2mm 1050 sheet minor cosmetic issues with welds?

[Chris Stevens]

Anyone advise on what might be causing tiny cosmetic defects in welds on 1050 sheet, which only show when the parts are highly polished? Filler rod is 1050, Syncrowave 250, and welds appear to be 100% perfect until scurfed off and polished. Get the feeling that maybe 1050 might not be the very best material for welded parts which need to be polished?

 

[Richard.]

Got any pics Chris. It's difficult to know what you mean without seeing it.

 

[Chris Stevens]

Its tiny little pin prick indentations, which only show up after weld has been linished off and parts polished. Not asking for myself, so no pics but can probably get some. Si rod I think is better for 1050, but cant use it in this case as different colour when polished.

 

[hotrodder]

Sounds like hydrogen porosity, i can't think of any other suspects (other than sanding marks which don't really fit the description) without pics anyway? The 1xxx series is maybe fussier than other flavours regarding porosity as there's no alloying elements to speak of so they have a more sharply defined melting point than Al alloys. 4043 for example has a melting range between 575ish and 625ish °C while 1050 melts at ~650°C give or take a few degrees. If the weldpool freezes more quickly then there's less time for any hydrogen to escape as the solidifying weldpool rejects it

This isn't the wires or materials fault, if it is porosity that's noticable* to the naked eye then it's user error

4043 or any other 4xxx series filler wire is wrong for welding 1xxx or 3xxx series to themselves or each other. Aside from colour match the 4xxx series are a chunk harder and more brittle. Welds will be harder, less ductile, more prone to fatigue cracks and almost guarenteed to crack if they're planished out and/or wheeled. 1050 welded with 1050 should be able to withstand this sort of abuse http://www.mig-welding.co.uk/forum/media/albums/ally-weld-abuse.743/ Probably not much in it but i'd have thought 1050 would have better corrosion resistance too

* It's pretty much impossible to totally eliminate hydrogen porosity without switching to oxyfuel and flux, all you can really do is minimise it by reducing any sources of hydrogen... moisture, hydrocarbons like drawing oils/soaps on wire that wasn't shaved properly or degreased etc. Everything happens faster with MIG and there's more chances for the wire to get contaminated/dirty making it more difficult to reduce porosity to acceptable levels. TIG, being slower, is less fussy and some new/clean thinnish 1050 shouldn't need OCD/internet levels of preweld cleaning to get porosity levels low enough you need to macro etch a sample to highlight any

Dunno if it'd help any with regards to porosity but 1450 is a 99.5% pure ally wire with the remaining 0.5% containing more Ti than usual. The Ti acts as a grain refiner, more here http://www.mig-welding.co.uk/forum/threads/1450-aluminium-wire.29036/ If nothing else it's unlikely to exist to exist in cheapnese quality that's still covered in drawing oils/soaps

 

[Chris Stevens]

Sounds like hydrogen porosity, i can't think of any other suspects (other than sanding marks which don't really fit the description) without pics anyway? The 1xxx series is maybe fussier than other flavours regarding porosity as there's no alloying elements to speak of so they have a more sharply defined melting point than Al alloys. 4043 for example has a melting range between 575ish and 625ish °C while 1050 melts at ~650°C give or take a few degrees. If the weldpool freezes more quickly then there's less time for any hydrogen to escape as the solidifying weldpool rejects it

This isn't the wires or materials fault, if it is porosity that's noticable* to the naked eye then it's user error

4043 or any other 4xxx series filler wire is wrong for welding 1xxx or 3xxx series to themselves or each other. Aside from colour match the 4xxx series are a chunk harder and more brittle. Welds will be harder, less ductile, more prone to fatigue cracks and almost guarenteed to crack if they're planished out and/or wheeled. 1050 welded with 1050 should be able to withstand this sort of abuse http://www.mig-welding.co.uk/forum/media/albums/ally-weld-abuse.743/ Probably not much in it but i'd have thought 1050 would have better corrosion resistance too

* It's pretty much impossible to totally eliminate hydrogen porosity without switching to oxyfuel and flux, all you can really do is minimise it by reducing any sources of hydrogen... moisture, hydrocarbons like drawing oils/soaps on wire that wasn't shaved properly or degreased etc. Everything happens faster with MIG and there's more chances for the wire to get contaminated/dirty making it more difficult to reduce porosity to acceptable levels. TIG, being slower, is less fussy and some new/clean thinnish 1050 shouldn't need OCD/internet levels of preweld cleaning to get porosity levels low enough you need to macro etch a sample to highlight any

Dunno if it'd help any with regards to porosity but 1450 is a 99.5% pure ally wire with the remaining 0.5% containing more Ti than usual. The Ti acts as a grain refiner, more here http://www.mig-welding.co.uk/forum/threads/1450-aluminium-wire.29036/ If nothing else it's unlikely to exist to exist in cheapnese quality that's still covered in drawing oils/soaps

Thanks Hotrodder, thats very useful info and sounds a very likely explanation for the problems that are occurring. Guy having the problems is using SIF wire, and have already suggested trying another brand of wire and see if that makes any difference. I will ask him to send me some pics tomorrow, and I would be very interested to hear what you think. Welds are pretty long on relatively large 2mm sheet parts, so I guess premature cooling of the weld pool and trapped hydrogen may well be the problem. He has a transformer, and an inverter, and I felt these parts seemed to weld nicer using the inverter on mixed wave setting (Kemppi machine), but he suggests he cant get on with inverter.................

