Copper Alloy CU250s

Updated: 2026-07-31

Overview

CU250S, also known as C26000 or cartridge brass, is a copper-zinc alloy containing approximately 70% copper and 30% zinc. This combination delivers an optimal balance of strength, formability, and corrosion resistance. The alloy's golden color and polishing characteristics make it suitable for both functional and decorative applications. First developed for ammunition casings in the 19th century, CU250S remains one of the most versatile brass alloys in modern manufacturing. Its excellent cold-working properties allow for deep drawing and complex forming operations without annealing, making it particularly valuable for high-volume production.

Physical and Chemical Properties

The 70/30 copper-zinc ratio in CU250S provides superior mechanical properties compared to other brass alloys. It exhibits a tensile strength of 300-400 MPa (depending on temper) with elongation rates exceeding 65% in annealed conditions. The alloy maintains good strength at elevated temperatures up to 200°C. Chemically, CU250S demonstrates excellent resistance to dezincification in most environments, though acidic or high-chloride conditions may require protective coatings. Its electrical conductivity is approximately 28% IACS (International Annealed Copper Standard), making it suitable for many electrical applications where corrosion resistance is prioritized over maximum conductivity.

Main Applications

In industrial settings, CU250S is extensively used for plumbing components like valve stems, pump parts, and compression fittings due to its corrosion resistance and pressure tightness. The electrical industry employs it for connectors, terminals, and RF shielding where conductivity and durability are required. The automotive sector utilizes CU250S for fuel system components, radiator cores, and decorative trim. Its historical use in ammunition casings continues today, while modern applications include musical instruments, architectural hardware, and precision turned parts requiring excellent machinability (80% free-cutting brass standard).

Safety and Storage

When machining CU250S, proper dust collection is essential as brass particles can accumulate in lungs with chronic exposure. The alloy contains no lead in standard compositions, eliminating lead exposure concerns in most applications. However, some specialty variants may contain trace elements requiring Material Safety Data Sheet (MSDS) review. For storage, keep material in original packaging or under protective covers to prevent surface oxidation. Indoor storage with controlled humidity (below 60% RH) is recommended for long-term preservation. Avoid contact with ammonia-based cleaners or other chemicals that may cause stress corrosion cracking.

B2B Procurement Guide

Industrial buyers should specify temper (e.g., H01 cold rolled, O60 annealed) based on intended forming operations. Verify compliance with relevant standards such as ASTM B36 for sheet/plate or ASTM B134 for wire. For critical applications, request certified mill test reports including chemical analysis and mechanical properties. Consider ordering with protective coatings (oil, lacquer) if parts will be stored before fabrication. Lead time for specialty tempers or custom sizes may range 4-8 weeks. For large-volume purchases (10+ metric tons), negotiate pricing based on current LME copper prices plus processing fees.