Effect of Heat Treatments on the Relief of Residual Stresses and Recrystallization Behaviour of Shot Peened ZR-2.5NB Pressure

Author:  Amouzouvi, Styles, Clegg, McCooeye, Zhao, Koul
Source:  Conf Proc: ICSP-6, (p.166-173)
Doc ID:  1996063
Year of Publication:  1996
Abstract:  
The effect of heat treatment on stress relief and recrystallization behaviour of shot peened Zr-2.5Nb pressure tube material was investigated to understand the mechanisms involved in the significant improvement in long term corrosion and deuterium uptake resistance of this material after shot peening. Shot peened Zr-2.5Nb material was found to recrystallize at temperatures as low as 400 deg C after 24 h stress relief. Residual stress measurements by x-ray diffraction technique show that the residual stess relief a 300 deg C is fast, and the stress relief is nearly completed in less than 5 h. It was concluded that the improvement in corrosion and deuterium uptake resistance in sht peened Zr-2.5Nb material is not due to the presence of compressive residual stresses. The Microstructural changes due to shot peening and post peening heat treatment (the destruction and decomposition of the B-phase networks, and the fine and uniform dispersion of this phase) are responsible for the improvement in the corrosio and deuterium uptake resistance of this material.