Study Of Fatigue Behavior Of1420Aluminum Alloy

In the paper, the fatigue behavior of1420alloy was studied in three differentconditions, which are air at room temperature(RT), vacuum at RT and vacuum atlow-temperature, the tensile test of1420alloy was tested both at RT andlow-temperature, the photos got by scanning electron microscope (SEM) andtransmission electron microscope(TEM) were also observed, then got the effaction ofthe vacuum and low-temperature on the fatigue performance of1420alloy.Results indicate that the strength of1420alloy at low-temperature is higher thanthat at RT, while the ductility of1420alloy turns weaken at low-temperature. Comparedto the fatigue performance of1420alloy in air at RT, the vacuum or low-temperaturehave an effect on it, especially the low-temperature. At the same load, the fatiguelifetime of1420alloy in vacuum at low-temperature is the longest, the lifetime isshorter in vacuum at RT, and the shortest fatigue lifetime of1420alloy is got in air atRT. The fatigue limit of1420alloy in air at RT is between100MPa~110MPa, Thefatigue limit of1420alloy in vacuum at RT is between110MPa~120MPa, The fatiguelimit of1420alloy in vacuum at low-temperature is between220MPa~240MPa.1420alloy shows good tenacity in three different conditions, the fracturemechanisms are all ductile fracture, in the condition of vacuum at low-temperature,1420alloy shows some features of brittle fracture slightly. From microcosm, there aremany dimples distribute on the fatigue fracture of1420alloy in all the three conditions.Compared with the original structure of1420alloy, in every condition, there are alarge number of dimples assemble near the fatigue fracture, in vacuum atlow-temperature, the dislocation density of1420alloy is the highest, followed by thecondition of vacuum at RT, the dislocation density in air at RT is the lowest.