Welding 50ksi Structural to Q&T Plate
Welding 50ksi Structural to Q&T Plate
(OP)
I am trying to redesign an existing piece of outdoor structural equipment and bring it in line with code. I have two options to rework a deficiency where a square HSS member joins to a plate with a fillet weld around the square HSS:
1. Replace an 1 1/4" A36 plate with a ~80 ksi plate. Likely will have to a quenched and tempered plate to get that strength.
Q: How difficult is it to weld a 50ksi plain carbon structural steel to a 80+ ksi Q&T plate? I suspect a detailed weld procedure (preheat, rod selection, etc) will be required.
2. Upgrade to a 50ksi plate but it will still be plain carbon steel. To get the increased strength add gussets/braces where required. Can continue to use the existing 7018 rods we are currently using. Will be heavier but "simpler" and maybe more cost effective in the end.
I suspect most will pick option 2 as the preferred option.
1. Replace an 1 1/4" A36 plate with a ~80 ksi plate. Likely will have to a quenched and tempered plate to get that strength.
Q: How difficult is it to weld a 50ksi plain carbon structural steel to a 80+ ksi Q&T plate? I suspect a detailed weld procedure (preheat, rod selection, etc) will be required.
2. Upgrade to a 50ksi plate but it will still be plain carbon steel. To get the increased strength add gussets/braces where required. Can continue to use the existing 7018 rods we are currently using. Will be heavier but "simpler" and maybe more cost effective in the end.
I suspect most will pick option 2 as the preferred option.





RE: Welding 50ksi Structural to Q&T Plate
It is not difficult to weld carbon steel (A 36) to a low alloy quenched and tempered steel plate, certain precautions are required. Preheat will need to be reduced to 150 deg F or less, and the interpass temeprature would need to remain at or below 350 deg F (this is critical). Because you are dealing with a base material that has been heat treated by quenching and tempering, post weld heat treatment should not be performed.
I would suggest a E9018M filler metal if you are using the SMAW process. This filler metal is typically used for welding ASTM A 514 low alloy steel plate that is quenched and tempered to itself or to a lesser grade carbon steel.
I would strongly suggest you qualify a welding procedure for this base material combination.
item 2; yes.
RE: Welding 50ksi Structural to Q&T Plate
RE: Welding 50ksi Structural to Q&T Plate
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