Hi there.
Ali Pulse GMAW...

Tried posting first on s.e.j.w. but sadly have to accept that defunct
now.
So here - hope this is interesting for you.

I'm trying to interpret.
I tried fairly identical fillet welds on 6mm (1/4inch) extruded 6082
(Al-Mg-Si) at
230A and "+9" on trim (as hot as it will adjust) - reporting about 26V
215A and no trim (synergic recommended)
185A and no trim (synergic recommended)
and broke them.
The 230A weld was beautiful but broke easiest, seeming soft. The
tear-out was a good part of a millimetre (about 30 thou inch) into the
plate under the fillet.
No difference was obvious with the breaks of the fillets at 215A and
185A both no "trim". In blows to break or appearance of the very
shallow tear-out.
Anyone help to interpret this?
I was told to be careful of beautiful smooth Ali welds as they will be
seen to be the first to break when on a boat. Quite a cold looking
welds with ripples best, he said.

I never tried breaking spray-transfer welds in previous jobs, which
are smooth and run best (?) with simple constant progression but the
smooth judged-ideal condition was at a bit lower Amps and Volts and
the weld-pool was a very shallow "slanting finger-nail" on the front
of a rapidly progressing fillet bead. Able to comment about these?
Was on 10m/min (394ipm) and 23V as notes of day record (web search
suggests 220A at 10m/min wire feed speed)

Correction - 10m/min (395ipm) is probably more like 200A.

More comment - the 200A 23V spray would be less than pulse is
reporting to do the same job.
(reporting - you have to rely on the pulse machine to give you an
average, without a datalogger sampling at thousands of times per
second and post-processing the log to get the true average power)
Direct evidence would be that I have never seen a lingering liquid
"stop" weldpool in "spray" - new one on me.

So, yes, experience?

"Richard Smith" wrote in message news:ly35jzwmsr.fsf@void.com...

....So, yes, experience?

---------------------

No experience, but I do have some training in chemistry and metallurgy.
However a search for heat treating or alloy degradation of 6082 returned
little useful. If the fracture is just beyond the weld the parent metal may
be reduced to the -O condition or enhanced/depleted into a weaker state by
diffusion. That may be why the colder-looking welds are stronger. Perhaps an
XRF analysis comparing the bulk alloy composition to that at the break
surface would be helpful.

https://www.metals4u.co.uk/blog/6082-6082t-aluminium
"Grade 6082 Aluminium alloy provides good weld ability, however the strength
located at the weld zones is lowered.

If you are welding 6082 alloy to its self then it is recommended that alloy
4043 wire is used. If you want to weld 6082 to 7005 alloys, then the
recommended wire should be 5356 alloy."

In certain percentage ranges otherwise flexible alloys can be very brittle.
Two examples are the copper/tin alloy "speculum metal" and tin/lead solder
on gold plating that wasn't molten long enough to dissolve all the gold.

"Richard Smith" wrote in message news:ly35jzwmsr.fsf@void.com...
.............
I just read an article on WW2 ship construction in which welding problems
with distortion and progressive cracking were solved by partially returning
to riveting.

Re datalogging, I've low-pass-filtered the voltage output of a clamp-on
AC+DC current probe to reduce high frequency switching noise before sampling
it.

"Jim Wilkins" <muratlanne@gmail.com> writes:

> "Richard Smith" wrote in message news:ly35jzwmsr.fsf@void.com...
>
> ...So, yes, experience?
>
> ---------------------
>
> No experience, but I do have some training in chemistry and
> metallurgy. However a search for heat treating or alloy degradation of
> 6082 returned little useful. If the fracture is just beyond the weld
> the parent metal may be reduced to the -O condition or
> enhanced/depleted into a weaker state by diffusion. That may be why
> the colder-looking welds are stronger. Perhaps an XRF analysis
> comparing the bulk alloy composition to that at the break surface
> would be helpful.
>
> https://www.metals4u.co.uk/blog/6082-6082t-aluminium
> "Grade 6082 Aluminium alloy provides good weld ability, however the
> strength located at the weld zones is lowered.
>
> If you are welding 6082 alloy to its self then it is recommended that
> alloy 4043 wire is used. If you want to weld 6082 to 7005 alloys, then
> the recommended wire should be 5356 alloy."
>
> ...

You make a good point.
Doing tests on 6000-series is not a good way to comprehend weld
quality. Because what happens to the heat-treatment is complicating /
confounding.
The 5000-series Al-Mg is solution-strengthening and has essentially
unchanged properties after welding.
(stating commonly accepted wisdom - "simply" solution hardened alloys
lose no properties on welding, as their state is unchanged by welding.
Well, higher-order nuances include - if it was cold-rolled and has
work-hardening, that will go - then if you use too much heat and there
is grain-growth that will cause property loss)
I should do these tests on 5000-series.