cbfinn_99 wrote:Thanks for the advise and quick replies. I talked with our welding supervisor about changing to a different wire brand as recommended here. He said that he has already talked to the "chief" about a better brand of wire but he is dead set on using Alcotec 5356.
Thanks again for all of your help! We have a good group of welders in the shop, and it helps knowing there is a possibility the wire may be causing us trouble, not our technique.
Tell the "chief" (head yes sir-knee pad boy) to weld it. Idiots.That's why I could never work for anyone. I'd bitch slap the idiot and walk out.
That fits well with my dishonorable bye bye from another useless azskisser wearing his halloween suit with cute little stars and stripes.....oh so many years ago.What a joke.
I am no expect but looking at all you have done so far.
In one of your latest test, weld with no filler material was fine (But you did not indicate if you tested for porosity).
the weld with filler wire had a lot of black in it (once again no indication on porosity but assuming it is there).
So the common denominators, The Pipe and Filler Wire, are your two constants.
And the test with out the wire looked good.
By process of elimination I would say it seems like the filler wire is at root cause of this issue.
The most economical resolution is a diff filler wire.
I would do three coupons/test. Prep and machine set up should be the same for all three make no changes to anything and perform these one after another all at the same time to standardize environmental and work conditions.
1. No Fill
2. With current filler rod
3. With new filler rod
Cut and polish all three, if you see no porosity in the first and last test case then you know the cause. If you see it in all three then again you know the cause is most likely the pipe material.
One thing that has not been discussed here yet is the propensity for molten aluminium to absorb hydrogen in large amounts, the hotter the puddle, the more hydrogen is absorbed. As the puddle cools to solidification, the solubility of hydrogen suddenly decreases by as much as 20 times causing excess hydrogen to gas out and mostly be trapped in the solidified puddle in the form of porosity.
Where does all this hydrogen come from?
1. Surface contamination. Anything containing hydrogen must be removed in preparation including solvents, water, dirt etc. Maybe just wire brushing is the way to go.
2. Impurities in shield gas, worth checking I suppose.
3. Impurities in the filler metal. Definitely worth checking. If others can attest to a certain brand of wire exploding (sounds like gas expansion) is this not reason enough to try another brand?
Reactions in the arc region can be excluded from what I have read and by now you must have checked for leaks in your gas line a hundred times so air contamination must be unlikely.
Our lateset attempt was to take the coupons from the machine shop, wipe them in acetone inside and out. Then we put them in an oven @ 200 degrees for at least 24 hours. We took the coupons out, used a new small stainless hand brush with one direction strokes to clean pipe to a shine. We only wiped the wire with the rags menioned in an earlier post until nothing transfered to the rag. Next we just tacked them up and welded them in 6G on the positioner. No porosity was seen after we cut the pipe at the cap pass toe and sanded all the way through the root.
We took two more tests this way and are going to send them off for xray and see where we are.
I have not seen any of the 4043 wire that was on order. Maybe it will be in this week.
