Like other alloys, titanium alloys consist of a mixture of chemical elements. They are characterized by a very high tensile strength, toughness and corrosion resistance. In Addition, titanium alloys are able to resist extremely high temperatures of up to 760° C (1400 °C) and are density low compared to steel and other superalloys. Therefore, titanium alloys are comparably light. However, on the other hand, these advantages are offset by high production and material costs.
Pure titanium exist in form of β-phase at temperatures above 885 °C (1625 °F) and in form of α-phase at temperatures below 885 °C. The alloying elements may either stabilize the α- or β-phase. Alloys that stabilize α-phase include aluminium, oxygen and nitrogen. Molybdenum, tungsten and tantalum stabilize β-phase.
Annealing is a heat treatment process. The main goal of the procedure is to alter the microstructure and therefore the physical and chemical properties of metals. In steels, annealing reduces hardness, and internal stresses on the one hand and increases ductility on the other. Therefore, the process makes the material more formable and workable and prevents it from brittle failure.
The hardness of a material is the quality of being able to withstand localized permanent or plastic deformation, penetration, scratching or bending. If hardness increases, so does the resistance to wear, on the one hand. However, hard materials on the other hand are hard to change in shape. Therefore, hardness is an important property of metals.
Normalizing is a heat treatment process which is used to make metal, such as steel, more ductile and tough. Thermal and mechanical hardening processes decrease ductility and increase hardness of steel parts. Therefore, normalizing can reform the microstructure into more ductile structures. This reduces the residual stress of the workpiece. Further, normalizing makes the steel more formable and machinable.