Mild Steel

[ukracer]

you seem to have yr head locked in the mode of if it is not 100% right it is no good.

as tig welders, most do strive to master the art, every thing needs to be spot on the produce that perfect weld,

yes we all know this, you are not teaching nothing new

but surly you have heard the term, "fit for purpose" ????

I am not even going to argue if a weld, done on clean carbon steel will or will not produce porosity.

so we have this autogenous weld, done on carbon steel, even with some porosity.

are you trying to say it is NOT fit for ANY purpose?????????????.



as I said, there is a disscusion going on on an other welding forum, regarding this very topic,

one guy is saying, he works in a factory that builds cookers, he is claiming that on some parts NO FILLER wire is used, (brackets etc)

Are all these cookers no good then, should they be sent back????

Whenever i bring 2 pieces of steel together (thin) by just melting the two ime a little concerned the metal goes brittle with the process....Do i always need to use filler or is the "fusion" method consided a decent joining process in terms of strength??

I think the answer is NO.... BUT if it does not have to be strong then maybe! lol

 

[Richard.]

Ok mate I give up. Roof man so long as it holds you can do it however you chose. As piero said it doesn't matter if you get porosity which is quite likely, as long as it's fit for purpose. You could mig it without gas or use pure argon on your mig if that's all you've got in the shop. Try a gas welding rod. All these will hold a bracket up no probs (fit for purpose). Or you could Tig weld them with a drop of A15 and make a job of it. All the options are there on the table and all are fit for purpose.

 

[Tinbasherdan]

I'm a sheet metal worker, and have done a fair amount of tig although on most occasions I will bow to Richards knowledge, however piero, an autogenous run on mild steel wouldn't be fit for purpose in any way shape or form in anything I have ever done. Whilst it "might do the job", if you have the gear why not strive to do a proper job? Why be content with it'll do? That attitude has ruined industry

 

[roofman]

Ok chaps i think ive had all my questions answed....thanks to all and safety catches can go back on the automatics now

 

[Piero]

What part off " I agree. The use off filler wire results in a better weld all round" ????? did you not get

Do I really need to repeat it?????

Thats not my point,


here is a cut and paste from said disscusion,

Are there products faulty in any way????

Should they be returned for re welding ????

perhaps the company in question, have not heard of filler wire, ???

maybe some one should tell them!!!!!!!!!

(pasted from said forum).
I don't want to get flamed here, so don't take me the wrong way. I'm not endorsing this by any means, I know it isn't ideal.

I work for a sheet metal fab company. We make alot of parts for home appliances like stoves and dishwashers, among other things. The other day I walked over to a guy "TIG welding", and asked to borrow his torch for a second to repair a broken tool. I looked around, and asked him where he keeps his filler. I got a confused look from him. He didn't even know what filler is! He welds brackets for mounting screws onto oven door frames. They are colled rolled mild steel about 16ga. He just lays the frame and brackets in his jig and fuses the pieces together, been doing it for years.

Also I have fused mild steel on several occasions building pulsejets. When running these things produce extreme vibration. Extreme enough to rattle my neighbors windows 100 yards away, and have even had broken engine mounts before. None of my fused welds have ever failed.


on page two of the forum topic, a guys shows a photo of a pulse engine he built with OUT filler wire.

he quotes this "Here's a little food for thought.


All the welds on the little engine are fused mild steel. As you can see, pulsejets operate under extreme conditions. They get really hot, and the internal pressure fluctuates from ~150psi to below atmoshperic pressure approximately 150 times per second for this particular engine.


the topic actuly started on a BMW car forum, and spread to this other welding forum,

I cant find the direct BMW link,

SOME PLEASE TRY TO awneser my question, as to if the cooker making firm, are they doing there welding wrong????

 

[Piero]

here is said pulse engine

 

[Piero]

This is interesting

Quote from welding forum topic
"Lincoln's TIG training video provides two examples of welding without filler metal. The first was an edge weld and the second was a lap joint. Both using mild steel."

a reply to that was this
Quote "So does Miller's"

I have not seen the Lincon or miller videos in question, so I cant comment,

I would sure like to find them lol

 

[premmington]

Well I do allot of autogenous runs on mild steel tubing, car exhausts and adding O2 sensor threaded ports to mild and stainless exhausts.

I do have a filler rod in my other hand, mostly just to add a little to the start weld pool, just to get it flowing.

Sometimes I even give them a second pass with TIG braze just to give them some strength.


