Nickel Alloy Alumel
GB Alumel
Alumel is the Ni-Al-Mn-Si negative leg of Type K thermocouples, run against Chromel and supplied as E230 Type K (-) / Type KN wire.
Reference datasheet — Alumel 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.
Values for the ANN condition
Alumel tempers and conditions
Alumel is supplied in 5 conditions, soft to hard. ANN is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefault Annealed | Standard stocked condition for K-type negative-leg wire: stable EMF, easy to bend, strip and weld. | 230 | 570 | 32 | 135 HB | — |
Thermocouple grade, standard limits of error | Default calibration class for general industrial K-type sensors: ±2.2 °C or ±0.75 % above 0 °C. | 230 | 570 | 32 | 135 HB | 5.9 % IACS |
Thermocouple grade, special limits of error | Select when tighter accuracy is required: ±1.1 °C or ±0.4 % above 0 °C, matched KP/KN pairs. | 230 | 570 | 32 | 135 HB | 5.9 % IACS |
Stress relieved | Compromise condition: most of the cold-work strength retained with reduced residual stress and better EMF stability than as-drawn. | 520 | 700 | 15 | 13 HRC | 5.9 % IACS |
Cold drawn | Choose when wire stiffness/spring-back or higher tensile is needed (self-supporting probe legs); EMF must be re-checked after cold work. | 700 | 830 | 6 | 21 HRC | 5.7 % IACS |
Supply forms, finishes and certifications
Ways Alumel is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
EXT | Extension grade wire | Supply form |
What is Alumel?
Alumel is the Ni-Al-Mn-Si negative leg of Type K thermocouples, run against Chromel and supplied as E230 Type K (-) / Type KN wire. It is selected for matched thermoelectric output rather than mechanical duty and is available annealed, cold-drawn, stress-relieved, as standard (TC-STD) or special-limits (TC-SPL) thermocouple wire and as extension-grade conductor. Maximum service temperature is 1100 °C in clean oxidising atmospheres; the alloy is magnetic and its emf drifts if it is contaminated by sulphur or run in reducing conditions, so it is normally protected in a sheath or MI cable. Alumel has a density of 8.6 g/cm³ (0.311 lb/in³), heavier than 67% of nickel alloy grades. It melts at 1,399°C (2,550 °F). Alumel has a yield strength of 230 MPa (33.4 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 92% of nickel alloy grades. Elongation at break is 32% and the elastic modulus is 186 GPa (27 Msi).
What is Alumel used for?
- Type K thermocouples
- Temperature sensor wire
- Mineral-insulated thermocouple cable conductors
- Type K extension and compensating cable
- Furnace and kiln sensor assemblies
- Sheathed immersion probes
Advantages
- High electrical conductivity — 5.9 % IACS, better than 94% of nickel alloy grades
- Conducts heat well — 29.7 W/m·K (17.2 BTU/hr·ft·°F), better than 92% of nickel alloy grades
- Easy to machine — 30/100, better than 90% of nickel alloy grades
- High service temperature — 1,100°C (2,012 °F), better than 88% of nickel alloy grades
- Forms and bends easily — 75/100, better than 82% of nickel alloy grades
Limitations
- Low strength — 230 MPa (33.4 ksi), worse than 92% of nickel alloy grades
- Needs corrosion protection — 62/100, worse than 87% of nickel alloy grades
- Hard to polish — 60/100, worse than 84% of nickel alloy grades
Alumel properties
Typical room-temperature values for Alumel-ANN; bars are the position among nickel alloy grades.
Physical3
Alumel has a density of 8.6 g/cm³ (0.311 lb/in³), heavier than 67% of nickel alloy grades. It melts at 1,399°C (2,550 °F).
Mechanical12
Alumel has a yield strength of 230 MPa (33.4 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 92% of nickel alloy grades. Elongation at break is 32% and the elastic modulus is 186 GPa (27 Msi).
Thermal6
Alumel is rated for continuous service to 1,100°C (2,012 °F). It conducts heat at 29.7 W/m·K (17.2 BTU/hr·ft·°F), better than 92% of nickel alloy grades. Thermal expansion is 12.9 µm/m·K (7.17 µin/in·°F).
Electrical3
Alumel conducts electricity at 5.9 % IACS, better than 94% of nickel alloy grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 87% of nickel alloy grades.
