Causes Analysis of Tread Spalling Defects on Solid Rolled Wheels of SS3B and DF8B Locomotives

In order to find out the causes of locomotive wheel tread spalling defects,the tread spalling of solid rolled wheels were sampled for routine examinations,including the SS3B31024047 wheels of the SS3B locomotive, the DF8B31644017 wheels and the DF8B32774060 wheels of the DF8B locomotive. The macroscopic feature and microstructure of the tread spalling area were analyzed in terms of the TJZJ-01-98,with light micro-scope observation and electronic scanning. The test results show that the surface metal of DF8B32774060 wheels mainly underwent plastic deformation under contact stress,and the spalling was caused by the rolling contact fatigue. However,SS3B31024047and DF8B31644017 wheels' tread spalling was attributed to the plastic deformation layer in the tread spalling area caused by thermal fatigue. Therefore,reduction of the wheel tread spalling caused by the rolling contact fatigue could be achieved by adjustment of the chemical composition of steel,improvement of the heat treatment and tread processing technologies of wheels; and the thermal fatigue spalling can be alleviated by changing the braking mode and optimizing the traction operation.