Study On Extrusion Shear Composite Forming Technology And Microstructure Properties Of Al/Mg Bimetals

With the development of composite material preparation technology,the preparation technology of bimetallic materials has become the focus of lightweight research and has attracted extensive attention in various fields.This project focuses on the research of extrusion and shear composite forming technology and microstructure properties of Al/Mg bimetallic materials.First,design the extrusion shear mould was established based on UG and double metal model,and by using Deform-3D numerical simulation software to simulate the composite forming process of the double metal extrusion shear,explore the double metal billet in the process of extrusion,equivalent stress and strain,temperature field,flow law of damage value distribution and the influence of process parameters on the forming load;Secondly,the influence of main technological parameters on the forming load was studied by using orthogonal experimental design.Finally,under different temperature and different extrusion process by means of double metal extrusion experiment,the probe temperature and extrusion process of double metal surface quality of the samples,and use the advanced material testing technology of metal sample grain size morphology,combination of double layer morphology,element distribution and micro hardness distribution system research.The research results of this paper are as follows:?1?Through the simulation of the compound forming process of 6063/AZ31 bimetal extrusion and shearing,it is found that the flow of outer Al blank is slower than that of inner Mg blank as the extrusion process goes on.The equivalent stress,strain and temperature increase with the extrusion and decrease at the exit of the die.The damage value changes little in the whole process;The forming load decreases with the increase of extrusion temperature and with the decrease of extrusion speed and Mg alloy blank thickness.through the orthogonal test analysis,it was found that the temperature had the greatest influence on the forming load,and the optimal technological parameters for the preparation of 6063/AZ31 bimetallic materials were obtained:extrusion temperature t=420?,extrusion speed v=1mm/s,Mg alloy blank thickness h=5.2mm,friction factor?=0.1.?2?Through the macroscopic analysis of 6063/AZ31 bimetal extrusion experimental samples under different temperatures and different extrusion processes,it is found that the uniformity of the aluminum layer thickness of the samples is proportional to the extrusion temperature;The surface of the sample was smooth without obvious defects under the extrusion and shearing process at t=420?,while the wavy defects appeared under the extrusion and shearing process at t=360?.?3?Through the microscopic analysis of the sample binding layer,it is found that the distribution of elements in the binding layer is related to the distance of the parent material,and the farther the distance,the lower the concentration;The diffusion layer thickness of both ordinary and extruded shear samples increases with the increase of temperature.At the same temperature,the thickness of the diffusion layer is larger than that of the ordinary extrusion.It was found that there were cracks in the bonding area of t=360?and no diffusion layer was formed,while other samples all formed diffusion layers of different thickness.t=420?extrusion shear sample bonding layer without hole defects,thickness of about 22 m,of which 11 m is the stable layer,and the diffusion layer near the magnesium side is Mg₁₇Al₁₂???,the diffusion layer near the aluminum side is Mg₂Al₃???,the intermediate stable layer is MgAl???.?4?Through the microhardness analysis of the extruded shear sample at t=420?,it was found that the average hardness value of magnesium matrix was 62 HV,the average hardness value of aluminum matrix was 90.2 HV,and the average hardness value of bonding layer was 221 HV.