolling and subsequent annealing on the microstructure and shear response of A286 superalloy were investigated. The present report has begun with a discussion on the alloy when it is cold-worked, with special emphasis on the formation of deformation bands. Next, following an annealing process in the temperature range of 900–1050 °C for 2–20 min, we have proceeded to depict static recrystallization, grain growth and precipitation phenomena. The mechanical properties evolution and the fracture surface analysis showed the occurrence of softening phenomenon in the temperature range of 900–950 °C as a result of either partial or full recrystallization. At 1050 °C, precipitation of Nb-rich phase caused an increase in ultimate shear strength of the alloy. Additionally, shear punch fracture surfaces of the samples annealed at 900–1000 °C represented dimple mode, with grain boundary decohesion being seen to occur at higher temperatures.