Why can the type of steel not be determined visually?

Determining the type of steel visually can be challenging because various types of steel can have similar appearances, making it difficult to distinguish between them based solely on looks. Different alloys may be treated or finished in ways that result in visually similar characteristics, such as color or texture, even though they may have different properties or compositions.

To accurately identify the type of steel, it is usually necessary to reference the service manual or other documentation, which provides specific information about the materials used in a particular vehicle or component. This ensures that the correct type of steel is recognized, which is essential for proper repair or replacement in auto body work. Relying on visual inspection alone would not guarantee the right assessment of the material, and referencing the service manual provides a reliable source for this critical information.