Jet forming technology of wheel hub forgings

Jet forming technology of wheel hub forgings

Jet forming technology is developed on the basis of rapid solidification and powder metallurgy process, direct preparation of metal material billet or semi-finished advanced preparation technology, the prepared material has the advantages of fine grain, uniform structure, less oxidation, small degree of segregation, etc., widely used in the preparation of various advanced materials and traditional materials. Jet forming technology is the innovation of traditional casting and powder metallurgy, breaking through the casting process solidification slow, macro segregation and loose, and powder metallurgy process is difficult to densify, small component specifications of the technical bottleneck, to achieve the double improvement of material performance and large specifications. As an important structural material, ultra-high strength Al-Zn-Mg-Cu(7000 series) aluminum alloy has the characteristics of low density, high strength, good processability and weldability, and is widely used in aerospace, transportation and civil industry and other fields [3]. The existing wheel hub material is basically LD5, LD10, tensile strength ≥420MPa, yield strength ≥380MPa, elongation ≥2.5%~9%, because of its low strength, so the design wheel must have the corresponding thickness and quality; If the 7055 material forging machine wheel is used, the tensile strength, yield strength, elongation and other aspects are greatly improved, which can make the wheel properly reduce the quality. Foreign 7055 aluminum alloy has been mature for high load wheel hub. In China, this study is the first time to apply 7055 aluminum alloy jet forming to the wheel hub. However, due to the pursuit of high strength to achieve the effect of reducing mass in the preliminary test, the selected T6 heat treated material has great stress, and there is stress concentration in the weak part of the wheel hub, which leads to premature failure and brittle fracture in the installation test. If the heat treatment method is changed to double-stage over-aging treatment, the fracture toughness of the alloy can be effectively improved. But so far, there has been no report on the effect of double aging system on the strength, plasticity and toughness of 7055 aluminum alloy wheel hub forgings by jet forming. In this paper, the author adopts self-developed automatic control reciprocating jet forming technology and industrial specifications device to prepare large 7055 aluminum alloy ingot with a diameter of 495mm. After hot extrusion and double forging, the wheel hub forging is made. After two-stage solution treatment, the two-stage aging treatment is carried out to test the mechanical properties and electrical conductivity under different aging systems. The influence of two-stage aging treatment system on the mechanical properties and electrical conductivity of wheel hub forgings in each sampling direction was studied. The results showed that 7055 aluminum alloy was successfully applied to wheel hub in China, and then the wheel weight reduction was realized.

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