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Therefore, it is a primary objective of the present invention to provide a high-strength aluminium-magnesium-silicon alloy with better strength, hardness and fatigue resistance than the present existing aluminium-magnesium-silicon alloys and to further provide a manufacturing process of the high-strength aluminium-magnesium silicon alloy. To achieve the aforementioned objective, the present invention improves the mechanical properties including the strength, hardness and fatigue resistance of an aluminium-magnesium silicon alloy by adjusting the composition of an alloy material, and setting the heat treatment parameters. adjusting the composition of an alloy material In the aspect of adjusting the composition, trace elements such as Vanadium (V) and Zirconium (Zr) are added into the aluminium-magnesium-silicon alloy to perform a grain refinement of the material in order to improve the strength of an alloy product of the present invention. In the composition of the alloy material of the present invention, the trace elements including 0.4-1. wt.% silicon (Si), less than 0.7 wt.% iron (Fe), 0.2-1.0 wt.% copper (Cu), less than 0.2 wt.% manganese (Mn), 0.6-1.6 wt.% magnesium (Mg), less than 0.2 wt.% zinc (Zn), less than 0.10 wt. % titanium (Ti), 0.05-0.3 wt.% chromium (Cr), 0.1-0.5 wt.% vanadium (V), 0.1-0.5 wt.% zirconium (Zr) and less than 0.15 wt.% of impurity are added into the main material aluminium (Al). picture
setting the heat treatment parameters The alloy heat treatment of the present invention comprises the following steps: (a) Solution treatment step, wherein a finished good is put into a solution furnace heated to a temperature of 530-580° C. and held at the temperature for 1-3 hours; (b) Quenching treatment step, wherein the finished good processed by the Solution treatment is immersed into a quenching liquid of 50-70° C. for a quenching treatment time of 15-45 minutes; (c) Aging treatment step, wherein the produced processed by the quenching treatment is put into an aging furnace and heated to 160-180° C. and held at the temperature for 14-18 hours. After the aforementioned three steps are completed, the finished good is cooled by air to form an alloy product with a better strength. picture
Advantages and effects In summation, the present invention adopting the aforementioned technical measures has the following advantages and effects: The present invention adds the trace elements including vanadium (V) and Zirconium (Zr) into an aluminium-magnesium-silicon alloy to refine the grains of the material to a diameter from 50 m to 100 m and thus reducing the grain size by 20% over the grain size of the Aluminium 6061 alloy cast ingot to improve the mechanical properties of the subsequent alloy product. The material of the present invention is hot forged and molded, and then a solution heat treatment is performed to melt magnesium (Mg) and silicon (Si) atoms into an aluminium (Al) base to result in a lattice deformation and achieve a strengthening effect, and then an aging heat treatment is performed to precipitate (MgSi) from grains in a precipitated phase, and the precipitated particles act as obstacles to dislocation movement, so that the alloy product of the present invention has a yield strength up to 400 MPa, an ultimate strength up to 505 MPa, a Brinell hardness (HBW) of 127.3 HBW and a fatigue strength of 155 MPa. (Picture) Compared with the Aluminium 6061 alloy - T6, the present invention increases the yield strength of the alloy product by 31%, the ultimate strength by 39%, the hardness by 34%, and the fatigue strength by 55.4%, so that the alloy product of the invention can be used in components with a high structural strength requirement. Such as aluminium bicycle frames and frame tubes, aluminium alloy wheels, control arms of a car Suspension system as well as alloy products of the transportation means industry, mechanical tool industry, national defense and weapon industry, aerospace industry, 3C electronic industry, and sports and leisure goods industry.
With reference to Figure 1 for a high-strength aluminium-magnesium-silicon alloy and its manufacturing process in accordance with the present invention, the manufacturing process comprises the following steps: (a) an alloy composition adjusting step; (b) a material casting step; (c) a material preheating step; (d) a hot forging step; (e) a heat treatment step. In the alloy composition adjusting step (a) as shown in FIGS. 3 and 4 , the microstructure shows whether there are too many cast holes, cracks and defects, and a better composition is chosen to satisfy the required mechanical properties of an aluminium-magnesium-silicon alloy and enhance the fatigue resistance effectively. In Figure 2 , the content of trace elements is adjusted and the traced elements are melted into a main material aluminium (Al). The silicon (Si) content is 0.4- 1.2 wt.% and used for improving the flowing capability of the molten aluminium (Al), the hot- cracking resistance, the specific gravity and thermal expansion coefficient, and obtaining a solid solution strengthening effect in the subsequent heat treatment step of the present invention. The iron (Fe) content is less than 0.7 wt.% and used for improving the hot-cracking resistance of the alloy, and achieving a grain refinement of the material of the present invention. The copper (Cu) content is 0.2-1.0 wt.% and used for improving the strength and hardness of the alloy significantly, but reducing the hot-cracking resistance), and obtaining a precipitation strengthening effect in the subsequent heat treatment step of the present invention. The magnesium (Mg) content is 0.6-1.6 wt.% and used for improving the strength and hardness of the alloy processed by heat treatment, and setting Mg-Si mainly in a precipitated phase, and obtaining the precipitation strengthening effect in the Subsequent heat treatment step of the present invention. The zinc (Zn) content is less than 0.2 wt.% and used for reducing oxidation in the alloy and obtaining the precipitation strengthening effect in the Subsequent heat treatment step of the present invention. The titanium (Ti) content is less than 0.10 wt.% and used for a grain refinement of the material of the present invention. The chromium (Cr) content is 0.05-0. wt.% and used for forming an intermetallic compound such as (CrFe) A17, and (CrMn)Al2 in
the operating temperature for the forging process is set within a range of 350-450° C., and the forging pressurization time is set to 3 seconds, and the forging pressure is set to 55000 KN. The material is forged into an alloy product of a predetermined shape, so that the hot forging step performs a plastic processing of the material to improve the grain structure of the material, and the material of the alloy product is reformed and homogenized. In addition, a mechanical fibrosis state caused by the continuous grain flow results in better mechanical properties including the fatigue resistance, tenacity, and impact resistance of the alloy product. In the heat treatment step (e) as shown in Figure 7 , the aforementioned alloy product is put into a solution furnace and heated to a temperature of 530-580° C., and that temperature is held for 1- 3 hours, and then the alloy product processed by the solution treatment is immersed completely into warm water of 50-70° C., and the quenching treatment time is 15-45 minutes, and then quenched alloy product is put into an aging furnace and heated to a temperature of 160-180°C., and that temperature is held for 14-18 hours, Finally, the alloy product is air cooled to form the alloy product of the present invention. In the heat treatment step (e) , a solution treatment of the alloy product of the present invention is performed to melt magnesium (Mg) and silicon (Si) atoms into an aluminium (Al) base to cause a lattice deformation and achieve a strengthening effect, and then an aging heat treatment is performed to precipitate (MgSi) from grains in a precipitated phase, and the precipitated particles act as obstacles to dislocation movement, so as to enhance the strength of the alloy product of the present invention. With reference to FIGS. 8 and 9 , several samples of the alloy product produced according to the aforementioned manufacturing process of the present invention are collected for testing, and test results show that the alloy product has an average yield strength of 400.33 MPa, an ultimate strength of 504.87 MPa, an elongation of 7.67 EL 96, and an average Brinell hardness of 127. HBW. Compared with the general AA6061 material, the material of the present invention has much higher strength, hardness and fatigue resistance.
