Since you are looking for a "free download," you are likely a student, a hobbyist, or a professional trying to save a buck on a standard that costs around $60 officially. Before you dive into the darker corners of the internet looking for a PDF, you need to understand exactly what this document is, why the "photographs" are its most valuable asset, and the risks involved in downloading unofficial copies.
Scribd: Contains various uploads of the ASTM E125 Reference Photographs Guide and related MPT indication charts. astm e125 reference photographs pdf free download
If your project requires 100% compliance, here is the safest route: Since you are looking for a "free download,"
Official ASTM Purchase: The standard and its associated high-resolution reference photographs (the "adjunct") are primarily available for purchase through the ASTM International Store or the ANSI Webstore. Step-by-Step Guide to Downloading the Official PDF (If
Our Recommendation: Use the free methods first (library, school, company drive). If those fail, purchase the official PDF from ASTM. But if you are a student or a hobbyist needing a visual reference, you can find educational versions of the plates by searching for "Magnetic Particle Reference Plates Severity Levels" without the stringent ASTM copyright.