Metallography plays an important role in the quality control of titanium and its alloys from the initial monitoring of the production process to the evaluation of the porosity of castings and the control of heat treatment. It also plays an important role in the research and development of titanium alloys and products.
Commercial titanium grades and alloys fall into four categories:
Non-alloy commercial pure titanium (CP)
α and near α alloys, such as Ti-6Al-2Sn-4Zr-2Mo
α-β alloy, such as Ti-6Al-4V β alloy, high in vanadium, chromium and molybdenum
At 882°C, titanium undergoes allotropy from a densely packed hexagonal structure (α) at low temperature to a body-centered cubic structure (β). This transformation can be used to produce alloys with α, β or mixed α/β microstructure and can be used with heat treatment and thermo-mechanical treatment.
Therefore, a variety of properties can be obtained by using relatively few alloy components. However, to ensure the ideal combination of microstructure and performance, tight control over the processing must be maintained. This makes metallography very important.
In the production of titanium and titanium alloys, the relationship between hot forming, heat treatment, microstructure and physical properties is very complicated. Examples of the most common microstructures of titanium are shown below. Due to its high toughness, long chips are often produced when titanium is machined or cut. Therefore, metallographic cutting using conventional alumina cutting wheels is not effective and often results in thermal damage, as shown in Figure 5.
The solution to this problem is to use a silicon carbide cutting wheel, which is specially developed for cutting titanium (e.g. 20SXX).
Cutting titanium produces a special smell that is very noticeable when cutting large or large amounts of titanium. In this case, we recommend that you connect a smoke exhaust device to the cutting machine.
