# UNS C14500 copper

Specify tellurium copper by product standard, form and temper; interpret machining ratings, conductivity and joining guidance without transferring them to finished-part guarantees.

Reviewed: 2026-11-01

Tags: materials, copper, c14500, tellurium-copper, machining

## Material identity and selection

Concast lists **38 ksi minimum tensile** and **30 ksi minimum yield** for **H02 C14500 rod over ¼ through 2⅝ in diameter** under its **ASTM B301/B301M-13(2020)** table. Yield uses **0.5% extension under load**. The **12% minimum elongation** uses four times the specimen diameter or thickness. [Concast H02 mechanical table](https://www.concast.com/c14500.php)

**UNS C14500 is tellurium-bearing copper**, used where conductivity and fine machining matter together. Wieland Concast supplies extruded and drawn product in **H02 half-hard and H04 hard** conditions. It should not inherit the purity specification or processing assumptions of oxygen-free electronic copper. [Concast C14500 product](https://www.concast.com/c14500.php)

The German Copper Institute's machining guide cross-references **CuTeP, CW118C and C14500**. Its discussion explains the use of chip-breaking additions in otherwise difficult-to-machine copper. A cross-reference helps discovery; it does not replace confirmation that the delivered material meets the required product specification. [DKI machining guide, material tables and alloying discussion](https://kupfer.de/wp-content/uploads/2021/08/Recommended-machining-parameters-for-copper-and-copper-alloys.pdf)

## Read the chemistry footnotes

Concast's composition chart lists **Te 0.40–0.70%**, **P 0.004–0.012%** and a **99.90% minimum Cu entry whose footnote includes tellurium and phosphorus**. Do not interpret that last entry as 99.90% elemental copper plus the listed additions. [Concast wrought chemistry chart, p. 1 and footnote 3](https://www.concast.com/files/wrought_chem_comp.pdf)

Retain the composition basis and relevant impurity requirements with the purchasing record. For sensitive service, obtain the applicable lot certificate rather than substituting a nominal composition from a sales page. Do not infer an oxygen limit, lead certification or regulatory approval from the word “tellurium.” Define any such requirement explicitly.

## Machinability is a comparative assessment

Concast publishes a **machinability rating of 85** for C14500. That number is not a percentage of material removal, a spindle-speed multiplier or a guaranteed reduction in cycle time. [Concast machining data](https://www.concast.com/c14500.php)

DKI evaluates machinability through tool life, cutting force, surface quality and chip shape. Its guidance separates operations, tool materials, geometry and cutting conditions. Use these distinctions when comparing process trials; one index cannot describe every small hole, thread, interrupted cut or polished contact surface. [DKI machining assessment and process chapters](https://kupfer.de/wp-content/uploads/2021/08/Recommended-machining-parameters-for-copper-and-copper-alloys.pdf)

Qualify tooling, coolant, feeds and speeds on the actual stock condition and feature. Define chip control, burr acceptance, surface condition and inspection before production. Evaluate the full cost of a finished accepted part, including tool changes, deburring and rejects. A machining advantage only becomes a production result when the specific process demonstrates it.

DKI also cautions against mixing CuTeP chips with other copper chips because tellurium contamination can impair hot-forming behavior. Keep scrap streams identified rather than treating all copper swarf as equivalent. [DKI alloying discussion, printed p. 25](https://kupfer.de/wp-content/uploads/2021/08/Recommended-machining-parameters-for-copper-and-copper-alloys.pdf)

## Form, size and temper constrain strength values

Concast's ASTM B301/B301M-13(2020) table gives this **H02 rod** example for diameter **over 1/4 through 2 5/8 in.**:

| Requirement | Published value |
| --- | --- |
| Minimum tensile strength | 38 ksi / 260 MPa |
| Minimum yield at 0.5% extension under load | 30 ksi / 205 MPa |
| Minimum elongation, 4× diameter or specimen thickness | 12% |

These are the source's paired units; use the required standard's unit system for acceptance. [Concast mechanical table](https://www.concast.com/c14500.php)

For a structural feature, establish loads, stress concentrations, working temperature and acceptable deformation. Define whether subsequent forming or joining changes the delivered condition. Parent-stock strength alone cannot qualify a threaded connection or a heat-affected region.

## Conductivity and a bounded calculation

Concast's CDA-sourced physical table lists **93% IACS** and **0.539 MS/cm at 20°C**. The latter converts to **53.9 MS/m**. Treat catalog physical data separately from any contractual conductivity minimum. [Concast electrical properties](https://www.concast.com/c14500.php)

As an original illustration, assume uniform material at that conductivity, length **0.1 m** and cross-section **10 mm²**. Then `R = L/(σA) = 0.1/(53.9 × 10⁶ × 10 × 10⁻⁶) ≈ 0.0001855 Ω`, or **0.1855 mΩ**. This excludes contacts, surface films and heating. It is a bulk-resistance calculation, not an ampacity rating or a prediction for an assembled connector.

For electrical service, specify conductivity or resistance with temperature and measurement method. Assess the finished geometry, joints, contact pressure, cooling and permissible temperature rise. IACS is a conductivity reference scale rather than a chemical-purity percentage. Do not borrow another copper grade's conductivity because both are described as highly conductive.

## Joining and service qualification

James Coppell Lee's rod/bar sheet rates soft and silver soldering **good–excellent**, gas-shielded arc welding **fair**, and oxyacetylene and coated-metal-arc welding **not recommended**. These are supplier guidance ratings, not an approved procedure or joint-strength guarantee. [JCL C14500 fabrication sheet](https://www.jclbronzealloys.com.au/download.php?file=26&library=document&type=pdf)

Select a joining process for the actual design and validate filler, cleaning, thermal cycle, joint clearance and inspection. Establish the resulting properties near the joint. Do not interpret easy machining as universal weldability, or a soldering rating as evidence that a completed current-carrying joint will remain stable in service.

Define chemical exposure by fluid or gas, concentration, temperature, flow and duration. Qualify coatings and cleaning processes with the application. For a contact, nozzle or conductor, retain dimensional, surface and functional acceptance separately; the material designation cannot establish performance of all three.

## Release record and source dates

Retain manufacturer, lot, form, temper, specification, drawing revision and required test results. Review substitutions against machining, electrical, mechanical and joining requirements together.

Sources reviewed November 1, 2026. DKI's cited monograph explicitly prints **Print run 2010**, despite its 2021 upload path. The Concast chemistry chart and JCL sheet have no explicit printed revision date; the Concast web page's website copyright is not treated as a technical revision. Its mechanical table identifies the specific **ASTM B301/B301M-13(2020)** basis; use the edition required by the purchase contract.

## Related reference

[Grades, conditions and material selection](../grades-tempers-and-conditions.md)