Study On Melt Inclusions Of High-speed Continuous Casted And Rolled AA5052Aluminum Alloy Sheet

High-speed continuous casting and rolling process is a new and efficient shortprocess of the production process, the process by the high-speed continuous castingand hot rolling mill triple direct distribution directly to the molten aluminum intoslabs1~2mm, productivity up to50t/h. However, inclusions content of fluidelectrolytic aluminum is high and molten aluminum casting quickly, the level ofinclusion content will directly affect the performance of the subsequent products. Sothe high-speed continuous casting and rolling process of molten aluminum inclusionsdistribution is very important.Excessive refiner will introduce more molten aluminuminclusions, less thinning effect will affect the impact of molten aluminum refinersquality of the key technologies of the process.Due to the high inclusion content andnozzle material in high-speed casting and rolling process molten aluminum, dross ofnozzle problems are more prominent, the study of dross of nozzle mechanism andoptimization methods become an important technology.In this paper, we aimed at the studying of detection means of high-speed castingand rolling process of molten aluminum inclusions, using the domestic equipmentused to study new and efficient analysis technique of the microstructure to detectinclusions in molten aluminum combined the Image-Pro Plus computer analysissoftware.Using a new metallurgical analysis and abroad PoDFA, Prefil-Footprinterdetection and analysis methods to make a detailed study of the distribution ofAA5052molten aluminum inclusions and IPP metallurgical analysis compared withthe results of PoDFA.Through the experimental simulation and industrial onlineconditions investigating the refining effect of the Al5TiB for the AA5052alloy andmaking comparative analysis, making a research of the effects of different levels ofrefiners Al5TiB on molten aluminum quality, especially on the inclusioncontent.Through the dross combination of nozzle and import wide nozzle materialsresearch determined the basic mechanism of dross of nozzle, and made a comparisonstudy of colloidal graphite, boron nitride, kaolin and mold release coating optimization effect on the dross of nozzle.The main results are as follows:(1)High-speed continuous casting and rolling AA5052molten aluminuminclusions contains spinel, refiner particles, salt particles and the oxide film, the Frontoffice spinel content of97%, before the tank office inclusions mainly titanium boronaggregated particles and spinel particles, both of which accounted for more than80%of the total content of the inclusions.(2)High-speed continuous casting and rolling AA5052aluminum melt inclusionsat higher levels in the front office, after SNIF degassing treatment significantlyreduced,and after filtering inclusion content achieved the minimum, but the numberof the inclusions in the front office sharply increased.(3)After refiner Al5TiB join into the AA5052melt, the number of inclusions inmolten aluminum is also increasing, but the average size of the inclusions isobviously smaller than inclusions without aluminum titanium boron; AA5052alloymelt mobility increasing with refiner Al5TiB amount increasing, and finallystabilized; after refiner is added, the grain has been significantly refinement, theoptimal amount of refiner Al5TiB joining into high-speed continuous casting androlling production AA5052is about0.25%.(4)High-speed continuous casting and rolling process to produce AA5052aluminum alloy dross compound of nozzle cavity consisted of spinel, forsterite,magnesium, etc., abundant spinel the most, and forsterite second.(5)The SiO2or Al2O3, AA5052among the nozzle and melt Al, Mg, MgO reactsin the process of casting and rolling, producing spinel, magnesium silicate,magnesium olivine as a result of the dross of nozzle. Nozzle surface roughness has adirect impact on nozzle dross reaction.(6)Nozzle coating can effectively isolate the molten aluminum and nozzlematerial, reducing or avoiding the occurrence of reactions, reducing dross of nozzle.Boron nitride coating compared with other coating:high binding force, smallroughness, nonstick aluminum (large wetting angle), etc., so it can replace importedgraphite emulsion coated nozzle.