The Study Of The Closed Die Forging Process Of Aluminium Alloy Connecting Rod

The closed die forging technology is one of the advanced near-net shape forming technology。The study of the microstructure evolution law is the key problem to save the materials and the energy, raise the productivity and the quality, raise the mechanical property and the service life, and reduce the production costs in the closed die forging process for aluminium alloy connecting rod。The goal of investigating the microstructure evolution law in the closed die forging process for aluminum alloy connecting rod is to obtain the precision forgings of connecting rod, which with good distribution of the forging flow lines and even distribution of the little crystal grain, higher utilization of material and productivity, close dimensional tolerance, high surface quality and lower production cost, to provide the suitable deformation process and the deformation parameters, to satisfy the demand of production for the small two-stroke gasoline engine and the automobile industry, to raise the technical ability of aluminium alloy forging technology。The hot compression deformation test of 2A12 aluminum alloy was made on the Gleeble-3800 thermal simulation machine, the compression stress-strain curves were obtained at 350℃-500℃ temperature and 0.001～5s-1 strain rate。At the same time, the microstructure of the samples in the hot compression deformation test of 2A12 aluminum alloy were obtained。According to the experimental datas, the material parameters such as the energy of activation Q, stress intensity parameter a, structural factor A and the stress exponent n were calculated by linear retrogression method by use of the Origin software。The flow stress model which can be reflected on the deformation temperature and strain rate was obtained by the double-curve relationship of Arrhenius, and the flow stresses were made a comparison between the experimental value and the calculated value, the error is 1.407%。 Referred to the recrystallization critical deformation model, the recrystallization grain size model and the percentage of recrystallization model in DEFORM-3D, adopted the values of rex which obtained in the hot compression deformation test of 2A12 aluminum alloy, the recrystallization critical deformation model, recrystallization grain size model and the percentage of recrystallization model for 2A12 aluminum alloy were established。Adopted the recrystallization grain size model and the percentage of recrystallization model for 2A12 aluminum alloy, the numerical simulation of the microstructure evolution was completed for the hot compression deformation test, the influence of the deformation degree and the deformation temperature etc. on the recrystallization grain size and the percentage of recrystallization were obtained, and the comparison between microstructure obtained by the DEFORM-3D and the microstructure of the sample for the hot compression deformation test was finished, it was shown by the compared results that the recrystallization model for 2A12 aluminum alloy was correct。In view of the construction features of GT999 aluminum alloy connecting rod, the three-direction closed die forging process and the one-direction closed die forging process with combined head die were designed, and the 3D models were established for the DEFORM-3D numerical simulation by the CAD and the SolidWorks。At the same time, adopted the recrystallization model and the flow stress model for 2A12 aluminum alloy, the numerical simulation of the closed die forging process of aluminum alloy connecting rod was performed by Deform-3D rigid-plastic finite element software, the effective stress distribution, the effective strain distribution, metal flows law, load curve, the germination and the expand of forging defect, the recrystallization grain size and the percentage of recrystallization were obtained。It was shown by these numerical simulation results that the one-direction closed die forging process with combined head die was reasonable。The one-direction closed die forging process with combined head die for 2A12 aluminum alloy connecting rod was determined:Rodâ†'Sawingâ†'Local Upsettingâ†'Preforgingâ†'Finish-forgingThe forging drawing, the preforging drawing and the local upsetting drawing were designed according to the one-direction closed die forging process。The shape and the dimensions of blank was determined according to the constancy of volume。 The die structures and the die were designed by the CAD and the SolidWorks for the local upsetting process, preforging process and finish-forging process。...