Fatigue Properties of Cold Sprayed Bell Metal

Mechanical and fatigue properties of cold sprayed (CS) Cu₂₀Sn bell metal were tested in order to assess the potential applicability of the technology to repair impact areas of church bells. The CS bell metal was compared to its traditional cast counterparts, a fine-grained Cu₂₂Sn bell metal seen in small bells, and a coarse-grained Cu₂₀Sn seen in large bells. Similar to other CS metals, it was shown that both the strength as well as the fatigue crack growth rates at low loading are similar to the cast materials. The fracture toughness of the CS material was comparable with the finegrained Cu₂₂Sn bell metal, while both were significantly lower than the coarse-grained Cu₂₀Sn bell metal. The impact damage rate of the CS material determined by a periodic impact test was significantly higher than the (finegrained) cast material. Both materials showed a stabilized, very slow damage rate after the relatively fast initial crater formation. The results presented in this paper identify CS as a feasible restoration technology for church bells, and the introduced methodology presents a characterization method for quantitative description of bell metal impact damage.