Conversion of 3D models from STEP format (.stp, .step) to a 3D ACIS model (.sat) should be possible in many CAD/3D modeling programs or some specially designed conversion utilities. Many CAD/3D modeling tools support it, so just pick one from the list below, all should support step to sat conversion.
Open STEP file Open SAT fileA set of 3D modeling tools
A converter for 3D formats
A CAD conversion software