In the technical guidance report submitted by Canada in the "Fasture Anti-Frozen Brittle", the hydrogen embrittlement mechanism, hydrogen embrittlement failure conditions and dehydrogenation baking technical measures of fasteners were analyzed in detail; ISO/TC2/SC14 proposed and submitted for review, and Issued ISO/DTR 20491-2017 "Steel fasteners based on hydrogen embrittlement foundation" technical guidelines.
High-strength fasteners are often used in critical applications such as bridges, vehicle engines, spacecraft, and failure of these fasteners can have catastrophic consequences. Preventing the failure caused by hydrogen embrittlement and preventing the risk of hydrogen embrittlement are fundamental issues that need to be considered throughout the fastener supply chain.
Relevant links include steel mills, fastener manufacturers, surface coating suppliers, application engineers, connection designers, and end users. Due to the complex failure mechanism of hydrogen embrittlement and numerous influencing factors, the hydrogen embrittlement failure of fasteners has not been predicted so far.
The purpose of the ISO Technical Report is to extract the latest knowledge about hydrogen embrittlement and turn it into a complete and simple technology that can be used directly in the production of fasteners. The technical guidance includes the description of the theory and mechanism of hydrogen embrittlement damage, three basic conditions for hydrogen embrittlement failure, followed by hydrogen embrittlement test method and process, surface k-side cleaning, coating (especially electroplating), baking Guidance in other aspects.
Two types of hydrogen embrittlement
1. Internal hydrogen embrittlement IHE
Hydrogen remaining inside the material during processes such as pickling or plating
- such as steel
- Hydrogen remaining inside the material during pickling or plating processes
2. Environmental hydrogen embrittlement EHE
Due to the external source of hydrogen caused by stress
——stress corrosion cracking, hydrogen induced stress corrosion cracking and hydrogen promoting stress corrosion cracking, etc.
- such as fasteners in service
—— Ocean, acid service environment