Personally I have really only done autogenous joints on overlapping tube joints and edges of sheet metal, where there is enough parent metal to make a good joint.


Over the years I have used a TIG welder and even a OXY-fuel torch to get a gas tight seal with no filler rod, then added a TIG or MIG run over the top!


Away from the subject, I am finding so many more uses for TIG brazing. It is so quick as well! The joints made are very strong. Super process, wish I had discovered it years ago!

 

[Richard.]

Well then we agree and this is pointless. I agree it will hold certain things I agree it will be as you put it fit for purpose. Great. I was only answering the question that the welds are brittle and probably porus for the said reason. Yes you can do it as you can do lots of things that will work but my point is making it right and doing a proper job. It's not over engineering it by adding filler to dioxidise the pool. I'm a stickler for doing the best I can within practical reason. I won't weld something in a manner that I think may cause porus welds just because I think it will do the job. The question was will it be a decent weld fused together mild steel and the answer is no. Any weld containing porosity is not decent. Will it hold? Yes, will it contain porosity? Maybe/maybe not but why risk it. Cold rolled steel would be a better choice if this is a must but. Decent I would say no. I just think we are answering 2 different questions. I'm answering "is it decent?" I say no. Your answering is it fit for purpose well I agree with you it probably is but the op asked will it be decent. I say no.

 

[ukracer]

Well I do allot of autogenous runs on mild steel tubing, car exhausts and adding O2 sensor threaded ports to mild and stainless exhausts.

I do have a filler rod in my other hand, mostly just to add a little to the start weld pool, just to get it flowing.

Sometimes I even give them a second pass with TIG braze

What is tig braze??

 

[premmington]

What is tig braze??

TIG Brazing. Excellent but little known process. All you need is DC scratch start welder TIG welder, plenty of Argon & SIF silicon brazing rods (non flux cored). Don't try it with ordinary brazing rods as they contain zinc which boils off and makes a real mess. Using a large-ish thoirated or ceriated tungston electrode of 1.6mm or 2.4mm in a TIG torch connected DC negative at about 25-30amps per mm of the metal to be joined. Because bronze rods melt at about 920ºC, mild steel rods melt at about 1450ºC, this process is perfect for joining or repairing dissimilar metals where lots of heat would cause cracking or distortion. TIG brazing is nothing like Oxy-Acetylene brazing with flux in practice, it is more like TIG welding steel but with a higher metal deposition rate. A very useful process & you may already have the equipment to perform it.

 

[Piero]

I done a little recently my self on a petrol tank.

Your right. You do need a little more gas coverage.

The filler wire is very expensive.

Some people use it on ac/dc when welding cast iron.

Help keeps the cast clean so they say.

 

[premmington]

I done a little recently my self on a petrol tank.

Your right. You do need a little more gas coverage.

The filler wire is very expensive.

Some people use it on ac/dc when welding cast iron.

Help keeps the cast clean so they say.

Yes the filler wire is expensive!

But you can lay it down very quickly!

(below is a random picture from the internet)

 

[Piero]

Looks lovely.
But on a headstock!!!!!

 

[premmington]

Looks lovely.
But on a headstock!!!!!

Yeah a head stock!

Most TIG brazing I do is exhausts, with one bit of tubing slipped into another! Like a lugged cycle frame that is brazed.

Another thing about TIG brazing exhausts, if you get it wrong, you can just reverse it! No grinding just melt the braze away and reposition and start again!

No grinding welds away for rectifying mistakes!

 

[Chris Stevens]

I would guess that frame has been joined with gas not TIG process, and while some frame builders TIG weld, those that braze all seem to use gas fluxers? Was at the builder who now makes Rickman Mettise frames a couple of weeks ago, and they are all put together with gas, which I am told is faster than TIG. Most TIG brazing is DC process, but if you are using aluminium bronze AC is required.

 

[hotrodder]

Yeah that motorbike frame is definately 'bronze welded' with oxyfuel, almost certainly using a gas fluxer although they make life nicer/faster/easier rather than being a necessity. In the right hands (with a gas fluxer to sidestep flux cleanup) waaaaay faster than TIG welding and better properties than TIG brazing which doesn't wet out or flow as well (way less capilliary action) making it next to impossible to build up the required fillet size without slowing down and cooking everything

 

[premmington]

I have seen someone brazing bicycle frames for disabled trikes using a gas fluxer with oxy fuel. It was quick!

 

[wheresmejumper]

I would only ever autogenously tig ms if it was temporary to hold something and be ground out (not welded over) after.