A mathematical model was developed to predict the residual stress distribution of an A356 alloy wheel, taking into account (1) the residual stress evolution during the T6 quench process and (2) redistribution of residual stress due to material removal at the machining stage. Isothermal compression tests in a GLEEBLE 3500 were performed to characterize the flow stress of an A356 alloy in the as-solutionized condition. The stress was found to be both temperature and strain rate dependent. Incorporating these data into the model revealed that residual stress predictions are sensitive to the flow stress data. Using the as-solutionized data, the predicted strains matched the measured strains more accurately, halving the error as compared to as-cast data in regions that experience high strain rates during quench (e.g., thin sections). The quench-induced residual stress evolves mainly between 200 deg C and 350 deg C, leading to a predicted final stress distribution of compression on the surface and tension in the core. The predicted elastic strains during the quench were in good agreement with those measured using strain gages and sequential sectioning. Subsequent machining relaxed the residual stresses, decreasing their magnitude by 10 to 20 pct. However, the removal of the compressive surface layer exposes areas of tensile residual stress, which will reduce fatigue performance. The fatigue life of an A356 wheel was predicted by integrating residual stresses into the in-service loading and wheel casting defects (pores). Residual stresses showed a moderate influence on fatigue life for this componentit was more sensitive to casting pore size and service stress due to applied loads.
Simulating the residual stress in an A356 automotive wheel and its impact on fatigue life
Simulation der Eigenspannung und Ermüdungslebensdauer in einem Autorad aus der Legierung A356 unter Stoßbelastung
2007
11 Seiten, 17 Bilder, 3 Tabellen, 24 Quellen
Aufsatz (Konferenz)
Englisch
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