Though macroscopic inspection

chemical composition analysis

mechanical performance test

metallographic examination

energy spectrum analysis

and fracture analysis etc.

the bolt fracture failure of high-pressure inner cylinder for steam turbine no.2 in Xiangfan Power Generation Co Ltd has been analysed

the results show that the impact toughness of the bolt to be obviously lower

and the material of the bolt to be fragile

the fracture extended from thread root toward another side

having remarkable feature of brittle fracture.