Electrode E7018-H4

[carlomaderazo]

I would like to know the difference of E7018-H4 to E7018. In our WPS it's mentioned the electrode classification to be used is E7018. Can we use E7018-H4 without amending or changing the WPS?

Thanks.

 

[strider6]

In my opinion is possible to use it. the low hydrogen is specified when there is risk of cold cracking of the weld due to ingress of hydrogen in the weld metals, so if the WPS is qualified for a E7018 it shloud be also qualified for a filler with a controlled diffusible hydrogen:

Cold Cracks: Causes and Cures

http://www.kobelco.co.jp/english/welding/files/v4n4.7.pdf

"HZ -- Designates an electrode, an electrode/rod, or an electrode/flux combination that will meet an average diffusible hydrogen level Z when tested in accordance with ANSI/AWS A4.3, Standard Methods for Determination of the Diffusible Hydrogen Content of Martensitic, Bainitic and Ferritic Steel Weld Metal Produced by Arc Welding. The Z designator is usually limited to 16, 8 or 4 maximum average diffusible hydrogen in mL(H2) per 100 g of deposited weld metal. Other Z designators , such as 2, may be added for some classification systems, where appropriate. Examples: E7018H4, E7018H4R, E7018-1H4R, E71T-12H8, E8018-B2H8, F8A2-EW-WH8 and ER70S-3H4."

http://www.aws.org/wj/feb/wjarticle.html

S

Corrosion Prevention & Corrosion Control

 

[metengr]

would like to know the difference of E7018-H4 to E7018. In our WPS it's mentioned the electrode classification to be used is E7018. Can we use E7018-H4 without amending or changing the WPS?

Yes. This is a low hydrogen electrode where the maximum hydrogen content is specified by the supplier. This is not an essential variable change for your WPS.

 

[stanweld]

Yes you may. Be aware that some weldability issues result with the H4 designated E7018. Arc stability decreases somewhat due to a reduction of arc stabilizers in the coating to permit the low diffusible hydrogen. Shorter arc lengths are required to be maintained by the welder.

 

[carlomaderazo]

Thanks everybody for your prompt reply.