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STEEL is an alloy of iron with carbon (up to 2.14%) and associated elements (Mn, Si, P, S, Cu), which entered the steel in production. In addition to these accompanying elements contain some steel elements intentionally added, the additive elements such as Cr, W, Mo, V, Ni, etc. for the production of steel fasteners - maximum of 1.5% C.

 

Unalloyed and Low-carbon steel

According to DIN 17 111 with C content less than 22% are consumed in the production of nuts and bolts of lower strength classes.

carbon steel according to DIN 1654 steel for cold forming, DIN 17200 steel for quenching and tempering, DIN 17210 steel hardening. They can be divided into three groups:

Quality contant of C…0,35%, P and S…max. 0,045%
High quality contant of C…0,35%, P a S…max. 0,035%
The cold forming contant of C…0,35%, P a S…max. 0,035%, have special characteristics for cold forming.

Unalloyed and Low-carbon steel

According to DIN 1654 steel for cold forming, DIN 17200 Steel for case-hardening and tempering, DIN 17210 Steel for carburizing. In this group of steels, the percentage of contained elements (which are normally found in harmful percentage representation, or some unnecessarily included, others are missing), and adjusts to achieve the characteristic features: excellent mechanical properties, better corrosion resistance and resistance to high or low temperatures.

  • Carbon (C): is the most important component - primarily affects the mechanical properties. For the production of fasteners is used the maximum amount of 0.5%. With increasing carbon content increases strength but reduces ductility by cold. Steel with carbon content from 0.3% can be further refined.
  • Nickel (Ni): Increases case-hardenability, resistance to low temperatures, antimagnetic resistance. The combination of at least 8% Ni with 18% Cr get the austenitic form of stainless steel in quality A2.
  • Chromium (Cr): Also increases resistance and strength. The minimum amount is 12.5% ​​in order to be classed as stainless steel.

Molybdeum (Mo): increases strength while reducing the tempering fragility. When is  added to the 2-3% Mo steel alloy with chromium content of 18% and 12% Ni, thereby sharply increasing the resistance to corrosion. This type of austenitic stainless steel is called A4.

Manganese (Mn): occurs as Si, P, S, mostly as an impurity. Adding Mn to increase strength, wear resistance, but the steel becomes brittle during tempering.

Titanium (Ti): is used in the form of carbide against intergranular corrosion of stainless steels. Elements such as niobium (Nb) and tantalum (Ta) cause the same effect.

Boron (B): is an innovation in production technology for steel fasteners. Only a very small amount (.002 to .003%) had improved hardening. Application of boron treated steel is still popular in the production of fasteners formed hot and cold.

Steel case-hardening

It is used for highly stressed components in the section on the surface. They contain a relatively low percentage of carbon (C from 0.06 to 0.2%), which is added during heat treatment. Core strength is relatively low, but high toughness. Cemented layer hardness after hardening and tempering is HRC = 62nd This type of steel used in the production of self-tapping screws, tapping screws, universal screws, etc.

Stainless steel

viz. Chemical composition of the material
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