Abstract
The test of fatigue crack growth was achieved using CT specimens of aluminum alloy die casting ADC12 which were varied in thickness from 2.9mm to 25.4mm And the relation between the rate of fatigue crack growth da/dN and the stress intensity factor range ΔK was obtaind. From the result, the fatigue fracture toughness Kfc and the threshold stress intensity factor range ΔKth in each specimen were calculated. The same test was carried out in heat-treated die castings ADC12, B390, and aluminum cast alloy AC4A specimens. The results were as follows.
(1) In ADC12, both Kfc and ΔKth were independent of the thickness of CT specimens.
(2) Heat-treamant in ADC12 and B390 caused increase of Kfc. but little change in ΔKth.
(3) Kfc in ADC12, was as same as in aluminum alloy AC4A cast using a sand mold, but was smaller than cast using a metal mold. In ΔKth there were very little difference between AD12 and all AC4A specimens.
