Datasheet · Type K · Rev. 08

Type K Bare Wire
Chromel / Alumel

Solid single-strand thermocouple wire. φ0.025mm ultra-fine to φ5.0mm standard. Bright or oxidized finish.

Last updated 2026-09-12

Type K Bare Wire: φ0.025mm – φ5.0mm, −200°C to +1370°C, IEC 60584-1 Class 1

Ø range

φ0.025mm – φ5.0mm

Temp

−200°C to +1370°C

EMF tol.

±1.5°C (0–375°C) / ±0.4% (375–1000°C)

Testing

100%

Technical Specifications

Type K Bare Wire — Chromel / Alumel at −200°C to +1370°C, solid single strand from φ0.025mm – φ5.0mm, supplied to IEC 60584-1 Class 1.

How to specify Type K Bare Wire

1. Confirm the alloy for your operating temperature — Chromel / Alumel, rated −200°C to +1370°C in air.
2. Pick the conductor diameter from φ0.025mm – φ5.0mm (diameter tolerance ±0.005mm (fine) / ±0.02mm (standard)) — solid single-strand Chromel / Alumel at the ultra-fine end of the −200°C to +1370°C range.
3. Choose the temper condition for this K · Chromel / Alumel wire — Hard (cold-drawn) / Soft (annealed) / Bright finished. The temper is chosen for the solid K sensing element held in the furnace or panel.
4. Choose the surface finish for K · Chromel / Alumel — Bright / Oxidized / Electro-polished. Finish is selected for the atmosphere the K element will sit in.
5. Choose the packaging — DIN 125 spool / Coil / Custom reel, standard coil weights 5kg / 10kg / 20kg standard. Spooled to protect the K solid conductor in transit and handling.
6. Quote Type K Bare Wire against IEC 60584-1 Class 1 and request the MTC / EMF calibration certificate with the batch number for traceability.

Which thermocouple type fits the job

These are the K-type ranges as they apply to the solid single-strand form described on this page. Confirm the type first, then pick the conductor diameter.

Type	Alloy	Range	EMF tolerance
J	Iron / Constantan	−40 … +750 °C	±1.5°C (0–275°C) / ±0.4% (275–750°C)
K this page	Chromel / Alumel	−200 … +1370 °C	±1.5°C (0–375°C) / ±0.4% (375–1000°C)
N	Nicrosil / Nisil	−270 … +1300 °C	±1.5°C (0–375°C) / ±0.4% (375–1000°C)

See the full 5-type comparison →

Who uses Type K Bare Wire — and where it does not fit

Furnace & heat-treatment equipment builders

Bare wire as the sensing element in annealing, tempering and hardening furnaces

±0.4 % EMF tolerance across 375–1000 °C covers the band where most heat-treatment setpoints sit, up to a +1370 °C ceiling

Instrumentation & control-panel integrators

Bulk bare wire for building thermocouple assemblies and extension junctions

IEC 60584-1 Class 1 tolerance plus per-coil batch traceability keeps loop calibration defensible in audits

Calibration & metrology laboratories

Working-standard bare wire for calibrating thermocouple readouts

Each coil ships with an EMF calibration certificate and furnace batch traceability

Cryogenic & low-temperature instrument makers

Low-temperature process instrumentation at the cold end of the range

Type K reaches −200 °C at the lower limit, unlike Type J

Not suitable · Vibrating or flexing installations

Not suitable — specify stranded Type K wire instead

A solid conductor work-hardens and eventually fractures under vibration, flexing or thermal cycling

What drives the price of Type K Bare Wire

Cost driver	Why it moves the price
Diameter & tolerance class	φ0.025 mm ultra-fine through φ5.0 mm standard; ±0.005 mm (fine) vs ±0.02 mm (standard) diameter tolerance
Alloy leg cost	Chromel (NiCr 90/10) and Alumel (NiAl 95/5 + Mn 2/Si 1) — nickel-based legs track the nickel market
EMF tolerance grade	IEC 60584-1 Class 1 (±1.5 °C / ±0.4 %) costs more than Class 2 — tighter grades mean more testing and more scrap
Order quantity & coil weight	Standard 5 kg / 10 kg / 20 kg coils (DIN 125 spool, coil or custom reel); smaller lots carry a higher unit rate
Testing & certification depth	100 % eddy-current + resistance + dimensional, MTC, EMF calibration certificate and furnace batch traceability are quoted per order

Quote is built from the specification above — diameter, tolerance class, coil weight and testing depth. Send the six specification points for Type K Bare Wire and we return a priced offer with the MTC and EMF calibration certificate scope.

Verification & quality evidence

• IEC 60584-1 Class 1 / ASTM E230 / DIN EN 60584
• 100% eddy-current + resistance + dimensional · MTC · EMF calibration certificate · Furnace batch traceability
• Third-party testimonials and site references are being collected for this product line — ask for Type K Bare Wire reference contacts in comparable static installations when you request a quote.

Frequently Asked Questions

What alloy is Type K bare wire made from?

Chromel (NiCr 90/10) for the positive leg and Alumel (NiAl 95/5 with Mn 2/Si 1) for the negative leg.

What temperature range and diameters does Type K bare wire cover?

−200 °C to +1370 °C, in diameters from φ0.025 mm to φ5.0 mm, with ±0.005 mm tolerance on fine sizes.

Can Type K bare wire be used in vacuum or reducing atmospheres?

Not above 800 °C. In low-oxygen or reducing conditions the Chromel leg suffers green-rot chromium oxidation, which drives a large negative EMF drift. Specify Type N for those atmospheres.

Is solid Type K wire suitable where the installation vibrates?

No. A solid conductor work-hardens and eventually fractures under vibration, flexing or thermal cycling — use stranded Type K for those installations.