Ferrous materialsIt's an industrial rightiron、chromiumAnd manganese.It also includes alloys of these three metals, especially alloy, ferrous metal, steel and iron.The opposite of ferrous metals is nonferrous metals.In fact, pure iron and chromium are silver white, while manganese is silver gray.As the surface of steel is usually covered with black ferric oxide, manganese and chromium are mainly used to smelt black alloy steel.Therefore, it is "wrongly classified" as ferrous metal.
The classification of ferrous metals is also meaningful, because these three metals are the main raw materials for smelting steel, and steel plays an extremely important role in the national economy, and is also an important symbol to measure a country's national strength.The output of ferrous metals accounts for about 95% of the world's total metal output.
Mining terminology
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ferrous metal
The names of ferrous metals and nonferrous metals often make people misunderstand that ferrous metals must be black, but they are not.There are three kinds of ferrous metals: iron, manganese and chromium[1]。None of them is black.Pure iron is silver white;Chromium is silver white;Manganese is grayish white.Because the iron surface is often rusty, covered with a layer of blackFerric tetroxideAnd tanferric oxideIt looks black.So people call it "black metal".Often said“Ferrous metallurgy industry”, mainly refers tosteel industry。Because the most commonAlloy steelyesmanganese steelAndChrome steelIn this way, people compare manganese withchromiumIt can also be regarded as "black metal".
In addition to iron, manganese and chromium, other metals are nonferrous metals.
In nonferrous metals, there are also various classification methods.For example, according to the specific weight, the specific gravity of aluminum, magnesium, lithium, sodium, potassium, etc. is less than 4.5, which is called“Light metal”The proportion of copper, zinc, nickel, mercury, tin and lead is more than 4.5, which is called "heavy metal".Gold, silver, platinum, osmium and iridium are more expensive. They are called“noble metal”Radium, uranium, thorium, polonium, technetium, etc. are radioactive, called "radioactive metals", and niobium, tantalum, zirconium, lutetium, gold, radium, hafnium, uranium, etc. are also called "radioactive metals" because they are less or more dispersed in the crust“Rare metals”。
In 2004, the investment in ferrous metal mining, smelting and rolling processing industry was 154.6 billion yuan, up 40.5%.In 2005, the growth of ferrous metal industry was significantly accelerated, with the added value increasing 35.5% year on year.The output of pig iron, crude steel and steel was 27.7 million tons, 29.73 million tons and 31.106 million tons respectively.
In 2004, the world steel output reached 1054.8 million tons, with an increase of about 110 million tons, of which China's steel output increased to 52.34 million tons, accounting for 47.73% of the world's steel output growth.In 2004, China's steel output reached 272 million tons, ranking first in the world for nine consecutive years, the sum of steel output of Japan, the United States and Russia, which ranked second to fourth.China has become the largest steel production and consumption country in the world and the most concentrated area of steel investment.
In 2005Steel industryIt was a year when we began to focus on the merger and reorganization of steel enterprises.Tangshan Iron and Steel Group, Wuhan Iron and Steel Group and Panzhihua Iron and Steel Group have successively carried out consolidation and reorganization. The consolidation of statistical statements has put them in the top position, accelerated the internal structural adjustment of the enterprise, and improved the overall competitiveness of the enterprise.
《Iron and steel industry development policy》[2]The introduction of the "" is a major event in the development of China's steel industry, will play an important guiding role in the future development of China's steel industry, and is an important cornerstone to promote the healthy development of the steel industry.
iron
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iron
Iron is a chemical element and the most commonly used metal.It is a kind of transition metal.Iron is active and a strong reducing agent. The valence of iron is 0,+2,+3,+6. The most important valence states are+2 and+3.At room temperature, iron can slowly displace hydrogen from water, and the reaction speed increases above 500 ℃: iron is difficult to react with oxygen in dry air, but it is easy to corrode in humid air. If it corrodes faster in acid gas or halogen vapor atmosphere.Iron can reduce gold, platinum, silver, mercury, copper or tin plasma from solution.
Classification of cast iron
1. Cast iron can be divided into gray cast iron, white cast iron andHemp cast iron。
2. Cast iron can be divided into ordinary cast iron andAlloy cast iron。
3. Cast iron can be divided into ordinary gray cast iron, inoculation gray cast iron, malleable gray cast iron, nodular cast iron, vermicular cast iron andSpecial performance cast iron。
A brief history of the discovery of iron
Iron is one of the metals known in ancient times.Iron ore is one of the main components of the earth's crust, and iron is widely distributed in nature, but the discovery and utilization of iron is later than that of gold and copper.First of all, because iron in the natural simple state is very rare on the earth, and it is easy to oxidize and rust, and its melting point (1812K) is much higher than that of copper (1356K), it is harder to smelt than copper.The first iron discovered by humans is meteorite falling from the sky. The meteorite contains a high percentage of iron, which is a mixture of iron, nickel, cobalt and other metals. When the method of melting iron ore has not yet come out and it is impossible for humans to obtain a large amount of pig iron, iron has always been regarded as the most precious metal with mystery.
