Metals melt, as a rule, at a very high temperature, which can reach more than 3 thousand degrees. Although some of them can be melted at home, such as lead or tin. But mercury is melted at a temperature of minus 39 degrees. This cannot be achieved at home. Melting point is one of the important indicators of the production of not only the metal itself, but also its alloys. When smelting raw materials, specialists take into account other physical and chemical properties of the ore and metal.
STRUCTURE
Several polymorphic modifications have been established for iron, of which the high-temperature modification - γ-Fe (above 906°) forms a lattice of a face-centered cube of the Cu type (a0 = 3.63), and the low-temperature modification - the α-Fe lattice of a centered cube of the α-Fe type (a0 = 2.86).
Depending on the heating temperature, iron can be found in three modifications, characterized by different crystal lattice structures:
In the temperature range from the lowest to 910°C - a-ferrite (alpha ferrite), which has a crystal lattice structure in the form of a centered cube;
In the temperature range from 910 to 1390°C - austenite, the crystal lattice of which has the structure of a face-centered cube;
In the temperature range from 1390 to 1535 ° C (melting point) - d-ferrite (delta ferrite). The crystal lattice of d-ferrite is the same as that of a-ferrite. The only difference between them is the different (larger for d-ferrite) distances between the atoms.
When liquid iron is cooled, primary crystals (crystallization centers) appear simultaneously at many points in the cooled volume. With subsequent cooling, new crystalline cells are built around each center until the entire supply of liquid metal is exhausted.
The result is a granular structure of the metal. Each grain has a crystal lattice with a certain direction of its axes.
With subsequent cooling of solid iron, during the transition of d-ferrite to austenite and austenite to a-ferrite, new crystallization centers may appear with a corresponding change in grain size.
Strength of metals
In addition to the ability to transition from a solid to a liquid state, one of the important properties of a material is its strength - the ability of a solid body to resist destruction and irreversible changes in shape. The main indicator of strength is the resistance that occurs when a pre-annealed workpiece breaks. The concept of strength does not apply to mercury because it is in a liquid state. The designation of strength is accepted in MPa - Mega Pascals.
There are the following strength groups of metals:
- Fragile. Their resistance does not exceed 50MPa. These include tin, lead, soft-alkaline metals
- Durable, 50−500 MPa. Copper, aluminum, iron, titanium. Materials of this group are the basis of many structural alloys.
- High strength, over 500 MPa. For example, molybdenum and tungsten.
Metal strength table
| Metal | Resistance, MPa |
| Copper | 200−250 |
| Silver | 150 |
| Tin | 27 |
| Gold | 120 |
| Lead | 18 |
| Zinc | 120−140 |
| Magnesium | 120−200 |
| Iron | 200−300 |
| Aluminum | 120 |
| Titanium | 580 |
The most common alloys in everyday life
As can be seen from the table, the melting points of elements vary greatly even among materials commonly found in everyday life.
Thus, the minimum melting point of mercury is -38.9 °C, so at room temperature it is already in a liquid state. This explains why household thermometers have a lower mark of -39 degrees Celsius: below this indicator, mercury turns into a solid state.
The most common solders in household use contain a significant percentage of tin, which has a melting point of 231.9 °C, so most solders melt at the operating temperature of the soldering iron 250−400 °C.
In addition, there are low-melting solders with a lower melt limit, up to 30 °C, and are used when overheating of the materials being soldered is dangerous. For these purposes, there are solders with bismuth, and the melting of these materials lies in the range from 29.7 - 120 °C.
Melting of high-carbon materials, depending on alloying components, ranges from 1100 to 1500 °C.
The melting points of metals and their alloys are in a very wide temperature range, from very low temperatures (mercury) to several thousand degrees. Knowledge of these indicators, as well as other physical properties, is very important for people who work in the metallurgical field. For example, knowledge of the temperature at which gold and other metals melt will be useful to jewelers, foundries and smelters.
Metals melt, as a rule, at a very high temperature, which can reach more than 3 thousand degrees. Although some of them can be melted at home, such as lead or tin. But mercury is melted at a temperature of minus 39 degrees. This cannot be achieved at home. Melting point is one of the important indicators of the production of not only the metal itself, but also its alloys. When smelting raw materials, specialists take into account other physical and chemical properties of the ore and metal.
Read also: Why does stainless steel rust after welding?
PROPERTIES
In its pure form under normal conditions it is a solid. It has a silver-gray color and a pronounced metallic luster. The mechanical properties of iron include its level of hardness on the Mohs scale. It is equal to four (average). Iron has good electrical and thermal conductivity. The last feature can be felt by touching an iron object in a cold room. Because this material conducts heat quickly, it removes most of it from your skin in a short period of time, which is why you feel cold.
