Evolution of microstructure and mechanical properties of A356 aluminium alloy processed by hot spinning process

Luo

et al. 2019

Materials

The main purpose of this work was to investigate the microstructure and mechanical properties of spray-formed 2195-T6 Al-Li alloy welding joints produced by tungsten inert gas (TIG) with Al-Cu and Al-Si-Cu filler wires, so that they can be better used in space vehicle tanks. The porosity analysis indicates that the porosity area of the weld seam with the Al-Si-Cu filler wire is approximately 7.989 times larger than that of the Al-Cu filler wire. Furthermore, the microstructure and microhardness results indicate that the Al/Cu eutectic near the fusion line distributes more at the grain boundaries, while more dispersed Al2Cu phase is found inside the grain, which improves the strength of the joint when using Al-Cu filler wire. However, when using the Al-Si-Cu filler wire, more Si, Cu, and Ti elements are segregated at the grain boundaries, forming a brittle-hard network Al/Cu/Ti eutectic, which reduces the performance of the joint. Additionally, the tensile strength and elongation of the weld joint are about 68.6% and 89.9% of the base metal (BM) when using the Al-Cu filler wire, and can approach the level of friction stir welding (FSW). However, the tensile strength and elongation are only about 56.8% and 39.9%, respectively, of the BM in the weld joint when using the Al-Si-Cu filler wire. Lastly, the fractures both occur on the fusion line and the fracture morphology of the weld joint shows that it is a mixed fracture mode dominated by plastic fracture when using Al-Cu filler wire, while it is mainly a quasi-cleavage fracture mode when using Al-Si-Cu filler wire. Therefore, the joint strength when using Al-Si-Cu filler wire with high strength matching is not as good as that of Al-Cu filler wire with low strength matching.

Section: Resultsmentioning

confidence: 93%

Effects of Filler Wires on the Microstructure and Mechanical Properties of 2195-T6 Al-Li Alloy Spray Formed by TIG Welding

Luo

et al. 2019

Materials

“…From the above observation, tensile properties of Al-7Si alloys are enhanced by the addition of La element, this is due to the reduction of SDAS value and the refinement of eutectic Si particles. Based on the analysis of previous studies [1][2]22] , the ductility is more sensitive to Si morphology. So modification brings about a significant increase in the ductility of Al-7Si alloy when the La content is 0.1wt.% and the eutectic Si particles present granular morphology.…”

Section: Tensile Propertiesmentioning

confidence: 99%

“…

Aluminum alloys have been widely used in automotive industry as structural parts with superior mechanical performances to meet the lightweight development of automobile. Al-7Si alloys are the representative of aluminum alloys with excellent microstructure and properties [1,2] and are extensively used in wheels. It has been proved that the mechanical properties of cast Al-7Si alloy are determined by the microstructural characteristics, such as the morphology and size of α-Al primary phase [3] , eutectic Si particles [4] , and some precipitates (Mg 2 Si and Fe-rich phase) [5] and so on.

…”

mentioning

confidence: 99%

Effect of La addition on microstructure and mechanical properties of hypoeutectic Al-7Si aluminum alloy

Luo

et al. 2021

China Foundry

Self Cite

“…Al-7Si alloys have been extensively used in die casting to produce components that comply with the mechanical performance of lightweight structures, environmental and other requirements. The mechanical properties of hypoeutectic Al-7Si cast alloy are controlled by the casting process, heat treatment process and physical metallurgy, such as chemical composition and microstructural features [1][2][3][4][5]. Tensile properties, particularly ductility, are accepted to be mainly controlled by microstructural features, normally the morphology and size of the α-Al primary phase, silicon particles and other precipitate phases which may be present in the microstructure [6].…”

Section: Introductionmentioning

confidence: 99%

Multi-Refinement Effect of Rare Earth Lanthanum on α-Al and Eutectic Si Phase in Hypoeutectic Al-7Si Alloy

Jiang

et al. 2020

Metals

Self Cite

The effect of La addition on primary α-Al and the eutectic Si phase of Al-7Si alloy is investigated systematically in this work. The results indicate that La addition causes a multi-refining efficiency on the microstructure of Al-7Si alloy, including refinement of α-Al grains and secondary dendrite arm spacing as well as eutectic Si particles. The grain size, secondary dendrite arm spacing and area of eutectic Si particles are decreased by 26.8%, 7.7% and 26.7%, respectively, with the addition of 0.1 wt.% La. It is also found that La-rich phases of Al2Si2La form and distribute in the vicinity of the eutectic Si phase. The crystal structure and lattice parameter of Al2Si2La phase are determined to be hexagonal (a = b = 0.405 nm, c = 6.944 nm) based on the TEM analysis results. The multi-refinement effects are mainly attributed to the increased constitutional undercooling caused by the low solubility of La in Al alloy and the growth-restricting factor caused by the Al2Si2La phase.