TIG Filler Rod Chart: Selection, Size and AWS Classification
Use a TIG filler rod chart to match the base metal, AWS class and rod diameter before the first arc, because the wrong rod cannot be seen once the weld is finished. Choosing correctly protects strength, corrosion resistance and inspection results.
Quick Answer: A TIG filler rod chart matches the base metal to an AWS-classified rod: ER70S-2 or ER70S-6 for carbon steel, ER308L or ER316L for 304 and 316 stainless, ER80S-B2 for 1.25Cr-0.5Mo steel, and ER4043 or ER5356 for aluminium. Pick diameter from thickness, typically 1.6 mm (1/16 in) for thin sections and 2.4 mm (3/32 in) for 3 to 6 mm, and confirm against the WPS.
This guide explains how TIG welding filler rods are classified, gives a chart by base metal and ASME P-Number, and shows how to size rods and estimate their weight. It builds on the TIG welding process guide and the TIG filler rod selection guide, adding code-based selection and consumption calculations.
Values follow AWS and ASME practice. Where projects differ, the WPS and the contract specification decide.
Key Takeaways
- TIG filler rods are classified by AWS specification: A5.18 for carbon steel, A5.28 for low-alloy steel, A5.9 for stainless steel, A5.10 for aluminium and A5.14 for nickel alloys.
- ER70S-2 suits roots and light scale, ER70S-6 suits clean plate, and both give 70 ksi (480 MPa) minimum tensile strength.
- ER308L matches 304 and 304L, while ER316L is required for 316 and 316L because of its molybdenum content.
- Rod diameter follows thickness: about 1.6 mm for 1.5 to 3 mm, and 2.4 mm for 3 to 6 mm and pipe roots.
- A 2.4 mm steel rod weighs about 35.5 g per metre, which allows quick estimation of filler consumption.
What Is a TIG Filler Rod and How Is It Classified?
A TIG filler rod is a bare, solid wire that adds metal to the weld pool in gas tungsten arc welding and is classified by chemical composition. The American Welding Society (AWS) publishes one specification for each metal family, and the class printed on the rod tells you strength, alloy and use. The process itself is described in the gas tungsten arc welding (GTAW) guide; classification codes for other consumables are in the welding consumable nomenclature guide.
| AWS specification | Metal family | Example classes |
|---|---|---|
| A5.18 / ASME SFA-5.18 | Carbon steel | ER70S-2, ER70S-3, ER70S-6 |
| A5.28 / ASME SFA-5.28 | Low-alloy steel | ER80S-B2, ER90S-B3, ER90S-B9, ER80S-Ni1 |
| A5.9 / ASME SFA-5.9 | Stainless steel | ER308L, ER309L, ER316L, ER347, ER2209 |
| A5.10 | Aluminium and alloys | ER4043, ER5356, ER5183 |
| A5.14 | Nickel and nickel alloys | ERNiCr-3, ERNiCrMo-3, ERNiCrMo-4 |
The TIG filler rod selection guide on WeldFabWorld gives a beginner-oriented alloy and diameter walkthrough. This article takes a code-oriented view: classification, P-Number matching, rod weight and traceability for pressure equipment and piping.
TIG Filler Rod Chart: Which Rod Matches Which Base Metal?
What is the best TIG filler rod for common metals?
Match the rod to the base metal: ER70S-2 or ER70S-6 for carbon steel, ER308L for 304 stainless, ER316L for 316 stainless, ER309L for stainless-to-carbon joints, ER80S-B2 for 1.25Cr-0.5Mo steel, and ER4043 or ER5356 for aluminium. Confirm the exact class against the welding procedure specification (WPS) before welding.
| Base metal | ASME IX P-No. | Filler rod class | Notes |
|---|---|---|---|
| Carbon steel (A106 Gr B, A36) | 1 | ER70S-2 or ER70S-6 | -2 for roots and light scale; -6 for clean plate |
| 1.25Cr-0.5Mo (A335 P11) | 4 | ER80S-B2 | Preheat and PWHT per WPS |
| 2.25Cr-1Mo (A335 P22) | 5A | ER90S-B3 | Preheat and PWHT per WPS |
| 9Cr-1Mo-V (A335 P91) | 15E | ER90S-B9 | Tight WPS control; see the P91 guide |
| 304 / 304L | 8 | ER308L | Low carbon protects corrosion resistance |
| 316 / 316L | 8 | ER316L | Molybdenum for pitting resistance |
| 321 / 347 | 8 | ER347 | Niobium stabilised |
| 2205 duplex | 10H | ER2209 | Heat input control needed |
| Alloy 625 / C-276 | 43 | ERNiCrMo-3 / ERNiCrMo-4 | Argon shielding, clean joint |
| 6061 aluminium | 23 | ER4043 or ER5356 | Argon, AC current |
| 5052 aluminium | 22 | ER5356 | Not for sustained service above about 65 C |
P-Numbers group base metals for procedure qualification; the P-Number, F-Number and A-Number guide explains the grouping. Selection logic beyond this chart is in the welding consumable selection guide.
