The Effect of Lead (Pb) Addition to High-Tin Bronze Alloy on Tensile Strength

Abstract

High-tin bronze (CuSn), particularly those with over 17% tin (Sn), is commonly used in industries like gamelan and bell
production due to its excellent acoustic properties. However, it faces challenges such as high market costs and brittleness,
which can lead to cracking during forging or after use. This study examines the effect of lead (Pb) addition on the impact
strength and macrostructure of high-tin bronze alloys. Pb was chosen for its lower cost compared to tin (Sn) and its ability to
reduce porosity and improve the mechanical properties of other metals. Pb was added in quantities of 5%, 10%, and 15% to
observe its effect on the alloy. Tensile tests were performed, followed by macrofracture analysis using a digital camera. The
results revealed that Pb addition generally reduced the mechanical properties of CuSn. The alloy without Pb (0% Pb) had an
average yield strength of 103.4 MPa and an ultimate tensile strength (UTS) of 118.7 MPa, showing the best performance and
data consistency. With 5% Pb, strength decreased, yielding a yield strength of 73.7 MPa and UTS of 102.2 MPa. At 10% Pb,
results were highly inconsistent due to possible inhomogeneity. The 15% Pb alloy showed a partial strength recovery but still
fell short of the base material. All specimens exhibited brittle behavior, with no elongation or reduction in area, indicating no
plastic deformation before fracture.