What can indicate that a chain or hook has been affected by heat?

A change in color is a significant indicator that a chain or hook has been affected by heat. When materials such as steel are exposed to high temperatures, they can undergo a process known as tempering, where the color may shift to shades of blue, purple, or even yellow, indicating that the metal has been compromised. This color change is a result of oxidation and offers a visual cue that the integrity of the material may be impaired, potentially leading to failure under load.

While rusted appearance, minor kinks, and increased flexibility may suggest other types of wear or damage, they do not specifically relate to heat exposure. Rusting is associated with corrosion, kinks indicate physical deformation, and increased flexibility can suggest strain or wear from usage rather than thermal effects. Therefore, monitoring for color changes is a more direct way to assess whether a chain or hook has been adversely impacted by heat.