Effect of Forging Temperature on Microstructure and Mechanical Properties of Nb521 Alloy Bar

Nb521 alloy bars are forged in the temperature range of 1 000-1 400℃. The effects of forging temperature on microstructure and properties are studied by microhardness tester, metallographic microscope, tensile tester and ultrasonic flaw detector. The results show that the higher the forging temperature is, the higher the dynamic recrystallization ratio of the bar is, and the lower the annealing temperature for the subsequent recrystallization. When the forging temperature rises to 1 400℃, the microstructure of the annealed bar is fine and uniform, and the strength and plasticity match the best. Besides, it is confirmed by the ultrasonic flaw detection that increasing the forging temperature is beneficial to the homogenization of the microstructure and can significantly reduce the clutter level.