Forming Method of Aluminum Alloy Bracket Castings

Abstract

The present application relates to the technical field of material forming, and in particular to an aluminum alloy used to prepare bracket castings and a forming method thereof. In terms of mass percentage, the aluminum alloy provided by this application includes the following components: Si: 8.5%-11.5%; Mg: 0.45%-0.55%; Mn: 0.35%-0.6%; Ti: 0.06%-0.12%; Sr: 0.015%‑0.025%; Cr: 0.05%‑0.15%; Zr: 0.06%‑0.15%; lanthanum-cerium mixed rare earth: 0.08%‑0.12%; Fe≤0.10%; 0.01%; unavoidable impurity elements ≤ 0.1%; the balance is Al. The aluminum alloy provided by this application rationally optimizes the content of Fe, Si, Mg, Mn, Cr, Zr and other components, so that the aluminum alloy has excellent casting fluidity and corrosion resistance; using the aluminum alloy provided by this application Combined with the forming process, bracket castings with good casting formability, high yield strength and high toughness can be obtained.

Description

technical field [0001] The present application relates to the technical field of material forming, in particular to an aluminum alloy used to prepare bracket castings and a forming method thereof. Background technique [0002] With the development of lightweight automobiles, commercial vehicle bracket castings have begun to be made of lightweight aluminum alloy materials. The forming processes used mainly include metal gravity casting, high pressure die casting, low pressure casting, squeeze casting and forging. [0003] The above-mentioned forming process has the following defects: (1) The yield strength and fatigue performance of the high-pressure die-casting bracket are low because of the pores inside the casting and cannot be heat-treated. It is mainly used in the production and manufacture of high-load, durable and lightweight bracket parts; (2) Al-Si-Mg series ZL101A and Al-Si-Cu-Mg series ZL107 materials are mostly used for metal mold gravity casting bracket parts. Af...

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Problems solved by technology

[0003] The above-mentioned forming process has the following defects: (1) The yield strength and fatigue performance of the high-pressure die-casting bracket are low because of the pores inside the casting and cannot be heat-treated. It is mainly used in the production and manufacture of high-load, durable and lightweight bracket parts; (2) Al-Si-Mg series ZL101A and Al-Si-Cu-Mg series ZL107 materials are mostly used for metal mold gravity casting bracket parts. After forming, they pass T6 During heat treatment, turbulent air entrainment tends to occur when the casting is filled, resulting in oxidation inclusions and pinholes inside the casting. The cooling rate is slow during solidification. The secondary dendrites in the thick and large parts of the casting are developed, and the distance between dendrites is greater than 60 μm. Shrinkage cavity and other defects, the defect level of castings is below level 2; (3) Due to the high alloy casting temperature (generally at 710-720°C) and mold temperature (260-350°C) during the solidification and cooling stage of castings in the low-pressure casting forming process, Thick parts of the casting cool slowly and easily form large dendrite arms, the secondary dendrite spacing reaches 50-70μm, and there is micro-shrinkage, which affects the mechanical properties and fatigue properties of the casting. After heat treatment, the yield strength of the casting body is lower than 250MPa , the elongation rate is only about 4%; (4) In the extrusion casting process, there are problems such as turbulent flow, air entrainment and oxidation inclusions when the alloy is poured into the cavity during the direct extrusion process, which will lead to internal defects of the casting. Moreover, manual pouring is generally used, which is labor-intensive and low in production efficiency; indirect squeeze casting also inevitably produces turbulent flow and oxidation inclusions when the alloy is poured into the barrel, and defects such as inclusions and even pores are easily formed inside the casting. Squeeze casting equipment clamping force is limited, most of the castings can only be produced one type at a time, the casting runner is thick so that the yield rate is only 50-60%, and the manufacturing cost is high; (5) Most of the materials used in the forging forming process are Al-Si-Mg-Cu alloys such as 6061, 6082, etc. This process cannot form parts with complex shapes and large projected areas. Multiple sets of forming dies are required. The cost of deformed aluminum alloy materials is high, the machining allowance of forgings is large, and the yield rate is high. About 60-70%, so the manufacturing cost is high, not suitable for mass production of bracket parts with complex shapes

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