Directing against the failure problems of bolts on the reheated steam control valve of the steam turbine in one power plant

such as cracking

breakage

and snapping of threads etc.

comprehensive analysis has been carried out from aspects of chemical composition

mechanical performance

and metallorgraphic structure of bolts' materials

as well as macro-scopic and microscopic observations of the fracture.Results show that the main cause leading to bolt group failure is the lower comprehensive mechanical performance

in addition

the wrong material used

the redistribution of stress

and the improper tightening process etc.

make the bolt failure to be accelerated.For this

corresponding recommendations have been put forward.