Friday, 24 February 2017

More TIG Welding

You might have seen my recent post on my first attempts at TIG. This is the second lesson, repeating the first and adding some specific tasks related to the real welding jobs immediately at hand. To this end, I cut a piece of 1.0 mm cold rolled mild steel sheet, about 5" x 8", and cut three 1" strips so that I ended up with a 5" square and three 1" strips. I cleaned the metal with a wire brush in the bench grinder.

I set the machine up with pure argon shielding at 3-5 l/min; I used a 1.6 mm red band tungsten electrode ground in a long taper; a number 4 ceramic and a welding current of 30-50 Amps. Tungsten stick-out was about 3 mm in most cases.

I planned to do a lap weld. a butt weld, a fillet weld with thin to thin material and with thick to thin material, and to plug some holes. All these welds were to be autogenous - no filler rod was used.

Lap Weld

This is a simple lap weld, with two sheets of 1.0 mm; welding current was 30 Amps. The material was cleaned much more thoroughly this time, and the results are much more pleasing:

Plug Welds

I wanted to test the TIG set on some plug welds: I have to reduce the size of a hole in one of the toolbox lids which is 1.0 mm thick, so this is an attempt to close a hole prior to redrilling. The back of these plugs is the same 1.0 mm sheet that I used for the lap weld.

Again the welder is set to 30 Amps; this is possible a little high as there is some burning here.

This pictures shows good penetration from the lap joint. In the lap joint picture, you can see the penetration from these welds - not quite as good as the lap joint penetration.

Butt Joint

This is a 1.0 mm autogenous butt joint, welder set to 30 Amps. The fit here was much better than the previous attempt, and this shows in the quality of the weld:

Penetration is mostly good:

Fillet Welds

This is a 1.0 mm to 1.0 mm fillet joint. Fit as good for most of the length, worse at the left hand end where I have blown that hole:

Penetration is good too:

Thick to Thin Fillet

This is a 2 mm wall tube fillet welded to a 1.0 mm sheet. Not so successful, but this is more down to access than welding technique.

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