What are brasses?

Definition

Brasses are copper-zinc alloys. They are among the most widely used copper alloys due to their combination of strength, formability and corrosion resistance. Zinc content typically ranges from 5% to 45%, with small additions of other elements (such as lead, tin, aluminium or silicon) used to modify specific properties.

Composition

Copper: 55-95%
Zinc: 5-45%
Optional additions: Lead (improved machinability), Tin (enhanced corrosion resistance), Aluminium or Silicon (strength and wear resistance).

Key Properties

High corrosion resistance in air, water and many industrial atmospheres
Good strength relative to pure copper
Excellent cold and hot workability
Good electrical and thermal conductivity
Ease of machining, especially in free-cutting grades
Attractive golden appearance

Types of Brass

Alpha Brasses: Zinc up to ~37%. Single-phase structure, high ductility, easy to cold work.
Alpha-Beta (Duplex) Brasses: Zinc ~37-45%. Two-phase, higher strength, suited for hot working.
Leaded Brasses: Lead added (up to 3%) for improved machinability.
Special Brasses: Additions of aluminium, tin or silicon for improved strength, wear resistance or corrosion resistance.

Applications

Plumbing fittings and valves
Cartridge cases and ammunition
Heat exchanger tubes
Architectural hardware and decorative items
Electrical connectors and terminals
Marine equipment in certain brasses with enhanced corrosion resistance

Standards and Designations

ASTM B16, B453, B455, and EN 12164/12165 cover common wrought brasses.
Casting brasses are specified in ASTM B584 and EN 1982.

Corrosion Performance

Brasses resist corrosion in fresh water, indoor environments and mild industrial atmospheres. Dezincification-resistant (DZR) grades are specified where water chemistry may otherwise promote selective leaching of zinc.

Machinability

Free-machining brasses containing lead are widely used in high-volume turning, drilling and milling operations. Lead-free brasses are available for potable water systems to meet modern regulatory requirements.

Recycling

Brass is fully recyclable without loss of performance, and scrap recovery is a major source of feedstock for new brass production.