Abstract:
The non-metallic inclusions and fatigue properties of domestic and imported A286 superalloy bars for high performance fasteners were comparatively studied by using Aspex inclusion analyzer, scanning electron microscope and axial load fatigue test, etc. The types, compositions, morphologies, sizes and distributions of inclusions were analyzed. The fatigue properties and fatigue fracture surfaces of the two kinds of A286 alloys were also investigated. The results show that the types of inclusions in domestic and imported A286 alloy bars are similar, mainly Ti-containing inclusions and a small amount of oxide inclusions. The inclusion area fraction of domestic A286 alloy bar is 632.9870×10
-6, which is lower than that of imported A286 alloy bar (1013.0280×10
-6). According to the frequency statistics of inclusion sizes, the number of large-sized inclusions in domestic A286 alloy bar is lower than that in imported A286 alloy bar. When the failure probability is 50%, the fatigue strength of domestic A286 alloy bar is 22.67 kN, which is higher than that of imported A286 alloy bar (21.50 kN). Both domestic and imported A286 alloy fatigue specimens initiate cracks from the threaded area and finally fracture at the threaded area. The results can provide technical references for the promotion and application of domestic A286 superalloy to replace imported materials for high performance fasteners.