Research On The Process Of Al/Cu Bimetal Composite By Drawing

At present,in order to save energy and resources,the household appliances,lots of machinery,conveyer and living goods have a development of keeping the products lightweight,economical and high-performance.Therefore,the original aluminum or copper and other single materials can't be adapted to this requirement anymore,and the diversified and high-level materials are required.It is required for a new materials to meet this urgent demand,which have better properties and functions than the materials mentioned above.In this paper design a draw-off gear and draw mould that can be used to universal drawing machinery are designed.The variable specifications of different processing parameters have been discussed by using draw and rotary extrusion manufacture the Al-Cu composite bars;and then,the effect of heat treatment on properties and microstructure of Al-Cu draw bars has been researched.The experimental results show that,the designed draw-off gear and draw mould can composite Al-Cu bars.Different dimension stock Al-Cu composite bars,which were processed with surface treatment—spinning—front-end—spinning—rear-end—draw—diffusion annealing,have well structural properties and high surface quality.The analysis of draw composite process parameters shows that,the drawing load generally has a rising trend as the drawing speed increasing.Increasing amount of deformation can lead to the drawing load increasing,the bonding strength of aluminum and copper composite and diffusion degree can be advanced.The influences of wall thickness of copper pipe on the draw composite process of Al-Cu are different.The thicker wall thickness isn't beneficial to the draw composite formation and the thinner wall thickness can lead to draw flaw.The optimum wall thickness of copper pipe selected is 0.6mm.During the low-temperature diffusion annealing stage,the bonding strength of aluminum-copper interface increases at first and then decreases as the temperature and time increasing.The biggest peeling strength can achieve 15.2kNm^-1.After the morphology observation and composition analysis,the combining interface gradually changes from ductile fracture into brittle fracture according to the morphology observation and composition analysis of combined interface.Therefore,the best process of low-temperature annealing is in 250～350℃for 1～2 hours.During the high-temperature diffusion annealing stage,the bonding strength of aluminum-copper interface decreased gradually as the temperature and time increasing.The high-temperrature diffusion annealing is in 300～350℃.The largest bonding strength is 11.8kNm^-1.After the component analysis and morphology observation analysis,it can be seen that Al and Cu atoms diffuses quickly during the high-temperature stage and the morphology formed is completely different from morphology of the low-temperature annealing.And,the forming speed of the intermetallic compound increases that decreases the bonding strength.Therefore,the best high-temperature annealing process is the 560～580℃for 3～6 min.