TIG rods by material
What are TIG rods?
Section titled “What are TIG rods?”TIG rods are consumable filler metals used in the gas tungsten arc welding (GTAW) process. They are supplied as straight wire in various lengths and diameters and are fed manually or mechanically into the weld pool. They add extra metal to fill joints or reinforce the connection when the base material thickness requires it. The selection of the rod depends on the base metal, mechanical requirements, and service environment.
Classification of TIG rods by material
Section titled “Classification of TIG rods by material”TIG filler metals are identified by standardized classifications that define their chemical composition and properties. The following table summarizes the most commonly used ones by material family.
| AWS Classification | Target base metal | Typical composition | Representative applications |
|---|---|---|---|
| ER70S‑2 | Carbon steels | 0.07% C, 0.5% Si, 1.0% Mn, deoxidizers (Al, Ti, Zr) | Pipes, steel structures, boilers |
| ER70S‑6 | Carbon steels | 0.07‑0.15% C, 0.8‑1.1% Si, 1.4‑1.8% Mn | Sheets with mill scale or slightly rusted |
| ER80S‑D2 | Low-alloy steels (0.5% Mo) | 0.1% C, 0.5% Mo | Components subjected to high temperature |
| ER308L | Austenitic stainless steels (304, 304L) | 20% Cr, 10% Ni, low carbon (<0.03%) | Food, chemical, architectural industry |
| ER316L | Stainless steels 316/316L | 18% Cr, 12% Ni, 2‑3% Mo | Marine and chloride environments |
| ER4043 | Aluminum‑silicon (cast and wrought) | 5% Si | Repair of castings, automotive |
| ER5356 | Aluminum‑magnesium (5xxx series) | 5% Mg | Boats, structures exposed to weather |
| ERCuSi‑A | Copper‑silicon (silicon bronze) | 3% Si, 1% Mn, balance Cu | Joining copper, brass, galvanized steel |
| ERNiCrMo‑3 (Inconel 625) | Nickel alloys, duplex and superduplex stainless steels | 22% Cr, 9% Mo, 3.5% Nb | Chemical process equipment, offshore |
| ERTi‑2 | Commercially pure titanium | Ti pure (>99.2%) | Aerospace, medical implants, heat exchangers |
Mechanical properties of weld deposits
Section titled “Mechanical properties of weld deposits”Values correspond to TIG weld deposits made according to AWS standard test conditions under argon shielding. The table includes the modulus of elasticity estimated from literature for each alloy.
| AWS Classification | Tensile strength | Yield strength (0.2%) | Minimum elongation | Modulus of elasticity (E) |
|---|---|---|---|---|
| ER70S‑2 | 483 MPa / 70 ksi | 400 MPa / 58 ksi | 22% | 200 GPa / 29 Mpsi |
| ER70S‑6 | 483 MPa / 70 ksi | 400 MPa / 58 ksi | 22% | 200 GPa / 29 Mpsi |
| ER80S‑D2 | 552 MPa / 80 ksi | 470 MPa / 68 ksi | 19% | 200 GPa / 29 Mpsi |
| ER308L | 550 MPa / 80 ksi | 350 MPa / 51 ksi | 35% | 180 GPa / 26 Mpsi |
| ER316L | 520 MPa / 75 ksi | 320 MPa / 46 ksi | 35% | 180 GPa / 26 Mpsi |
| ER4043 | 165 MPa / 24 ksi | 95 MPa / 14 ksi | 4% | 70 GPa / 10 Mpsi |
| ER5356 | 240 MPa / 35 ksi | 110 MPa / 16 ksi | 17% | 70 GPa / 10 Mpsi |
| ERCuSi‑A | 345 MPa / 50 ksi | 140 MPa / 20 ksi | 20% | 117 GPa / 17 Mpsi |
| ERNiCrMo‑3 | 760 MPa / 110 ksi | 415 MPa / 60 ksi | 30% | 214 GPa / 31 Mpsi |
| ERTi‑2 | 345 MPa / 50 ksi | 275 MPa / 40 ksi | 20% | 105‑120 GPa / 15‑17 Mpsi |
Welding parameters by material
Section titled “Welding parameters by material”Parameters are for manual welding in flat position with pure argon gas (except where another mixture is indicated). Direct current electrode negative (DCEN) for most materials; aluminum and magnesium require alternating current (AC). Gas flow rate is maintained between 8‑12 L/min (17‑25 ft³/h). Rod diameters are shown in millimeters and their inch equivalent.
