Steel is a black metal, not a non-ferrous metal. Based on characteristics such as color and properties, metals are classified into two main categories: ferrous metals and non-ferrous metals. Ferrous metals primarily include iron, manganese, chromium, and their alloys, such as steel, pig iron, iron alloys, and cast iron. Metals other than ferrous metals are referred to as non-ferrous metals.
The name “ferrous” can be misleading as it might suggest that ferrous metals are always black, which is not the case. There are only three types of ferrous metals: iron, manganese, and chromium. However, none of these three metals are actually black. Pure iron is silvery-white, chromium is also silvery-white, and manganese is gray-white. Because iron tends to rust on its surface, forming a layer of black iron(III) oxide and brownish iron oxide mixture, it appears black. This is why people refer to it as “black metal.” The term “black metallurgy” commonly refers to the iron and steel industry. As manganese and chromium are often present in alloy steels, they are also considered part of the “black metals.”
Non-ferrous metals generally refer to all metals except iron (and sometimes excluding manganese and chromium) and iron-based alloys. Non-ferrous metals can be categorized into heavy metals (e.g., copper, lead, zinc), light metals (e.g., aluminum, magnesium), precious metals (e.g., gold, silver, platinum), and rare metals (e.g., tungsten, molybdenum, germanium, lithium, lanthanum, uranium).
Steel is a collective term for iron-carbon alloys with carbon content ranging from 0.02% to 2.06% by mass. The chemical composition of steel can vary widely, and steel with only carbon as an alloying element is called carbon steel or plain steel. In practical production, steel often contains different alloying elements like manganese, nickel, vanadium, etc., depending on its intended use.
Comprehensive Classification:
- Tool Steel: (a) Carbon Tool Steel; (b) Alloy Tool Steel; (c) High-Speed Tool Steel.
- Specialty Steel: (a) Stainless Acid-Resistant Steel; (b) Heat-Resistant Steel; (c) Electric Heating Alloy Steel; (d) Electrical Steel; (e) High Manganese Wear-Resistant Steel; (f) High-Quality Structural Steel for Specific Uses.
Common Properties of Steel:
- Brittleness: This property represents the tendency of a metal to fracture easily. Cast iron has high brittleness and can even fracture when dropped.
- Ductility: Also known as malleability, it’s the property of a metal to undergo permanent deformation under external forces without fracturing. Ductile metals can be drawn into thin wires.
- Elasticity: It’s the property of a metal to return to its original shape after deformation when the external force is removed. Spring steel is an example of a highly elastic material.
- Malleability: Also known as workability, it’s another expression of a metal’s ductility or malleability. Malleability allows metal to be hammered or rolled into shape without breaking.
- Toughness: It’s the ability of a metal to withstand shock or impact. Toughness is the opposite of brittleness.
Please note that this translation has been provided for informational purposes and might need further refinement based on the specific context or usage.