OpenSCAD User Manual/CSG Export
The CSG Format is a subset of the OpenSCAD file format.
Being a subset, CSG is much easier to read/interpret for other CAD software, then a direct OpenSCAD File.
Currently, Freecad can import CSG, but it does not support the full format.
Using Freecad, OpenSCAD files can be converted into step files. (Off-course, the limitations of the Freecad import has to be kept in mind, when using Freecad as a converter)