Sustainability4
Producing a kilogram of Alumel takes about 160 MJ of energy and emits 11.5 kg of CO₂ — less than 53% of nickel alloy grades. Typical recycled content is 15%.
Manufacturability7
Alumel's machinability is poor (30/100, better than 90% of nickel alloy grades); weldability good (60/100); formability very good (75/100).
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 nickel alloy family
Yield strength against density for every nickel alloy grade FabDigit runs. Alumel is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Alumel
Is Alumel easy to machine?
Gummy nickel solid solution: use sharp positive-rake carbide, low speed, heavy feed and flood coolant; rarely machined since supplied as wire.
Can Alumel be welded?
Junctions are made by capacitive-discharge, laser or TIG butt welding to Chromel/KP; avoid filler metals and any contamination that shifts EMF, and keep heat input low.
Can Alumel be formed, bent or molded?
Excellent fine-wire drawability in the annealed state with interpass anneals; cold work raises strength but must be relieved for stable thermoelectric output.
Alumel 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 |
|---|---|---|
| Mn | 1.8 – 2.5 | 2 |
| Al | 1.6 – 2.4 | 2 |
| Si | 0.8 – 1.2 | 1 |
| Feresidual | ≤ 0.5 | 0.2 |
| Coresidual, EMF-sensitive | ≤ 0.5 | |
| Cresidual | ≤ 0.05 | |
| Ni | ≥ 94 (balance) |
What surface finishes work on Alumel?
Not anodizable; supplied bright or oxidized, usually insulated with fiberglass/PFA/ceramic beads or sheathed in Inconel/SS MI cable rather than plated.
Surface treatments FabDigit runs on nickel alloy parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Nickel Alloy Alumel in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Also called
- Alumel / KN
How much does Alumel cost?
Alumel is a high-cost nickel 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.
Alumel — frequently asked
What is Alumel used for?
Alumel is typically used for type K thermocouples, temperature sensor wire, mineral-insulated thermocouple cable conductors, type K extension and compensating cable, furnace and kiln sensor assemblies and sheathed immersion probes. In short: type K negative leg; matched pair with Chromel; magnetic nickel-base wire.
What is the yield strength of Alumel?
Alumel has a typical yield strength of 230 MPa (33.4 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 92% of nickel alloy grades. Strength varies by condition: see the 5 listed tempers.
Is Alumel easy to machine?
Not especially — machinability is rated poor (30/100, better than 90% of nickel alloy grades). Gummy nickel solid solution: use sharp positive-rake carbide, low speed, heavy feed and flood coolant; rarely machined since supplied as wire.
Can Alumel be welded?
Yes — weldability is rated good (60/100). Junctions are made by capacitive-discharge, laser or TIG butt welding to Chromel/KP; avoid filler metals and any contamination that shifts EMF, and keep heat input low.
What surface finishes work on Alumel?
Not anodizable; supplied bright or oxidized, usually insulated with fiberglass/PFA/ceramic beads or sheathed in Inconel/SS MI cable rather than plated.
Can Alumel be formed, bent or molded?
Excellent fine-wire drawability in the annealed state with interpass anneals; cold work raises strength but must be relieved for stable thermoelectric output.
What is the maximum service temperature of Alumel?
Alumel is rated for continuous use to about 1,100°C (2,012 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Alumel-ANN and Alumel-CD?
ANN is the default condition — standard stocked condition for K-type negative-leg wire: stable EMF, easy to bend, strip and weld. CD: choose when wire stiffness/spring-back or higher tensile is needed (self-supporting probe legs); EMF must be re-checked after cold work. Yield strength is 230 MPa in ANN versus 700 MPa in CD.
How much does Alumel cost?
Alumel is a high-cost nickel 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
- ASTM E230/E230M — Temperature-EMF Tables for Standardized Thermocouples — ASTM (2023)
- ASTM E585/E585M — Compacted Mineral-Insulated Thermocouple Cable — ASTM (2021)
- IEC 60584-1 Thermocouples — EMF specifications and tolerances — IEC (2013)
- ASM Handbook Vol. 2 — Properties of Nonferrous Alloys (electrical resistance and thermocouple alloys) — ASM International (1990)
- ASTM MNL 12 — Manual on the Use of Thermocouples in Temperature Measurement — ASTM (1993)
- NIST ITS-90 Thermocouple Database (Monograph 175) — NIST (1993)
- Type K thermocouple alloy wire (KP/KN) technical data — thermocouple wire producers (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.