Tungsten Alloy EWTh-2
AISI/SAE AWS A5.12 EWTh-2 · GB GB/T 4189 WT20 · ISO 6848 WT20
EWTh-2 (WT20) is a sintered tungsten electrode rod doped with 2% thoria (ThO2), supplied to AWS A5.12 and GB/T 4189 as a non-consumable arc electrode.
Reference datasheet — EWTh-2 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
EWTh-2 tempers and conditions
EWTh-2 is supplied in one standard condition, SR.
Supply forms, finishes and certifications
Ways EWTh-2 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
Black | As-swaged / black surface rod | Surface finish |
CLEANED | Cleaned finish | Surface finish |
GroundDefault | Ground finish | Surface finish |
What is EWTh-2?
EWTh-2 (WT20) is a sintered tungsten electrode rod doped with 2% thoria (ThO2), supplied to AWS A5.12 and GB/T 4189 as a non-consumable arc electrode. The thoria addition lowers the work function, giving easy DC arc initiation, a stable low-current arc and long tip life on carbon and stainless steel; forms are ground bright, chemically cleaned or black-finished rods in cut lengths. Tensile strength is about 1400 MPa with 1150 MPa yield and only 2% elongation, so the rod is brittle at room temperature, and service temperature reaches 2500 °C with thermal conductivity of 125 W/m·K. Thoria is radioactive and the grade is being withdrawn; EWLa-1 or EWCe-2 are the usual drop-in replacements. EWTh-2 has a density of 19.1 g/cm³ (0.69 lb/in³), heavier than 52% of tungsten alloy grades. It melts at 3,410°C (6,170 °F). EWTh-2 has a yield strength of 1,150 MPa (167 ksi) and a tensile strength of 1,400 MPa (203 ksi) — stronger than 83% of tungsten alloy grades. Elongation at break is 2% and the elastic modulus is 400 GPa (58 Msi).
What is EWTh-2 used for?
- DC TIG welding of carbon steel
- Stainless steel welding
- Precision arc starting applications
Advantages
- High service temperature — 2,500°C (4,532 °F), better than 95% of tungsten alloy grades
- High strength — 1,150 MPa (167 ksi), better than 83% of tungsten alloy grades
Limitations
- Low fracture toughness — 10 MPa·√m (9.1 ksi·√in), worse than 83% of tungsten alloy grades
- Hard to polish — 60/100, worse than 83% of tungsten alloy grades
EWTh-2 properties
Typical room-temperature values; bars are the position among tungsten alloy grades.
Physical3
EWTh-2 has a density of 19.1 g/cm³ (0.69 lb/in³), heavier than 52% of tungsten alloy grades. It melts at 3,410°C (6,170 °F).
Mechanical12
EWTh-2 has a yield strength of 1,150 MPa (167 ksi) and a tensile strength of 1,400 MPa (203 ksi) — stronger than 83% of tungsten alloy grades. Elongation at break is 2% and the elastic modulus is 400 GPa (58 Msi).
Thermal5
EWTh-2 is rated for continuous service to 2,500°C (4,532 °F). It conducts heat at 125 W/m·K (72.2 BTU/hr·ft·°F), worse than 57% of tungsten alloy grades. Thermal expansion is 4.5 µm/m·K (2.5 µin/in·°F).
Electrical3
EWTh-2 conducts electricity at 28 % IACS, worse than 57% of tungsten alloy grades.
Chemical & Environmental3
Corrosion resistance is good (60/100), better than 50% of tungsten alloy grades.
Sustainability4
Producing a kilogram of EWTh-2 takes about 380 MJ of energy and emits 27 kg of CO₂ — less than 62% of tungsten alloy grades. Typical recycled content is 5%.
Manufacturability7
EWTh-2's machinability is not recommended (8/100, worse than 71% of tungsten alloy grades); weldability not recommended (10/100); formability not recommended (5/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the tungsten alloy family
Yield strength against density for every tungsten alloy grade FabDigit runs. EWTh-2 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with EWTh-2
Is EWTh-2 easy to machine?
