TIG welding (TIG, Tungsten Inert Gas Welding), as a representative of high-precision welding process, is widely used in aerospace, nuclear industry, medical equipment, precision manufacturing and other industries. But behind its smooth and beautiful weld, hiding a lot of easily overlooked technical details and misunderstandings, today we dig deep from a professional point of view you may not know those things.

1.TIG is one of the “most controllable heat input” processes in all welding

TIG welding uses non-melting pole argon arc as the heat source, with a stable DC or AC output, can realize the precise control of the very low heat input, especially suitable for:

-   Thin-walled parts (such as 0.3mm stainless steel)

-   Thermal materials (titanium, nickel, magnesium alloy)

-  Precision joints (such as microtubes for instrumentation) Precision joints (such as microtubes for instruments) The things you may not know about TIG welding

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Compared with MIG or manual arc welding, TIG has a smaller heat-affected zone, denser weld structure and more controllable deformation.

2.the surface is beautiful ≠ internal reliability, welding the back of the same vital

Many welders are easy to ignore the “back protection” when learning TIG.  

Especially in the welding of stainless steel, titanium alloy and other extremely sensitive to oxidation of the metal, if the back is not filled with argon, the internal oxidation layer, decarburization layer, intergranular corrosion point is very easy to generate, resulting in increased corrosion rate, the service life decreased significantly.

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Solution:

- Argon protection inside the tube (back gas)

- Use special gas blocking ring, gas guide ceramic

- Control the flow rate and replacement time (> 2 times the volume).

3.the purity of argon gas directly determines the quality of the weld – do not believe that “99.9% is enough”

In ordinary structural welding, industrial-grade argon gas (purity ≥ 99.99%) can meet. However, for the following scenarios:

- Aerospace parts

- High-vacuum chambers

- Medical clean systems

even trace impurities (e.g. oxygen, moisture, hydrogen) can lead to slag, pinholes, porosity and even microcracks inside the weld.

Recommendations:

- For high-end manufacturing prefer argon (5N) with a purity of ≥99.995%

- Use a gas supply system with humidity/dew point alarms.

4.Different colors of tungsten electrodes are not just “brand difference”, but welding performance difference.

Tungsten electrode colors Ingredients Features Application suggestions
Green (WP) Pure tungsten Arc dispersion, weak startup Only for AC aluminum welding
Red (WT20) Welding of 2% Thorium Concentration of the arc, long service life DC welding of carbon and stainless steels (note that there is a slight radioactivity)
Gray (WZr) Containing Zirconium Good resistance to contamination Recommended for welding titanium alloys
Purple (WX) Rare-earth alloys Highly versatile, stable arc Recommended for modern welding machines

Wrong choice of tungsten electrode not only affects the stability of the arc, but also leads to tungsten electrode contamination of the molten pool and generation of inclusions.

5.The “beauty” of the mirror weld, is the result of micro-metallurgical organization

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TIG welding is known for its smooth weld, fish scale uniformity, but behind these “appearances”, is its very low spatter and stable dynamic behavior of the molten pool.  

Under proper parameter control, the weld has a fine grain size, a homogeneous organization and mechanical properties (especially fatigue life) that are significantly better than those of other manual welding methods.

The microscopic characteristics of a good quality TIG weld include:

- microstructure of equiaxed crystals or fine columnar crystals

- no significant slag, porosity, cracks

- fracture with ductile fracture pattern

6.TIG welding is not “slow work”, but “wide range of applications”

TIG is often considered slow, high cost, but its real advantages are:

- very high weld quality controllability (especially in the zero-defect requirements of the industry)

- can be used for a variety of metals (steel, copper, aluminum, Aluminum, nickel, titanium, etc.)

- Easy to automate, such as orbital automated TIG, robotic TIG welding, etc.

In automated systems, TIG can reach welding speeds of tens of centimeters per minute, which is particularly suitable for high-volume production requiring high consistency.

7.After the gas protection, not optional, but the key to determine the life of the weld

TIG welding arc off moment, the molten pool is still in a high temperature state, if you immediately move away from the torch, the oxygen and nitrogen in the air is very easy to penetrate into the crystals, the formation of porosity, oxidation layer, resulting in early failure of the weld.

Professional advice:

- set the arc off after the gas delay time ≥ 3s (according to the material can be delayed to 6s)

- keep the torch posture unchanged until the gas flow completely

- use the “gas protection” function of the welder to set the parameters

8.TIG welding is not a separate process, but the “system engineering “

An excellent TIG welding results, involving a number of systems with:

- power supply system (stability, current response)

- gas protection system (pressure, purity, flow rate)

- process parameters (current, voltage, polarity, waveform)

- operating skills (torch angle, wire feed mode, gun speed)

- auxiliary control (such as foot pedal, arc start control mode, automation control) In other words, TIG is not “operating a welder”, but controlling **a welding ecosystem**.

Conclusion

The “difficulty” of TIG welding lies not in the equipment, but in the extreme demands on detail and specialization. But it is precisely because of these details that it can take its place in the most demanding industries.

If you can understand the science behind it and implement the specifications it requires, you’re not just welding metal, you’re creating a high-quality industrial standard.


Post time: Apr-18-2025