Low hydrogen does not mean zero hydrogen. Any moisture present can lead to hydrogen being ionized and absorbed by the weld metal and adjacent HAZ. Cracking is much less likely using low hydrogen electrodes provided appropriate preheating and PWHT is done depending on the alloys propensity to form martensite upon cooling.
Using correct pre-heat, cleaning properly, storing the electrodes so that they are kept warm and dry, use high quality weld gases, and correct PWHT are all critical to controlling hydrogen in welds.
Thank u for your reply Weldstan
I have one doubt.
Low hydrogen electrode means electrode has hydrogen as low. Is it correct or not.
If correct why hydrogen in electrodes. Because, hydrogen will causes create fracture in weld metal
Moisture in very small quantities is in the flux/metal coverings of SMAW electrodes, in the fluxes of flux cored electrides and the Submerged arc welding processes and in shielding gasses used in GTAW and GMAW processes. You can call this moisture as an inevitable contaminate.
By your questions, you are obviosly a novice with regard to the science of welding wjth no skill set at all in welding metallurgy. Do read volumes of the AWS Weling Handbook to get a better understanding. Hire a consulting Welding Engineer/MEtallurgist to provide specific information involving your specific welding needs.
In addition, hydrogen causes different types of defects in different base metals. There are many metals where a (limited) quantity of hydrogen are not to be worried about.
