What material are shackles for most overhead lifting made of for increased toughness?

Shackles used for most overhead lifting are commonly made of forged steel because this material offers superior toughness, strength, and durability compared to other materials. Forged steel is created through a process that involves heating the steel above its recrystallization temperature and then shaping it through deformation, which leads to a refined grain structure. This results in a tougher and more reliable component that can withstand the stresses and strains associated with lifting heavy loads.

The use of forged steel ensures that shackles maintain their integrity under significant load and impact forces, making them suitable for demanding rigging applications. Their high tensile strength makes them less likely to deform or break, providing a safer option for overhead lifting tasks. Moreover, forged steel shackles often come with safety factors and ratings that help to ensure they are adequate for the intended lifting purposes.