CSA W59 Weld Electrodes — E48XX, E55XX, E62XX Classification & Selection
Complete reference for welding electrode classification per CSA W59-18 (Welded Steel Construction) and CSA W48 (Filler Metals and Allied Materials). Electrode selection for CSA G40.21 structural steel grades, matching requirements, welding process selection for SMAW, GMAW, FCAW, and submerged arc welding (SAW).
Quick access: CSA W59 minimum weld sizes → | Welded connection calculator → | CSA S16 design guide →
CSA W59 Electrode Classification System
CSA W59 adopts electrode designations from CSA W48 (Filler Metals and Allied Materials for Metal Arc Welding). The Canadian classification system is similar to the AWS system but uses metric strength designations.
Electrode Designation Format: E48XX
- E: Electrode (for SMAW stick electrodes). For wire electrodes: E (solid GMAW), E (FCAW), EM (SAW)
- 48: Minimum tensile strength in ksi = 48 ksi, or approximately 480 MPa. (Canadian designation uses ksi units for historical compatibility with the AWS system.)
- XX: Position, flux type, operating characteristics
E48XX (480 MPa) Electrodes — Standard Structural
E48XX electrodes have Xu = 480 MPa minimum tensile strength. These are the standard electrodes for welding CSA G40.21 260W, 300W, 350W, 350A, 350WT, and 350AT grades.
| CSA W48 Classification | AWS Equivalent | Process | Position | Flux/Slag Type | Typical Application |
|---|---|---|---|---|---|
| E48018 | E7018 | SMAW | All | Low-hydrogen | General structural welding, beams, columns |
| E48013 | E7013 | SMAW | All | Rutile | Non-structural, sheet metal, light fabrication |
| E48S-6 | ER70S-6 | GMAW | All | Solid wire | Most common GMAW electrode for 350W |
| E480T-1 | E71T-1 | FCAW | All | Rutile | General structural, high deposition |
| E480T-5 | E71T-5 | FCAW | All | Basic (low-H) | High toughness requirements, low temperature |
| E480T-9 | E71T-9 | FCAW | All | Rutile | Higher impact toughness than T-1 |
E55XX (550 MPa) Electrodes — High Strength
E55XX electrodes have Xu = 550 MPa minimum tensile strength. Used for CSA G40.21 400W and 480W base metals.
| CSA W48 Classification | AWS Equivalent | Process | Position | Typical Application |
|---|---|---|---|---|
| E55018 | E8018 | SMAW | All | 400W columns, transfer girders |
| E55S-6 | ER80S-D2 | GMAW | All | High-strength GMAW, 400W/480W |
| E550T-1 | E81T-1 | FCAW | All | 400W structural, high deposition |
| E550T-5 | E81T-5 | FCAW | All | High toughness, 400W low-temp applications |
E62XX (620 MPa) Electrodes — Extra High Strength
E62XX electrodes have Xu = 620 MPa minimum tensile strength. Used for CSA G40.21 700Q quenched and tempered steel.
| CSA W48 Classification | AWS Equivalent | Process | Position | Typical Application |
|---|---|---|---|---|
| E62018 | E9018 | SMAW | All | 700Q welding, heavy equipment |
| E62S-6 | ER90S-G | GMAW | All | 700Q GMAW with controlled HIC |
| E620T-1 | E91T-1 | FCAW | All | 700Q structural |
Electrode Selection by Base Metal
Per CSA W59 Table 5.2, the electrode tensile strength must be matched to the base metal grade:
| Base Metal Grade | Minimum Electrode Grade | Electrode Xu (MPa) | Nominal Weld Strength X_u (MPa) |
|---|---|---|---|
| CSA G40.21 260W | E48XX | 480 | 480 |
| CSA G40.21 300W | E48XX | 480 | 480 |
| CSA G40.21 350W | E48XX | 480 | 480 |
| CSA G40.21 350A | E48XX | 480 | 480 |
| CSA G40.21 350WT | E48XX | 480 | 480 |
| CSA G40.21 350AT | E48XX | 480 | 480 |
| CSA G40.21 400W | E55XX | 550 | 550 |
| CSA G40.21 480W | E55XX | 550 | 550 |
| CSA G40.21 700Q | E62XX | 620 | 620 |
Overmatching
Overmatching (using a higher-strength electrode than required for the base metal) is generally permitted per CSA W59 provided:
- The welding procedure is qualified with the overmatched electrode
- Weld metal ductility is adequate — overmatched welds are typically less ductile than the base metal
- For seismic connections (CSA S16-19 Clause 27.5), overmatching is permitted for connections in moderately ductile and limited ductility systems, but overmatching requirements are specified for ductile systems
Undermatching
Undermatching (using a lower-strength electrode) is permitted per CSA W59 Clause 5.6 only when:
- The weld is designed with adequate size to compensate for the lower electrode strength
