Choosing electrodes for structural fillet welds in steel
By Bill Mohr on Wednesday, October 31st, 2012
While doing a comparison between two widely used steel structural welding codes, I found a difference that may cause users of the codes to choose welding electrodes differently. The two codes are AWS http://www.aws.org/w/a/ D1.1 and Eurocode 3 (Here I mean EN 1993 1-8 for those who prefer a higher number to letter ratio). In the US you might obtain this code through http://www.saiglobal.com/Information/Standards/.
For fillet welds, Eurocode 3 requires matching electrode for fillets and then bases the strength calculation not on the weld metal properties, but on the base metal grade and properties. D1.1 allows undermatched fillet welds and bases the strength calculation on the the weld metal strength classification.
Now, normally the users of D1.1 still match the fillet weld strength to the base steel rather than choosing undermatched electrodes that can only be used for fillet welds and not for tension-loaded butt welds. But the effect of judging fillet strength on electrode class rather than base metal grade is also noticable for overmatched electrodes. No additional allowable strength is provided by an overmatched electrode in Eurocode 3. Additional allowable strength is available in AWS D1.1.
This use of higher strength weld material may have additional design complications. Check in with EWI, if you would like to learn more.