C69430: The silicon red brass is specified for underground service lines since it offers great corrosion resistance to all types of potable waters, and has moderate strength and good retention of spring properties. Silicon brasses are part of the subgroup of high strength brasses. Silicon Brass contain less than 20% zinc and less than 6% silicon. The silicon brasses are solid solution strengthened. Silicon brasses are typically chosen because of their high strength and moderately high corrosion resistance.

Chemical Composition

Elements Min (%) Max (%)
Cu 80.00 83.00
Si 3.50 4.50
Pb 0.30
Fe 0.20
As 0.03 0.06
Zn Remainder

Mechanical properties according to ASTM B371 (as per temper HO2)

Range (inch) UTS Min
(ksi)
UTS Max
(ksi)
PS Min
(ksi)
Elongation Min
(%)
Hardness
Hardness Min
(HRB)
Hardness Max
(HRB)
Round (Dia) 0.059 – 1.000 80 40 15
1.000 – 2.000 75 35 15
2.000 – 2.953 65 35 15
Hex (A/F) 0.118 – 1.000 80 40 15
1.000 – 2.000 75 35 15
2.000 – 2.755 65 35 15
Square (A/F) 0.118 – 1.000 80 40 15
1.000 – 2.000 75 35 15
2.000 – 2.362 65 35 15

Range (mm) UTS Min
(MPa)
UTS Max
(MPa)
PS Min
(MPa)
Elongation Min
(%)
Hardness Min
(HRB)
Hardness Max
(HRB)
Round (Dia) 1.5 25 550 250 15
25 50 515 240 15
50 75 450 240 15
Hex (A/F) 3 25 550 250 15
25 50 515 240 15
50 70 450 240 15
Octagon (A/F) 3 25 550 250 15
25 50 515 240 15
50 60 450 240 15

PHYSICAL PROPERTIES
Melting Point – Liquidus °F 1685
Melting Point – Solidus °F 1510
Density lb/cu in. at 68°F 0.26
Specific Gravity 8.19
Electrical Conductivity % IACS at 68°F 6.2
Thermal Conductivity Btu/sq ft/ft hr/°F at 68°F 15
Coefficient of Thermal Expansion 68–572 × 10⁻⁶ per °F 11.2
Specific Heat Capacity Btu/lb/°F at 68°F 0.09
Modulus of Elasticity in Tension ksi 16000
FABRICATION PROPERTIES
Technique Suitability
Soldering Excellent
Brazing Excellent
Oxyacetylene Welding Good
Spot Weld Good
Seam Weld Good
Butt Weld Good
Capacity for Being Cold Worked Good
Capacity for Being Hot Formed Excellent
Forgeability Rating 80
Machinability Rating 70

Typical Uses

Valves Stems

Valves Stems