ISO 898-2-2012 pdf free download

ISO 898-2-2012 pdf free download.Mechanical properties of fasteners made of carbon steel and alloy steel — Part 2:Nuts with specified property classes — Coarse thread and fine pitch thread
Caractérisfiques mécaniques des éléments de fixation en acier au carbone et en acier ailé — Partie 2: Ecrous de classes de qualité spécifiées — Filetages a pas gros et filetages a pas fin.
A.1 Basic design principles of nuts
A bolted joint basically consists of two workpieces, which are clamped together using an externally threaded part (bolt or screw) on one side and an internally threaded part or a nut on the other side.
An optimized bolted joint, consisting of a bolt, screw or stud of a given property class according to ISO 898-1 assembled with a regular or high nut of the mating property class according to this part of ISO 898 is able to provide a maximum preload, using the full strength of the bolt. In the case of over-tightening, the fracture occurs in the loaded threaded part of the bolt, which gives an obvious indication of a tightening failure.
Under tensile load, the fracture mode of bolt and nut assemblies corresponds to the lowest value of the following three loads:
a) thread stripping load in the nut;
b) thread stripping load In the bolt, screw or stud;
c) breaking load in the bolt, screw or stud. (Bolt breaking is the intended fracture mode of bolt and nut assemblies in case of overloading.)
These three loads mainly depend on:
— hardness, height, effective length of the full thread, diameter, pitch and thread tolerance class of the nut,
— hardness, diameter, pitch and thread tolerance class of the bolt.
Furthermore, these three loads are linked. For example, an increase of hardness of the bolt can induce an increase of the thread stripping load in the nut. The hardness also determines the functional toughness of the nut and, therefore, an upper limit is specified for each property class.
The analytical basis for the calculation of the different stripping loads has been worked out in the publication by Alexander(141. Extensive experimental tests proved Alexander’s theory through practical results. Actual studies, including FEM-based calculations, confirmed Alexander’s theory(1 51.
The three styles of nut (see 4.1) are distinguished by their heights. This gives the manufacturer for certain property classes the option of using a quench and tempering process with less material to achieve the required properties, or using more material without any additional heat treatment.ISO 898-2-2012 pdf free download.