The West Asian Hittites were the first to discover and master iron making technology.China has been making iron since the Eastern Zhou DynastySpring and Autumn Period and Warring States PeriodPopularization is one of the countries that mastered iron smelting technology earlier.In 1973, a bronze axe with iron blade of the Shang Dynasty was unearthed in Hebei Province, China, which shows that the working people of our country had known iron more than 3300 years ago, were familiar with the forging properties of iron, recognized the difference between iron and bronze in nature, and cast iron inBronze weaponThe cutting edge of the copper can strengthen the toughness of the copper.Through scientific appraisal, it is proved that the iron blade is forged from meteorite iron.With the maturity of bronze smelting technology, it has gradually created conditions for the development of iron smelting technology.The earliest artificially smelted iron in China appeared at the turn of the Spring and Autumn Period and the Warring States Period.The iron bars and iron balls unearthed from the Spring and Autumn Tomb in Liuhe County, Jiangsu Province, and the iron fronds unearthed from the early Warring States pits in Luoyang, Henan Province, can be determined to be the earliest pig iron tools in China so far.The appearance of pig iron smelting technology, its role in feudal society and the influence of steam engine oncapitalist society Its function is comparable.The discovery and large-scale use of iron is a glorious milestone in the history of human development. It has brought mankind from the Stone Age and the Bronze Age to the Iron Age and promoted the development of human civilization.Up to now, iron is still the foundation of modern chemical industry and an indispensable metal material for human progress.
Properties of iron
It is a bright silver white metal.Density 7.86 g/cm3.The melting point is 1535 ℃, and the boiling point is 2750 ℃.Common valence+2 and+3 have good ductility and thermal conductivity.It can also conduct electricity.Pure iron can be magnetized and demagnetized quickly.The ionization energy is 7.870Electron volt。The chemical property is relatively active, and it is a good reducing agent.If there are impurities, it is easy to rust in humid air;Rusting is faster in wet air with acid gas or halogen vapor.Easily soluble in dilute acid.It can be passivated in concentrated nitric acid.When heated, it can combine with halogen, sulfur, silicon, carbon, phosphorus, etc.In addition to generating+2 and+3 valence oxidesComposite oxideFe3O4 (magnetic oxide) is generated.Iron isindustrial sector An indispensable metal.
Chemical properties of iron
Iron Fe, atomic number 26,Relative atomic mass55.847。Iron has many allotropes, such as α iron, β iron, γ iron, б iron, etc.Iron is a relatively active metal, ranking ahead of hydrogen in the metal activity sequence table.At normal temperature, iron is not easy to react with non-metallic simple substances such as oxygen, sulfur and chlorine in dry air. At high temperature, it will react violently.Iron burns in oxygen to generate Fe3O4, and red hot iron reacts with water vapor to generate Fe3O4.Iron is easily soluble in dilute inorganic acid and concentrated hydrochloric acid to generate ferrous salts and release hydrogen.When encountering concentrated sulfuric acid or nitric acid at normal temperature, a layer of oxide protective film will be formed on the surface to "passivate" iron, so iron products can be used to contain concentrated sulfuric acid or nitric acid.Iron is a variable valence element, and the common valence states are+2 and+3.Iron and sulfurCopper sulfate solution, hydrochloric acid, dilute sulfuric acid, etc. lose two electrons and become+2 valence.It reacts with Cl2, Br2, nitric acid and hot concentrated sulfuric acid and is oxidized to Fe3+.Fe3O4 generated by the reaction of iron with oxygen or water vapor can be regarded as FeO · Fe2O3, in which 1/3 of Fe is+2 valence, and 2/3 is+3 valence.The+3 valence compound of iron is relatively stable.
chromium
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definition
ferrous metal
Silver white metal, hard and brittle.Density 7.20 g/cm3.Melting point 1857 ± 20 ℃, boiling point 2672 ℃.Valence+2,+3 and+6.The ionization energy is 6.766 eV.Metal chromium in acid is generally characterized by surface passivation.Once the passivation is removed, it is easily soluble in almost all inorganic acids, but insoluble in nitric acid.Chromium is soluble in sulfuric acid, but insoluble in nitric acid.It is oxidized by water vapor at high temperature and oxidized by water vapor at 1000 ℃carbon monoxideOxidized.At high temperatures, chromium reacts with nitrogen and is eroded by molten alkali metals.Soluble in strong alkali solution.Chromium has a high corrosion resistance. In the air, it oxidizes slowly even in the state of red heat.Insoluble in water.
