Reasons Analysis on Fracture of Elevator Drive Shaft

Fracture failure happened to an elevator drive shaft with material of Q345Asteel after service for a short time,and the fracture reasons were analyzed by means of chemical compositions analysis,metallographic examination,hardness test and scanning electronic microscope analysis.The results show that fracture property of the drive shaft was multisource rotary bending fatigue fracture.The fracture sources located at the stress concentrated heat affected zone of traction wheel and the actuating shaft welded construction.At the same time, there were obvious machining marks and hard and brittle martensite at the fracture source,which further intensified the stress concentration.So cracks emerged and fracture happened under the action of the twisting force.