Abstract
Problem Statement (Relevance): It is the Al-Sr grain refiners that are primarily used with Al-Si cast alloys to enhance the mechanical properties of automobile wheel discs which are cast from the above material. The traditional methods of manufacturing grain refiner rods by fusion and electrolysis are characterized with low efficiency and high labor costs, and they are not practicable without waste disposal. Objectives: This study aims to develop an efficient Al-Sr grain refiner production technique based on the use of silumin chips from automobile wheel disc machining and dehydrated strontium salt under the regimes that exclude fusion or electrolysis. Methods Applied: To achieve the above objective some laboratory tests were carried out, for which a rod extrusion press container with a lateral material flow (to the die hole) was used, together with a laboratory machine with a continuous material feed to the moving part of a two-part container. The crystallized metal was then pressed following the Conform method. The grain refining capacity of the resulting rods was analysed in the metallographic laboratory of an automobile wheel disc plant by optical and scanning electron microscopy. Originality: This study offers an original proven solution for manufacturing 6 mm Al–Sr grain refining rods based on the combined continuous casting and extrusion technique. Findings: It was found that the most efficient manufacturing process for industrial application Al–Sr grain refiners involves the following stages: grinding a mixture of the AK12 silumin chips and strontium salt, briquetting the mixture with no preheat applied, melting the briquette and taking the melt through the combined continuous casting and extrusion machine (the Conform method).
Keywords
Al-Sr grain refiners, inoculation of aluminium alloys, manufacturing technique, continuous casting and extrusion, the Conform method.
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