Tig welding rusty old cars

[MGA]

Hi All

I'm new to the forum.And would like to say straight off im an engineer with limited welding experience.

For many years i have been rebuilding classic cars manly MGs and have always used oxy/act for Chassis and body work repairs.

I have access to a small inverter Tig set and have been trying it out with some test samples. Old metal to new metal.The problem i have is when i weld the two together using a metal filler rod what i can only describe as bubbles of metal form on the weld.The bead is ok but little holes form on the bead.Im assuming that this is impurities in the old metal. I then tryed using a S/S filler rod and there was no bubbles and the weld was clean with good penetration.I did a intricate test for the strength of the weld. (well to be truthful i hit it with a hammer) and it was fine for my needs.

1/ So is there anyway i can get a clean weld using the mild steel filler rods?

2/ Is there any reason i cannot use S/S filler rods?

Any advice would be appreciated

 

[hotrodder]

1. Is the mild steel wire proper TIG wire or is it oxyfuel wire? The later will result in porosity with TIG as oxyfuel doesn't need (or want) the deoxidisers needed with TIG. MIG wire can be used with TIG, being typically smaller diameter it's easier to produce welds with less bead to planish/grind as TIG welds don't planish out quite as nicely as oxy fuel (1.0mm diameter A15/er70-s2 TIG wire is a better solution)
2. Brittle welds are one possible side effect of welding mild with stainless (or visa versa). 309 stainless is specifically alloyed to avoid this but will still 'mop up' porosity. The other potential issue is preferential corrosion

 

[MGA]

Hi hotrodder

Iv adjusted the gas flow up and down!

Adjusted the power up and down!

All to no avail.

At no time did i ever think about the Tig wire!!!

I think you could be right and it is oxyfuel wire. Will get some Mig wire and try with that.

Never heard of "preferential corrosion" just read up on it very interesting.Hopefully if i can get correct wire and get some good welds all should be well



Thank you very much for you time.

 

[hotrodder]

If you're nicking a little MIG wire from your (or a mates) set then after feeding some off you can straighten it by clamping one end in a vice, the other in a drill chuck and with it under a little tension giving it a spin. If you're paying for it then check the 'forum shop'... Weldequip sells A15 in small quantites http://www.weldequip.com/mild-steel-tig-rods.htm, not so many welding suppliers carry it in 1.0mm especially smaller quantities but other suspects would be Rtech, Rapidwelding i think and Weldmet

 

[langy]

I just welded a new sump into a 1946 tank and using 1mm A15 rod, welded nicely but occassionly you will see a flare up, It needs to be clean clean clean.

 

[MGA]

Thanks langy
If i can get my welds half as good as that,Well bunny's and happiness springs to mind.

90% of the time every thing i weld on the cars has been sandblasted.

I will be in my workshop this weekend to try with the MiG wire,But i will be buying proper tig wire next week.Any suggestions as to which type of wire to ask for? is as you have used 1mm A15 a good place to start ? The thickness of steel im welding is 1.25mm.



hotrodder.

Thanks again for the tip.

If you don't mind, i will post some pictures over the weekend of the set i am using.And if you could give me some advice as to how to get the best results from it.

Thanks again guys

 

[langy]

Thanks langy
If i can get my welds half as good as that,Well bunny's and happiness springs to mind.

90% of the time every thing i weld on the cars has been sandblasted.

I will be in my workshop this weekend to try with the MiG wire,But i will be buying proper tig wire next week.Any suggestions as to which type of wire to ask for? is as you have used 1mm A15 a good place to start ? The thickness of steel im welding is 1.25mm.



hotrodder.

Thanks again for the tip.

If you don't mind, i will post some pictures over the weekend of the set i am using.And if you could give me some advice as to how to get the best results from it.

Thanks again guys

Just ask for A15 rods mate, they should know what they are if they are any good.
I used a 1.6mm tungsten but can't help with amps as I use a pedal.

 

[MGA]

So what did i find when i had a ferret around under the bench today?
Yep you got it,More A15 tig rods than you can shake a stick at.
So im all set up to attack the plate in anger.

Got a new De Walt nail gun today!Not bad hey
It can drive a 16-D nail through a 2x4 at 200 yards.

This makes construction a breeze, you can sit in your lawn chair and build a fence.

Just get your wife to hold the fence boards in place while you sit back,

And relax and when she has the board in the right place, just fire away.

With the hundred round magazine, you can build the fence with a minimum of reloading. After a day of fence building with the new DeWalt Rapid fire nail gun, the wife will not ask you to build or fix anything else, probably, ever again.

 

[Shox Dr]

Will it manage a 100 nails before it breaks

 

[PTvor]

Love it.

Does it go fully auto?

 

[MGA]

For a little more Wonga you can have the camouflaged model with spotter scope.

You do have to train your own spotter up.

For a small fee you could hire mine.

 

[Norm]

love it