Tin lead bronze bushing (CAC604)

Symbol	Chemical Composition mass/%
	Cu	Sn	Al	Fe	Mn	Ni	Pb	Si	P	Zn
CAC604C	74.0-78.0	7.0-9.0	0.005	0.2	-	1	14.0-16.0	0.005	0.05	1
Mechanical properties
Tensile strength	Yield strength	Elongation %	Brinell hardness
220	100	8	60

Lead is actually insoluble in the copper-tin alloy and is distributed in the interdendrite as a single phase black inclusions.Lead is not easily distributed evenly in ingots, and a small amount of nickel is usually added to improve the distribution and refine the microstructure.Lead reduces the friction coefficient of tin bronze, improves the wear resistance and machinability, but slightly reduces the mechanical properties.3% ~ 5% zinc is often added to the copper-tin-lead alloy to improve its mechanical properties.The addition of 0.02%-0.1% zirconium or 0.02%-0.1% boron, especially the addition of 0.02%-0.2% rare-earth elements, can refine the lead particles and make them evenly distributed, so as to improve the microstructure, casting and mechanical properties of lead-containing tin bronze.