ER70S-2 or ER70S-6 for carbon steel?
ER70S-2 is triple deoxidised, so it copes with light scale and gives clean pipe roots. ER70S-6 has more silicon and manganese and wets clean plate smoothly. Both deliver 70 ksi (480 MPa) minimum tensile strength.
Why are L grades used for stainless steel?
The L in ER308L and ER316L limits carbon to 0.03 percent maximum, reducing chromium carbide formation in the heat-affected zone. The mechanism is explained in the guide to stainless steel weld decay. For titanium-stabilised 321, ER347 is the preferred filler; for duplex, see duplex stainless steel welding.
Code note. Where a project specifies ISO classifications instead, ISO 636 covers TIG rods for non-alloy and fine-grain steels and ISO 14343 covers stainless and heat-resisting steel wires and rods. Equivalence is not exact, so use the class the WPS names.
Which TIG Filler Rod Suits Dissimilar Joints?
Dissimilar joints need a filler that tolerates dilution from both base metals. For stainless steel to carbon or low-alloy steel, ER309L is the usual austenitic choice because the extra chromium and nickel absorb dilution from the carbon steel side.
| Joint | Typical filler | Reason |
|---|---|---|
| 304L to carbon steel | ER309L | Extra Cr and Ni offset dilution |
| 316L to carbon steel | ER309L (or 309LMo where specified) | Same dilution logic; Mo variant per WPS |
| Austenitic stainless to Cr-Mo steel, high temperature | ERNiCr-3 | Nickel filler reduces carbon migration and thermal expansion mismatch |
| Carbon steel to low-alloy steel | Class matching the higher-alloy side or as WPS states | Mechanical properties and PWHT response |
Caution. Dissimilar joints in elevated-temperature service need qualified procedures. Do not select the filler from a general chart alone.
What Size TIG Filler Rod Should You Use?
TIG filler rod diameter is chosen from base metal thickness, joint gap and pool size, and it must be small enough to melt smoothly without chilling the pool. Table 4 and Figure 3 give typical starting sizes; rod lengths are commonly 1,000 mm (about 39 in) or 36 in.
| Rod diameter | Typical base metal thickness |
|---|---|
| 0.8 – 1.0 mm | 0.5 – 1.5 mm |
| 1.6 mm (1/16 in) | 1.5 – 3 mm |
| 2.4 mm (3/32 in) | 3 – 6 mm, pipe roots |
| 3.2 mm (1/8 in) | 6 – 12 mm fill passes |
| 4.0 mm (5/32 in) | Over 12 mm heavy sections |
Rod size affects current and travel speed, so cross-check with the TIG welding settings calculator. Joint geometry, described in welding joint types explained, also drives the diameter: wide root gaps take heavier rod, tight gaps take lighter rod.
How Much TIG Filler Rod Does a Joint Need?
Filler rod consumption is the mass of weld metal in the joint divided by the fraction of rod that actually reaches the weld. Rod weight per metre follows from the cross-section area and density.
| Rod diameter | Steel, 7,850 kg/m3 | Stainless, 7,900 kg/m3 | Aluminium, 2,700 kg/m3 |
|---|---|---|---|
| 1.0 mm | 6.2 g | 6.2 g | 2.1 g |
| 1.6 mm | 15.8 g | 15.9 g | 5.4 g |
| 2.4 mm | 35.5 g | 35.7 g | 12.2 g |
| 3.2 mm | 63.1 g | 63.5 g | 21.7 g |
| 4.0 mm | 98.6 g | 99.3 g | 33.9 g |
Losses vary with stub length and welder technique, so the 10 percent figure is an assumption. For other joints, use the V-groove weld consumable calculator.
How to Select a TIG Filler Rod in Six Steps
Selecting a TIG filler rod is a short, repeatable check that ends with the WPS. Follow these steps in order.
- Identify the base metal. Record the exact grade and product form, for example A106 Gr B pipe, 316L plate or 6061 sheet.
- Find the P-Number and service. Note the ASME Section IX P-Number and the service: temperature, corrosion, toughness or cryogenic.
- Choose the AWS class. Select the class from the chart and confirm the specification named on the WPS.
- Check chemistry against service. Confirm carbon level, molybdenum, stabilisation or alloy needs for the service.
- Select the diameter. Choose rod diameter from thickness and joint, then cross-check current with the TIG settings.
- Verify the consumable. Check the rod marking, batch and certificate before welding.
Field tip. Inspectors check that the rod class in your hand matches the WPS and the material test certificate. Confirm this before opening a new tube.
How Should TIG Filler Rods Be Identified and Stored?
TIG filler rods must be identifiable to the batch, because the wrong alloy is invisible after welding. Each rod normally carries its AWS class as a flag tag or imprint, and the packaging carries the heat or lot number matched to the certificate.
- Traceability: project specifications often require an EN 10204 type 3.1 certificate for consumables and positive material identification (PMI) of alloy welds.
