Welding ASTM A706 Grade 80 1

[STrctPono]

I can't seem to find any information anywhere regarding welding ASTM A706 Grade 80. The ASTM references the latest AWS D1.4 but when I checked the 2018 version of AWS D1.4, there was nothing regarding filler metal, amperage, etc..

I contacted AWS and they sent me the following response:

As you noted D1.4:2018 does not address A706 Grade 80 material.

It should be noted that D1.4 does not provide some of the details (i.e. amperage) for any filler metal. In regards to filler metal selection, since the Code does not specify options for grade 80, you will have to determine what filler metal (matching or undermatching) may be appropriate for the application. Those type of decisions can be construed as a consulting nature which I can not provide.

In regards to preheat, Clause 7.2 provides details for determining preheat.

This doesn't really help me and it sounds like AWS is basically saying that they haven't done the testing or research regarding ASTM A706 Grade 80 so they are not going to take a stance on the matter...

Does this mean that the welding contractor will need to submit a PQR for this application and get it approved by the EOR?

 

[bridgebuster]

The attached brochure from Lincoln Electric may be of some help. They don't have a WPS but they do identify filler materials. The thing with Grade 80 is that it's fairly new, at least in the bridge business.

 

[STrctPono]

Thanks. I had found that previously but if you look at the yield strength for the 706 on the brochure, it is grade 60 bar. They have nothing for grade 80. I actually contacted Lincoln Electric a few weeks ago and they did end up recommending some filler metals based on a matching strength condition. I am wary of this without further guidance from AWS. If welding vertical steel for a drilled shaft I want to ensure that you get as much ductility out of that weld as you do from the base metal. I guess that's why the only conclusion I can come up with is that I would only accept a PQR for this weld from the Contractor. In my opinion this is not prequalified in any way.

 

[Mr168]

When using an unlisted material, you fall into 1.1 of D1.4, i.e., the Engineer/contract documents must stipulate what the acceptance criteria and qualification requirements are. This will likely be driven, at a minimum, by the intended design usage per Table 4.1, with the caveat that the fabricator will have to provide a PQR that meets 125% of the bars specified minimum yield strength anyways.

Unlike several other AWS Codes, D1.4 does not currently include provisions for any prequalified welding outside of fillet welds for the materials listed, so odds are prequalification would not be an option regardless of specified grade.

The materials in D1.4 are largely driven by ACI 318. ACI 318 has commentary noting that there is insufficient data to confirm applicability of existing code provisions for Grade 80 bars, and consequently, it's permitted only in conjunction with additional testing and analytical studies to support its use. Even if the material were acceptable as commonplace, the corresponding rules for welding need to be proposed to the appropriate AWS committee, undergo an extensive discussion/comment resolution period, and then be voted at multiple committee levels for incorporation. Often, those proposals must be approved a year before the next publication cycle for incorporation, so it's not uncommon for the codes to lag behind several years in that regard.

 

[STrctPono]

Mr168, excellent information and explanation. Thank you for clarifying!