There is no way to actually determine between types of steel visually. Industries that require specific grades of steel use instrumentation to analyze the material to be able to confirm the exact type of alloy in order to make certain the wrong alloy is not used for a job that requires a specific alloy.
Automated Hyperspectral Logging. The successful development of iron ore resources is fundamentally linked to our ability to accurately identify not only multiple species of iron oxide minerals, but also sub-species, phases (eg. ochreous vs. hard) and associated gangue minerologies.