Investigation Of Microstructure And Mechanical Properties For A356 Alloys Melted With Grain-refining Aluminium Ingots

A356 alloys are widely used in automotive industry because of excellent castability and mechanical properties, The more high requirement is presented following the development of automotive light weight. In this paper, the influence of content of titanium, boron and rare-earth on microstructures and mechanical properties of A356 alloys with refinement of grain-refining aluminium ingots have been studied, the mechanisms of refinement and modification have been analysised. The results may be help the development of application of grain-refining aluminium ingots.The experimental results show, (l)the grain refinement effect of grain-refining aluminum ingots is similar with aluminum-titanium master alloys, The size of grain doesn't decrease with the increasing content of titanium at the range of 0.07%~0.19%. Because grain-refining aluminum ingots is cheap, it's optimum titanium content is 0.1%. (2)The grain refinement effect of boron to A356 alloys is evident, The addition of boron get more efficient refinement effect to A356 alloys on basis of the addition of titanium. The addition of 0.01% titanium and 0.03% boron to A356 alloys has the more efficient grain refinement effect, the microstructures is mainly composed of refined equiaxed grain. (3)The second dendrite arm spaceing refinement effect of rare-earth to A356 alloys melted with grain-refining aluminium ingots is obvious. Morphology of eutectic silicon in A356 alloys with content of rare-earth≥0.3% is partially modified. (4)The second dendrite arm spaceing refinement effect of lanthanum to A356 alloys melted with grain-refining aluminium ingots is obvious. Morphology of eutectic silicon in A356 alloys with content of lanthanum≥0.05% is partially modified. (5)The second dendrite arm spaceing refinement effect of rare-earth to A356 alloys melted with grain-refining aluminium ingots and strontium modified is obvious. the pinhole in A356 alloys with addition of rare-earth or lanthanum is little. (6)The grain refinement and modification effect of rare-earth and lanthanum to A356 alloys melted with grain-refining...