Metal, steel, iron - these are terms that are nowadays mostly used as synonyms, both in everyday life and in business communication. The prevailing view is that all rusty products are automatically defined as iron, and when see shiny subjects with the smooth surface, then we're talking about metals. ...
So today we have hardware stores - stores that sell iron and iron processing tools. They sell various "iron" products such as metal screws, bolts, metal rods and profiles, and other metal products. They usually assort cutting discs for metal, drills for metal, metal keys and screwdrivers etc. in group of tools for processing iron. In fact, most of these products are actually made from steel, and it would be more appropriate to name them steel products.
Is it really that important? Is there a difference between metal, steel and iron?
The answer is short and clear: Yes, there is a difference.
What is the difference between metal and iron?
To determine the differences, it is best to start with the basic definition of each of these terms.
Metal is every pure chemical element which has an outstanding electrical and thermal conductivity because of the way its atoms are connected (metal bond). Most metals can be found in the solid state in nature, except mercury which is liquid. They usualy have opaque and glossy surface. They have good mechanical properties, and can be bent, stretched, rolled and fused. In the periodic table of elements, metals cover two thirds of all known chemical elements.
Metals are divided according to the resistance to oxidation (corrosion):
precious metals (do not corrode) - gold (Au), silver (Ag), platinum (Pt)
Semi-metals (in contact with air form a thin protective layer that prevents corrosion) - aluminum (Al), lead (Pb), copper (Cu)
basic metals (exposed to air and moisture can corrode and deteriorate)
Iron is a natural element which has a silvery sheen in its pure state, is relatively soft, and its symbol is Fe (lat. Ferrum). Due to its chemical reactivity, in nature can be found mainly in the mineral admixtures with other elements. It is estimated that its share in the Earth's crust is about 6.2%, which ranks it in fourth place, just behind the oxygen (O), silicon (Si) and aluminum (Al). It is good conducter of electricity and heat. It also has ferromagnetic properties, which means that it can take the magnetic properties when exposed to the source of magnetism. Exposed to air and moisture it corrodes easily. Therefore it belongs to the group of basic metals.
Since iron is a metal, it is difficult to clearly draw the line metal and iron.
Simply put, iron is a metal, but the metal is not only iron.
What is the difference between iron and steel?
Definition of steel to the European standard EN 10020, which defines and classifies types of steel:
Steel is a material in which the weight ratio of iron is higher from any other base part, and should contain up to 2% carbon. The limit of 2% of carbon was agreed boundary that differentiates steel from cast iron. Simply, the steel is alloy of iron, carbon and other alloying elements.
Proportion of iron in steel ranges from 87% to 99%. Regarding the fact that the proportion of carbon and other alloying elements drastically change the basic properties of iron, regardless of the total mass fraction, the final material is not iron. The greatest differences between steel from iron is in its mechanical characteristics. Steel is a very strong material can be corrosion resistant (stainless steel), more or less electrically conductive (transformer steel), non-magnetic, resistant to high temperatures, etc.
Iron and carbon are both integral parts of steel, but because of differences in the chemical composition and mechanical properties neither steel is not iron, nor iron can not be treated as steel.
What is the difference between metal and steel?
Steel is the material that is often good conductor of electricity and heat. Steel surface can be smooth with gray-bluish glow. Some types of steel corrode easily, while others form a protective oxide layer as well as the semi-metals. Steel, therefore, has all the properties that can be defined as metal.
Then why steel is not a metal?
Steel is not a pure chemical element, but it is an alloy of two or more other chemical elements, therefore it can not be defined as a metal, neither added to the periodic table of elements. Besides it contains carbon and other non-metallic impurities which also excludes it from the group of metals.
Steel is a material with the properties of a metal, but it is not a metal.
We can conclude that the comparison of metal, iron and steel is equivalent to comparison of fruits, apples and jam. Apple is a fruit, but the fruit is a much broader concept than apple and apple jam contains other additives. In the everyday world of all metal products, we are most frequently encountered with steel. Therefore, it would be proper to call such products - steel products. Copper, aluminum, gold and silver are also metals, but they are seldom or never generalized.