Low hydrogen welding rods with a 'basic' flux coating, what does this mean?
'Basic' in this context is an applied chemistry description and means usually more calcium carbonate type additions to the flux coating and less titanates. This reduces the hydrogen potential of the arc zone.
The term "basic" thus refers to the chemical nature of the flux coating and always indicates tighter hydrogen control. Lesser known in the public domain is also the very important feature that basic slags yield lower deposit oxygen and therefore improved toughness because of fewer non-metallic inclusion content.
The more 'basic' a flux is, the less user friendly it usually is to the welder. So the formulation is a compromise. Usually the liquid , protective slag with a "basic" coating tends to be more difficult to manipulate and welders prefer easier performance.
The opposite chemistry term to "basic" is "acidic" coating in the flux make-up. "Acidic" coatings contain more rutile and are easier to work with but can have a higher hydrogen potential. All E70 coated electrodes produce a mild steel deposit, suitable for general purpose structural steels.
So look for steel deposits with:
- Carbon ~ 0.07 -0.12 wt%
- Silicon ~ 0.3 -0.6%
- Mn ~ 0.70 -1.50%
and everything else just about minimum. There is also undeclared trace amounts of Ti or Al as deoxidisers. E7016 and E7018 coated electrodes provide this type of chemistry.