In nature, it mainly exists in the form of chromite FeCr2O4.It is produced by reduction of chromium oxide with aluminum, or electrolysis of chromic alum or chromic acid.According to its content in the earth's crust, chromium is one of the widely distributed elements.It has more cobalt, nickel, molybdenum and tungsten than those found before it.This may be because the natural compound of chromium is very stable and insoluble in water, so it is difficult to reduce.Some people think thatvauquelin The obtained metal chromium may be chromium carbide.
Chromium is used to make stainless steel, auto parts, tools, tapes and videotapes.Chromium plating on metal can prevent rust, also known as Kedomi, solid and beautiful.Chromium can be used to make stainless steel.Red and emerald colors also come from chrome.As the most important metal in modern science and technology, the chrome nickel steel fused with different percentages is ever-changing and has an incredible variety.The toxicity of chromium is related to its existing valence statetrivalent chromiumThe toxicity is 100 times higher, and it is easy to be absorbed and accumulated in the body. Trivalent and hexavalent chromium can be transformed into each other. Natural water does not contain chromium;The average concentration of chromium in seawater is 0.05ug/l;Drinking water is lower. The sources of chromium pollution include sewage discharged from chrome ore processing, metal surface treatment, leather tanning, printing and dyeing, etc.
Chromium is an essential trace element for human body, which plays a special role in the metabolism of glucose and lipid in the body.Trivalent chromium is beneficial to human body, while hexavalent chromium is toxic.The absorption and utilization rate of inorganic chromium by human body is extremely low, less than 1%;The utilization rate of organic chromium in human body can reach 10-25%.The content of chromium in natural food is low and exists in trivalent form.
Specifically, the physiological function of chromium is to work together with other substances that control metabolism, such as hormones, insulin, various enzymes, cell genetic materials (DNA and RNA), etc.
physiological function
1. In vivoGlucose tolerance factor(glucose tolerance factor, GTF): GTF is composed of trivalent chromium, nicotinic acid, glutamic acid, glycine andSulfur-containing amino acidIt can enhance the biological effect of insulin, accelerate the utilization of glucose in the body by activating glucose phosphate mutase, and promote the conversion of glucose into fat.
3. Promotionprotein metabolism And growth and development: Chromium is high in nucleoprotein. Studies have found that it can promote the synthesis of RNA, and chromium also affects the transport of amino acids in the body.When chromium intake is insufficient, growth retardation may occur in experimental animals.
Normal healthy adults lose about 1 microgram of chromium in their urine every day.beer yeastWaste molasses, cheese, eggs, liver, apple peel, bananas, beef, flour, chicken and potatoes are the main sources of chromium.Chromium is skinAllergen, can cause allergic dermatitis or eczema, the course of the disease is long, long without healing.Neodymium is highly irritating to eyes and mucous membranes, and moderately irritating to skin. Inhalation of neodymium can also cause pulmonary embolism and liver damage.These two elements are listed as prohibited substances in cosmetics in relevant regulations of China, EU and other countries.
steel
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definition
steel
Steel is a kind of material with various shapes, sizes and properties that is made from ingots, billets and other materials through pressure processing.
Steel with carbon content between 0.04% and 2.3%Ferrocarbon alloy。(In theory, the steel with carbon content less than 2.11% is generally called steel) In order to ensure its toughness and plasticity, the carbon content is generally not more than 1.7%.In addition to iron and carbon, the main elements of steel include silicon, manganese, sulfur, phosphorus, etc.
Classification by quality
(1) Ordinary steel (P ≤ 0.045%, S ≤ 0.050%)
(2) High quality steel (P, S ≤ 0.035%)
(3) High quality steel (P ≤ 0.035%, S ≤ 0.030%
Classification by chemical composition
(1) Carbon steel: a. Low carbon steel (C ≤ 0.25%);b. Medium carbon steel (C ≤ 0.25~0.60%);c. High carbon steel (0.60% ≤ C ≤ 2.11%).
(2) Alloy steel: a. Low alloy steel (total content of alloy elements ≤ 5%);b. Medium alloy steel (the total content of alloy elements is 5~10%);c. High alloy steel (total alloy element content>10%).
