Welding Tips and Tricks

Hi all, I posted these pics in my introduction post, but thought I would repeat it here under this topic heading.
Hi from NZ.
I’ve been dabbling in Tig welding for a bit, I borrowed a lift tig machine and did some tack welding on my project (little bi plane rebuild )
I recently bought an AC DC 200E machine from Weldpro same as a Bossweld it’s a relatively cheap Chinese machine but seems to do the job and I’m only doing very light work with short runs.
I’ve been practicing and feel I’m ready to do some real parts now.
I’d like some feed back on my welds please. Can anyone spot some major problems ?
I’ve cut the tubes and cleaned them up a bit, seems some cross sections are quite good (to me) and others have some areas that contain small voids at the root of the joint. Section DD is one where I did one pass on one side and then 3 passes on the other side, just to try it out a bit.
Thanks for taking the time to look at this.
Cheers
Dom
forgot to state this is 4130 steel .030 tube onto .090 sheet and .049 tube through .090 sheet using ER70S-2 rod

What size filler rod? What was your amperage setting? What size electrode? What cfm on the argon? The pros on here will want to know so they can give you better advice.

Good point, thanks for that.

Tungsten is 1/16 2% thoriated

My set up is in Ltrs but I have about 12-14 chf
.5 sec pre flow and 7 sec post flow

45-49 Amps set for tubes / Flat .090 tear drop washers,I think I set 85 Amps...
Foot pedal

.030 rod on .035 tube ( did try 1/16 on a couple of places but think it was to big
and 1/16 rod on 2nd and 3rd pass on .049 tube
1/16 on flat .090

ER 70S-2

17 CK world wide torch
Fupa #12 ceramic

Many thanks for any help / advice
Cheers Dom

Your definitely getting penetration even on the A set. It’s kinda hard to say for sure because of the oxidation from welding. If you had back purged the parts I’m guessing even the A ones would look pretty good. With such small parts it’s hard to back purge and it’s probably not practical unless you used a purge box.

Thanks Josh, yes I think there is penetration, I’m not sure about the little voids on some of the cuts, is it normal to have that, there seems to be good fusion above and beside a d the weld material is thicker than the original tube so I imagine strength is not an issue ?
But I wonder if cracking will propagate from the void?

i know nothing on 4130 however i suspect your a tad cold. if your getting the C (you can see it at the start and end of some of the welds) then your not flowing into the root of the joint, which leaves gaps at the bottom of the weld and poor root penetration. need to get it flowing down in there and push that puddle along.
hope that helps.

Any voids or pin hole divots will be stress points. Cold edges on a weld, posible if your travel speed is off, can also create stress points were cracking will start.

Yeah, as evidenced best by B and C you're not getting fusion down into the root of the joint and your beads have a bit of a crowned cold look to them.

Cheers all, I do find that sometimes the puddle is flowing well at the edges and looks like needs to keep moving for risk of melting a hole in the .035 tube but the section of puddle at the root is slightly curved in and that’s where I think I get the voids.
What’s the solution more amps and heat but faster travel speed?

Dom wrote:Cheers all, I do find that sometimes the puddle is flowing well at the edges and looks like needs to keep moving for risk of melting a hole in the .035 tube but the section of puddle at the root is slightly curved in and that’s where I think I get the voids.
What’s the solution more amps and heat but faster travel speed?

When I need really good penetration on a joint like you're doing, what I find helps me is to machine the ends of the tube. Just a super fine skim cut so there are no more saw marks where contamination could collect. If I can wipe the edge perfectly clean, everything flows better. I find that's especially true on aluminum sheet. Most of what I work with is shear cut and you really have to smooth that off to get a good flow.

It's hard for me to recommend a tighter Arc or sharpener tungsten because I really think that's splitting hairs for most weld applications. But if this is for an aircraft, you really do want them right.

Maybe you could experiment with beveling the tubing or using a gap, though that would have to be a really fine Gap.