Types,Sources And Restraining Measures Of Typical Inclusions In 5XXX Aluminum Alloy Melt

5XXX aluminum alloy has high strength,good corrosion resistance,fatigue and weldability,and has a wide range of applications.However,the 5XXX aluminum alloy has high content of magnesium,which is prone to make inclusion defects.In the subsequent application,the inclusion defect is likely to cause the pinhole in can lid,which causes the fail of food package seal;resulting in an anodized material linear,which seriously affects the appearance of the product.Therefore,it is necessary to research the types and sources of inclusions in the 5XXX aluminum alloy in the casting,and formulate restraining measures.In this paper,the Prefil-Footprinter is used to test the sampling of each key process of casting,and research the composition of the inclusions by SEM.The following conclusions are obtained:(1)Typical inclusions in 5XXX alloy melts are mainly Al2O3,oxide film,MgO,spinel,TiB2,spinel-like,spinel crystal,AIN.(2)Analysis of the full process of 5XXX alloy casting,it is found that the inclusions are gradually reduced,and the converter has a good purification effect on the melt,and the rest of melt in holding furnace will reduce the inclusions;the effect of removing the inclusions by the degasser is not obvious;the deep bed filter's effect of remove the inclusions can reach about 95%,but the throughput must be strictly controlled.With the increase of the throughput,the filtration effect of the deep bed filter is obviously reduced.(3)The source of inclusions is mainly the high temperature of aluminum alloy melting leading to oxide and nitride inclusions;the erosion of refractory by magnesium will lead to the formation of spinel-like and spinel crystals;commonly used grain refiner Al-5Ti-B is the main cause of the formation of TiB2 inclusion.(4)The defects of the can lid material and the anodized material were corresponding to the melt inclusions.It was confirmed that the melt inclusions was the main reason for the 5XXX can lid pinhole and anodized material linear.(5)Optimize the melt treatment method,use the divided melting and holding furnace,control the quality of raw materials,strengthen the furnace cleaning,optimize the filtration process,select suitable refractory materials,timely maintenance and replacement,and optimize the grain refiner addition and other restraining means,can eliminate most of the product quality defects caused by inclusions.