Surface Treatment of Fasteners - Oxidation
Avril Xu
BAIDU
2024-01-23 09:58:18
Oxidizing blackening + oiling is a popular coating for industrial fasteners because it is the cheapest and looks good until the oil runs out. In the oil state of its neutral salt spray test can only reach 3 ~ 5 hours. Blackened fastener torque-pretightening force consistency is also poor. To improve this, grease can be applied to the internal threads during assembly before screwing.
The following picture shows an oxidized blackened bolt.