Titanium TIG filler rod – AWS A5.16 (ERTi-2 / ERTi-5 / ERTi-7 / ERTi-9)
Filler metal for GTAW welding of CP titanium and titanium alloys
Straight rods classified by AWS A5.16/A5.16M (ISO 24034), with lower interstitials than the base metal to preserve bead ductility. The class must match the grade of the base metal.
Designations and equivalents
| System | Designation |
|---|---|
| UNS | ERTi-2: R50120; ERTi-5: R56402; ERTi-7: R52401; ERTi-9: R56321 |
| W.Nr./EN | ISO 24034 (equivalent classes) |
| Trade names | Titanium TIG rod, Ti filler wire |
| Others | ASME SFA-5.16 |
Standards by product form
| Form | Standard |
|---|---|
| Rod/wire | AWS A5.16/A5.16M; ASME SFA-5.16 |
| International | ISO 24034 |
| Qualification | ASME IX / AWS D17.1 (aerospace) |
| Color inspection | AWS D17.1; AWS G2.4 |
Chemical composition (%)
AWS A5.16 (% by mass)
| Element | Range (%) |
|---|---|
| C | ERTi-2/7: ≤ 0.03 · ERTi-5: ≤ 0.05 · ERTi-9: ≤ 0.03 |
| O | ERTi-2/7: 0.08 – 0.16 · ERTi-5: 0.12 – 0.20 · ERTi-9: 0.06 – 0.12 |
| N | ERTi-2/7: ≤ 0.015 · ERTi-5: ≤ 0.03 · ERTi-9: ≤ 0.012 |
| H | ERTi-2/7: ≤ 0.008 · ERTi-5: ≤ 0.015 · ERTi-9: ≤ 0.005 |
| Fe | ERTi-2/7: ≤ 0.12 · ERTi-5: ≤ 0.22 · ERTi-9: ≤ 0.20 |
| Pd | ERTi-7: 0.12 – 0.25 |
| Al | ERTi-5: 5.5 – 6.75 · ERTi-9: 2.5 – 3.5 |
| V | ERTi-5: 3.5 – 4.5 · ERTi-9: 2.0 – 3.0 |
| Ti | balance |
Mechanical properties
AWS A5.16 classifies by composition only; typical deposited metal values
| Property | Value |
|---|---|
| ERTi-2 / ERTi-7 – tensile | ≈ 340 – 345 MPa (typical) |
| ERTi-2 / ERTi-7 – yield | ≈ 280 MPa (typical) |
| ERTi-2 / ERTi-7 – elongation | ≈ 20% (typical) |
| ERTi-5 – tensile | ≈ 895 MPa (typical, as Gr 5) |
Typical physical properties
| Property | Value |
|---|---|
| Usual diameters | 0.8 / 1.0 / 1.2 / 1.6 / 2.0 / 2.4 / 3.2 mm |
| Length | 914 mm (36") or 1,000 mm |
| Density | ERTi-2/7: 4.51 g/cm³ · ERTi-5: 4.43 g/cm³ |
| Shielding gas | argon ≥ 99.995% (or Ar-He); dew point ≤ -50 °C |
| Root purge | residual O2 < 50 ppm (ideally < 20 ppm) |
| Shielding until | metal < ~430 °C |
Heat treatment, welding and machining
| Item | Usual practice |
|---|---|
| Service temperature | Follows the base metal (CP Ti up to 316 °C per ASME; Gr 5 up to ~400 °C). |
| Heat treatment | Not applicable to the rod. Gr 5 joints may receive post-weld stress relief (≈ 540 – 650 °C) in vacuum or inert atmosphere. |
| Welding | Selection: Gr 1/2 → ERTi-1 or ERTi-2; Gr 7 → ERTi-7; Gr 5 → ERTi-5 or ERTi-23 (ELI, tougher bead); Gr 9 → ERTi-9; Gr 12 → ERTi-12. Torch with gas lens and large cup, trailing shield and root purge. Bead color: silver or light straw acceptable; dark straw and blue require evaluation; purple, gray or white = reject and remove. |
| Machining | Clean base metal and rod with acetone or alcohol (avoid chlorinated solvents); use a stainless brush dedicated to titanium, clean gloves and cut off the oxidized tip of the rod. |
Typical applications
- Chemical process piping and vessels in CP Ti (ERTi-2)
- Equipment for reducing acids and brines (ERTi-7)
- Aircraft structures in Ti-6Al-4V (ERTi-5/ERTi-23)
- Hydraulic tubing and bicycle frames (ERTi-9)
- Heat exchangers and condensers
- Repair of titanium parts
Alternatives: Always use the class compatible with the base metal; ERTi-23 instead of ERTi-5 when bead toughness or fatigue is critical; ERTi-7 (or ERTi-16) in reducing corrosive service, so as not to lose the Pd effect.
