Thermomechanical processing (TMP) and strain-induced phase transformation in titanium alloys
It is generally accepted that the physical and mechanical properties of metallic materials are primarily a function of the material's composition and microstructure. These properties dictate the material's ability to achieve preferred tasks and, therefore, determine the applications of that material. The microstructure itself is affected by many parameters including but not limited to manufacturing methods and techniques. Then, a thorough understanding of a materials microstructure, including how this may be affected or manipulated during manufacturing and processing, is desirable in order to assess the material's suitability for a given application. Technical developments over recent decades, particularly in the aerospace industry, have driven development of new low density, high strength materials. In this field titanium and its alloys are particularly popular as they are able to produce high strength with low density and also offer good corrosion resistance in a wide range of environments. There is a large variety of titanium based alloys, with each having a different chemical composition and microstructure, producing a unique combination of properties, and hence a given specific family of applications to which it best suited. Despite the selection of a proper composition of Ti alloy for a certain application, the manufacturing methods and especially the controlling factors during manufacturing methods are significantly important to get desired mechanical properties from the final product. Thermomechanical processing (TMP), which is a combination of deformation and heat treatment, are among the most important industrial methods for manufacturing of different titanium parts in aerospace industry. With the increased interest in, and use of, titanium based alloys; there have been many studies concerning the thermomechanical processing and resulting microstructures. These studies have been predominately focused on development of new and novel TMP for manufacturing of high performance Ti alloys for aerospace and other industrial applications. This work refers some scientific issues on thermomechanical processing of titanium alloys. The microstructure development during TMP and different phenomenon including dynamic and static recovery and recrystallization has been explicated in detail. Also, "strain induced phase transformation" as a more complicated and powerful tool in controlling microstructure and mechanical properties during TMP of titanium alloys, has been explicit in detail.