What is the only definitive method to demonstrate actual melting of steel?

The definitive method to demonstrate actual melting of steel is through metallurgical examination. This process involves analyzing the microstructure of the steel after it has been subjected to different heat conditions. When steel melts, its crystalline structure changes, and these changes can be identified through microscopic techniques.

Metallurgical examination can reveal key features such as grain structure and phase transformations that occur during melting, which are not visible through other methods. For instance, visual inspection might allow one to observe large structural deformities but does not provide the precise analysis needed to confirm whether melting has occurred. Similarly, thermal imaging can detect changes in temperature but cannot confirm the physical state of the steel itself. Chemical analysis may determine the composition of a material, but it does not indicate whether the steel has melted or retained its solid structure. Thus, metallurgical examination is the only method that can definitively attest to the melting of steel through direct observation of its altered microstructure.