Al-Si焼結合金の疲労信頼性に係わるき裂発生・進展挙動について

抄録

A plane bending fatigue test of Al-Si sintered alloy was carried out employing a compact testing machine. Crack initiation and growth behavior were investigated in comparison with those of casting alloy from the mesoscopic point of view. The main results were as follows. (1) The fatigue lint of sintered alloy could not be found. The fatigue strength of sintered alloy was higher that that of casting alloy. (2) Fatigue fracture of sintered alloy were controlled by brittleness. Crack initiation life accounted for the greater part of fatigue life. (3) Crack propagation characteristics of sintered alloy were determined controlled by ΔK. Crack propagation rate was higher than that of casting alloy since the fracture toughness of Al-Si sintered alloy is higher than that of HIP-treated casting alloy. (4) the crack propagation rate of Al-Si sintered alloy was very high and fracture mode rapidly changed into monotonic brittle facture. It is suggested that in engineering design emplcying Al-Si sintered alloy, consideration of brittle fracture is important.