Why fasteners’ surface has some white color substances?

　　After all of the cleaning processes had been finished, but on the surface of the excavator segment bolt still exist some strange substances in white color, the writer attention these white color substances maybe the phosphide substances, the main reason why this phenomenon happen is because production manufacturer never use the acid type cleaning agents to washing these excavator segment bolt, besides, the cleaners also never carefully check if there are some impurities and oily substances among the cleaning tank.

　　So after these excavator segment bolt had finished the heating process, workers need according to the curtain rule or method to display these fasteners products, because among the quenching oil, these fasteners may easy to has some tiny oxidation phenomenon, but if these problem can’t be solve timely, it can be directly influence the fasteners mechanical performances and shorten its total use life or causes the earlier damage or lose problem happen.