An alloy of iron and carbon is called steel. However, not every type of steel is suitable for every application. A safety component in a machine or car has different requirements than a knob of a kitchen cabinet. To make steel suitable for high-quality applications, it is alloyed. A steel is alloyed when it contains between 1.5% and 5% of alloys (excluding carbon).
By a combination of chemical elements, production process, and heat treatment, steel is made “higher quality”; so-called alloying. According to the “stahlschlussel”, hundreds of types of alloyed steel are standardized, each with its unique properties and applications.
Alloying, however, is different from refining. Refining of steel is the changing of mechanical values (Rm, Re, and elongation) while maintaining the chemical analysis. Refining of steel is done through temperature (ovens) or through electricity (induction). By achieving an optimum of temperature, time, and cooling speed, the values are brought within the desired range.
Common refining notations are:
Scroll horizontally in the table to see everything
||Annealed with "spheroidized carbides", for example for ball bearing steel
||Quenching and tempering
Note: if an alloyed steel is indicated with +AR (as rolled), no refining has taken place.