Drawing No. EH–MT–010 // Engineering Materials
Copper Properties
Reviewed September 2026
C11000 ETP copper is the common high-conductivity copper reference. Its thermal and electrical conductivity are exceptional, while mechanical strength depends strongly on temper and cold work.
Representative properties
Switch units without changing the underlying material reference.
What changes these properties?
Engineering variability
- Annealed copper is soft and ductile; cold-worked tempers raise yield and tensile strength substantially.
- The displayed Poisson ratio is derived from the CDA room-temperature Young’s and shear moduli.
- Thermal conductivity is strongly temperature- and purity-dependent.
- C11000 melts over a narrow solidus–liquidus range rather than at one exact temperature.
Selection note
Excellent for electrical conductors, heat exchangers, busbars and thermal spreaders. Mass, cost, softness and galvanic interactions may govern in structural applications.
Do not combine strength from one grade/condition with modulus, thermal data or temperature limits from another without checking compatibility. Where the overview shows a range, it is intended to expose variability—not establish allowable bounds.
Copper in practice
Specified for what it conducts — electricity, heat, and in some applications, nothing at all in the biological sense.
Where it is specified
Electrical: busbars, windings, cable, switchgear and earthing, where the benchmark is 100% IACS conductivity by definition. ETP copper (C11000) is standard; oxygen-free grades (C10100, C10200) are used where hydrogen embrittlement during brazing or a vacuum environment matters.
Thermal: heat exchanger tube, heat sinks, vacuum brazed cold plates, cryogenic thermal links — copper's thermal conductivity is roughly twice aluminium's and twenty times stainless.
Plumbing and gas: domestic and medical gas pipework, where jointing is simple and the material is proven over a century of service.
Antimicrobial touch surfaces in hospitals, an application resting on copper's contact biocidal action.
Chosen over what
Against aluminium in electrical work: copper has 60% higher conductivity per unit volume, but aluminium has roughly twice the conductivity per unit mass and is far cheaper. Transmission conductors are therefore aluminium; building wiring and windings are copper, largely because of connection reliability — aluminium creeps under a terminal screw and forms an insulating oxide, which caused a generation of building fires.
Against stainless in heat exchangers: vastly better conductivity but poor resistance to ammonia, sulphides and high-velocity seawater.
How it fails
Erosion-corrosion above roughly 1.5 m/s in water, and worse with entrained air or particulates. Undersized pipework and sharp fittings produce the characteristic horseshoe-shaped pits on the downstream side of bends.
Ammonia stress-corrosion cracking — copper alloys crack in ammonia and amine environments, which rules them out of many refrigeration and fertiliser duties.
Pitting in soft or aggressive waters, and dezincification in brasses rather than pure copper.
Creep at modest temperature. Copper creeps under sustained load well below its melting point, which is why bolted busbar joints use Belleville washers to maintain contact force as the material relaxes.
Fabrication notes
Machinability of pure copper is poor — roughly 20% of B1112 — because the material is gummy and smears rather than shearing. Free-machining copper (C14500, tellurium-bearing) reaches around 80% and is the right choice for turned electrical parts.
Joining is usually brazing or soldering rather than fusion welding, because copper's conductivity draws heat away from the joint and demands high preheat. Oxygen-bearing ETP copper suffers hydrogen embrittlement when brazed in a reducing atmosphere, forming steam at grain boundaries; oxygen-free grades exist precisely for this.
Work hardening is rapid, so deep-drawn parts need interstage annealing. Tempers are specified as H (hard) or O (annealed), and the difference in yield strength is several-fold.
Electrical joints need attention to contact pressure and oxide: plated or greased joints, correct torque, and Belleville washers on busbar work.
Specifications and standards
ASTM B187 (bus bar), B152 (sheet/plate), B88 (water tube), B280 (refrigeration tube); EN 1057 for plumbing tube; UNS C10100–C11000 designations; IEC 60028 defines the International Annealed Copper Standard.
References
Copper Development Association technical data; ASM Handbook Vol. 2, Properties and Selection: Nonferrous Alloys; IEC 60287 for current-carrying capacity of cables.
Property interpretation
Stiffness vs strength
Young’s modulus controls elastic deformation. Yield or fracture strength controls how far the material can be stressed. These are separate material characteristics.
Thermal response
Thermal conductivity controls temperature gradients, specific heat contributes to thermal inertia, and expansion controls thermally induced strain when movement is restrained.
Temperature transition
The final property card is deliberately labeled “melting / transition.” Metals often have a solidus–liquidus range; amorphous polymers and glass use softening or glass-transition concepts; concrete and wood decompose instead of exhibiting one clean melt point.
Technical sources
Source hierarchy favors manufacturers, industry associations, standards bodies and government engineering references. Strength data must still be reconciled with the exact procurement specification.