EFFECTS OF IMPURITIES AND Ce ON FRACTURE BEHAVIOUR OF 8090 ALLOY SHEETS IN DIFFERENT ORIENTATIONS
有害杂质及Ce对8090合金薄板不同加载方向断裂特性的影响

The effects of the impurities and Ce on the fracture behaviour of 8090 alloy sheets were experimentally investigated.Test results show that Fe and Si in 8090 alloy sheets decrease the plane stress fracture toughness in all orientations tested and the crack initiation and propagation resistance in 45°orientation. Na and K decrease the fracture properties in all orientations tested except the crack initiation resistance in T-L orientation.Adding 0.09% Ce into 8090 alloy sheets shows the beneficial effect on the plane stress fracture toughness.The fracture properties of 8090 alloy sheets containing more Fe and Si could be improved by adding 0.28% Ce. The reason behind it may be attributed to that Ce dissolved in a matrix could make the recrystallization microstructure of 8090 alloy sheets more uniform and finer,and reduce the compound particles precipitated along the grain boundaries, which is benefitcal to suppress the tendency of brittle fracture.Correspondent:(MENG Liang,associate professor,Department of Materials Science and Engineering.Northwestern Polytechnical University,Hi'an,710072)