Microstructure And Properties Of Aluminum Alloy Castings With Complex Structure Used On Aircraft

The metallurgical quality, microstructure and mechanical properties of revestmentprecision casting with complex structure in aircraft are studied in detail, and compare thewelding microstructure and properties of sand castings and investment castings, then theobtained results can provide experimental guides for design, application and qualityinspection of aluminum alloy casting with complex structure uded in aircraft.The chemical composition of ZL116, ZL101, ZL210A revestment precision castingwith complex structure in aircraft is qualified and steady, with excellent and stableinternal and external metallurgy quality, that can meet the requirements of the technicalstandard. The nondestructive inspection qualification rate of ZL116alloy precisioncasting is93%, ZL101alloy precision casting reaches94%, and ZL210A alloy precisioncasting is up to100%.Microstructure characteristics of ZL116aluminum alloy (T5)and ZL101aluminumalloy (T4) are α (Al) dendrite and eutectic microstructure distributed homogeneously, andeutectic silicon present the dot or worm-like shape. characteristics of ZL210A aluminumalloy (T5) is that α (Al) is the matrix, and a small amount of T phase along grainboundary is not integrated into the matrix.The mechanical properties of ZL116revestment precision casting with complexstructure in aircraft is significantly higher than that produced by sand casting, especiallyfor the improved tensile strength、elongation and hardness. Average value of theseproperties are333MPa,7.3%and102respectively, which is up to111%,365%and120%of the standard respectively.The mechanical properties of ZL101precision castingaircraft complex thin-wall parts is also higher than of sand mold casting, conform to therequirements of the standard, with higher tensile strength, elongation and hardness,average values are227.2MPa,9.52%and65.95respectively, which is151%,238%and139%of the sand mold casting mechanical performance standard.ZL210A aluminum alloy casting with complex structure in aircraft has matchedmechanical properties of sand mold casting, conform to the requirements of the standard,the parts also have higher tensile strength, elongation and hardness, its average values are430MPa,12.3%and122respectively, which is107%,176%and107%of the standardrespectively. The chemical composition and mechanical performance of aluminum alloy byvacuum revestment precision casting can meet the technical requirements; The castinghas good metallurgical quality, fluorescence detection surface quality and X-ray flawdetection internal quality. The qualified rates of fluorescence detection、X-ray flawdetection and metallurgical quality are up to92.8%、96.2%and89.3%respectively.Welding qualified rate of vacuum investment casting is significantly higher thanordinary sand casting, and there are no serious welding defects such as linear porosity.The assembly welding performance of vacuum casting aluminum alloy and LF21, LF2can compared with ordinary sand casting aluminum alloy and LF21and LF2, themicrostructure of weld area is normal.Typical ZL101welding specimen has the sametensile strength with ZL101welding specimen of sand mold casting, both of thespecimens fracture in the plate area; The tensile strength of typical ZL116weldingspecimen is slightly higher than that of ZL116sand mold welding specimen, both of thespecimen break in the casting area.