A913-65 welded to A572-50 Double Check Please

Date 03-17-2010 20:07

We are bidding a project that calls for heavy group 4/5 material of A913- grade 65 W shapes to be welded to plates of A572-50.
Could someone please confirm my matching/ undermatching is correct?

D1.1 FCAW E71T-1
Table 3.1 (pg 64-67) Pre-qual base metals/ Filler Metals
A913-65 is group III calls for 80 series filler wire
A572-50 is group II calls for 70 series filler wire

3.3 (pg 59) Base/ Filler Metal Combinations
My relationship is undermatching= any steel to any steel in any group. It is undermatching because the tensile strength of the A572-50 (tensile minimum is 50 ksi) is less than the tensile strength of the A913-65 (tensile minimum is 65ksi).

So I can use a filler metal listed for a lower strength ( A572-50 in this case). Which means I can stay w/ my E71T-1 series wire versus having to increase it to an 80 series wire. This is the part I want to make sure I got right in case I have to change wires, but I don't believe that's the case. I'm ok as is.

I checked the pre-heat chart and there is a different preheat for the thick A913 vs the A572, no problem there.

Thanks in Advance
Chris

By supermoto (***)

Date 03-17-2010 20:20

We have had the same issue and the EOR wanted 80ksi wire to be used on any joint that joined A913-65 material. If you weld A913 to A913 than you don't need preheat at all no matter thickness but if you weld to any other material you need to take the preheat requirements of that material (A572-50)

You can use up to 10ksi less than the required 80ksi.

Maybe check with the EOR.

By Stephen32 (*)

Date 03-17-2010 21:21

I am reading it to say that you will be ok to undermatch the filler wire. But as supermoto stated, you might want to check with the EOR.

By waccobird (****)

Date 03-18-2010 13:25

supermoto
AWS D1.1 2008
Clause 3.5 Minimum Preheat and interpass Temperature Requirements
3.5.1 The minimum preheat or interpass temperature applied to a joint composed of base metals with different minimum preheats from table 3.2 (based on Category and thickness shall be the highest of these minimum preheats)
Table 3.2 Prequalified Minimum Preheat and interpass Temperature
Shows preheat for A572-50 Category B metal thickness 1/8" to 3/4" incl. at 32°
Shows preheat for A913-65 Category C metal thickness 1/8" to 3/4" incl. at 50° F.
Where do I find that if welding A913 to A913 preheat is not required?
Respectfully
Marshall

By MBSims

Date 03-17-2010 22:06

Just to be clear, A572-50 has a 50 ksi minimum yield strength, 65 ksi minimum tensile strength. A913-65 has a 65 ksi minimum yield strength, 80 ksi minimum tensile strength. As long as the thickness of both materials is the same for butt welds, I see no reason E71T can not be used for welds joining the two materials. The joint will be stronger than the weaker of the two materials, any failure would be expected to occur in the A572 base metal.

The use of E71T would definitely be a point to be mentioned in the proposal to the customer.

By eekpod

Date 03-18-2010 10:54

Thanks guys, I really appreciate your input and thoughts.

Since we are still in the bidding phase I can definalty have the estimators make a comment about what wire this price is for and what it would cost if it were to change to the 80XX.

I don't know it I would have automatically pointed out to the EOR that we are using 70XX as long as it meets code, and that's why I wanted to be double checked to make sure I was intrpepting D1.1 correctly, but since you've been through this before and I haven't with the A913, I can certainly learn from your past experiences. So thanks and I'll make sure we mention what wire we plan to use up front right from the beginning.

Chris

By eekpod

Date 03-18-2010 15:24 Edited 03-18-2010 15:26

wacobird/ supermoto

OK I see catagory D, I had stopped at catagory C when I saw my material listed.

But be careful because A913-65 in order to be a catagory D must have a welding process of "SMAW, SAW,GMAW, and FCAW w/ electrodes capable of depositing weld metal with a maximum diffusible hrdorgen content of 8ml/100g (H8)".
So if my filler metal doesn't meet that requirement, it doesn't meet the requirements of catagory D, so I would then have to call it a catagory C and use those preheats listed.

(which now that I looked up my filler wire does meet the catagory D, so your right, my preheat would be 32 minimum)
Chris

By waccobird (****)

Date 03-18-2010 19:45

supermoto
Thank You
Marshall