Chromium is dissolved in γ iron to about 12% in the austenite with the content of about 0.5% carbon - 20%.
In the α iron solubility is unlimited, but below the temperature of 815% in the limits of 25-75%. The addition of
chromium (depending on quantity) gives the steel hardness, corrosion resistance, heat resistance, resistance to
organic acids, improves hardenability. High carbon steels with a carbon content of 1-1.5%
and 3-4% chromium, are have a very high hardness. Steels with chromium contents up to 12% are not resistant to corrosion,
but are resistant to higher temperatures. Steels with the content of 12-17% Cr are characterized by high hardness,
abrasion resistance, good resistance to corrosion, are not resistant to acids. Steels with the content of 17-27% chromium
are characterized by heat resistance and acid resistance. Chromium wolframic steel is used for making fast cutting tools,
the low chromium alloy with the addition of vanadium are very hard, durable and resilient, the addition of nickel and vanadium
to chromium steel makes it very resistant to corrosion, high resistant and plastic, and in combination with nickel and molybdenum
is has even better heat resistance. Chromium is an essential alloying addition to stainless steel ( stainless steel, INOX)
heat-resistant steel and creep steel.
Chrome - atomic number 24, atomic weight 51.996 melting point 1800 ° C, boiling point 2300 ° C,
density of 7.188 g / cm 3 (Encyclopedia of Technology, Publishing House "Silesia")
In the late eighteenth and early nineteenth century in Europe there was a very famous chemical laboratory in Paris that belonged to
the pharmacist and chemist Louis Nicolas Vauquelina (1763 1829). Once a shipment was sent to the laboratory from Russia,
containing reddish red mineral from the mine Jekaterynbura. The first analysis showed the content of lead, iron and aluminum
compounds. The result however was not very satisfactory for the Russians. In 1787, Vauquelin conducted another analysis.
Vauquelin was intrigued by a yellow solution which was obtained in the analysis. After numerous tests and experiments, that took
almost a year finally brought the solution to form a pure oxide (CrO). Antoine François, Count de Fourcroy (1755 -1809), a famous
French chemist who first introduced the principle of chemical vocabulary, called new metal chromium, from the Greek word chroma-hue.
Chromium metal was turned out to be significant for the technique, mostly as an alloying addition to steel. Chrome steel production
was introduced in France in 1877, and in Germany in 1880. A great importance in metallurgy had the invention of methods of receiving
ferrochromium. In 1860 in Styria a high-chromium pig iron form a big furnace was obtained. Ferroalloy is a metallurgic resource-rich
in alloy components, which are used for the receiving of steel and cast iron alloy. Chromium gives the steel high hardness, corrosion
resistance and increases durability. Most popular stainless steels contain up to 27% chromium. They are used in knives, instruments,
parts of scientific apparatus production. Steels with chromium contents less than 12% are not resistant to corrosion at all.
In the industry very common is so-called chromium plating, which is covering metal objects with a thin layer of solutions containing
chromium salts and chromic acid. In metallurgy more than 80% of chromium production is used for alloy steels production.
Mineral from Swieradłów, from which Franuz Vauquelin received chromium first, then did not play any significant role in metallurgy.
Nowadays chrome is obtained only from one mineral, which is called chromite FeO. Cr 2 O 2.
In the late eighteenth and early nineteenth century in Europe there was a very famous chemical laboratory in Paris that belonged to the pharmacist and chemist Louis Nicolas Vauquelina (1763 1829). Once a shipment was sent to the laboratory from Russia, containing reddish red mineral from the mine Jekaterynbura. The first analysis showed the content of lead, iron and aluminum compounds. The result however was not very satisfactory for the Russians. In 1787, Vauquelin conducted another analysis. Vauquelin was intrigued by a yellow solution which was obtained in the analysis. After numerous tests and experiments, that took almost a year finally brought the solution to form a pure oxide (CrO). Antoine François, Count de Fourcroy (1755 -1809), a famous French chemist who first introduced the principle of chemical vocabulary, called new metal chromium, from the Greek word chroma-hue.
