Manufacture of a β-titanium hollow shaft by incremental forming
Excellent mechanical properties and corrosion resistance combined with low weight qualify β-titanium materials for lightweight applications in aviation, automotive and energy engineering. Thus far, actual applications of these materials have been limited due to high material costs and limited processing knowledge. One approach for developing resource-efficient manufacturing methods is the application of incremental forming methods. This article focuses on the development of the incremental spin extrusion process, which creates hollow profiles from solid bars. This method allows hollow shape manufacturing with a much higher flexibility than other forming methods and a significantly improved material utilization in comparison to machining methods, such as deep hole drilling. Beta-titanium alloys basically have very good cold forming suitability and the resulting material properties can be controlled. The application of incremental forming methods with high hydrostatic compressive stress is a promising manufacturing approach. The β-titanium Ti-10V-2Fe-3Al material has an excellent combination of the properties strength, ductility and fatigue strength. In order to utilize these properties the forming conditions and the temperature control need to be optimized. The investigations show that the Ti-10V-2Fe-3Al material can be formed only in a narrow semi-hot forming temperature window. The paper describes the investigation and presents results on the design of partial forming process sequences, forming properties, microstructure formation and failure prevention. The process design objective is a very fine microstructure with a homogeneous secondary α-phase and very small grained β-phase.
Titanium: A Technical Guide
Designed to support the need of engineering, management, and other professionals for information on titanium by providing an overview of the major topics, this book provides a concise summary of the most useful information required to understand titanium and its alloys. The author provides a review of the significant features of the metallurgy and application of titanium and its alloys. All technical aspects of the use of titanium are covered, with sufficient metals property data for most users. Because of its unique density, corrosion resistance, and relative strength advantages over competing materials such as aluminum, steels, and superalloys, titanium has found a niche in many industries. Much of this use has occurred through military research, and subsequent applications in aircraft, of gas turbine engines, although more recent use features replacement joints, golf clubs, and bicycles. Contents include: A primer on titanium and its alloys, Introduction to selection of titanium alloys, Understanding titanium's metallurgy and mill products, Forging and forming, Castings, Powder metallurgy, Heat treating, Joining technology and practice, Machining, Cleaning and finishing, Structure/processing/property relationships, Corrosion resistance, Advanced alloys and future directions, Appendices: Summary table of titanium alloys, Titanium alloy datasheets, Cross-reference to titanium alloys, Listing of selected specification and standardization organizations, Selected manufacturers, suppliers, services, Corrosion data, Machining data.
Ignition and burning rates of segregated waste combustion in packed beds.
Recent developments in national recycling and re-use programmes for municipal waste have led to segregation of an increasing proportion of waste to enhance material recovery. Several of the segregated streams contain materials that can not viably be re-used or recycled but can be used for energy recovery. In this study, the combustion of cardboard and waste wood was investigated in a small-scale packed bed reactor in order to provide fundamental data for the design/operation of moving bed furnaces. Key parameters of combustion including the ignition and burning rates were evaluated for various air flowrates and compared to the modelling results. Two successive stages of combustion were identified for both samples: the propagation of ignition front into the bed and combustion of the fuel above the ignition front. The burning rate of cardboard reached a peak of about 300 kg/m(2)h at the air flowrate of 936 kg/m(2)h and decreased at higher air flowrates. For waste wood, both the ignition and burning rates increased in the tested range of the air flowrate up to 702 kg/m(2)h, of which the values were very close to those for the cardboard. The model prediction was in good agreement with the test results for waste wood. However, the burning rate for cardboard was under-predicted due to strongly irregular shapes of the fuel.