- Marking: keep the identification on the rod until it is used, and return unmarked offcuts to scrap.
- Storage: keep sealed, dry and separated by alloy, and store stainless and nickel rods away from carbon steel.
- Cleaning: wipe rods with a lint-free cloth and a suitable solvent if oil or dust is present.
Regional note. In humid coastal and monsoon conditions, and in Gulf summers, condensation on rods causes porosity. Store rods in closed tubes and keep the work area dry.
Common Mistakes and Limits When Choosing TIG Filler Rods
Most filler mistakes come from choosing by habit instead of by specification. Requirements depend on the code edition and contract specification applicable to your project.
- Using ER308L on 316L base metal and losing molybdenum.
- Using ER70S-6 where the WPS names ER70S-2, or the reverse, without a supporting procedure qualification.
- Choosing a rod so thick that it chills the pool and causes lack of fusion.
- Mixing loose rods from different tubes and losing identification.
- Using ER5356 on aluminium parts in sustained warm service.
Limit. A general chart cannot replace the WPS or the material specification. Creep, low-temperature and corrosion-critical services carry extra filler requirements.
Quick Reference: TIG Filler Rod Rules of Thumb
| Rule | Guideline |
|---|---|
| Carbon steel | ER70S-2 for roots and scale; ER70S-6 for clean plate |
| 304 / 304L | ER308L |
| 316 / 316L | ER316L (never ER308L) |
| Stainless to carbon steel | ER309L |
| Cr-Mo steels | Match: B2, B3, B9 per grade |
| Aluminium | ER4043 for flow; ER5356 for strength |
| Thin sheet | 1.6 mm rod or smaller |
| 3 to 6 mm and pipe roots | 2.4 mm rod |
| Shielding | Argon for all metals here; helium blends for thick aluminium |
| Final authority | The WPS and material certificate |
Frequently Asked Questions
What is the difference between ER70S-2 and ER70S-6 for TIG welding?
Can I use ER308L on 316L stainless steel?
What diameter TIG filler rod should I use for 3 mm plate?
Can MIG wire be used as TIG filler rod?
How should TIG filler rods be stored?
Which TIG filler rod is used for P91 (Grade 91) steel?
Is ER4043 or ER5356 better for 6061 aluminium?
Key Terms
- Filler rod
- A bare wire fed by hand into the weld pool to add metal.
- Classification
- The AWS code such as ER70S-2 that states chemistry and, for steels, strength.
- P-Number
- An ASME Section IX grouping of base metals with similar weldability.
- Deoxidiser
- An element such as aluminium, titanium or zirconium that removes oxygen from the pool.
- Dilution
- The share of base metal melted into the weld metal.
- WPS
- The welding procedure specification that names the approved filler.
- PMI
- Positive material identification, a check of alloy content.
Conclusion
The correct TIG filler rod chart entry starts with the base metal, then confirms the AWS class, the diameter and the certificate against the WPS. Carbon steel uses ER70S-2 or ER70S-6, 304 and 316 stainless use ER308L and ER316L, Cr-Mo steels use matching B-series rods, and aluminium uses ER4043 or ER5356. Choose 1.6 mm rod for thin sections and 2.4 mm for 3 to 6 mm work, and keep rods traceable. As a next step, calculate the rod quantity with the weld consumable calculator or set current with the TIG settings calculator.
About This Guide
This guide was prepared by the WeldFabWorld technical team from the standards listed in References. Verify all requirements against the code edition and specification applicable to your project.
Standards and References
- AWS A5.18/A5.18M – Carbon steel electrodes and rods for gas shielded arc welding. American Welding Society (AWS).
- AWS A5.28/A5.28M – Low-alloy steel electrodes and rods for gas shielded arc welding. American Welding Society (AWS).
- AWS A5.9/A5.9M – Bare stainless steel welding electrodes and rods. American Welding Society (AWS).
- AWS A5.10/A5.10M – Bare aluminum and aluminum-alloy welding electrodes and rods. American Welding Society (AWS).
- AWS A5.14/A5.14M – Nickel and nickel-alloy bare welding electrodes and rods. American Welding Society (AWS).
- AWS A5.01/A5.01M – Filler metal procurement guidelines. American Welding Society (AWS).
- ASME BPVC Section II Part C – Specifications for Welding Rods, Electrodes, and Filler Metals (SFA). American Society of Mechanical Engineers (ASME).
- ASME BPVC Section IX – Welding, Brazing, and Fusing Qualifications. American Society of Mechanical Engineers (ASME).
- ISO 636 – Welding consumables – Rods, wires and deposits for TIG welding of non-alloy and fine-grain steels – Classification. International Organization for Standardization (ISO).
- ISO 14343 – Welding consumables – Wire electrodes, strip electrodes, wires and rods for arc welding of stainless and heat resisting steels – Classification. International Organization for Standardization (ISO).
- EN 10204 – Metallic products – Types of inspection documents. European Committee for Standardization (CEN).
Official sources: American Welding Society, ASME and ISO.