How did iron become steel?

2% to 4.3% of pig iron is extracted from iron ore (hematite, siderite, magnetite, etc.). ), and then the excess carbon and other impurities are oxidized by oxidant at high temperature. Usually, oxygen top-blown converter steelmaking (blowing oxygen) removes gas or slag and converts it into steel containing 0.03% ~ 2% carbon. When steelmaking, alloys such as silicon, manganese and aluminum are added as deoxidation. ? . The reagent is used to adjust the composition of molten steel to make steel that meets the specifications. At the same time, some necessary elements can be added to make it an alloy with various excellent properties.

1, steel, is the general name of iron-carbon alloys with carbon content between 0.02% and 2.11%. The chemical composition of steel varies greatly. Steel containing only carbon element is called carbon steel (carbon steel) or ordinary steel. In actual production, steel often contains different alloying elements, such as manganese, nickel and vanadium, according to different uses.

2. Elements of "steel":

(1) carbon

It exists in all steels and is the most important hardening element. This helps to increase the strength of steel. We usually hope that the carbon content of tool-grade steel is above 0.6%, which is also called high carbon steel.

(2) Chromium

Increase wear resistance, hardness and, most importantly, corrosion resistance. More than 13% is considered as stainless steel. Nevertheless, all steel will rust if it is not properly maintained.

(3) Manganese

An important austenite stabilizing element, which is helpful to generate texture structure and increase firmness, strength and wear resistance. The steel is deoxidized during heat treatment and rolling. Except for A-2, L-6 and CPM 420V, most steel used for knife and scissors is deoxidized.

(4) molybdenum

Carbonizing agent appears in many steels, which prevents steel from becoming brittle and maintains its strength at high temperature. Air-hardened steels (such as A-2 and ATS-34) usually contain 1% or more molybdenum, so they can be hardened in air.

(5) Nickel coins

Maintain strength, corrosion resistance and toughness. Appears in L-6\AUS-6 and AUS-8.

Extended data:

Identification method of steel:

The American Iron and Steel Association uses three numbers to represent various standard grades of malleable stainless steel. These include:

(1) Austenitic stainless steel is marked with 200 and 300 series numbers. For example, some common austenitic stainless steels are marked with 20 1, 304, 3 16, 3 10.

(2) Ferritic and martensitic stainless steels are represented by 400 series numbers.

(3) Ferritic stainless steels are labeled 430 and 446, and martensitic stainless steels are labeled 4 10, 420 and 440C, which are duplex (austenite-ferrite).

(4) Stainless steel, precipitation hardened stainless steel and high alloy with iron content less than 50% are usually named by patent names or trademarks.

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