Stole

this article treats the material steel. For further meanings see steel (term clarifying).

Steel designates all metallic alloys, whose main part is iron and which are plastic transformable by Schmieden or rollers.

Table of contents

Definition

according to the classical definition is steel an iron carbon alloy, which contains less than 2.06% (mass) carbon. This definition follows also DIN EN 10020, after steel of materials, whose proportion at iron is larger than the every other element,its carbon content generally smaller than 2 Gew. - % C are.

With higher portions of carbon one speaks of cast irons, here is present carbon in the form of graphite .

At present there are however some groups of steel, in those carbonno more alloying constituent is. An example of it are IF-steel, in whose iron matrix no carbon is interstitially stored.

characteristics

of steel are to most used metallic materials. By alloyage with carbon and other elements in combinationwith warm and its characteristics for a broad range of application can be adapted to thermalmechanical treatment (simultaneous of thermal treatment with plastic shaping).

The steel can be manufactured for example very softly and for it excellently ductile, as for instance the tinplate of cans. In contrast to thisit can be manufactured very hard and but inflexibly, as for instance martensitic steel for measurer (cutlery steel). Modern developments aim at it to manufacture the steel at the same time firmly and duktil (ductile) as contribution for lightweight construction of machines.

The most important alloying element inSteel is carbon. It is present either elementarily or as connection (cementite =Fe 3 C). The meaning of carbon in the steel results from its influence on the steel characteristics and phase conversions.

Generally steel with higher carbon portion becomes more firmly,in addition, more inflexibly. From alloyage with carbon different phases result as a function of the concentration and the ambient temperature:Austenite, ferrite, pearlite, Ledeburit and primary, secondary and tertiary cementite. By accelerated cooling of austenite, in carbon, can the further phases as fine (ex Sorbit) and feinststreifiger pearlite (ex Troostit) is solved as well as more nadeliger/granular bay rivet (“intermediate stage”) and more substantially/nadeliger martensite and/or. Hardenit develop (see also to hardnesses (steel)).

The phase composition from steel becomes for the equilibriumwith the iron carbide diagram described.

The density of steel and/or. Iron amounts to approximately 7,85 · 10 ³ kg/m ³, the elastic module approx. 210 kN/mm ².

change of steel characteristics

steel knows intended characteristics (hardness, ductility, notched-bar impact-strength…) assume. Thosethree fundamental methods for the change of the steel characteristics are:

kinds from steel

to DIN EN 10020 becomes between the two main grades

differentiated. The Kurznamen of the steel are fixed in the DIN EN 10027. Today become approx. 2500 different steel grades manufactured.

The steel plant materials are divided according to the alloying elements, the structural constituents and the mechanical characteristics in groups.

As a function of the alloy content divided into:

unalloyed steel

unalloyed steel is divided into steel plant materials, which are not intended for a thermal treatment, and into steel for a thermal treatment.

low-alloy steel

(the content of all alloying elementsexcept carbon amounts to < 5%)

Low-alloy steel has similar in principle characteristics as unalloyed steel. Technically importantly their substantially better suitability is for the influence of the mechanical characteristics by thermal treatment and with special alloy combinations also the increased heat resistance.

Highly alloyed steel

(the content one of the alloying elements amounts to at least 5%)

highly alloyed steel is necessary for special characteristics. Zunderbeständigkeit or special physical characteristics can be produced only by highly alloyed steel

organization after areas of application

further one important characteristics for the userare the areas of application and ranges of application of the steel. Therefore also a marking is meaningful, out of which this can be taken:

production

see: Steelmaking

economical one and historical meaning

the material steel and the increaseits production accompanied over approximately 130 years directly with the world-economical development into the present. In some economic sectors (z. B.Shipbuilding) represented the steel production the only growth border. The technical technisch-industrielle revolution of the second half 19. Centuryand the enormous increase of the steel production caused themselves mutually. That Paris Eiffelturm symbolizes this time period as enormous structural steelwork. The steel production of a national economy was regarded long time even as measure for its efficiency.

Before and after the Second World War that playedSteel with the production of armaments, in particular of tanks, the main role. Of Germany Norway campaign because of the Swedish iron ore one undertook, and the allied ones wanted to inundate the Ruhr district, at that time the largest geographical weapon producer of Europe, by means of purposeful dam failures.

In thatPost-war period was created in Europe the Coal and Steel Community, in order to hold the steel production under control. From this connection the European union developed in several steps.

raw material situation

although the earth's crust to five per cent from iron, the most important raw materialfor steel, at present the requirements of raw materials of the industry exists is not covered. Beginning in 2. Half-year 2003 shows up a dramatically changed raw material situation, those particularly by the strongly rising steel need of the national economies in the People's Republic of China, India and Brazilone caused. For some years alone the steel production grows in China annually by more than the present total production of Germany. Suddenly the production of the ore mines was not sufficient, which were handling capacities of the ore ports exhausted, and were also not moreenough ships for ore transport available. Similar developments resulted for coke, which is needed for the pig iron production, and for scrap iron as secondary raw material for the steelmaking.

The consequences from this development were underestimated by the large steel manufacturers of the industrialized countries, sothat the current requirements of raw materials cannot be covered. Consequently the prices for raw materials and steel products multiplied. At present steel is limited and expensive.

It is not a change of trend in view, the steel production and the requirements of raw materials will continue to rise, although thoseGrowth rate by national interferences at present sinks. The need of iron ore could be covered by opening new extraction areas.

Except the steel industry also concrete and aluminum are affected by this phenomenon. A cause for the high petroleum price is likewise thatrisen requirements of raw materials of the developing countries.

stands

for competition materials steel in particular in the automobile industry in direct competition with materials with smaller specific weight, like aluminum, magnesium, plastics and GRP components materials. There these materials however throughout less firmlyare as steel, the weight advantage can by purposeful using of high-strength steel and constructional measures (thinner sheet metal with recesses however for it Sicken) become balanced.

ecology

steel is from ecological view a outstanding material, there it almostwithout quality loss is for an unlimited period recycelbar, as the scrap iron is again melted.

In contrast to this the blast furnace process is ecologically precarious, since he is an important emitter of carbon dioxide. Therefore at new procedures of the pig iron production one researches intensively. So far this happened however without considerableSuccess.

see also

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