Study On Microstructure And Properties Strengthening Mechanism Of 2A14 Aluminum Alloy Extrusion Parts

2A14 aluminum alloy has a wide range of applications in the aerospace and high-speed train industry,and its good mechanical properties are an important guarantee for safety issues.At present,the thermomechanieal treatment technology is an important means to strengthen the performance of extrusions,but the strengthening mechanism is still unclear.In order to explore the optimal thermomechanieal treatment technology of2A14 aluminum alloy extrusions,promote the development and promotion of high-strength aluminum alloy industry in China,and clarify that different deformation heat treatment systems are essential for the microstructure and performance strengthening mechanism of 2A14 aluminum alloy extrusions.Based on DEORM software,the influence of different process parameters on the extrusion load of 2A14 aluminum alloy bar was studied.The die structure and extrusion process parameters were optimized,and the reliability of the parameters was verified by extrusion experiments.The yield strength and tensile strength of the extruded 2A14 aluminum alloy were 249.6MPa,375.3MPa.XRD,DSC,TEM,OM and other experiments were used to study the strengthening mechanism of different tensile cold deformation on the properties of forged 2A14 aluminum alloy,and compared with different compression cold deformation.Under the same amount of cold deformation,the precipitation strengthening value after tensile cold deformation is larger than compression deformation,7.4-14.6 MPa.The dislocation strengthening introduced by the tensile cold deformation is larger,23-36 MPa.The introduction of tensile and compression cold deformation is beneficial to refine the grain size of the alloy.However,tensile cold deformation introduce more holes and dislocations,which is more conducive to the diffusion and migration of solute atoms in the alloy.Therefore,the effect of tensile cold deformation on the performance enhancement of 2A14 aluminum alloy is more obvious,and the strengthening effect is more remarkable as the deformation amount increases.It was found that the yield strength of extruded 2A14 aluminum alloy by T851 and T852 increased by 10.6%-23.8% and 6.2%-10.2%,respectively.The T851 treatmentincreased the elongation by 0.6%-1.1%,and the T852 treatment reduced the elongation by 0.8%-2.6%.The strengthening effect of T851 is more obvious.Due to the T851 treatment,the density of the dislocation introduced into the extruded 2A14 alloy is greater.On the other hand,the precipitation strengthening value of the alloy is more obvious after the T851 treatment.In grain boundary strengthening and solid solution strengthening,the strengthening effect of T851 and T852 treatment on the alloy is not much different.Therefore,the T851 treatment is the best deformation heat treatment for the performance enhancement of 2A14 aluminum alloy extrusions.