Aiming at a batch of failed needle valve couples,the failure mechanism is analyzed by macroscopic detection,SEM and EDS detection.The results show that the wear failure of the guide section is caused by some tiny sharp points on the working surface of the needle body.The source of the tiny sharp points is further studied from machining and heat treatment process,and it is finally found that the root cause is the formation of a small amount of large eutectic carbides in raw material,which caused local sharp points to scratch the needle valve body during the operation of the needle valve couples.Based on this,improvement measures are proposed.No similar failure phonemenon occurred after that,indicating that the cause is accurately identified and the improve-ment measures are effective.
维普
万方数据