Outside corner TIG welding on steel: a step-by-step guide

Joanne McIntyre - 6 April 2017

TIG, or Tungsten Inert Gas welding – more properly known as Gas Tungsten Arc Welding (GTAW) – is a technique that uses a non-consumable tungsten electrode to supply current to the welding arc. Guest blogger Morgan Franklin has prepared a guide for mastering this technique.

About the author

Mrs Joanne McIntyre
Joanne McIntyre is the Editor in Chief of Stainless Steel World magazine, and Conference Coordinator for the Duplex Seminar & Summit.
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If you’ve done any oxy-acetylene welding before, then you’ll immediately recognise certain key similarities with TIG welding: both are reasonably advanced techniques, requiring the operator to feed a rod of non-consumable filler material into the arc with one hand while holding the torch with the other.
Welding outside corners, too, is often seen as one of the trickier welding procedures. This is due primarily to the fact that the gas has no inward-facing surfaces to bounce back from, meaning it can be difficult for less experienced welders to keep the stream close enough to the weld to protect the work as it’s created.
In the video below, Morgan Franklin of R-Tech Welding has put together a detailed tutorial to guide viewers through the process of welding a 2.0mm steel outside corner weld, using the R-Tech Analogue AC/DC TIG Welder. Watching the full (3min 48sec) video is the best way to see all the detailed steps linked together sequentially, but Morgan has also listed the main bullet point instructions below.

TIG Outside Corner Welding: 2mm Stainless Steel with the R-Tech Analogue AC/DC TIG Welder.

Step-by-step instructions

1. Connect the earth lead into the +/positive socket and earth clamp onto workpiece
2. Connect the torch into -/negative socket
3. Connect the foot pedal plug to 7-pin socket. (If using torch switch operation, fit 7-pin plug from torch lead)
4. Fit male quick-release gas fitting onto the torch lead
5. Set gas flow rate to 8LPM (litres per minute) on gas regulator. For fine gas control, we recommend using a gas flow meter
6. Set base current to 50A (assuming a 1.6mm filler rod) with your gas flow at 8LMP. When the foot pedal is fully depressed, this is the maximum amperage you will achieve
7. Set pulse current to 5A, the lowest setting (when set to minimum, pulse welding is switched off)
8. Set post flow gas to 8s – insufficient post flow gas can result in oxidisation of tungsten, resulting in poor re-striking and an unstable arc during welding
9. Set pulse width to 0.1 and pulse frequency to 0.5Hz
10. Set up-slope and down-slope both to 0 (not required when using the foot pedal to control amperage)
11. Also set arc force to 0, the minimum setting (not required in TIG mode, only for MMA/consumable stick welding). TIG mode switch should be in the on position. AC/DC switch should be set to DC in our example (stainless steel welding). AC is used for welding aluminium alloys, DC for steels
12. Tack both ends of material to avoid warping during main weld
13. Hold torch at 45 degrees to work, and ensure arc is evenly focused on both pieces. Wait until a molten pool forms on both and then joins together. (A circular or side-to-side movement will help achieve this join)
14. Press down fully on the pedal to start the weld, lifting off slightly to reduce amps and fully releasing to stop
15. Hold the filler od ready to start the weld, about 4cm from the torch
16. If using a torch switch, press it to start the arc. Hold the torch at a 45-degree angle to the work, and point it in the direction of the weld, ensuring the tungsten is sticking out roughly 2-3 times its diameter from the end of the ceramic nozzle
17. Start the arc and wait for the pool to become molten – focus arc on both pieces so that the molten pool is equal on both parts
18. Insert the filler rod into the molten pool at an approximately 15-degree angle, until the weld is filled. Insert and remove the filler rod from the molten pool in a swift motion while moving the torch along the weld, taking care not to touch it against the torch tungsten. Ensuring a consistent speed will help keep the weld bead uniform
19. If the weld gets too hot, slightly lift off on the pedal to reduce welding power. Keep the filler rod away from the pool when it’s not actually inserted, in order to avoid melting and oxidising it
20. When coming to the end of a weld, remember to hold the torch in the same position after you stop welding. This will help ensure there’s no oxidisation to the surface of the weld during the cooling process
For more instructional videos covering numerous welding techniques and equipment demonstrations, check out the full R-Tech YouTube channel, or visit http://www.r-techwelding.co.uk

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