Ductility

Ductility – or deformability – is an important property in the lifting industry. Chains and lifting components are made from alloys that not only increase the strength of the steel, but also improve its ductility. Ductility is a key factor in the design and manufacture of lifting and hoisting equipment. A higher degree of ductility leads to greater safety. But what exactly is ductility, and why does it improve safety?

First, we'll explain tensile strength before looking at ductility. Tensile strength is the maximum mechanical load a material can withstand. Once this limit is reached, the material – in this case steel – will begin to neck and eventually break. The stronger the material, the more load it can withstand.

For example, Grade 80 refers to a type of steel made from an alloy of chromium, nickel and molybdenum (Cr-Ni-Mo), which is hardened and stress-relieved. During tempering, internal stresses are reduced, and the hardness is carefully lowered to improve ductility and impact resistance. This also reduces the risk of brittleness, such as stress corrosion and hydrogen embrittlement. The term "Grade" indicates the nominal breaking strength of the material, expressed in Newtons per mm². For Grade 80, this is 800 N/mm².

Naturally, you don’t want a chain to snap in two the moment its maximum tensile strength is exceeded. To prevent this, the deformation (ductility) of the material is important. Ductility is the ability a metal has to deform under tensile stress. Ductile metals can, for example, be drawn into a wire when put under tension.

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