The Effect of Hot Oscillatory Pressing Temperature on Microstructure and Tensile Behavior of Powder Metallurgy Superalloy

The effect of the hot oscillatory pressing (HOPing) temperature on the microstructure and tensile behavior of the powder metallurgy superalloys was investigated and compared with those of the hot pressed (HPed) sample. The results show that as the HOPing temperature rises, the pores and residual dendrites disappear, the grain size becomes coarser and more uniform, the prior particle boundaries (PPBs) scale decreases; the yield strength decreases gradually; the ultimate tensile strength and elongation increase first and then decrease; the tensile property stability gradually increases. The highest ultimate tensile strength and elongation of 1403 MPa and 35%, respectively, are reached when the HOPing temperature is 1160 degrees C. The fracture mode of the sample hot oscillatory pressed (HOPed) at 1160 degrees C is a transgranular and intergranular mixed fracture. Compared with the HPed sample, room temperature tensile properties of the HOPed sample improve remarkably due to the reduced size and density of PPBs precipitates.