Investigation On A Hot Gas Bulging With Clustering Balls And Evaluation Of Performance Of 5083 Alloy With Box-shaped Parts

To promote modern industry to achieve the goals of peak carbon dioxide emissions and carbon neutrality,we will vigorously develop the lightweight of production components.Aluminum alloy materials with high specific strength and light weight are becoming more and more popular in industry.To overcome the problems of aluminum alloy parts with complex shapes,such as difficult forming at room temperature,large springback,low production efficiency,uneven thickness and poor performance of the traditional hot gas bulging process,a novel hot gas bulging process is proposed in this paper.Clustering balls are applied to the hot gas bulging process,and at the same time,high dimensional accuracy,excellent performance and uniform microstructure of the formed parts are realized.In this experiment,the domestic commercial 5083Al-Mg alloy material is taken as the research material,and different hot gas bulging processes are compared through formability and performance of the formed parts,so as to reveal the hot deformation mechanism of the material and the best technological parameters of forming,explore the change law of the performance of the formed parts,discuss the strengthening mechanism,and provide theoretical guidance and technical support for practical industrial application.The specific research of this paper is as follows:(1)The hot tensile tests of 5083 aluminum alloy were carried out at different hot deformation temperatures(400-500?)and strain rates(0.03 s^-1,0.003 s^-1 and 0.0003 s^-1),and the hot mechanical properties were analyzed.The characteristics of flow stress changes during hot tensile were discussed,and a constitutive model was established.Through the hot gas bulging test,the influence of air pressure on the deformation behavior of sheets in different hot gas bulging processes was studied,the contour change and wall thickness distribution in different bulging stages were analyzed,and the advantages of the hot gas bulging process with clustering balls were summarized.(2)By means of SEM and EBSD,the microstructure changes and texture evolution in different deformation areas were studied,and the micro-physical mechanism of thermal deformation was revealed.Deformation mechanisms are grain boundary and dislocation slip,and dynamic hardening and softening mechanisms exist in the process of thermal deformation.The difference of microstructure evolution mechanism depends on the degree of deformation.When the degree of deformation is small(the strain is less than 0.36),it is a dynamic recovery.When the deformation degree is larger(the strain is greater than 0.36),the dynamic recovery in the early stage of deformation can promote the occurrence of dynamic recrystallization,leading to the appearance of fine recrystallized grains at grain boundaries.The tensile fracture analysis of the material before and after forming at room temperature shows that the micro-pore aggregation type transgranular fracture occurs before forming.After forming,it is a mixed form of transgranular fracture and intergranular fracture,and the higher the deformation temperature,the larger the proportion of intergranular fracture.The microstructure of the formed parts is mainly Brass texture and Cube texture,and with the increase of deformation,the grain orientation gradually changes from Copper{112}<111>and Goss{110}<001>to Brass{110}<112>and Cube{100}<001>,and the appearance of recrystallization texture also indicates dynamic recrystallization.The tensile strength,hardness and corrosion resistance of the material are strengthened during HGBB.(3)There are three strengthening mechanisms,i.e.,fine-grain strengthening,second phase strengthening and geometrically necessary dislocation strengthening.The precipitated phases and their distribution were characterized by SEM,XRD,TEM and EDS,which revealed the promotion mechanism of deformation on grain refinement and precipitation of the second phase,which showed that thermal deformation led to the increase of dislocation density and the formation of a large number of GBs,which provided more nucleation particles for Al₆Mn and Mg₂Si phases to precipitate in large quantities.The greater the deformation degree of the material,the more obvious the strengthening effect.According to the calculation,the three strengthening effects account for 37.8%,26.1%and 36.2%respectively.