Alloy steel

Alloy steel is steel containing intentionally added elements beyond carbon to modify properties such as strength, hardness, toughness, or corrosion resistance.

Iron–carbon phase diagram: A diagram showing the equilibrium phases of iron–carbon alloys as temperature and carbon content change. It maps the phases alloying elements alter in steel.
Solid-solution strengthening: Strengthening caused by dissolved atoms that impede dislocation motion in a crystal. Elements such as nickel and manganese can strengthen steel while remaining in solid solution.
Stainless steel: Steel containing enough chromium to form a protective passive surface film and resist corrosion. It is the best-known alloy-steel family designed primarily for corrosion resistance.
Carbon steel: Steel whose properties depend chiefly on carbon content, with no substantial intentional alloy additions. It is the baseline comparison for steels strengthened through deliberate alloying.
Austenite: A face-centered cubic phase of iron that can dissolve more carbon than ferrite. Many alloying elements change austenite’s stability and transformation behavior.
Precipitation hardening: Strengthening produced by fine particles that obstruct dislocation motion within a metal. Some alloy steels gain strength from controlled precipitation of alloy-rich compounds.
High-speed steel: A tool steel that retains hardness at elevated temperatures during high-speed cutting. Tungsten, molybdenum, and other additions help cutting tools resist heat and wear.
Low-alloy steel: Steel with alloying additions totaling a relatively small fraction of its composition, commonly below five percent. It is a major subset of alloy steel, distinct from high-alloy grades.
Martensite: A hard, supersaturated phase formed when austenite transforms rapidly without diffusion. Hardenability describes how deeply alloy steel can form this phase during quenching.
Carbide: A compound of carbon with a less electronegative element, often hard and wear resistant. Chromium, molybdenum, and vanadium can form carbides that affect hardness and wear.

Linked from 6 pages