Have you ever had someone who should know better, tell you something that you thought was so far fetched you were actually offended that they thought you might buy it? Hypothetical;
You are asked to bless a weld between two steel castings, the material is quenched and tempered, and has an avg. tensile strength of 115k psi. The joint is a single V with backing, 1.5" thick, .25" root opening and a 45-deg inclusive angle. You're told they used a FCAW E81Txxxx wire. You're told that the mismatch in tensile strength will be made up due to the dilution of the weld metal and base metal. Just for the fun of it, you ask to see a WPS and supporting PQR, none exist, but the weld engineer seems to recall something about a test. You suggest that at a minimum an E100 or E110Txxxx wire should have been qualified for this weld. You also suggest that dilution is a two way street, and that the base metal adjacent to the weld will also be diluted, thus weakening it, not to mention the root zone/backing bar dilution that may have occured.
Also, given the volume of the weld, you suggest that dilution will only occur with any significant effects in the weld metal/base metal fusion zone, leaving the rest of the weld metal pretty close to the strength specifications which the filler metal manufacturer has put forth for weld metal only, and even then provided that it was deposited correctly.
If thats not bad enough, you're told this joint design and filler metal base metal combo are pre-approved IAW AWS D1.1.
My question is, where do you start? LOL. I say you start over! Anyone ever run across things like this?
I guess I should have posted this in Shop Talk, sorry.
I had a fabricator that attempted to qualify a WPS where two of the bends failed, a tensile test failed, all the Charpys failed and the "welding engineer" who held a P.E. stamp asked if they could start production welding because, "I know where we went wrong. The production welds will be just fine, trust me."
The kick in the butt was I said no production welding until you pass the tests required to qualify the WPS. He went crying to my client's upper management and told them it would have an adverse impact on delivery if he was forced to pass all the tests. Upper management bought it hook line and sinker.
I told him before they even started qualifying the WPS that what was proposed was not likely to work. He insisted he knew what he was doing, after all, he was a P.E.
Best regards - Al
I would write a Corrective Action Report and have him answer it.That way you're covered.
Done. It accompanied the nonconformance report. I cant wait to hear the answer. Comic relief is important in todays work environment I believe.
Unbelievable! Hope you post the answer!!!!
Regards
I've had a supplier weld up and ship a part, because purchasing told them it was OK, then they run they're PQR using the same procedure and it failed, spectacularly. I still remember the look on the big mans face when he realized he had to pay for the part, even though he couldn't use it. Priceless. I will carry that image with me the rest of my life lol.
Stupid is as stupid does.
Al
If I may, base metal doesn't get diluted. If it melts and diffuses, its now weld metal. If it melts and doesn't diffuse (as in some high viscosity mushy zone alloys) then by definition it hasn't diffused to be diluted.
There is always some evolution of elements across boundaries, but the language needs to be careful here. This is not dilution in the normal sense and shouldn't be used as such.
You're right of course. Thank you.
What I don't get is why they would even ask you to "bless the weld" when there is no procedure present or implied. Whats to verify? The fact that some filler material was applied between 2 pieces?
Tensile achieved by Quenched & Tempered was null and void by welding process never mind the what ever filler was used.
Well that's what makes it so ridiculous! Like I told them, start over! I am being told that this weld will tensile test in the high 90's because of dilution. Its all just ridiculous. The whole shebang.
Something else to keep in mind here. Once you weld this stuff you will no longer have a Q and T microstructure in the HAZ. It will be closer to a normalized microstructure and not near as strong as the uneffected base metal. We are worrying about the weld metal but the HAZ stands to be the weakest link. This is always the case with Q and T's. Even when you use weld metal that meets or exceeds the UBM.
And there is some validity to the dilution argument, in that the micralloying elements are what allow Q and t to become Q and T, though far less than in the orginal BM. In the end though, Al is absolutely correct in that, check the test data.
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