It should be quite possible to convert SolidWorks assembly files (.sldasm) to STEP format (.stp, .step). Some programs are able to disassembly files to parts automatically whilst with other you will need to do it before you can perform sldasm to step conversion.
Open SLDASM file Open STEP fileA CAD viewer program with conversion capabilities
A set of 3D modeling tools
A CAD converter with huge format support
A CAD visualizaton, analyzation and translating system
A dedicated CAD converter