Titanium TIG filler rod: complete guide
Titanium rod for TIG welding: classes and use
Welding of titanium almost always uses the TIG process, with a non-consumable tungsten electrode, inert gas and a filler rod from the same family as the base metal. The rod is not "generally Ti-6Al-4V": the AWS A5.16 standard defines classes for each grade, with lower oxygen, nitrogen and hydrogen contents than the base metal to compensate for the unavoidable contamination during welding. The right choice is the class equal to, or lower in interstitials than, the material being welded.
Which class to use
For titanium Grade 2, and in general for the commercially pure grades, ERTi-2 is used, or ERTi-1 when maximum joint ductility is wanted. For Ti-6Al-4V ERTi-5 is used or, for toughness, ERTi-23 (ELI). For Grade 7 the rod must be ERTi-7, with palladium, so that the joint keeps its crevice resistance; for Grade 9, ERTi-9.
Gas shielding
Titanium reacts with oxygen, nitrogen and hydrogen above about 430 °C, and contaminated metal becomes brittle. That is why shielding goes beyond the torch: argon with a minimum purity of 99.995% and a dew point of −50 °C or lower, a wide cup with a gas lens, a trailing shield that follows the bead until it cools, and root purging to below 50 ppm of oxygen before striking the arc. Controlled-atmosphere chambers are no longer mandatory, but shielding discipline is.
Cleaning and parameters
Base metal and rod must be degreased with acetone or isopropyl alcohol and brushed with a stainless steel brush dedicated to titanium; nothing that has touched steel may touch titanium, because iron particles initiate corrosion and porosity. Welding is done with direct current electrode negative, a sharpened tungsten electrode, a short arc, high-frequency arc start and long post-flow, with low heat input and interpass of up to 150 °C. The tip of the rod exposed to hot air must be cut off at every restart.
Acceptance criterion by color
The color of the bead and the heat-affected zone indicates contamination: silver or light straw pass; blue requires evaluation, because it indicates light oxidation; purple, gray or dull white fail, and the weld must be removed and redone with better shielding. The criterion is in the AWS D1.9 code and must be part of the welding procedure.
Supply
Rods are supplied in diameters of 1.0, 1.6, 2.4 and 3.2 mm and a standard length of 914 mm (36 inches), in sealed packages identified by AWS class and lot, with the manufacturer's certificate. Dustre informs on request the classes and diameters in stock and supplies alongside them titanium bars in Grades 2, 5, 7 and 9, with cutting and machining to size.
Frequently asked questions
What is the chemical composition of Titanium TIG filler rod?
Per AWS A5.16 (% by mass): C ERTi-2/7: ≤ 0.03 · ERTi-5: ≤ 0.05 · ERTi-9: ≤ 0.03; O ERTi-2/7: 0.08 – 0.16 · ERTi-5: 0.12 – 0.20 · ERTi-9: 0.06 – 0.12; N ERTi-2/7: ≤ 0.015 · ERTi-5: ≤ 0.03 · ERTi-9: ≤ 0.012; H ERTi-2/7: ≤ 0.008 · ERTi-5: ≤ 0.015 · ERTi-9: ≤ 0.005; Fe ERTi-2/7: ≤ 0.12 · ERTi-5: ≤ 0.22 · ERTi-9: ≤ 0.20; Pd ERTi-7: 0.12 – 0.25.
Which standards cover Titanium TIG filler rod?
Rod/wire: AWS A5.16/A5.16M; ASME SFA-5.16. International: ISO 24034. Qualification: ASME IX / AWS D17.1 (aerospace). Color inspection: AWS D17.1; AWS G2.4.
Up to what temperature can Titanium TIG filler rod be used?
Follows the base metal (CP Ti up to 316 °C per ASME; Gr 5 up to ~400 °C).
Which materials can replace Titanium TIG filler rod?
Always use the class compatible with the base metal; ERTi-23 instead of ERTi-5 when bead toughness or fatigue is critical; ERTi-7 (or ERTi-16) in reducing corrosive service, so as not to lose the Pd effect.
