Friction stir processing and post process artificial ageing was successfully carried out on AA7075 with and without reinforcement of SiC particles producing defect free processed zone with uniform distribution of fill...Friction stir processing and post process artificial ageing was successfully carried out on AA7075 with and without reinforcement of SiC particles producing defect free processed zone with uniform distribution of filler material.Effect of SiC particle reinforcement and artificial ageing times on the microstructural modifications was characterized using optical and electron microscopy,electron backscattered diffraction and X-Ray diffraction.Hardness,impact and wear tests were carried out to investigate mechanical behaviour before and after processing.Reinforcement of SiC particles during FSP and subsequent age hardening treatment brought about nearly twofold increase in hardness and impact toughness values by the combined effect of grain refinement,Zener pinning,dispersion strengthening and precipitation hardening.Significant improvement in wear resistance in terms of wear loss was also observed after processing compared to the reference material AA7075-T6.Fractured surface of post FSP age hardened AA7075 alloy exhibited features of ductile fracture during Charpy impact test.展开更多
First the architecture of the integrated CAD/CAM system developed for machining large scale steel-concrete girders using I-DEAS and other developing tools are introduced; then the involved technologies in the developm...First the architecture of the integrated CAD/CAM system developed for machining large scale steel-concrete girders using I-DEAS and other developing tools are introduced; then the involved technologies in the development of the system are presented, which include the method for determining the position and orientation of the manufacturing features, the method for geometrical modeling of the girders, the techniques for generating the toolpaths for the 5-axis machining centers, the generative process planning technique and the postprocssing technique for the specific machines etc. Moreover some related special technical issues are also discussed. The CAD/CAM system is a network-based workshop-oriented manufacturing system, in which every machining cell can work independently serving two machining lines. The cell server take charge of the management of work schedules, personnel, machining resources, databases etc. the control computer serves to monitor the whole manufacturing lines, to arrange tasks, and to communicate; the two CAD/CAM workstations’ work is to model the girders using the CAD data, to plan the process and to generate the NC programs. The CL files that describe the toolpaths generated are ATP-format files. In order to translate them into NC codes that can be directly used by the 5-axis machining centers, a specific postprocessing program is developed for these distinct machines. The system has been successfully realized and applied in Shanghai Maglev Transrapid project. In the developing process, the following technical problems are solved: 1. Algorithms for measuring, positioning, and machining complex objects. 2. Methods for Modeling. 3. Animation and postprocess techniques for 5-axis machining centers. 4. Technologies for machining large-scale concrete-steel structures Although further evolution is needed for this system, the facts have proven its performance satisfactory and the technologies and the methods developed suitable.展开更多
基金The authors would like to acknowledge National Facility for Texture and OIM(A DST-IRPHA project),IIT Mumbai for XRD and EBSD measurements.One of the authors VDH would like to acknowledge Science and Engineering Research Board(SERB)for financial assistance(EEQ/2016/000422)to carry out project work.
文摘Friction stir processing and post process artificial ageing was successfully carried out on AA7075 with and without reinforcement of SiC particles producing defect free processed zone with uniform distribution of filler material.Effect of SiC particle reinforcement and artificial ageing times on the microstructural modifications was characterized using optical and electron microscopy,electron backscattered diffraction and X-Ray diffraction.Hardness,impact and wear tests were carried out to investigate mechanical behaviour before and after processing.Reinforcement of SiC particles during FSP and subsequent age hardening treatment brought about nearly twofold increase in hardness and impact toughness values by the combined effect of grain refinement,Zener pinning,dispersion strengthening and precipitation hardening.Significant improvement in wear resistance in terms of wear loss was also observed after processing compared to the reference material AA7075-T6.Fractured surface of post FSP age hardened AA7075 alloy exhibited features of ductile fracture during Charpy impact test.
文摘First the architecture of the integrated CAD/CAM system developed for machining large scale steel-concrete girders using I-DEAS and other developing tools are introduced; then the involved technologies in the development of the system are presented, which include the method for determining the position and orientation of the manufacturing features, the method for geometrical modeling of the girders, the techniques for generating the toolpaths for the 5-axis machining centers, the generative process planning technique and the postprocssing technique for the specific machines etc. Moreover some related special technical issues are also discussed. The CAD/CAM system is a network-based workshop-oriented manufacturing system, in which every machining cell can work independently serving two machining lines. The cell server take charge of the management of work schedules, personnel, machining resources, databases etc. the control computer serves to monitor the whole manufacturing lines, to arrange tasks, and to communicate; the two CAD/CAM workstations’ work is to model the girders using the CAD data, to plan the process and to generate the NC programs. The CL files that describe the toolpaths generated are ATP-format files. In order to translate them into NC codes that can be directly used by the 5-axis machining centers, a specific postprocessing program is developed for these distinct machines. The system has been successfully realized and applied in Shanghai Maglev Transrapid project. In the developing process, the following technical problems are solved: 1. Algorithms for measuring, positioning, and machining complex objects. 2. Methods for Modeling. 3. Animation and postprocess techniques for 5-axis machining centers. 4. Technologies for machining large-scale concrete-steel structures Although further evolution is needed for this system, the facts have proven its performance satisfactory and the technologies and the methods developed suitable.
