High-strength aluminum-magnesium silicon alloy and manufacturing process thereof

Abstract

A high-strength aluminum-magnesium silicon alloy and its manufacturing process which includes a composition adjusting step to add vanadium (V) and zirconium (Zr) in an aluminum-magnesium silicon alloy to refine grains of the alloy; a material casting step, a material preheating step, a hot forging step and a heat treatment step to melt magnesium and silicon atoms into an aluminum base to cause a lattice distortion and achieve a strengthening effect and precipitate Mg 2 Si from the grains of the alloy, and the precipitated particles act as obstacles to dislocation movement. Therefore, the alloy product has a yield strength improved by 31%, the ultimate strength by 39%, the hardness by 34%, and the fatigue strength by 55%. Therefore, the alloy product can be used in components with a high strength requirement such as the aluminum alloy wheels and the control arms of a car suspension system.

What is claimed is: 
     
         1 . A high-strength aluminum-magnesium silicon alloy, with a trace element composition comprising: 0.4˜1.2 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. % impurity which are melted with aluminum (Al) to produce a material. 
     
     
         2 . The high-strength aluminum-magnesium silicon alloy of  claim 1 , wherein grains of the high-strength aluminum-magnesium silicon alloy are refined to a diameter from 50 μm to 100 μm to improve mechanical properties of a subsequent alloy product. 
     
     
         3 . A high-strength aluminum-magnesium silicon alloy manufacturing process, comprising the steps of: 
       (a) an alloy melting step that melts a plurality of trace elements into a balanced amount of aluminum raw material, and the trace elements comprising: 0.4˜1.2 wt. % Si, less than 0.7 wt. % Fe, 0.2˜1.0 wt. % Cu, less than 0.2 wt. % Mn, 0.6˜1.6 wt. % Mg, less than 0.2 wt. % Zn, less than 0.10 wt. % Ti, 0.05˜0.3 wt. % Cr, 0.1˜0.5 wt. % V, 0.1˜0.5 wt. % Zr and less than 0.15 wt. % impurity; 
       (b) a material casting step, wherein a molten alloy material is casted and formed into a material, and grains of the high-strength aluminum-magnesium silicon alloy are refined to a diameter of 50 μm˜100 μm; 
       (c) a forging preheating step, wherein the molded material is put into a preheating furnace at a temperature of 300˜500° C. and held at said temperature for at least 120˜180 minutes; 
       (d) a hot forging step, wherein a mold is heated to 200˜400° C., and an operating temperature during forging is set to a temperature range of 250˜500° C., and the molded material is forged to form an alloy product; and 
       (e) a heat treatment step, wherein a solution treatment, a quenching treatment, an artifical aging treatment of the alloy product are performed sequentially, and then the alloy product is cooled in air to form a high-strength aluminum-magnesium silicon alloy product. 
     
     
         4 . The high-strength aluminum-magnesium silicon alloy manufacturing process of  claim 3 , wherein the heat treatment step is to put the alloy product in a solution furnace heated to 530˜580° C. and maintaining the temperature for 1˜3 hours, and then submerge the alloy product completely into a quenching liquid of 50˜70° C., and after a quenching treatment time of 15˜45 minutes, the quenched alloy product is put into an aging furnace heated to 160˜180° C. and maintaining the temperature for 14˜18 hours, and then the alloy product is cooled in air to produce the aluminum-magnesium-silicon alloy product. 
     
     
         5 . The high-strength aluminum-magnesium silicon alloy manufacturing process of  claim 3 , wherein the aluminum-magnesium silicon alloy product has a yield strength up to 400 MPa, an ultimate strength up to 505 MPa, a Brinell hardness up to 127.3 HBW and a fatigue strength up to 155 MPa.