1.3.6 Hydrogen in Weld Metals
Invariably, there is some amount of hydrogen present in the solidified and cooled weld zone. This
hydrogen is introduced by the arc heat breaking down the moisture present in and around the welding
arc. Possible sources of this moisture include the electrode covering, flux, shielding gas, atmospheric
humidity and condensation on the work pieces.
When welding steels, absorbed hydrogen can cause cracking (this will be discussed further in Chapter
9).Therefore, in welding carbon and low alloy steels, martensitic stainless steels, etc., an important
consideration in selecting the welding process and filler metals is the amount of hydrogen that might be
introduced into the weld zone. Non-ferrous materials react differently to hydrogen.