H68 Brass

Designation and Standards

Standard Designation: H68 (Common Brass)
International/National Standards: GB/T 5231-2012, GB/T 2059-2000 (Strips)
Other Name: Arsenical Brass (H68A with trace arsenic for enhanced corrosion resistance)
Material Category: Copper-Zinc Alloy (Cu-Zn), Copper content 67.0%-70.0%, Zinc as the remainder.

Product Features

Excellent Plasticity: H68 has the best plasticity among commom brass, with outstanding cold and hot working ability, making it suitable for deep drawing, bending, and other complex forming processes.
High Strength and Ductility Balance: Tensile strength ranges widely (M≥290 MPa, up to 660 MPa9(Y)).
Corrosion Resistance: Good resistance to freshwater and atmospheric corrosion. However, it is susceptible to stress corrosion cracking in ammonia and seawater environments (corrosion rate approximately 0.1 mm/a).
Versatile Processability: Supports cold rolling, hot rolling, welding, soldering and brazing, making it ideal for shell casings and precision components.

Common Product Forms and Specifications

Product Form	Specification Range	Typical Applications
Plate	Thickness 0.2-100mm, Width 305-1000mm	Architectural decoration, instrument housings
Strip	Thickness 0.01-3.0mm	Electronic components, metal meshes
Tube	Outer diameter 6-530mm, Wall thickness 0.5-50mm	Condenser tubes, radiators
Bar	Diameter 4-350mm, Length 2500-6000mm	Mechanical parts, Shell casings
Wire	Diameter 0.1-12.7mm	Welding wires, Spring components

Chemical Composition

Element	Cu	Zn	Pb	Fe	Total Impurities	As (H68A)
Content (%)	67.0-70.0	Remainder	≤0.03	≤0.10	≤0.3	Trace Addition

Physical Properties

Property	Value	Remarks
Density	8.5 g/cm³	Lightweight design advantage
Thermal Conductivity	116.7-141.7 W/(m·K)	Close to pure copper, suitable for heat dissipation components
Melting Point	966-1001℃	Alloy melting range
Coefficient of Thermal Expansion	19.1×10⁻⁶/℃ (20-300℃)	Good thermal stability
Electrical Conductivity	~32% IACS (M)	Lower than pure copper, sufficient for general conductivity needs

Mechanical Properties

Property	Value	Test Condition
Tensile Strength (σb)	370-660 MPa	M≥290 MPa, Y ≥660 MPa
Elongation (δ10)	≥15% (Y)	Up to 45% (M)
Hardness (HV)	55-190	Higher hardness (Y)
Annealing Temperature	520-650℃ (Conventional Furnace Annealing)	Eliminate cold work hardening
Low-Temperature Annealing	260-270℃	Relieve internal stress

Core Advantages

Outstanding Comprehensive Performance: Best plasticity among brasses with balanced strength, suitable for deep drawing and bending.
Environmental Corrosion Resistance: Longer service life in freshwater and atmospheric environments compared to common carbon steel.
Versatile Product Forms: Available in plates, tubes, wires, and more to meet industrial customization needs.

Main Application Fields

Military Manufacturing: Shell casings, weapon components (core application).
Electronics and Electricals: Waveguides, heat sink casings, connectors.
Construction and Marine: Condenser tubes, decorative grilles, plumbing fittings (marine protection recommended).
Industrial Equipment: Pump bodies, valves, cold-formed parts, chains.

Processing Considerations

Temperature Control: Hot working temperature should be maintained at 750-830℃ to avoid zinc evaporation and performance degradation.
Annealing Process: Perform low-temperature annealing at 260-270℃ after cold working to mitigate stress corrosion risks.
Welding Requirements: Preferably use argon protected welding to reduce porosity defects.

Frequently Asked Questions

Q: What is the difference between H68 and H68A?

A: H68A contains trace arsenic (As) to significantly enhance corrosion resistance and prevent dezincification, making it suitable for harsher environments.

Q: Is H68 suitable for seawater environments?

A: Direct exposure results in a relatively high corrosion rate (0.1 mm/a). A protective coating or choosing H68A is recommended.

Q: Why is H68 referred to as "Cartridge-Case Brass"?

A: Due to its excellent plasticity and strength, it is widely used for efficiently stamping complex shell casing structures in military applications.

Standard References

Chemical Composition and Processing: GB/T 5231-2012, GB/T 2059-2000.
Mechanical Property Testing: GB/T 228.1 (Metal Tensile Testing).

Note: The above data is compiled from multiple industrial standards and technical documents. Actual performance may vary depending on production processes and testing conditions. Refer to supplier test reports for specific values.

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