Microstructures and Fatigue Crack Growth Rates of Domestic and Imported 5083-H116 Aliuminum Alloy

The microstructures and fatigue crack growth behavior of domestic and imported 5083-H116 aluminum alloys were researched. Experimental results showed that the chemical constitutions of domestic and imported 5083-H116 aluminum alloys both met the standard requirements. Both of the microstructures of do mestic and imported alloys contain a lot of coarse second phases, and the latter more. The grain size and distribution of imported alloy were apparently smaller and more uniform than those of domestic alloy. Compared with the imported alloy, domestic alloy had higher tensile strength and yield strength and lower elongation. The fracture analysis showed that the fracture was both featured with three typical regions. Fatigue striations were observed in both alloys at the crack initiation area, and the area in domestic alloy presented delamination and was flatter than the imported one. The fatigue crack growth rate of imported alloy was lower than that of domestic alloy, and the crack growth rate of imported alloy decreased by more than 32% when ΔK=15 MPa·m^1/2. Obvious fatigue striations were observed at the crack propagation area, and the intervals were respectively 0.405 5 μm and 0.282 3 μm. At the transient break area, the imported alloy had more and smaller dimples.