Fatigue strength improvement in CuAl8Fe3 bronze via diamond burnishing

The purpose of this study was to increase the fatigue strength of single-phase CuAl8Fe3 aluminum bronze via surface cold work. CuAl8Fe3 bronze possesses a unique combination of mechanical and chemical properties: good strength, excellent electro-chemical and general corrosion resistance, high ductility and wear resistance. However, due to its low aluminum content (below 8.5%), this bronze cannot be heat treated. Thus, the fatigue strength increase was achieved via diamond burnishing (DB). The quantification of the fatigue behavior of this bronze was achieved through rotating bending fatigue tests. The assessment of the fatigue strength improvement (FSI) due to DB was made on the basis of the S – N curve obtained from fatigue tests of samples processed by fine turning. FSI due to single-pass DB fluctuates between 12 and 13%, with the maximum value achieved at the beginning of the megacycle fatigue field. The increase in the number of passes leads to a significant increase in FSI of between 16.6 and 24.4%. Since a direct correlation exists between the surface integrity (SI) and fatigue behavior, the positive effect of DB on FSI is explained by the improved SI—appropriate surface texture, increased micro-hardness, useful compressive residual stresses and grain refinement in the microstructure of the surface and sub-surface layers.