ThePipingMart Blog Grades 770 Brass (CB770S) – Composition, Properties, and Uses

770 Brass (CB770S) – Composition, Properties, and Uses

Brass 770

CB770S is an alloy of copper and zinc with a variety of applications ranging from industrial to decorative. It is renowned for its corrosion resistance, heat resistance, machining properties, and mechanical properties. Let’s take a look at the composition, chemical properties, physical properties, uses, corrosion resistance, heat resistance, heat treatment, machining capabilities and welding characteristics of brass 770.

What Forms is Brass 770 Available at Piping Mart?

  • Brass 770 Pipes
  • Brass 770 Bolts
  • Brass 770 Flanges
  • Brass 770 Bars
  • Brass 770 Pipe Fittings
  • Brass 770 Tubing
  • Brass 770 Sheet
  • Brass 770 Plates

770 Brass Composition

CB770S is made up of 70 percent copper and 30 percent zinc. This combination creates alloy 770 extremely strong and durable yet still malleable enough to be heated-treated and machined with relative ease.

Copper (Cu): 55%
Nickel (Ni): 18%
Oxygen (O2):
Phosphorus (P):
Tin (Sn):
Zinc (Zn): 27%

770 Brass Chemical Properties

The chemical properties of CB770S include high levels of chromium (Cr) and iron (Fe). These two elements create a metal that is resistant to wear and tear over time. Additionally, the combination of copper and zinc makes it resistant to many common acids as well as salt water.

770 Brass Mechanical Properties

Brass 770 offers many attractive properties, from high strength and excellent corrosion resistance to machinability and weldability. It can also be used in a variety of applications and is especially ideal for manufacturing in demanding environments. Its strength, which is far greater than other types of brass alloys, is due to its zinc content. The combination of zinc and copper offers impressive machine characteristics without having to sacrifice quality or durability. Its low electrical conductivity makes it the ideal choice for applications such as electrical components, while its good formability allows it to be easily formed into complex shapes. For this reason, alloy 770 can usually be found in industrial parts and components, valves, pumps, armatures, fasteners, gear wheels, fittings and other related items that require high performance with long-term dependability.

Mechanical Properties Metric English Comments
Hardness, Rockwell 30T 63 – 75

63 – 75

Thickness > 0.020 Inch
Tensile Strength, Ultimate 476 – 600 MPa

69000 – 87000 psi

Tensile Strength, Yield 303 – 572 MPa

44000 – 83000 psi

0.2% offset
Elongation at Break 11 – 41 %

11 – 41 %

in 2 in.
Tensile Modulus 124 GPa

18000 ksi

770 Brass Physical Properties

CB770S has a high tensile strength which makes it ideal for use in applications where strength and durability are required. It also has excellent ductility, which means it can be easily formed into different shapes without cracking or breaking under pressure.

Physical Properties Metric English Comments
Density 8.69 g/cc

0.314 lb/in³


770 Brass Thermal Properties

Thermal Properties Metric English Comments
CTE, linear 16.7 µm/m-°C

@Temperature 20.0 – 300 °C
9.30 µin/in-°F

@Temperature 68.0 – 572 °F
Thermal Conductivity 29.4 W/m-K

204 BTU-in/hr-ft²-°F

Brass 770 Specifications

  • ASTM B122
  • ASTM B151QQ
  • W321SAE
  • J461SAE
  • J463UNS
  • C77000

770 Brass Uses

Due to its combination of strength and malleability, CB770S is used extensively in many industries ranging from automotive manufacturing to electrical wiring applications. Its corrosion resistance also makes it ideal for use in marine environments such as underwater shipbuilding or oil rigs. Following are most most common uses of 770 Brass:

  • Ammunition – 770 brass, specifically, is often used in larger calibre ammunition such as .308 Winchester and .30-06 Springfield.
  • Musical Instruments – Brass instruments, such as trumpets and trombones, are also made using 770 brass. It helps in producing a bright sound that is ideal for musical performances.
  • Plumbing: Another common use for 770 brass is in plumbing fixtures and fittings. Its corrosion resistance makes it a popular choice for pipes, valves, and faucets. 
  • Decorative Items- 770 brass is also commonly used in decorative items such as doorknobs, cabinet hardware, and light fixtures due to its attractive golden colour and ease of polishing.

Corrosion Resistance

As mentioned above, cb770s has excellent corrosion resistance due to its high concentration of chromium and iron components. This resistance makes it suitable for long-term outdoor use without fear of rusting or corroding over time.

Heat Resistance

Brass 770 also has excellent heat resistance, which allows it to withstand extreme temperatures without losing any of its structural integrity or becoming brittle over time.

Heat Treatment

If you need even greater levels of strength from your brass 770, then you can heat-treat the alloy by heating it up before cooling it down rapidly using specialized equipment known as a quench tank or quench oven. Heat Treatment can help improve the hardness as well as other physical properties like tensile strength

Machining Capabilities

UNS CB770S has excellent machinability, which means you can easily cut shape drill mill turn thread etc., with standard tools

Welding Characteristics

The high zinc content in brass 770 gives it good welding characteristics making it suitable for both MIG TIG brazing etc.


In conclusion, brass770 provides an incredibly versatile alloy perfect for use in many different industries thanks to its unique combination of physical, chemical mechanical corrosion, heat treatment machining welding capabilities all rolled into one! Whether you’re looking for something that’s strong, durable, easy to machine shape weld or something that offers great corrosion resistance heat treatment, then brass770 could be just what you need! With so much going on, this alloy 770 really stands out from the crowd!

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