| Base material | Rod diameter | Current type | Amperage range | Shielding gas |
|---|---|---|---|---|
| Carbon steel | 1.6 mm / 1/16 in | DCEN | 60‑80 A | Argon 100% |
| Carbon steel | 2.4 mm / 3/32 in | DCEN | 90‑120 A | Argon 100% |
| Carbon steel | 3.2 mm / 1/8 in | DCEN | 120‑160 A | Argon 100% |
| Stainless steel | 1.6 mm / 1/16 in | DCEN | 50‑70 A | Argon 100% or Argon + 2% H₂ |
| Stainless steel | 2.4 mm / 3/32 in | DCEN | 70‑100 A | Argon 100% or Argon + 2% H₂ |
| Stainless steel | 3.2 mm / 1/8 in | DCEN | 100‑140 A | Argon 100% or Argon + 2% H₂ |
| Aluminum | 1.6 mm / 1/16 in | AC (60‑80 Hz) | 60‑90 A | Argon 100% |
| Aluminum | 2.4 mm / 3/32 in | AC (60‑80 Hz) | 90‑130 A | Argon 100% |
| Aluminum | 3.2 mm / 1/8 in | AC (60‑80 Hz) | 120‑180 A | Argon 100% |
| Silicon bronze | 1.6 mm / 1/16 in | DCEN | 40‑60 A | Argon 100% |
| Silicon bronze | 2.4 mm / 3/32 in | DCEN | 60‑100 A | Argon 100% |
| Inconel 625 | 1.6 mm / 1/16 in | DCEN | 60‑80 A | Argon 100% or Argon + 30% He |
| Inconel 625 | 2.4 mm / 3/32 in | DCEN | 80‑120 A | Argon 100% or Argon + 30% He |
| Titanium | 1.6 mm / 1/16 in | DCEN | 50‑70 A | Argon 100% (chamber or inert backup) |
| Titanium | 2.4 mm / 3/32 in | DCEN | 70‑100 A | Argon 100% (chamber or inert backup) |
Selection guide
Section titled “Selection guide”Selecting the correct TIG rod follows a logical order: identify the base metal, define the required mechanical properties, and consider the service conditions.
- Chemical compatibility: the filler metal composition should be as close as possible to the base metal to avoid hot cracking and ensure corrosion resistance. For dissimilar joints, choose a filler of intermediate alloy or with a higher alloy content.
- Mechanical strength: the deposit should equal or exceed the minimum specified tensile strength of the base metal. For carbon steels, ER70S‑2 and ER70S‑6 cover most structural applications (up to 483 MPa / 70 ksi).
- Service conditions: if exposure to high temperatures exists, use rods with molybdenum (ER80S‑D2, ERNiCrMo‑3). For marine or chloride chemical environments, rods with molybdenum such as ER316L are preferred. In cryogenics, low-carbon austenitic stainless steels (ER308L, ER316L) maintain toughness.
- Deoxidizers: for steels with mill scale or slightly rusted, ER70S‑6 offers better wetting due to its higher silicon and manganese content.
- Aluminum: ER4043 is used on castings and Al‑Si alloys (good fluidity, lower cracking tendency); ER5356 is used on Al‑Mg alloys (higher mechanical strength and better toughness after welding).
- Titanium and nickel alloys: require extreme purity of the filler metal and redundant gas shielding to prevent embrittlement.
Advantages and limitations
Section titled “Advantages and limitations”Advantages
- The wide variety of available alloys covers almost all weldable engineering metals.
- Bare rods, containing no flux, produce clean welds without slag to remove.
- They allow obtaining deposits with mechanical properties very close to those of the base metal.
- The combination with pure argon or inert mixtures produces beads of great aesthetic quality and leak-tightness.
- The low hydrogen content in the deposits reduces the risk of cold cracking.
Limitations
- The deposition rate is low compared to other processes, making them uneconomical for large volumes.
- Manual feeding requires high welder skill to avoid defects such as lack of fusion or porosity.
- Aluminum rods require alternating current and high-frequency equipment, increasing initial investment.
- Some alloys (titanium, magnesium) demand ultra-pure atmospheres and gas chambers, increasing process cost.
- The absence of flux makes surface preparation and cleaning of the base metal critical for weld quality.
Frequently Asked Questions (FAQ)
Section titled “Frequently Asked Questions (FAQ)”What is the most commonly used TIG rod for carbon steel?
Section titled “What is the most commonly used TIG rod for carbon steel?”ER70S‑2 is the most common for general applications; it has a minimum tensile strength of 483 MPa / 70 ksi and good deoxidation.
What rod diameter is recommended for welding 1.5 mm / 0.06 in thick steel sheet?
Section titled “What rod diameter is recommended for welding 1.5 mm / 0.06 in thick steel sheet?”A diameter of 1.6 mm / 1/16 in is recommended, with direct current in the range of 40‑70 A depending on position and travel speed.
Can a stainless steel rod be used on carbon steel?
Section titled “Can a stainless steel rod be used on carbon steel?”Only in certain dissimilar cases with controlled procedures; the difference in coefficient of thermal expansion (slightly higher in austenitic stainless steels) can generate stresses and cracking under thermal service.
What shielding gas is suitable for welding aluminum with ER4043 rod?
Section titled “What shielding gas is suitable for welding aluminum with ER4043 rod?”Use 100% argon with high-frequency alternating current; typical flow is 10‑12 L/min / 21‑25 ft³/h in standard #6‑8 nozzles.
What amperage is recommended for a 2.4 mm / 3/32 in rod on 304 stainless steel?
Section titled “What amperage is recommended for a 2.4 mm / 3/32 in rod on 304 stainless steel?”In DCEN with argon, the optimal range is 70‑100 A, depending on part thickness and welding position.
What tensile strength can be expected from a deposit with ER5356 rod on aluminum?
Section titled “What tensile strength can be expected from a deposit with ER5356 rod on aluminum?”The deposit typically reaches a tensile strength of 240 MPa / 35 ksi, with 17% elongation, sufficient for marine and transportation structures.
References
Section titled “References”- engineeringtoolbox.com: https://www.engineeringtoolbox.com/young-modulus-d_417.html
- efunda.com: https://www.efunda.com/eds/list_company_bycat.cfm/id/1107/cat/Electrical%20and%20Electronic%20Components%20%26gt%3B%20Fasteners%20and%20Hardware/
- manufacturingguide.com: https://www.manufacturingguide.com/en/tig-welding