Beginner Topic 676 of 1102 Inorganic Chemistry
Steel
Iron with controlled carbon content and other elements for strength.
In-depth explanation of Steel
Steel is an alloy of iron with carbon, typically containing 0.2 to 2 percent carbon by mass, and other elements are added for particular properties. Carbon atoms sit in the interstitial spaces of the iron lattice and hinder the movement of dislocations, which increases strength but also brittleness. Pig iron is refined in a basic oxygen converter, where oxygen oxidizes the excess carbon and impurities. Chromium gives stainless steel its corrosion resistance by forming a protective oxide film. Manganese, vanadium and tungsten improve hardness and toughness in tool steels.
Going deeper: Steel
Key ideas: Alloy of iron with 0.1 to 1.5 percent carbon. Low carbon (mild) steel is soft and ductile, high carbon is hard and brittle. Bessemer, basic oxygen furnace: O2 blown through molten pig iron oxidizes C, Si, P and S, with CaO flux absorbing P as phosphate slag. Stainless steel contains at least 10.5 percent Cr, forming a passive oxide film; Ni and Mn improve toughness. Heat treatment, quenching and tempering change properties.
Common mistakes and connections: Students think steel is a compound; it is a substitutional or interstitial alloy. Increasing carbon beyond about 2 percent gives cast iron. Stainless steel can still corrode in chloride. Slag chemistry concerns basic lining for phosphorus removal. Links to blast furnace, alloys, interstitial carbides and corrosion.
Visualization of Steel
Steel is nearly all iron; a small fraction of carbon (0.2 to 2 percent) in the interstitial gaps blocks dislocations and greatly raises strength. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Mild steel, with about 0.2 percent carbon, is used for building beams, while high-carbon tool steel is much harder.
Frequently asked questions about Steel
What is Steel?
Iron with controlled carbon content and other elements for strength.
Is Steel a beginner, intermediate or advanced topic?
Steel is a beginner topic in Inorganic Chemistry. It needs no earlier chemistry lessons and is a good starting point.
What should I learn before Steel?
Study these earlier topics in Inorganic Chemistry first: Magnetic Properties of Transition Metals, Iron Chemistry, Blast Furnace.
What comes after Steel?
The next topics in Inorganic Chemistry are Copper Chemistry and Zinc Chemistry.
Can I practise Steel with quizzes?
Yes. The interactive lesson includes a self-check question on Steel, and the Inorganic Chemistry quiz draws on every topic in this area.
Where Steel fits in Inorganic Chemistry
Steel is topic 61 of 113 in Inorganic Chemistry.