Hydrogen can cause failure or reduce the strength in components in three different ways:
- by a chemical reaction between the carbon in the steel by forming methane gas, or reacting with the alloying elements as Ti, Ni to form hydrides that weaken the component.
- interstitally trapped Hydrogen that over time aggregates between the lattices in the grain structure. The problem is similar to the problem with hydrogen cracking of welds.
- Hydrogen in the environment can cause the same problem as above when the Hydrogen diffundate into the material. The problem has been noted for high strength steels in seawater. Also cathodic protection can contribute to the problem and is known to reduce the capacity of duplex and superduplex steels in this enviroment.
Plating of bolts is also known to cause hydrogen embrittlement, and the bolt specifications should therefore
require the bolts to be baked at approx. 190 deg C for not less than 23 hours. The baking shall take place not
more than 2 hours after the plating.
Parent Directory 16-Feb-1999 15:44 -