A while ago I tried to find out how to convert a .STEP file to a format that I could use in Blender and I noticed some people didn't think it was possible and some others gave links to blender addons that had no working free versions. That's why below I will tell anyone looking for the information I was previously after as simply as possible.
There is a free program you can get called CAD exchanger, it's the only option I have found that actually works. You just put in your file and it allows conversion to many useful formats. I've found that collada works best for Blender, as the obj was blank when I tried it.