 

[hotrodder]

Cheers. I sometimes end up buying SIF wire as it's all both of the LWS (and many of the usual mail order suspects) stock... never had any problems with their 1050 and it's usually pretty clean (as it should be being sold as shaved wire). Found their 4043 & 5356 more variable, sometimes a solvent wipe gets loads of crud off it other times it's clean and some batches of 4043 seem more sensitive to grainy welds
Doubt it'd make a massive difference to porosity(?) but if anything a posh waveform on a posh inverter should make things worse... whenever i use a transformer machine on ally i find myself forced to slow down a bit compared to using a decent squarewave inverter

 

[Chris Stevens]

I think the problem here might well be linked to travel speed a bit fast (would agree transformer does seem to mean travel speeds up a fair bit), so using inverter on mixed wave might help cure the problem, as slower speed means the weld pool doesnt cool as quickly?

 

[Richard.]

I find a transformer forces my travel speed to be slightly slower. I'm always welding faster with an inverter on square wave.

 

[hotrodder]

I think the problem here might well be linked to travel speed a bit fast (would agree transformer does seem to mean travel speeds up a fair bit), so using inverter on mixed wave might help cure the problem, as slower speed means the weld pool doesnt cool as quickly?

Other way around for me like i said...

whenever i use a transformer machine on ally i find myself forced to slow down a bit

My v205t doesn't do mixed AC but like Richard i can weld faster with inverter square or triangular waves than i can with a squarewave transformer machine and with a properly old/basic sinewave TIG i'm forced to slowdown a bit more

The more efficient arc puts more (useful) heat into the part and less into the tungsten, the arc is typicaly stiffer and more focused as a result so for a given weldpool size everything happens faster if that makes sense

Regardless of machine if he's welding a bit too quickly/cold then yep, more likely to get porosity

 

[Richard.]

Yes that's pretty much what I have noticed from frequently dotting between the two types of power sources in a previous job. Never used a square wave transformer but the soft sine wave does slightly hold back the rate of travel when compared to the advanced wave generated by the inverters. It's only slightly mind and tbh things like current ,filling habits and joint type are much more likely candidates for bringing travel speed up and down.
I'm no expert on the mixed AC thing but I would say if anything it would bring the travel speed up. Heavy spikes of DC- is putting more heat into work piece there for logically youd be expected to travel quicker (based on current always been equal between machine types).

 

[Chris Stevens]

My GP2 on mixed I think is pretty close to perfect for welding aluminuim quickly and effectively. Something like a 250 Syncro is very good though, but maybe mixed wave on an inverter is something which might resolve this problem for my mate?

 

[Richard.]

Well it might Chris but I'd be looking to address the problem with in more of a practical manner. He doesn't "need" a mixed wave power source to bring his travel rate in line and by the sounds of it going faster isn't the solution. My Rehm tiger doesn't offer mixed arc and it's certainly never been a feature I've thought "God I could do with that to help with my travel" I just do what everyone does and set up to suit. It would be silly to assume the machine is at fault here. Like Hotrodder said in his opening post it's likely down to driver error alone.

 

[hotrodder]

I can't see waveforms or machine types fixing porosity by themselves. People have been producing 'the goods' with aluminium on all sorts of 100% X-ray work since waaaaaay before posh inverters and fancy waveforms existed

The only way i can see a machine change helping is if the problem is the result of a miniscule water or gas leak but in either case i'd expect a LOT more issues than some obvious* porosity... the other year when swapping out gas BOC gave me a brand spanking new cylinder of pureshield that nearly drove me insane. Perfectly clean & shiny welds on stainless but horrible manky looking welds on aluminium. Given the results on stainless gas issues initially never crossed my mind and i thought my v205 had spat it's dummy until i hooked it up to a mates cylinder. No idea what the cylinder was contaminated with but whatever it was made aluminium impossible to weld without visually affecting stainless. I always used to try and get the cleanest looking cylinder on the grounds that it was maybe less likely to have a FUBARed valve seat from monkeys over tightening regulators. Now i have to try and avoid the really new and the really manky looking examples to lessen the odds of having to waste time backing it

I suppose maybe weldpool agitation from higher frequencies (AC in whatever waveform or pulse) could maybe help but that'd be offset by higher travel speeds and a faster freezing weldpool if you take proper advantage of them?