- The weld is not part of a seismic force-resisting system requiring overmatching
- The base metal thickness does not exceed 40 mm (thicker sections require matched or overmatched electrodes for fusion and HAZ control)
- The base metal is not quenched and tempered (700Q)
Welding Process Selection
SMAW — Shielded Metal Arc Welding (Manual)
| Feature | Detail |
|---|---|
| Electrode types | E48018 (E7018 low-hydrogen) most common for structural |
| Diameters | 2.5 mm to 6.0 mm |
| Deposition rate | 1-3 kg/hr (lowest of all processes) |
| Best for | Field welding, short welds, out-of-position, repairs |
| Limitations | Slower than FCAW, requires stop/start for electrode changes |
E48018 is the most common SMAW electrode for Canadian structural steel. It provides:
- Low-hydrogen coating (maximum diffusible hydrogen: 8 mL/100 g deposit)
- Excellent toughness at low temperatures (meets 27 J at -20 deg C minimum)
- All-position capability (flat, horizontal, vertical-up, overhead)
- Good mechanical properties matching 350W base metal
GMAW — Gas Metal Arc Welding (Semiautomatic)
| Feature | Detail |
|---|---|
| Wire types | E48S-6 (ER70S-6) for 350W, E55S-6 for 400W |
| Shielding gas | 90% Ar / 10% CO2 (C10) or 75% Ar / 25% CO2 (C25) |
| Diameters | 0.9 mm to 1.6 mm |
| Deposition rate | 3-8 kg/hr |
| Best for | Shop fabrication, long continuous welds, high production |
| Limitations | Wind-sensitive (requires shielding), less portable than SMAW |
E48S-6 is the standard GMAW wire for 350W steel. It contains higher silicon and manganese deoxidiser levels than E48S-3, providing better wetting action on mill scale and superior puddle control.
FCAW — Flux Cored Arc Welding (Semiautomatic)
| Feature | Detail |
|---|---|
| Wire types | E480T-1 (E71T-1) most common, E480T-5 for toughness |
| Shielding | Self-shielded (E480T-8, E480T-11) or gas-shielded |
| Diameters | 1.2 mm to 2.4 mm |
| Deposition rate | 3-10 kg/hr (highest of all-position processes) |
| Best for | Heavy structural fabrication, high deposition, out-of-position |
| Limitations | Fume generation higher than GMAW, slag removal required |
FCAW is the most popular process for Canadian structural steel fabrication because of its high deposition rate combined with all-position capability. E480T-1 (rutile slag) provides good operator appeal and mechanical properties. For Charpy requirements at -45 deg C, E480T-5 (basic slag) is preferred.
SAW — Submerged Arc Welding (Automatic)
| Feature | Detail |
|---|---|
| Wire types | EM48K (L-61) for 350W, EM55K for 400W |
| Flux | Agglomerated (F48A) or fused (F48P) |
| Diameters | 2.0 mm to 5.0 mm |
| Deposition rate | 5-20 kg/hr (highest of all processes) |
| Best for | Long straight welds, girder fabrication, pipe mills |
| Limitations | Flat position only, flux handling required, limited to shop |
SAW is used primarily for WWF (welded wide flange) girder fabrication and heavy plate welding in structural steel shops. Panasonic, Lincoln, and ESAB are common SAW equipment suppliers in the Canadian market.
Electrode Toughness Requirements
For low-temperature service, electrode toughness is critical. CSA W59 Table 5.6 specifies Charpy V-notch requirements for weld metal in fracture-critical applications:
| Service Temperature | Min Electrode CVN | Test Temp | Min Energy |
|---|---|---|---|
| > -20 deg C | Not required | — | — |
| -20 to -35 deg C | 27 J | -20 deg C | 27 J |
| -35 to -45 deg C | 27 J | -30 deg C | 27 J |
| < -45 deg C | 40 J | -45 deg C | 40 J |
Electrode Toughness Data
| CSA W48 Classification | Typical CVN (J at -30 deg C) | Suitable for Service Temp |
|---|---|---|
| E48018 (E7018) | 27-40 J | Down to -35 deg C |
| E48S-6 (ER70S-6) | 20-30 J | Down to -20 deg C |
| E480T-1 (E71T-1) | 20-30 J | Down to -20 deg C |
| E480T-5 (E71T-5) | 40-60 J | Down to -45 deg C |
| E480T-9 (E71T-9) | 30-40 J | Down to -35 deg C |
| E48S-3 (ER70S-3) | 15-25 J | Down to -20 deg C |
For bridges and Arctic structures requiring 350WT base metal properties, E480T-5 or E48018 electrodes should be specified to match the -45 deg C Charpy requirements of the base metal. Verify electrode mill certificates for actual CVN values at the required temperature.
