Fracture Analysis of the Galvanizing Bolt

The fracture of the galvanizing bolt happened after installed after 1~2 days. The fracture reason was investigated by means of chemical compositions analysis,microstructure analysis,hardness test and fracture analysis. The results show that the main reason which caused the bolt cracked was that hydrogen wasn’t removed thoroughly and a lot of hydrogen was existed in the bolt during the later acid cleaning and electroplating process. The other reason was that the improper heat treatment process which resulted the hardness of bott centre was highter than the required value. These co-caused hydrogen embrittlement fracture of galvanizing bolt.