Copper Alloy Free Cutting Brass C38500

 Product Data Sheet – Copper Alloys

Free Cutting Brass Alloy 385   UNS-C38500

Also known as Architectural Bronze

Chemical Composition

AS2738.2 – 1984, Compositions & Designations

Copper Lead Zinc
Min
56.0
2.5
Max
60.0
4.5
Remainder

 

Equivalent Alloy Specifications

Specification Designation
UNS
C38510
ISO
CuZn39Pb3
BSI
CZ121

Australian Product Specifications

Specification Product Form
AS1567
Wrought Rods, Bars & Sections
AS2738
Compositions & Designations

 

Fabrication Properties

Joining Technique Suitability
Soft Soldering
Good
Silver Soldering
Fair – Good
Brazing
Good
Oxy Acetylene Welding
Fair
Gas Shielded Arc Welding
Not Recommended
Coated Metal Arc Welding
Not Recommended
Resistance Welding
Not Recommended
Fabrication Technique Suitability
Capacity for Being Cold Worked
Poor
Capacity for Being Hot Worked
Fair
Hot Working Temperature
700 – 800 °C
Annealing Temperature
425 – 600 °C
Stress Relieving Temperature
250 – 300 °C
Machinability Rating
90% of free cutting brass (C36000)
Polishing/Electroplating Finish
Good

 

Mechanical Properties

AS1567, Wrought Rods, Bars & Sections

Temper
.2% Proof Stress
Tensile Strength
Elongation
Hardness
M (as manufactured)
MPa
MPa
%
HV
Typical Values
215
495
15
150
Minimum
380
12

Available Forms Austral Wright Metals are able to supply this alloy as extruded rods.

General Description Free cutting brass is a significantly improved form of 60/40 brass, with excellent free cutting characteristics. It is used in the mass production of brass components on high speed lathes where maximum output and longest tool life are required, and where no further cold forming after machining is needed.

The superior machining characteristics of alloy 385 are due to the rapid chill effect of continuous casting, which gives a fine uniform lead distribution without segregation, and suppresses the formation of brittle phases which cause tool wear.

The alloy gives:

  • Superior surface finish without tooling modification
  • Improved tool life and reduced tool sharpening
  • Cleaner threads with no build-up and no breakage
  • Cutting tools previously used with a negative rake can be modified to zero top rake

 

Typical applications are nuts, bolts & screw threads

Physical Properties

Property
Metric Units
Imperial Units
Melting Point (Liquidus)
890°C
1635°F
Melting Point (Solidus)
875°C
1610°F
Density
8.47 gm/cm³ @ 20°C
0.306 lb/in³ @ 68°F
Specific Gravity
8.47
8.47
Coefficient of Thermal Expansion
20.9 x 10 -6 / °C (20-300°C)
11.0 x 10 -6 / °F (68-392°F)
Themal Conductivity
121 W/m. °K @ 20°C
70 BTU/ft³/ft/hr/°F @ 68°F
Thermal Capacity (Specific Heat)
377 J/kg. °K @ 20°C
0.09 BTU/lb/°F @ 68°F
Electrical Conductivity
0.162 microhm.cm @ 20°C
28% IACS
Electrical Resistivity
6.16 microhm.cm @ 20°C
38 ohms (circ mil/ft)@ 68°F
Modulus of Elasticity (tension)
97 GPa @ 20°C
14.2 x 10 6 psi @ 68°F
Modulus of Rigidity (torsion)
37 GPa @ 20°C
5.3 x 10 6 psi @ 68°F
Poisson’s Ratio
0.32
0.32

Phase Diagram & Mechanical Properties

Copper Alloy Free Cutting Brass C38500 - Properties

 

Corrosion Resistance

Alloy 385 has good corrosion resistance to weathering and fair resistance to many waters.

Alloy 385 should not be used in contact with ammonia, ammonia compounds or amines, as it may suffer stress corrosion cracking.

Please consult Austral Wright Metals for specific advice on your application.

 

 

The technical advice and recommendations made in this Product Data Sheet should not be relied or acted upon without conducting your own further investigations, including corrosion exposure tests where needed. Please consult current editions of standards for design properties. Austral Wright Metals assumes no liability in connection with the information in this Product Data Sheet. Austral Wright Metals supplies a comprehensive range of stainless steels, copper alloys, nickel alloys and other high performance metals for challenging service conditions. Our engineers and metallurgists will be pleased to provide further data and applications advice.

 

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