Mig wire, hardness and annealing ?

[auscab]

Hi , does any one know this .
Im thinking of fabricating a part for a machine out of mild steel that will require shaping and filing or even machining afterwards .

Doing this sort of thing in the past with the Mig and its wire I have noticed the welded sections to be to hard to work afterwards , I would have been welding and quenching in water so I could go on handling the work. Or even just welding and cooling down on the work table in the air. It was way to hard to file , grinding was the only way to shape it.

If I anneal the whole piece after its made , will the welded sections become as soft as the rest of the work , or soft enough that a machinist would want to put it on his machine ?
Or if the machinist would not touch the piece , not wanting to damage his cutter , would it be soft enough to file?

Rob

[aametalmaster]

I have machined 100's of parts that were welded with solid steel mig wire and gas flux core wire with zero problems. I used to repair bearing bores in column pipes with weld then turn the bore back to size on the lathe. I also make face plates to sell and weld a large block onto a plate then machine the whole works into a nice looking part. Yes you can file it just as easily...Bob

[auscab]

Thanks Bob.
Did you prepare the welded up sections by annealing from when it was welded{ thats probably a bit hard to do ?}
or do a separate heat and cool slowly session on it ?

Rob

[aametalmaster]

I just weld and let cool. The only time i have had a problem is with some sort of cast steel. Tried to drill it and it was too hard. Mild steel is just fine weld and cool and go with it...Bob

[RustyArc]

I read this back when it was first posted, and didn't quite understand it: if you quench hot metal, you'll harden it. If you let it air cool, it'll be more ductile.

In general, weld metal tends to be a bit harder than mild steel, but still eminently machinable.

[Grahame Collins]

Doing this sort of thing in the past with the Mig and its wire I have noticed the welded sections to be to hard to work afterwards , I would have been welding and quenching in water so I could go on handling the work. Or even just welding and cooling down on the work table in the air. It was way to hard to file , grinding was the only way to shape it.

Thats your problem.
Though you don't ay the grade of wire i would say its probably LW1 maganese alloy which will harden the bead if given the treatment. Try letting a sample /test weld cool in air back to room temperature . Do the tests and betcha the problem will go away.

Get or make some tongs/ pliers/vice grips to handle the work.

Grahame

[auscab]

Thanks as well RustyArc and Grahame. Two thanks for Grahame because you answered me on the same question in another section and I never replied .

I will do some testing to see how it feels .
I dont know what grade wire it is , it might say on the roll , the box is long gone. I will have a look though.


Rob

[BobL]

If you are welding thin pieces of metal to a thick one the thick one can act as a serious heat sink and rapidly cool the weld. While not as rapid as a water quench it may pay you to preheat the thicker piece before welding to reduce the cooling.
It also reduces stresses on welds. Even a few hundred degrees can make a difference.

[Grahame Collins]

I dont know what grade wire it is , it might say on the roll , the box is long gone. I will have a look though.Rob

There is usually a label somewhere on the spool. Failing that a good clue is that the wire is copper coated and is springy- not easily bent.Its a pretty good indicator of a high tensile wire

Grahame

[auscab]

Thanks Bob , I'll remember that.

t the wire is copper coated and is springy- not easily bent

Grahame

That's what I have , and have always been given when I asked for a new roll . The only question I have been asked is what thickness I want .6 or .9 being the two sizes I have used. I thought all mig wire would have been the same so I never asked . I'm happy with it .

I thought it must have to be the high tensile to get it to go all the way down the lead and out the end of the gun without it fouling up inside. A softer wire could cause more feed problems maybe ? Ive had my bad days when the wire gets stuck and turns into a mess in the spool area , even with the high tensile. I fix it re adjust and it happens again , over and over . till I get it just right.

Rob

[Grahame Collins]

Ive had my bad days when the wire gets stuck and turns into a mess in the spool area , even with the high tensile. I fix it re adjust and it happens again , over and over . till I get it just right.

Rob

Wire tension should be such that it just has enough "grip " to be pulled through the rollers.

Set the tension just tight enough so it will just slip( when trigger is pulled) in the rollers when pinched between thumb and fore finger.You start at too tight and progressively loosen after each pinch until the wire just slips in the driven rolls.

You will be very unlikely to have a wire snarl again.

Conditions that contribute towards wire jams

• Dirty liner
• wrong liner
• Cable not kept as straight as it could be
• contact tip with spatter on it

Cheers
Grahame