Cause Analysis on Fracture of Automotive Suspension Spring

The automotive suspension spring was fractured during the quality test. The causes of spring fracture were analyzed by means of macro examination, chemical composition analysis, fracture analysis, metallographic examination, residual stress test, hardness test and durability test. The results show that the spring steel wire and cutter contacted too tightly in cold rolling process, and the heat was generated after the sharp friction, which caused spring tissue deformation and formed a hard and brittle white bright layer. Under the continuous impact loads, the white bright layer first produced cracks, which eventually led to the spring fracture.