Extremely brittle at room temperature: shape only by diamond or CBN wheel grinding, abrasive cut-off disc or EDM, never by turning, milling or drilling. Grind wet with local dust extraction, because thoria dust is both a radiological and a toxic hazard.
Can EWTh-2 be welded?
Not welded as a structural material; in service it is the non-consumable electrode in DC GTAW. If a joint is required, use vacuum electron-beam welding or Ni/Cu-base vacuum brazing and expect the recrystallised weld zone to be very brittle.
Can EWTh-2 be formed, bent or molded?
Shaped only at the mill by powder pressing, hydrogen sintering and rotary swaging or drawing at 1200–1600 °C. No cold formability at room temperature — bending fractures the rod, so cut to length instead of bending.
EWTh-2 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| ThO2ThO2 dispersoid; AWS A5.12 EWTh-2 / ISO 6848 WT20 | 1.7 – 2.2 | 2 |
| other (total impurities)maximum total impurities | ≤ 0.2 | 0.1 |
| Wbalance, W ≥ 97.30 % | balance | — |
What surface finishes work on EWTh-2?
Standard finishes are centreless-ground bright or chemically etched (black) surfaces; the end is marked with the ISO/AWS red identification colour. Before use, grind the tip taper longitudinally, with the angle chosen for the base material and welding current.
Equivalent designations
Standards and trade names that resolve to Tungsten Alloy EWTh-2 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- AISI / SAE
- AWS A5.12 EWTh-2
- ISO
- 6848 WT20
- GB (China)
- GB/T 4189 WT20
- Other
- WT20
How much does EWTh-2 cost?
EWTh-2 is a high-cost tungsten alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
EWTh-2 — frequently asked
What is EWTh-2 used for?
EWTh-2 is typically used for DC TIG welding of carbon steel, stainless steel welding and precision arc starting applications. In short: best DC arc starting; legacy thoriated electrode; radioactive, being phased out.
What is the yield strength of EWTh-2?
EWTh-2 has a typical yield strength of 1,150 MPa (167 ksi) and a tensile strength of 1,400 MPa (203 ksi) — stronger than 83% of tungsten alloy grades.
Is EWTh-2 easy to machine?
Not especially — machinability is rated not recommended (8/100, worse than 71% of tungsten alloy grades). Extremely brittle at room temperature: shape only by diamond or CBN wheel grinding, abrasive cut-off disc or EDM, never by turning, milling or drilling. Grind wet with local dust extraction, because thoria dust is both a radiological and a toxic hazard.
Can EWTh-2 be welded?
Not readily — weldability is rated not recommended (10/100). Not welded as a structural material; in service it is the non-consumable electrode in DC GTAW. If a joint is required, use vacuum electron-beam welding or Ni/Cu-base vacuum brazing and expect the recrystallised weld zone to be very brittle.
What surface finishes work on EWTh-2?
Standard finishes are centreless-ground bright or chemically etched (black) surfaces; the end is marked with the ISO/AWS red identification colour. Before use, grind the tip taper longitudinally, with the angle chosen for the base material and welding current.
Can EWTh-2 be formed, bent or molded?
Shaped only at the mill by powder pressing, hydrogen sintering and rotary swaging or drawing at 1200–1600 °C. No cold formability at room temperature — bending fractures the rod, so cut to length instead of bending.
What is the maximum service temperature of EWTh-2?
EWTh-2 is rated for continuous use to about 2,500°C (4,532 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does EWTh-2 cost?
EWTh-2 is a high-cost tungsten alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- AWS A5.12/A5.12M — Specification for Tungsten and Oxide Dispersed Tungsten Electrodes for Arc Welding and Cutting — AWS (2009)
- ISO 6848 — Arc welding and cutting: Nonconsumable tungsten electrodes — ISO (2015)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Refractory Metals) — ASM International (1990)
- Tungsten and tungsten alloy material properties — Plansee SE (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.