Reliability evaluation of 7A60 aluminum alloy with defects

Reliability of 7A60 Aluminum Alloy with defects is evaluated. Creep fracture time of the alloy with artificial scrape under constant load is measured at a dedicated temperature. In addition, size allowance of outer surface defects of the alloy is calculated and reliability of the alloy is evaluated according to the stress strength factor threshold K_th of creep fracture obtained by the creep testing of the alloy cylinders. The stress strength factor threshold K_th of creep rupture of Al alloy is 16MPam^1/2 and the depth allowance a_c ^* of outer surface scrape is 0.18 millimeter when the maximal service stress of Al alloy is half of the yield strength of the alloy and allowable stress strength factor K_I(allowance) is 8MPam^1/2. These results are consistent with that from the accelerated life testing of Al alloy cylinders with defects. These results indicate that Al alloy with cracks less than 0.18 millimeter in depth rarely creep or rupture and could be used safely in a high-speed rotary device for a long term.