Base Metal/Filler Metal Combinations

By jon20013 (*****)

Date 01-23-2006 17:33

There was concern and discussion about that several years back but I'm not sure its ever been resolved. It can account for some "unplanned" design issues! Hoping a current D1 Member will enlighten us both!

By waynekoe (**)

Date 01-23-2006 19:52

As long as nothing changes in regards to the essential variables, it is perfectly acceptable to have the higher strength class listed. This will enable them to use either E7xTx-x or E8xTx-x (both are A5.29)for any combination of groups I, II, and III without having to submit a second WPS(using an A5.20). The main factor will be ensuring welder qualification using the higher strength wire.

By jon20013 (*****)

Date 01-23-2006 20:16

I'm trying to remember exactly what the concern was (this is now probably 20 years back so if it hasn't surfaced it probably never became an issue)... during a few committee meetings there was some discussion about mismatched strengths. Naturally, when one designs a structure, it is anticipated if a failure occurs it should first fail at joint "X." Joint "X" could be defined as a beam to beam, for example. If either the base or the filler is stronger than originally thought, failure may move to joint "Y" which may for example be a beam to column. As I said, this discussion was many, many years (and brain cells) in my past so perhaps no longer a valid issue... or resolved somehow...

By jwright650 (*****)

Date 01-23-2006 21:00

Jon,
This came up in our AISC audit last year, but the material in question was not the filler but rather the base materials. In the process of identifying in-coming materials, we had elected not to color code our A36 materials, only the higher grades, so the auditor proposed a question asking if a piece of higher grade material was used in lieu of A36 how could we distinguish the difference if the piece wasn't marked for some reason? I stated that we wouldn't care if we supplied better steel than was specified, the customer was getting a better grade not a lesser grade. He didn't like my answer saying basically what you said in your earlier post about the unplanned design problems.
John Wright

By MBSims

Date 01-24-2006 02:28

See Table 3.3, 2nd sentence in the 1st General Note (for 2004 edition):

"Filler metals shall meet requirements of Table 3.1 in addition to the
compositional requirements listed above. The use of the same type
of filler metal having next higher tensile strength as listed in AWS
filler metal specification may be used."

By gerold

Date 01-24-2006 14:04

What would you think if the base metal was not a weathering steel and something like ASTM A572 Gr. 50, would it be appropriate to weld a Group II Steel with a Group III electrode in this case or something similar?

P.S. Thanks for the replies.

By CHGuilford (****)

Date 01-24-2006 14:30

Sorry, somehow I got 2 posts out of this. Not intended. CG

By CHGuilford (****)

Date 01-24-2006 14:37

I would think the WPS is no longer considered to be pre-qualified per D1.1 Section 3.

I didn't see it mentioned in previous posts but most likely the fabricator had a need in the past for a weathering color match for welds on A588 steel. They probably figured that if it was OK for one job, it should be OK for another.

Some notes you might want to point out to the fabricator are:

80 series electrodes usually cost more than 70 series electrodes. It is cheaper to weld most steels with Category II electrodes.

D1.1 -3.7.3 addresses weathering color matching with single pass Cat. II filler metals.

When color matching is required on welds larger than as addressed in 3.7.3, it might be just as easy to make most of the weld with 70 series wire and make the cap passes with weathering wire. Just remember that this too is not really pre-qualified, but is often accepted.

Chet Guilford

By jon20013 (*****)

Date 01-24-2006 14:54

I've sent the D1.1 Secretary an e-mail asking him to look into some past Committee Correspondence to see if anything ever came of this issue, perhaps he will make a posting in here once he has researched?

By jon20013 (*****)

Date 01-24-2006 18:36

Here is a response from the D1.1 Secretary along with some additional information authored by Dr. Duane Miller, Vice Chair of the D1.1 Committee:

I believe this article covers Duane Miller’s view of the concerns of using overmatching filler metals on structural steel applications pretty well.

http://www.jflf.org/pdfs/papers/design_file7.pdf

Duane also answered a FAQ on the D1.1 code’s requirements which was published in the Welding Journal. It is also posted here:

http://www.arcraftplasma.com/welding/weldingdata/weldingfaq.htm

Although no one individual can speak for the committee, I believe what he writes in these articles accurately reflects several committee individual’s thinking on this subject.