Hydrogen Embrittlement
Cracking observed in the HAZ which has been hardened by welding
- Hydrogen modifies the fracture surface energy and cohesion of the parent metal - the effect is proportional to hydrogen content
- Whether fracture occurs depends on the stress applied to the weld
Hydrogen embrittlement can be reduced by:-
- welding with low hydrogen processes (MIG, TIG)
- using hydrogen controlled fluxes (MMA)
- Heating to above 200oC for sufficient time to allow hydrogen to diffuse out of the HAZ