UNS C26000 brass
Selecting cartridge brass by supplier chemistry, product form, temper, forming direction and corrosion exposure.
Tags: materials, copper-alloys, brass
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C26000 is a copper-zinc alloy commonly called cartridge brass or 70/30 brass.
Identity and supplier chemistry
KME's EN 1652 C26000 rolled-product table gives 270–350 MPa tensile and 40% minimum A50 for R270, versus 550–640 MPa and 2% for R550. Its bend columns apply to strip ≤0.50 mm. Use a separate bar table and retain direction and gauge for forming. KME rolled-product table and bend conditions
Aurubis Stolberg's CuZn30 sheet, marked EN_2026_01, lists comparable designations UNS C26000, EN CW505L and JIS C2600. Its supplier composition table gives 69–71% copper, zinc remainder, and maximum limits for several other elements. These are that sheet's stated limits; do not assume every cross-referenced standard or supplier uses precisely the same composition interval and delivery conditions. A nominal 70/30 description is not a batch analysis. Aurubis, CuZn30 material datasheet
For example, bedra's bedra26000 bar page also references C26000/CW505L but lists 68.5–71.5% Cu, zinc balance, ≤0.03% Pb and ≤0.1% Fe. Preserve the ordered specification and manufacturer requirements instead of replacing their limits with a narrower supplier's table. The page describes a single-phase brass with good ductility; it does not certify an arbitrary supplied bar merely through the family name. bedra, bedra26000
Temper changes the forming tradeoff
KME's industrial rolled-product sheet carries the actual footer C26000 – CuZn30_10_2020, despite its 2021 filename. Its EN 1652 mechanical table includes:
| Rolled-product condition | Tensile strength Rm | Minimum elongation A50 |
|---|---|---|
| R270 | 270–350 MPa | 40% |
| R410 | 410–490 MPa | 9% |
| R550 | 550–640 MPa | 2% |
These rows illustrate changing requirements with condition; they are not a single C26000 strength range. The sheet marks several yield/hardness entries as informational and asks purchasers to confirm specifications. Retain its distinctions rather than converting the whole table into guaranteed limits. Its bend columns are also expressly scoped to strip ≤0.50 mm. KME, C26000 CuZn30 datasheet
Bar requires a separate property basis. bedra lists H02, diameter 10–25 mm, with minimum tensile strength 350 MPa, minimum yield strength 200 MPa, and minimum elongation 23%. Those are product- and size-scoped entries, not a conversion of an EN strip condition into an ASTM bar temper. Confirm the applicable specimen and governing standard for acceptance. bedra, H02 bar mechanical properties
For deep drawing or bending, define the starting condition, rolling direction, tool geometry and manufacturing sequence. Qualify the actual thickness and edge condition. A published zero bend ratio should not be read as a universal sharp-corner capability for any stock thickness, direction or forming method.
Conductivity and dimensions need conditions
Schlenk's CuZn30 foil datasheet is marked rev. 1/2018. It gives electrical conductivity 16 m/(Ω·mm²) at 20 °C in R270, thermal conductivity 120 W/(m·K) at 20 °C, and linear expansion 21 × 10⁻⁶/K over 20–270 °C. Keep the temperature, condition and units beside these values. Its material data are informational, not a warranty for an application.
The sheet lists rolls, spools and sheets over a stated manufacturing range, while noting that not every thickness/width combination is available. Confirm the actual supplied dimensions and property coverage instead of treating a catalog range as proof of every combination. Schlenk Metal Foils, CuZn30 technical datasheet
Illustrative free-expansion calculation: assuming that coefficient remains constant, a freely expanding 100 mm length heated uniformly from 20 to 120 °C grows by 100 × 21 × 10⁻⁶ × 100 = 0.21 mm. This predicts neither restrained thermal stress nor finished-part fit without the mating component and mounting conditions.
Joining and machining
KME rates soldering and brazing favorably, describes gas-shielded arc welding as fair, and rates machining less suitable than easier-machining materials in its comparison. These are selection indications, not qualified joint parameters. Establish filler/flux compatibility, cleaning, heat input and final-condition requirements on the actual part. Do not equate C26000 with a free-cutting brass simply because both can be machined. KME, fabrication properties
Heating and forming should be assessed against required final dimensions, strength and residual stress. Inspect critical holes, thin walls and sealing surfaces after the operations that determine their final condition. A successful trial joint does not automatically qualify fatigue, leakage or environmental performance.
Stress-corrosion cracking and dezincification differ
Aurubis warns that CuZn30 is susceptible to stress-corrosion cracking in an ammonia atmosphere and identifies stress relief as a mitigation. The practical requirement is to assess both stress state and exposure. Do not invent a universal stress-relief temperature/time, or assume that treating residual stress establishes immunity under subsequently applied loads. Aurubis, CuZn30 stress-corrosion guidance
Dezincification instead involves selective loss of zinc, leaving a copper-rich structure. The Canadian Conservation Institute documents yellow-to-pink changes and explains that severe attack can weaken or perforate brass. Its examples include chloride exposure and damage associated with some acidic cleaning products. A pink surface warrants investigation, but color alone cannot quantify remaining load capacity or section loss. Do not treat polishing away discoloration as restoration of structural integrity. Canadian Conservation Institute, Preventing and Treating Dezincification of Brass
AMPP distinguishes localized plug-type and broad uniform-layer dezincification and emphasizes actual water and deposit conditions. Consequently, “brass” or C26000 identification does not establish a dezincification-resistant designation or suitability for a particular valve, fitting or seawater application. Select against the actual medium, temperature, flow, deposits and required service life. AMPP, Dezincification
Release the finished product
Keep supplier typical data, contractual limits and batch results visibly separate. Record final temper, dimensions, forming/joining route, finish and exposure requirements. For wet, pressure-retaining or electrically loaded assemblies, qualify component performance separately from raw-stock chemistry. No revision date is inferred here from the undated bedra or corrosion webpages' crawl dates.