Bottom line there has to be either a source of hydrogen ('oily' wire or parent material, sopping wet workshop etc) that needs fixing or the welding parameters are out i.e. not enough heat input and/or too fast travel speed... sometimes with fiddly parts i'll initially tack them autogenously (due to not owning enough hands) and it's not uncommon to see what looks like a gas pore in that spot when welding the joint up properly or putting a proper tack in the same spot if/when the autogenous one cracks

* i more commonly see gross porosity when repairing manky castings, can usually see it's gonna be an issue while welding

 

[Chris Stevens]

I can't see waveforms or machine types fixing porosity by themselves. People have been producing 'the goods' with aluminium on all sorts of 100% X-ray work since waaaaaay before posh inverters and fancy waveforms existed

The only way i can see a machine change helping is if the problem is the result of a miniscule water or gas leak but in either case i'd expect a LOT more issues than some obvious* porosity... the other year when swapping out gas BOC gave me a brand spanking new cylinder of pureshield that nearly drove me insane. Perfectly clean & shiny welds on stainless but horrible manky looking welds on aluminium. Given the results on stainless gas issues initially never crossed my mind and i thought my v205 had spat it's dummy until i hooked it up to a mates cylinder. No idea what the cylinder was contaminated with but whatever it was made aluminium impossible to weld without visually affecting stainless. I always used to try and get the cleanest looking cylinder on the grounds that it was maybe less likely to have a FUBARed valve seat from monkeys over tightening regulators. Now i have to try and avoid the really new and the really manky looking examples to lessen the odds of having to waste time backing it

I suppose maybe weldpool agitation from higher frequencies (AC in whatever waveform or pulse) could maybe help but that'd be offset by higher travel speeds and a faster freezing weldpool if you take proper advantage of them?

Bottom line there has to be either a source of hydrogen ('oily' wire or parent material, sopping wet workshop etc) that needs fixing or the welding parameters are out i.e. not enough heat input and/or too fast travel speed... sometimes with fiddly parts i'll initially tack them autogenously (due to not owning enough hands) and it's not uncommon to see what looks like a gas pore in that spot when welding the joint up properly or putting a proper tack in the same spot if/when the autogenous one cracks

* i more commonly see gross porosity when repairing manky castings, can usually see it's gonna be an issue while welding

I think the problem is most likely caused by weld pool cooling too quickly, and entrapped gas as you suggested earlier. He has a Kemppi inverter and maybe using that on mixed wave, after addressing all possible sources of contamination would be worth a try at least? Going slower would also probably cure the problem, but in this case thats not an option, as almost nothing in the job as it is, and if it took say 20% longer to do wouldnt be worth doing at all.

 

[Maxakarudy]

I always use parent metal as a filler for 1050, I just guilotine off strips and never had a problem.

 

[hotrodder]

I think the problem is most likely caused by weld pool cooling too quickly, and entrapped gas as you suggested earlier. He has a Kemppi inverter and maybe using that on mixed wave, after addressing all possible sources of contamination would be worth a try at least? Going slower would also probably cure the problem, but in this case thats not an option, as almost nothing in the job as it is, and if it took say 20% longer to do wouldnt be worth doing at all.

Without pics (front and back as welded and of the defects after polishing) we're all shooting in the dark. Like i said i can't see a change of machine or waveform doing much, if anything, for porosity (especially if he doesn't like/can't get on with inverters) unless there's a gas or water leak on the syncrowave and if there was there's zero chance of the welds "looking 100% perfect" before sanding & polishing IMO

As Richard said the travel speed thing that both of us notice is relatively subtle... difficult to describe let alone quantify but should make very little difference to total job time. Obviously depends a lot on what's being made but most times i'd say the final welding is the quick and easy bit

 

[Chris Stevens]

In this case before final finishing the welds look 100% perfect (cosmetically at least). The actual weld time is the win or lose part of this job, and slowing down to any extent means the job isnt commercially viable. I get the feeling the best way forward here is to explain the situation to the customer, and advise that the very minor cosmetic issues can only be resolved with an increase in unit cost. Will see if I can get some pics today, but hydrogen entrapment as mentioned earlier seems very likely to be the cause, and weld pool cooling too quickly very possibly the cause of this?

 

[Richard.]

The actual weld time is the win or lose part of this job, and slowing down to any extent means the job isnt commercially viable

Is there that little profit in it that a slight decrease in travel speed will kill it?

 

[Chris Stevens]

There is a lot of welding in each part, and slowing down will reduce already very small profit. The defects arent happening all the time though, so its not certain that slower travel would resolve them anyway. Get the feeling that some sort of preheat might work, but would be difficult to arrange easily.

 

[HughF]

I was going to say preheat to drive off any moisture - that can be as simple as warming it all up with a heatgun