In order to determine the cause leading to fracture occurred on screwed hanging rod of PHB type constant force suspension bracket in one power plant

macroscopic analysis

mechanical performance test

metallographic examination

and scanning electronic microscope test have been carried out for the fractured screwed hanging rod.Results show that the main cause resulting in fracture of the screwed hanging rod is the very low impact toughness of material

being extremely brittle material

and far lower than the allowed value specified in the standards

hence

the fracture occurred under action of alternating tensile load and bending load.Besides

the PHB type suspension bracket has structure defects in design

it is recommended to amend and perfect the standard JB/T8130.1-1999.