Effect of Elevated Curing Temperature of Bonded Repair on Fatigue Crack Propagation Threshold Value of LY12CZ Aluminum Alloy Studied by In-situ Observation

The effects of elevated curing temperature on fatigue cracking propagation behavior of LY12CZ aluminum alloy during bonded repair process were studied by scanning electronic microscope (SEM) which could provide heating system in-situ observation technique. The results indicate that the elevated temperature would promote initiation and coalescence of inner hole, then accelerate initiation of small cracks and inclination of intergranular fracture, and finally decrease the fatigue resistance ability. The fatigue crack propagation threshold value of LY12CZ aluminum alloy decreased with the increase of the elevated temperature. What’s more, the fatigue crack propagation threshold value could not regain its value at room temperature with the elevated temperature removing. So the elevated curing temperature must be as low as possible to minimize the effect of temperature on fatigue resistance property of the matrix aluminum alloy.