Preheating and Interpass Temperature
Per CSA W59 Table 5.2, minimum preheat temperatures depend on the combination of base metal grade, electrode type (hydrogen level), and thickness:
Minimum Preheat for E48XX Low-Hydrogen Electrodes (350W Steel)
| Thickness (mm) | Minimum Preheat (deg C) |
|---|---|
| t <= 20 | 0 deg C (minimum ambient) |
| 20 < t <= 40 | 5 deg C |
| 40 < t <= 65 | 45 deg C |
| 65 < t <= 100 | 65 deg C |
| t > 100 | 95 deg C |
For E55XX and E62XX electrodes, preheat requirements are typically 15-25 deg C higher for the same thickness. For 700Q steel, the preheat must be within the range specified by the steel manufacturer (typically 100-150 deg C) to avoid hydrogen cracking while not exceeding the tempering temperature of the base metal.
Storage and Handling
Per CSA W59 Clause 5.3, electrode storage and handling requirements:
| Electrode Type | Storage Condition | Maximum Exposure Before Redry |
|---|---|---|
| E48018 (low-hydrogen) | 120-150 deg C holding oven | 4 hours (open air, 50% RH) |
| E480T-5 (basic flux) | 120-150 deg C holding oven | 2 hours (open air, 50% RH) |
| E480T-1 (rutile flux) | Sealed container | 24 hours (open air) |
| E48S-6 (solid GMAW wire) | Clean, dry storage (10-40 deg C) | No limit (in feeder) |
| SAW flux (agglomerated) | 120-150 deg C holding oven | 2 hours |
Exposure limits are critical in Canadian coastal and high-humidity environments (Vancouver, Halifax, Toronto in summer). Moisture in low-hydrogen electrodes introduces hydrogen into the weld pool, causing hydrogen-induced cracking (HIC) in the heat-affected zone. Re-drying procedures per CSA W59 Annex B must be followed for electrodes that exceed exposure limits.
Frequently Asked Questions
What electrode is used for welding CSA G40.21 350W steel? E48XX electrodes (Xu = 480 MPa) are specified per CSA W59 Table 5.2. The most common are: E48018 (E7018) for SMAW stick welding, E48S-6 (ER70S-6) for GMAW, and E480T-1 (E71T-1) for FCAW. For low-temperature service (-35 deg C or below), E480T-5 (basic flux) provides superior Charpy toughness. E55XX electrodes are NOT required for 350W — E48XX provides adequate strength matching.
What is the difference between E48XX and E55XX electrodes? E48XX has Xu = 480 MPa (70 ksi equivalent, matching 350W steel), while E55XX has Xu = 550 MPa (80 ksi equivalent, matching 400W/480W steel). E48XX is the standard structural electrode in Canada, used with 260W, 300W, 350W, and 350A grades. E55XX is specified for 400W and 480W base metals. Using E55XX on 350W (overmatching) is permitted but may produce less ductile welds and requires qualified welding procedures.
What welding process is most common for Canadian structural steel fabrication? FCAW (flux-cored arc welding) with E480T-1/E71T-1 electrodes is the most common process in Canadian structural steel shops due to its combination of high deposition rate (3-10 kg/hr) and all-position capability. For field welding and connections, SMAW with E48018 (E7018) remains common. For heavy girder fabrication (WWF sections), SAW (submerged arc welding) is used for long straight welds. GMAW with E48S-6 is common for lighter fabrication and robotic welding systems.
What are the Charpy requirements for weld metal in Canadian low-temperature service? Per CSA W59 Table 5.6, for service temperatures between -20 and -35 deg C, weld metal must provide 27 J at -20 deg C minimum. For service between -35 and -45 deg C, 27 J at -30 deg C is required. For service below -45 deg C, 40 J at -45 deg C is required. Electrodes meeting these requirements include E48018 (E7018), E480T-5 (E71T-5), and E480T-9 (E71T-9). Standard E480T-1 (E71T-1) electrodes typically provide only 20-30 J at -30 deg C and may not meet the most stringent requirements.
What is the minimum preheat for welding 25 mm 350W steel with E48018 electrodes? For 25 mm thickness (20 < t <= 40 mm bracket) with low-hydrogen E48018 electrodes on 350W steel, CSA W59 Table 5.2 specifies a minimum preheat of 5 deg C. In practice, most fabricators use 5-20 deg C minimum for thickness in this range. The ambient temperature of the steel (typically above 5 deg C in heated shops) usually satisfies the requirement. For thicker sections (40-65 mm), preheat increases to 45 deg C, which requires active heating with propane or electric resistance heaters.
Related Pages
- CSA W59 Minimum Weld Size — Fillet Weld Table
- CSA Bolt Capacity — A325M & A490M Tables
- Canadian Steel Grades — G40.21 300W, 350W, 400W
- Canadian Steel Properties — G40.21 Fy & Fu by Grade
- CSA S16 Code Overview
- Welded Connection Calculator
- Weld Symbol Chart
- Weld Joint Types Reference
- Steel Weld Inspection Methods
This page is for educational reference. All electrode data per CSA W59-18 and CSA W48. Verify electrode selection against the current code edition, project specifications, and welding procedure qualification records (WPQRs). For fracture-critical and seismic connections, follow additional Charpy and quality control requirements. Results are PRELIMINARY — NOT FOR CONSTRUCTION without independent PE/SE verification.