az91镁合金7075铝合金异种金属扩散焊的分析word格式论文.docxVIP

太原理工大学研、 l 研究生学位;在文RESEARCH ON DIFFUSION BONDll斗 G TECHNOLOGY OF AZ9J b也I\GNESIUM ALLOY /7075 ALUMINl爪-1 ALLOY DISSIMILAR MATERlALABSTRACTBoth aluminum alloy and magnesium alloy has some superior perforrnance such as high specific stiffness and specific streng巾， high dimcnsional stability， and damping shock absorption and so on. So it has extremely important value in the fields of automotive，electronics and communications products ，chemicals ， machinery，aviation ，and so on. However，the Jow meJting point of magnesium ， and the higher linear expansion coefficient and thermal conductivity makes it easy to form welding cracks，holes and other issues，which make the HAZ of thejoint to be too broad ，and easy to defOlm after welding，and other defects. Basedon the characteristics of fusion welding of magnesium alloy，soJid-phase connection has been becoming one of the hot topics of researches. Research shows that using the vacuum diffusion welding to connect the dissimilar metals of magnesium alloy and aluminum alloy can effectively reduce the aboveproblems. By vacuum di ffusion welding ，this paper achieves connections ofAZ91 magnesium alloy and 7075 aluminum alloy. The microstructure of the diffusion dissolution Jayer and the mechanical properties of joints are analyzed. Then the best diffusion welding process parameters are obtained.Firstly，tbe annealing recrystallization method is used to obtain fine-grainedAZ91 magnesium a1loy. So it can provide a better basis for the welding parent metal. The results show that the static recovery and recrystallization which occurs at the annealing process can significantly refine the grain，and the grain size firstly decreases and then increases witb a rise of tbe annealing temperatureJII‘〉à原理止 大学硕士研究生学位论文and an extension of the annealing time. Then a annealing treatment is done on the conditi on of temperature of 300 oC and holding time of 30 min to obtain the average grain size of 10.64μm recrystallizat ion，and grai n refine