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Re: WE-Electrode Strength

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On 9/9/97, Chris Serroels wrote:

> Could someone please explain the mystical world of weld
> filler metal?
> I am looking at the AWS Bridge Welding Code, Table 4.1,
> which specifies the electrode to be used. The electrode is
> dependent on the base metal strength and welding process
> to be used (SAW, SMAW, FCAW, ...).
> For the case of Grade 36 steel, both 60 and 70 ksi electrodes
> may be used depending on the welding process used by the
> fabricator.  Which value should I use in design?  Do I go the
> conservative route and assume 60 ksi?  Do I specify on my
> weld symbol the electrode strength to be used?  It seems that I would
> want to give the fabricator flexibility in the process used because
> I don't know which process is most appropriate - or is this
> statement irresponsible because I should be aware of the
> advantages and disadvantages of each of the weld processes (seems
> like a lot to try to keep straight).
> I have never gotten a clear explanation of this issue.  From discussions
> with many of my peers, it is obvious that I am not the only one confused
> on this issue.  Could someone please enlighten me(us)?

The engineer should make the basic decision as to the strength of 
weld filler metal to be used.  This will then determine the size of 
the various welds, required to suit the design strength demands.  
Either E60 or E70 electrodes are compatible with 36 ksi material.  
Twenty five years ago, E60 was almost universally specified.  Today, 
E70 is almost universally specified.   Given that the actual 
yield strength of modern "36 ksi" steel is likely to significantly 
exceed 36 ksi, and may be on the order of 50-60 ksi, the E70 material 
is a better match for modern structural steels.

The engineer should not specify the process (SMAW, FCAW, GMAW, SAW, 
etc) used.  This is the responsibility of the fabricator/erector.  
E70 material can be obtained with any of the above processes.

For an outstanding discussion of welding issues, I recommend that you 
obtain a copy of FEMA-288 "Steel Moment Frame Structures - Background 
Reports"  There is a paper on welding in this document that provides 
an excellent discussion of the various welding processes, the meaning 
of weld filler metal descriptions, and similar topics of interest.  
It may be obtained free of charge from FEMA 
Ronald O. Hamburger
Project Director for Product Development
SAC Joint Venture