Spring is one of basic component in machinary. There are kinds of springs,according to their shapes, there are coil spring, leaf spring, belleville spring, spiral spring,ect. According to load-bearing charateristics, there is compression spring, torsion spring, tension spring, ect. The stresses which spring withstand: bending stress, torsion stress, tension and compression stress, combined stress, ect.
     
The main failure modes of spring are fracture, distortion, relaxation and wear. In which the most important are fracture and distortion.
     
1, brittle fracture: most of fracture belong to brittle fracture. Only when the work temperature is higher, it might Appear.in engineering, fatigue fracture,stress corrosion fracture,hydrogen embrittlement fracture,ect are called brittle fracture.
    
2, fatigue fracture: under cycle loading, it caused spring fracture.
    
3, stress corrosion fracture: affected by tensile stress together with corrosion medium, it caused spring fracture.
     
4,corrosion fatigue fracture: affected by cyclic load together with corrosion medium, it caused spring fracture.
     
5, hydrogen brittleness,cadmium embrittlement: Higher impurities in the material, it caused spring fracture.
     
6, wear: wear is divided into abrasive wear, fatigue wear and corrosive wear.