Avaliação do efeito do Mg nas propriedades de fadiga em alta temperatura de ligas de Al-Si fundidas sob pressão em molde permanente / Magnesium addition effect on high temperature fatigue properties of permanent mold cast Al-Si alloys

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Gear Box housings are usually subjected to cyclic stresses generated during engine operation. Such stresses are more critical at high temperatures and long times. Thermal gradients induced within the components submitted to variation of temperature during working may result in internal stresses and strains. Thermal cycling can result in crack nucleation and propagation by the process of thermomechanical fatigue (TMF). The main aim of this work was to evaluate the effects of Mg content on the mechanical properties of permanent mold cast Al-Si alloys. Two alloys, one containing Mg addition ("A" alloy) and another without Mg ("B" alloy) were tested under strain temperature TMF controlled conditions. In this study were performed mechanical tests of hardness, tensile strength, and anisotropic / isothermal fatigue and microstrutural / photographic analysis by scanning electronic microscopy (SEM). Using the S-N approach inferred from the TMF results, "A" alloy (Mg-added) presented a slightly better performance then "B" alloy especially at low stress amplitude levels. However, in the TMF testing conditions was not observed any significant difference in fatigue resistance for both alloys.

ASSUNTO(S)

thermomechanical fatigue ligas al-si al-si alloys fadiga termodinâmica fundição sob pressão

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