What is the degree of hardness of bolt?
The hardness of bolts and nuts (in English: hardness) is one of the important characteristics of all types of bolts and nuts, which is very effective in their application. The degree of hardness of bolts and nuts refers to the degree of resistance of these parts against deformation under applied forces, especially tensile and compressive forces. This factor is determined based on special standards that are specified internationally, and is displayed with specific numbers that, as mentioned, express the tolerance of this tool against deformation and breaking. Different grades are categorized. Each of these grades has a specific hardness range that makes them suitable for specific applications.
Table
The range of hardness of bolts and nuts are measured and determined based on certain methods. The following three methods are used to determine the degree of hardness of bolts and nuts:
Vickers hardness
Brinell hardness
Rockwell Hardness
Factors affecting the amount of bolt hardness
Hardness is one of the characteristics that mostly depends on the materials used in bolts and nuts, but this hardness can be increased or decreased by adding metals or non-metals depending on its application in certain processes. In general, the following items are effective in the degree of fatigue of bolts and nuts.
Bolt
The type and amount of materials used in the preparation of various types of bolts and nuts determine their hardness. Different materials such as carbon steel, stainless steel, titanium and special alloys each have different hardness characteristics that are used in the construction of these parts and are used for different applications. For example, steel is harder than iron, which is why it is used to make bolts and nuts that require high hardness.
Bolt
By performing processes on bolts and nuts, especially during their manufacture, their hardness can be increased or decreased. Manufacturing methods such as cold or hot forging, rolling and heat treatment can affect the structure and hardness of bolts and nuts. These processes are carried out in the workshops of manufacturing these parts and in large furnaces with a very high heat degree, which, of course, cool them in some ways. Also, in the quality control laboratories after manufacturing, they are fully checked so that the standards required in their manufacturing have been met.
The degree of hardness of bolts
The degree of hardness of all types of bolts and nuts has a direct relationship with their higher grade. This means that grade 2 is the softest and the top grades like 12 are the hardest. Of course, among the hardest bolts and nuts, grade 8 is more useful and its use is more common. In general, grades 2, 5 and 8 are the most famous among the bolts and nuts widely used in various industries and for home use.
Hardness of grade 2 bolts and nuts: Grade 2 is one of the most common and economical types of steel bolts. These screws are usually unmarked and manufactured from low or medium quality steel and are widely used in general projects due to their lower cost.
Grade 5 bolt and nut hardness: Grade 5 bolts are made of medium carbon steel and are subjected to neutral and thermal processes to improve their strength. These screws are common in the automotive industry and are widely used due to their favorable resistance. Grade 5 screws usually have three evenly spaced radial lines on their heads, making them easy to identify.
Grade 8 Bolt and Nut Hardness: This grade of bolts is also produced from medium carbon alloy steel and is used in applications such as car suspension systems due to its high strength. Class 8 bolts are easily identified by having six evenly spaced radial lines on their heads.
