Study on Residual Stresses in Milling Aluminium Alloy 7050-T7451

The machining residual stresses can have significant effects on component life by influencing fatigue strength, creep, and stress-corrosion-cracking resistance. This paper studies the residual stresses induced in milling of aluminum alloy 7050-T7451. Particular attention is paid to the influence of cutting parameters, such as the cutting speed and feed rate. In the experiments, the residual stresses at the surface of the workpiece and in depth were measured by using X-ray diffraction technique in combination with electro-polishing technique. In order to correlate the residual stresses with the thermal and mechanical phenomena developed during milling, the orthogonal components of the cutting forces were measured using a Kistler 9257A type three-component piezoelectric dynamometer. The temperature fields of the machined workpiece surface were obtained with the combination of infrared thermal imaging system and finite element method. At last, the formation of the residual stresses can be explained by thermo-mechanical coupling effects.