E7016 & E7018

[duongwe]

I seen some WPSs with SMAW process and E7016 for Root and E7018 for rest. Can someone explain to me why to use E7016 for Root? how about difference between E7016 and E7018 for Root?

 

[DVWE]

duongwe,

Have a look at the AWS SFA-5.1 Annex A. This explains in good detail the differences between the electrodes.

The only reason I could see to use E7016 for root is that the covering is slightly less thick as compared to E7018, so the welder might be able to access the bottom (root) of the weld joint more easily. It is much more common to use E6010 for the root followed by E7018 for the remainder fill.

 

[gtaw]

E7016 is usually a special order, i.e., it isn't typically stocked by most welding suppliers here in the U.S.



Best regards - Al

 

[Mr168]

Conversely, E7016 is typically much more common than E7018 overseas. Almost every spec/recommendation I've seen coming from China or Japan has used -16 electrodes in lieu of -18.

 

[Kiwi2671]

duongwe,
The E7018 electrode contains iron powder in the flux whereas the E7016 does not.
The iron powder increases the deposition rate and subsequently a higher amperage is used.
With the root run a fast cooling electrode is desirable (that is why cellulosic electrodes are so commonly used)and the E7018 is not a fast cooling electrode.
Regards,
Kiwi

 

[duongwe]

thanks all, specially kiwi