Induction Furnace Refining Q&A

Author: Chief Editor: Song Wenlin
Publisher:
Publish Date: 1997-05-01
Features: Excerpt: Fundamental Theories of Steelmaking 1. What is a metal? Metal is a general term for more than 80 elements (including synthetic elements) listed in the periodic table. These elements share the following characteristics: (1) Except for mercury, metals are solid and crystalline at room temperature. (2) They have a special metallic luster and different colors, such as gold being golden yellow, silver being silver-white, and iron being iron-gray. (3) They have good electrical and thermal conductivity. (4) They have good ductility, allowing them to be cold- and hot-worked into bars, plates, pipes, wires, and foils. 2. What is an alloy? An alloy is a material with metallic properties composed of two or more elements (at least one of which must be a metal element). Alloys composed of two elements are called binary alloys, those composed of three elements are called ternary alloys, and those composed of more than three elements are called multicomponent alloys. The mechanical, physical, and chemical properties of alloys are often superior to those of pure metals, making them widely used in industry. 3. What are ferrous metals? In industry, metals are divided into two major categories: ferrous metals and non-ferrous metals. Ferrous metals typically refer to iron (sometimes also including manganese and chromium) and iron-based alloys. Iron is abundant in the Earth's crust, allowing for long-term and large-scale mining, making it suitable for mass production. Through different processing methods, it can be tailored to meet the performance requirements of various applications, making it the cheapest and most widely used metal among all metals. 4. What are non-ferrous metals? Non-ferrous metals generally refer to all metals except iron (sometimes excluding manganese and chromium) and iron-based alloys. Non-ferrous metals can be divided into four categories: (1) Heavy metals: Generally with a density of over 4.5 g/cm3, such as copper, lead, and zinc. (2) Light metals: Low density (0.53–4.5 g/cm3), highly reactive chemically, such as aluminum and magnesium. (3) Precious metals: Rare in the Earth's crust, difficult to extract, high in price, high in density, and stable chemically, such as gold, silver, and platinum. (4) Rare metals: Such as tungsten, molybdenum, germanium, lithium, lanthanum, and uranium. Due to their significant importance in modern industry, rare metals are sometimes classified separately from non-ferrous metals, forming a distinct category alongside ferrous and non-ferrous metals as one of the three major metal categories. 5. What are rare metals? Metals that are rare in the Earth's crust, widely scattered, and difficult to refine are called rare metals. Rare metals and their alloys are essential raw materials for the production of nuclear energy, aerospace, semiconductors, special steels, and heat-resistant alloys. Based on their physical and chemical properties and their occurrence in mineral deposits, rare metals can be divided into five categories: (1) High-melting rare metals: With high melting points, such as tungsten and aluminum. (2) Scattered metals: Mostly found in minerals of other elements, such as gallium, indium, and germanium. (3) Rare light metals: With low density, such as beryllium and lithium. (4) Rare earth metals: They have very similar chemical properties and often occur together in minerals, such as lanthanum and yttrium. (5) Radioactive rare metals: Including naturally occurring radioactive elements, such as uranium, thorium, and radium, as well as synthetic super-heavy elements, such as neptunium and plutonium. 6. What is pig iron? Pig iron is an alloy of iron and carbon. Iron-carbon alloys with a carbon content of 2.0% or higher are typically referred to as pig iron. In addition to carbon, pig iron also contains silicon, manganese, and small amounts of sulfur and phosphorus. The carbon content of pig iron is generally between 2.0% and 4.5%, giving it high strength and hardness but poor toughness and ductility, making it brittle and difficult to weld or forge. It can be machined but has good casting properties, allowing it to be cast into various shapes. Pig iron is widely used in industry. Based on its applications, pig iron can be divided into three types: pig iron for steelmaking (with lower silicon content), pig iron for casting (with higher silicon content), and special pig iron.