抄録
Cold flakes are one of irregular structures with fine grains having oxide layer, and when they are included in aluminum die-casts, unexpected failure of products appears under repeated loading and thermal cycling. The strength of the die-cast product is largely reduced due to the casting defect. The present work was carried out on the influence of the cold flake on fatigue properties of die-casts. The extended aim of this work is to verify the appearance of cracks initiation and propagation from the cold flakes of different size that influence the fatigue strength. For this purpose, at first, cold flakes were detected by acoustic microscopy and then specimens were prepared with positioning the cold flake in a center position of the specimen. Then the fatigue testing was carried out with specimens containing the cold flake of various sizes. The result shows that not only the size of the cold flake but also the position of the cold flake drastically reduces the fatigue life; the exposed cold flakes reduce the fatigue life greatly.
