**5. Applications of CO2 MWF Strategies**

The following work has been categorised according to the workpiece materials that are considered in a given article, such that the first section focuses upon the use of CO2 MWFs for the machining of steels, the second section focuses upon titanium alloys and the third considers any other material species that have been the subject of research. The order is of materials is chosen to be coincident with the volume of research that is available on a given material, wherein steels and titanium alloys are subject to the most research in the field. In addition to the research outlined in Sections 5.1–5.3, there are a small number of articles that consider multiple materials [20–22]. As these articles serve as important case studies for use in determining the relative cryogenic machinability of a given material (and do not easily fit into the proceeding sections), they are retained for Section 6.
