You can open STEP files with any txt editor and see the code. It contains the information only about geometry (vectors, edges ...) It means that there is no direct way of getting any other properties from STEP files
I had looked at the contents and the AP203 versions seems to have some non geometric metadata, albeit uninitialized, eg
#24 = APPROVAL_DATE_TIME ( #113, #251 ) ;
#25 = CALENDAR_DATE ( 2016, 4, 8 ) ;
#26 = PRODUCT ( 'SAMPLE PLATE AP203', 'SAMPLE PLATE AP203', '', ( #2 ) ) ;
#27 = EDGE_CURVE ( 'NONE', #35, #43, #219, .T. ) ;
#28 = PERSON_AND_ORGANIZATION ( #299, #349 ) ;
#29 = ADVANCED_FACE ( 'NONE', ( #380 ), #243, .F. ) ;
#30 = APPROVAL_PERSON_ORGANIZATION ( #28, #251, #355 ) ;
#31 = COORDINATED_UNIVERSAL_TIME_OFFSET ( 12, 0, .AHEAD. ) ;
#32 = LOCAL_TIME ( 9, 29, 54.00000000000000000, #31 ) ;
#33 = ORIENTED_EDGE ( 'NONE', *, *, #106, .F. ) ;
...while the AP214 (surprisingly to me) did not. This link suggests AP214 is capable of much more than just geometry: STEP AP203 and AP214 Protocols . Anyway at its not looking hopeful.
Sorry, you were right and the metadata could be included into STEP file. However, even SolidWorks has quite a good STEP exporter, it does not write material metadata to STEP. Also SolidWorks does not have any setting to include material into exported output.
I'd suggest to find the line into the generated by SolidWorks STEP file , which is understood by CAM as a material and try to modify it with a simple macro. Macro could read the material from the model and write it to STEP output.
You could try to write with a simple macro an XML map which could contain some metadata. Or have another option is to save the models as step with file names like: FILE_MATERIAL. This could be used by a person or macro to assign material for manufacturing or other purposes.
Hope this helps
Unfortunately encoding the material in the filename is not going to work for us, as a CAM vendor we are two steps removed from the people generating the STEP files; while we could suggest "recommended settings" for STEP export specifying how to name their files would be presumptuous of us.
I'm sorry I don't understand the XML approach (I'm familiar with XML but not how Solidworks would embed it when exporting a STEP file if that's what you are suggesting?), but I suspect similar to above it might be a step too far for customers two steps removed doing STEP exports