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TIG Welding Basics

TIG Welding Tips

How do I TIG weld?

   
"How-To Weld" Summary
  1. Establish an arc.
  1. Create a weld puddle.
  1. Add filler metal "dip" into the puddle while pushing the weld puddle along the weld joint.
  1. End the arc and leave the torch over the weld puddle to protect it until the puddle cools.
 
 

How do I prepare my weld joint?

 
  1. Clean
    Cleaning both the weld joint area and the filler metal is an important preparation. Remove all oil, grease, dirt, paint, etc. The presence of these contaminants may result in arc instability or contaminated welds.
  1. Clamp
    Clamping may be required if the work piece cannot be supported during welding.
  1. Tack weld
    Make short 1/4 in. tack welds along the work pieces to hold them together.

How do I position my TIG torch for different types of joints?

   
Butt weld, TIG welding

Butt welds

When welding a butt joint, center the weld pool on the adjoining edges. When finishing, decrease the heat (amperage) to aid in filling the crater.

TIG torch position for butt weld

 

Lap joint, TIG welding

Lap joint

For a lap weld, form the weld pool so that the edge of the overlapping piece and the flat surface of the second piece flow together. Since the edge will melt faster, dip the filler rod next to the edge and make sure you are using enough filler metal to complete the joint.

TIG torch position for welding lap joint

 

T-joint, TIG welding

T-joint

When welding a T-joint, the edge and the flat surface are to be joined together, and the edge will melt faster. Angle the torch to direct more heat to the flat surface and extend the electrode beyond the cup to hold a shorter arc. Deposit the filler rod where the edge is melting.

TIG torch position for welding a T-joint

 

Corner joint, TIG welding

Corner joint

For a corner joint, both edges of the adjoining pieces should be melted and the weld pool should be kept on the joint centerline. A convex bead is necessary for this joint, so a sufficient amount of filler metal is needed.

TIG torch position for welding corner joint


What can I do to improve arc starting?

 
  • Use the smallest diameter tungsten possible for the amperage you are using. Match the tungsten electrode size with the collet size.
  • Purchase the highest quality tungsten available - ask your distributor for Miller-branded tungsten.
  • Use a premium quality torch and work leads.
  • Keep the torch and work leads as short as possible and move the power source as close as possible to the work.
  • Make sure the Stick electrode holder is detached from the machine before TIG welding.
  • Check and tighten all connections.
  • Keep the torch cable from contacting any grounded metal.
  • Use 100% argon shielding gas.
  • When welding aluminum, use AC current and a ceriated (gray identifying band) or 1.5% lanthanated (gold identifying band) tungsten.
  • When welding steel and stainless steel, use DC-Straight Polarity (DCEN) and a 2% thoriated (red identifying band) tungsten . Prepare a pointed-end.
  • Always use a push technique with the TIG torch.
  • When welding a fillet, the leg of the weld should be equal to the thickness of the parts welded.

Why would I use Ceriated or Thoriated tungsten instead of Pure?

   

With the introduction of new power source technologies, the use of pure tungsten is decreasing.

 

Pure tungsten melts at a lower temperature causing it to easily form a rounded ball at the tip. When the ball grows too large, it interferes with your ability to see the weld puddle and causes the arc to become unstable.

 

Ceriated tungsten can withstand higher temperatures and works very well with the new squarewave and inverter machines for the following reasons:

  • Holds a point longer and starts well at low amperages.
  • Can be used on both AC and DC polarities. When welding aluminum, it has become very acceptable to grind a point on ceriated tungsten (especially when welding on thinner materials).
  • Allows welding amperages to be increased by 25-30% compared to Pure tungsten of the same diameter.

Types of Tungsten Electrodes

Type of Tungsten (Alloy)

Color Code

Remarks

Pure

Green

Provides good arc stability for AC welding. Reasonably good resistance to contamination. Lowest current carrying capacity. Least expensive. Maintains a balled end.

Ceriated

CeO2

1.8% to 2.2%

Gray

Similar performance to thoriated tungsten. Easy arc starting, good arc stability, long life. Possible replacement for thoriated.

Thoriated

ThO2

1.7% to 2.2%

Red, Yellow



Easier arc starting. Higher current capacity. Greater arc stability. High resistance to weld pool contamination. Difficult to maintain balled end on AC.

Lanthanated

La2O3

1.3% to 1.7%

Gold, Black, Blue

Similar performance to thoriated tungsten. Easy arc starting, good arc stability, long life, high current capacity. Possible replacement for thoriated.

Zirconiated

ZrO2

0.15% to 0.40%

Brown

Excellent for AC welding due to favorable retention of balled end, high resistance to contamination, and good arc starting. Preferred when tungsten contamination of weld is intolerable.

Typical Current Ranges for Tungsten Electrodes

Tungsten Diameter Gas Cup (Inside Dia.) Typical Current Range (Amps)
Direct Current, DC

Alternating Current,

AC

DCEN 70% Penetration (50/50) Balanced Wave AC

Ceriated

 

Thoriated


Lanthanated

Zirconiated

Pure

Ceriated

 

Thoriated


Lanthanated

Zirconiated

Pure

Ceriated

 

Thoriated


Lanthanated

.040 #5 (3/8 in) 15–80 20–60 15–80 10–30 20–60
.060 (1/16 in) #5 (3/8 in) 70–150 50–100 70–150 30–80 60–120
.093 (3/32 in) #8 (1/2 in) 150–250 100–160 140–235 60–130 100–180
.125 (1/8 in) #8 (1/2 in) 250–400 150–200 225–325 100–180 160–250

All values are based on the use of Argon as a shielding gas. Other current values may be employed depending on the shielding gas, type of equipment, and application.

DCEN = Direct Current Electrode Negative (Straight Polarity).


Recommended Current Type, Tungsten and Gas for TIG Welding

Metal
Thickness
Type of Current
Tungsten
Shielding Gas
Aluminum
All
AC

Pure
Ceriated

Thoriated

Lanthanated

Argon
All
AC Squarewave

Ceriated

Thoriated

Lanthanated

Argon
over 1/4"
AC

Ceriated

Thoriated

Lanthanated

Argon
Copper, copper alloys
All
DCEN

Ceriated

Thoriated

Argon
Magnesium alloys
All
AC

Ceriated

Thoriated

Lanthanated

Argon
Plain carbon, steels
All
DCEN

Ceriated

Thoriated

Lanthanated

Argon
Stainless steel
All
DCEN

Ceriated

Thoriated

Lanthanated

Argon

Additional TIG Resources from Miller

   

TIG Welding Articles
Read TIG related welding articles from Miller's Welding Library:

   

TIG Guidelines Booklet

Download Miller's Guideline to Gas Tungsten Arc Welding (GTAW) Handbook (PDF).  This 16-page booklet is a guide to TIG welding basics. Sections on Process, Arc Shaping, Tungsten Electrodes, and Shielding Gases give you the essentials.

   

Safety Quick-Guide

Download and read our Safety Quick-Guide (PDF) for welding and cutting the safe way! Practical, easy-to-read advice covering a wide range of hazardous situations.

Owner's Manuals

Get the most from your Miller welder by downloading the specific Owner's Manual for your unit. From safety, operations/setup, & maintenance to troubleshooting & parts.