To begin...
We are confronted with it every day in our sector. More and more people are aware of the different materials in circulation. In our world of safe hoisting, it is also becoming apparent which materials can and cannot be used.
For attachment materials such as chains, eye bolts, load hooks, etc., it is actually very simple. Under normal temperatures and conditions, Grade 8 or Grade 10 materials should be used as a minimum. This is for the simple reason that these materials fall under the heading of “non-aging steel”. In other words, Grade 8 and 10 materials are not subject to metal fatigue. By itself, this provides greater operational safety, but that's not all.
Technically speaking
Grade 8 was developed in 1970 as a new type of steel consisting of an alloy of Cr-Ni-Mo, which is hardened and stress-free. To designate the composition as Grade 8, at least 2 of the 3 metals must be present in a fixed percentage.
The term ‘Grade’ describes the nominal breaking stress of the material, expressed in Newtons per mm2. Grade 8 is therefore 800 N/mm2
Expectations for this steel are high. It can be assumed that this steel retains its strength and toughness due to the specific heat treatment. Fatigue is the keyword here. The parts must undergo fatigue tests consisting of 20,000 cycles under their rated load before they can be branded as Grade 8.
Grade 10
More than 30 years later, Grade 10 was developed as the logical successor to Grade 8. The technology had evolved so much that it became possible to obtain no less than 25% more hoisting capacity with the same diameter. This means, the user has 25% more hoisting capacity with the same chain diameter, thanks to the introduction of Grade 10.
The German Berufsgenossenschaften (BG) compiled a list of specifications for all Grade 10 components. Gunnebo's GrabiQ line was then approved under these new specifications. Gunnebo was one of the first companies in the world to meet these criteria, and has since then offered all its GrabiQ parts with Grade 10.
However, you must always pay attention! Some traders offer eyebolts or nuts for sale according to DIN 580 and DIN 582 claiming they are manufactured from 8.8. This gives the buyer the impression that this is the same as Grade 8. Nothing could be further from the truth. Only products branded Grade 8 because they meet the requirements may be sold under this name.
In 2020, Grade 12 has made an appearance. And we are certainly looking forward to further developments!