| In recent years, moderate grain refinement become a research hotspot in the international area which is an effective mean to improve material properties. Studies show that when the grain refined to lμm, the material will show a series of unusual physical and chemical properties. There are many methods to prepare fine grain materials. Large, bulk, high density materials can be prepared by cumulative clad rolling technology which is the most promising technology in industrialization zone and it's advantages with simple process and low cost has attracted much attention.Firstly, the purpose of this study was to analyze the rolling process parameters of 6063Al/AZ31/6063Al three-layer structure material prepared by clad rolling. The results of this study provided basis for preparing 6063Al/MB2/6063Al fine multi-layer structure clad material by ARB. Experimental results show that clad materials prepared under rolling process of from 300℃to 350℃and 50% to 60% meet the needs of further accumulative rolling.Secondly, the three-layer clad materials were treated with different heat treatment and then analyze the impact on the interface structure and properties. The results showed that, (1) High temperature and long heat preservation time has significant influence to interface structure and mechanical properties of the clad materials. (2) When heat preservation time is less than 10min, the materials had better thermal stability and overall properties, and the organization did not change significantly for the short time.Again, the rolling rule of three-layer structure clad materials were studied. One of the purpose was to provide the basis for selecting material thickness ratio for the ARB. The other one was to analysis if the interfacial bonding was enhanced after repeated rolling. The results show that,(1) The thickness of the metal clad layers were reduced proportionally with the increase of deformation and the gap of the thickness decreased. (2) Original compound interface can occur plastic deformation further by repeat rolling, so that the interface bonding strength increased.Finally, based on the above exploratory experiments, 6063Al/MB2/6063Al fine grain multi-layer structure clad materials were prepared by ARB to analysis the change of microstructure and properties after ARB and the influence of heat treatment on microstructure and properties of each pass. Results show that (1) Clad materials can be roll 5 times effectively by ARB technology under 350℃×10min×50% process. (2) ARB technology can refine organization effectively. The grain size of MB2 layer after ARB2 passed was least which was refined from about 16μm to 2μm. The grain size of Al layer after ARB5 passed was least which was refined from about 45μm to 0.8μm. (3) The overall mechanical properties of the clad materials were good after ARB process and the tensile strength and elongation were 192.5MPa and 18.64% respectively in the ARB2 pass which were the highest. (4) Heating treatment at temperature below 220℃for 60min, the organization of each pass had better thermal stability and the sample of each pass had higher tensile strength compared with normal temperature. Heating treatment at temperature above 220℃for 60min, the organization of each pass had grown gradually and tensile strength of each pass declined gradually with temperature increased. (5) In the same heat treatment temperature, heating time had different effects on tensile strength with difference pass. The higher the pass, the more significant the time on the strength and the bigger gap the tensile strength under heat treatment at different times. |
