Study On Preparing Ultra-fine Grained Construction Material

According to the phenomenon of friction interface transferring, two techniques of processing ultra-fine grain material were advanced to develop new method of preparing large bulk of ultra-fine grain material efficiently and economically. The first is the friction interface thermo-induced transfer method (FITT) for column part, and the second is the cooling friction stir processing(CFSP) for flat part. The relationship between thermo-deformation parameters and processing parameters were discussed. During the preparing course, the processing parameters were collected with computer testing system. And the effect of the processing parameters on the interface transferring velocity was studied. The ultra-fine grain samples were analyzed entirely through its appearance , metallographic structure and SEM appearance; and whose macroscopical hardness(HBS), microscopical hardness(HV), tensile capability , press capability and inflect capability were tested too. In addition, the ultra-fine grain material's damping capacity were studied as well.The results indicated: 1) The friction interface can transfer continuously and stably with the imbalance cooling thermo-induce. Ultra-fine grain column part can be prepared through it. And ultra-fine grain flat part can be obtained through jointing several ultra-fine grain strips in cooling friction stir processing 2)The refined grain size and the hardening result are mostly affected by the rotate speed, the friction press and the deformating temperature. The thermal conductivity decides the processing parameters choosing for a material, such as a sample material with low thermal conductivity need low rotate speed and high friction pressure. 3) The temperature and the deformation rate are the key factors to prepare ultra-fine grain materials. The interface transferring velocity increases with the input power directly. 4) While the processing parameters are appropriate, both of the indicated techniques can fabricate ultra-fine grain materials successfully. 5) The hardness and plasticity of the prepared ultra-fine grain materials are advanced generally; the elastic modulus is raised slightly; and the damping capacity increases 30~50 percent; however, the improvement in the intension is not distinct.