Brasses are alloys of Copper and Zinc. They may also contain small amounts of other alloying elements to impart advantageous properties. Brasses have high corrosion resistance and high tensile strength. They are also suited to fabrication by hot forging. Free machining grades of brass set the standard for machining, by which other metals are compared.
Copper, Brass & Bronze alloys explained
Brass Classes
Brasses are divided into two classes. The alpha alloys, with less than 37% zinc, and the alpha/beta alloys with 37-45% zinc. Alpha alloys are ductile and can be cold worked. Alpha/beta or duplex alloys have limited cold ductility and are harder and stronger. CZ121 is an alpha/beta alloy.
Alloy CZ114
Brass alloy CZ121 is used for machining. It has lead added to the composition to improve machinability. The lead remains insoluble in the microstructure of the brass and the soft particles act as chip breakers.
Alloy CZ121M
The name CZ121M is sometimes used to emphasise its machining properties.
Chemical Composition of Brass alloy CZ121
Table 1. Chemical composition for brass alloy CZ121
|
Chemical Element
|
%
|
|
Cu
|
57.00 - 59.00
|
|
Pb
|
2.50 - 3.50
|
|
Al
|
0.0 - 0.05 |
|
Fe
|
0.0 - 0.30 |
|
Ni
|
0.0 - 0.30 |
|
Others (Total)
|
0.0 - 0.20 |
|
Tin
|
0.0 - 0.30 |
|
Zn
|
Balance
|
Properties of Brass alloy CZ121
Mechanical Properties of Brass alloy CZ121
Table 2. Mechanical properties for brass alloy CZ121
|
Property
|
Flat Bar & Profiles
|
Rod |
|
Tensile Strength
|
360 - 500 MPa
|
360 - 500 MPa |
|
Proof Stress
|
220 - 350 MPa
|
230 - 350 MPa |
|
Elongation A
|
20 - 5%
|
20 - 5% |
|
Hardness Brinell
|
90 - 160 HB
|
90 - 160 HB |
Physical Properties of Brass alloy CZ121
Table 3. Physical properties for brass alloy CZ121
|
Property
|
Value
|
|
Density
|
8.47 kg/m3
|
|
Melting Point
|
875 °C
|
|
Modulus of Elasticity
|
97 GPa
|
|
Electrical Resistivity
|
0.62 x 10-6 Ω.m
|
|
Thermal Conductivity
|
123 W/m.K
|
|
Thermal Expansion
|
20.9 x 10-6/K
|
Alloy Designations
Brass alloy CZ121 corresponds to the following designations:
|
CEN
|
BS
|
UNS
|
ISO
|
|
CW614N
|
BS2874 CZ121
|
C38500
|
CuZn39Pb3
|
Corrosion Resistance of Brass alloy CZ121
The corrosion resistance of Brass alloy CZ121 is fair to excellent.
Fabrication of Brass alloy CZ121
Cold Working of Brass alloy CZ121
Cold working of Brass alloy CZ121 is poor and is not recommended. It can, however, be knurled if required.
Hot Working of Brass alloy CZ121
Fabrication of Brass alloy CZ121 by hot working is excellent. It is recommended that hot working be done between 630 and 730°C.
Heat Treatment of Brass alloy CZ121
Solution treatment or annealing can be done by rapid cooling after heating to 430-600°C.
Machinability
The machinability of alloy Brass alloy CZ121 is excellent. It has a machinability rating of 90 where Alloy 360 FC Brass is 100.
Welding and Joining of Brass alloy CZ121
Soldering of Brass alloy CZ121 is rated as “excellent” and brazing is “good”. Butt welding is fair but all other welding methods are not recommended.
Applications of Brass alloy CZ121
Brass alloy CZ121 is typically used in:
- High speed machined components
- Architectural extrusions
- Locks
- Hinges
Supplied Forms
Brass alloy CZ121 is typically supplied by Aalco in the following forms:
- Round bar
- Hexagon bar
- Square bar
- Flat bar
DISCLAIMER
This Data is indicative only and must not be seen as a substitute for the full specification from which it is drawn. In particular, the mechanical property requirements vary widely with temper, product and product dimensions. The information is based on our present knowledge and is given in good faith. However, no liability will be accepted by the Company is respect of any action taken by any third party in reliance thereon.
As the products detailed may be used for a wide variety of purposes and as the Company has no control over their use; the Company specifically excludes all conditions or warranties expressed or implied by statute or otherwise as to dimensions, properties and/or fitness for any particular purpose.
Any advice given by the Company to any third party is given for that party’s assistance only and without liability on the part of the Company. Any contract between the Company and a customer will be subject to the company’s Conditions of Sale. The extent of the Company’s liabilities to any customer is clearly set out in those Conditions; a copy of which is available on request.
This information has been sourced, reviewed and adapted from materials provided by Aalco - Ferrous and Non-Ferrous Metals Stockist.
For more information on this source, please visit Aalco - Ferrous and Non-Ferrous Metals Stockist.