| With the rapid development of the automotive industry,it is difficult for the traditional structural materials to meet the development requirements of lightweight vehicles.Therefore,looking for new structural materials with lower density and better mechanical properties is the mainstream trend in the development of the automobile manufacturing industry.Steering knuckle,as an important component linking the upper suspension system,braking system and steering system with the chassis,should have the properties of high precision,durability and low weight.The use of aluminum alloys instead of traditional steels for steering knuckles can reduce the weight of the structure.At the same time,the use of high-temperature forging can ensure the service performance of steering knuckles.However,the due to the complicated shape of steering knuckle,which is difficult to be produced via bulk forming during the forging process,finally resulting defects such as folds and filling dissatisfaction.The forging technologies of traditional knuckle for steel cannot be applied for aluminum alloys.The understanding of the deformation behaviors of aluminum alloys at high temperature is the prerequisite for developing its forging forming technology.Regarding the above circumstances,the aluminum alloy with grade of 6082 was adopted in this study.Based on a combination of basic physical tests and numerical simulations,the high-temperature flow mechanical behaviors of 6082 aluminum under different conditions of temperature,strain rate and displacement are investigated to provide a theoretical basis for the high-temperature forging process of aluminum alloy.The analysis on forming precise of the precis forging forming of aluminum alloy knuckle were conducted in Deform-3D,which was used to provide a specification for the technologies of forging forming of aluminum alloys at high temperature.The optimizations of the technologies of forging forming of aluminum alloys at high temperature were conducted combined with the on-site technology testof the enterprise.The heat treatment route after high-temperature forging for the aluminum alloy knuckle was initially explored,and the relevant technical indicators were measured.The main results and conclusions are summarized as follows:(1)Analysis on the flow behaviors of aluminum alloy at high temperatureBased on the simulated tests conducted in Gleeble,the flow behaviors of 6082 aluminum alloy were investigated and the corresponding high-temperature constitutive model was established by considering the influence of strain,strain rate and temperature,which can be used to characterize the deformation behaviors within the forging temperature ranges.The evolution law of microstructure of 6082 aluminum alloy during hot deformation was also analyzed.(2)Establishment of the hot processing map for aluminum alloyThe hot processing map of 6082 aluminum alloy was established accurately.The best ranges for strain rate and forging temperature were determine to provide data support for the subsequent analysis on process technology.(3)Analysis on the forging technologies of aluminum alloy steering knuckle at high temperatureThe flow law of 6082 aluminum alloy during the process of billet production,bending,pre-forging and final forging were analyzed via the simulation of high-temperature forging for the aluminum alloy knuckle.The types and formation law of macro and microstructure defects for the aluminum alloy knuckle were investigated.The optimal technology route of high-temperature forging for the aluminum alloy knuckle was determined.The volume of blanking,the geometric dimensions of forging part,the distribution of the blank volume,the material flow in each process as well as the related technology parameters were optimized reasonably.The emphasis is putted on the correlation between material flow and microstructure evolution to achieve the controllability for both shapes and properties of aluminum alloy knuckle simultaneously.(4)Optimization of high-temperature forging for the aluminum alloy steering knuckleThe on-site technology tests and the thermo-mechanical coupled finite element simulations of high-temperature forging for the 6082 aluminum alloy knuckle were conducted.Considering the quality of forging parts,mechanical properties of parts after forging,and forging cost,etc.The height and thickness of the mold bridge and the design of pre-forged bearing seat were optimized and the heat treatment route of forged parts were formulated for solving the defects of filling dissatisfaction,flashing,folding,cracking and long ears during the forging process of aluminum alloy parts. |
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