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WeldUK (Materials) (OP)
15 Feb 12 11:45
I'd like to pick your brain of some AWS D 1.1 users on this.

We intend to use E81T1-Ni1 filler wire (AWS SFA-5.29, min YS 468MPa, min UTS 550MPa) to weld an EN S355 grade (min YS 355MPa), the reference code is AWS D1.1:2010.

The loading is classified as 'tension normal to the effective area', hence according totable 2.3 in AWS D1.1, "matching filler metal shall be used".

The filler metal we propose is overmatching the tensile strength of the base metal and our client is not accepting it on this basis, they require the use of E7X... wire.

I could not find a definition of 'matching' in AWS D1.1, hence even a 70ksi wire (min YS 399MPa) could be seen as overmatching! If 'matching' means 'tensile strength equal to or greater...', then both E7X.. and E81.. wires would comply with the code.

In conclusion, I do not see why E81... should not be accepted, provided we carry out the welding procedure qualification and meet all mechanical test and NDT requirements.

Can anyone shed some light?
Helpful Member!  Duwe6 (Industrial)
15 Feb 12 12:26
Your EN S355 is the equivalent to ASTM 572 Gr. 50.  AWS gives you the choice of 60 or 70-series filler metals for this steel, meaning that they have deemed them a "match" in the practical sense.

For the pendantically impractical, the only "Closly Matched" filler would be the Oxy-Acetylene gas rod RG-50.  I hate gas welding.
gtaw (Structural)
19 Feb 12 20:16
Reference AWS D1.1-2010

You may want to review the requirements of Table 2.3 to see when matching or undermatching filler metal is required.

Then review the table found in clause 3.3 which is used in conjunction with table 3.1 for a listing of prequalified base metals with matching or undermatching  filler metal.

One problem you face is that the base metal you intend to use is not a listed prequalified base metal. As such, you need to determine which of the prequalified base metals it most closely matches to determine which filler metal is "matching". Then because your base metal isn't prequalified, you have to qualify the WPS using the proposed base metal and the "matching" filler metal to demonstrate it will produce the mechanical properties expected.

 

Best regards - Al  

Helpful Member!  gtaw (Structural)
19 Feb 12 20:41
Sorry, my computer is acting up and it sent my response before I was done.

Assuming the base metal you propose to use is similar to ASTM A572 Grade 50, it is found in table 3.1 as a Group II base metal.  The matching filler metals are found in the right hand column. The welding process is selected, then the filler metal specification is listed, i.e., A5.X, and then the far right column list the electrode classification you make your final selection from.

In this case, let's assume you are going to use the shielded metal arc welding process; you could use any E70XX electrode that meets low hydrogen requirements, i.e., no more than 16 milliliters of diffusible hydrogen per 100 grams of weld deposit.

You cannot use a low hydrogen electrode meeting 80ksi tensile strength because that is considered overmatching and that isn't permitted per clause 3.3.
 

Best regards - Al  

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