If you touch, for example, wood, you will notice that its thermal conductivity is much lower. The physical properties of iron include its melting and boiling points. The first is 1539 degrees Celsius, the second is 2860 degrees Celsius. We can conclude that the characteristic properties of iron are good ductility and fusibility. But that's not all. Also, the physical properties of iron include its ferromagnetism. What it is? Iron, whose magnetic properties we can observe in practical examples every day, is the only metal that has such a unique distinctive feature. This is explained by the fact that this material is capable of magnetization under the influence of a magnetic field. And after the end of the action of the latter, the iron, the magnetic properties of which have just been formed, remains a magnet for a long time. This phenomenon can be explained by the fact that in the structure of this metal there are many free electrons that are able to move.
Melting point table
It is important for anyone involved in the metallurgical industry, whether a welder, foundry worker, smelter or jeweler, to know the temperatures at which the materials they work with melt. The table below shows the melting points of the most common substances.
Read also: What can be cast from lead
Table of melting temperatures of metals and alloys
| Name | T pl, °C |
| Aluminum | 660,4 |
| Copper | 1084,5 |
| Tin | 231,9 |
| Zinc | 419,5 |
| Tungsten | 3420 |
| Nickel | 1455 |
| Silver | 960 |
| Gold | 1064,4 |
| Platinum | 1768 |
| Titanium | 1668 |
| Duralumin | 650 |
| Carbon steel | 1100−1500 |
| Cast iron | 1110−1400 |
| Iron | 1539 |
| Mercury | -38,9 |
| Cupronickel | 1170 |
| Zirconium | 3530 |
| Silicon | 1414 |
| Nichrome | 1400 |
| Bismuth | 271,4 |
| Germanium | 938,2 |
| Tin | 1300−1500 |
| Bronze | 930−1140 |
| Cobalt | 1494 |
| Potassium | 63 |
| Sodium | 93,8 |
| Brass | 1000 |
| Magnesium | 650 |
| Manganese | 1246 |
| Chromium | 2130 |
| Molybdenum | 2890 |
| Lead | 327,4 |
| Beryllium | 1287 |
| Will win | 3150 |
| Fechral | 1460 |
| Antimony | 630,6 |
| titanium carbide | 3150 |
| zirconium carbide | 3530 |
| Gallium | 29,76 |
In addition to the melting table, there are many other supporting materials. For example, the answer to the question what is the boiling point of iron lies in the table of boiling substances. In addition to boiling, metals have a number of other physical properties, such as strength.
RESERVES AND PRODUCTION
Iron is one of the most common elements in the solar system, especially on the terrestrial planets, in particular on Earth. A significant part of the iron of the terrestrial planets is located in the cores of the planets, where its content is estimated to be about 90%. The iron content in the earth's crust is 5%, and in the mantle about 12%.
Iron is quite widespread in the earth's crust - it accounts for about 4.1% of the mass of the earth's crust (4th place among all elements, 2nd among metals). In the mantle and earth's crust, iron is concentrated mainly in silicates, while its content is significant in basic and ultrabasic rocks, and low in acidic and intermediate rocks.
A large number of ores and minerals containing iron are known. Of greatest practical importance are red iron ore (hematite, Fe2O3; contains up to 70% Fe), magnetic iron ore (magnetite, FeFe2O4, Fe3O4; contains 72.4% Fe), brown iron ore or limonite (goethite and hydrogoethite, respectively FeOOH and FeOOH nH2O ). Goethite and hydrogoethite are most often found in weathering crusts, forming so-called “iron hats”, the thickness of which reaches several hundred meters. They can also be of sedimentary origin, falling out of colloidal solutions in lakes or coastal areas of the seas. In this case, oolitic, or legume, iron ores are formed. Vivianite Fe3(PO4)2·8H2O is often found in them, forming black elongated crystals and radial aggregates.
The iron content in sea water is 1·10−5-1·10−8%
Industrially, iron is obtained from iron ore, mainly hematite (Fe2O3) and magnetite (FeO Fe2O3).
There are various ways to extract iron from ores. The most common is the domain process.
The first stage of production is the reduction of iron with carbon in a blast furnace at a temperature of 2000 °C. In a blast furnace, carbon in the form of coke, iron ore in the form of agglomerate or pellets, and flux (such as limestone) are fed from above, and are met by a stream of forced hot air from below.
In addition to the blast furnace process, the process of direct iron production is common. In this case, pre-crushed ore is mixed with special clay, forming pellets. The pellets are fired and treated in a shaft furnace with hot methane conversion products, which contain hydrogen. Hydrogen easily reduces iron without contaminating the iron with impurities such as sulfur and phosphorus, which are common impurities in coal. Iron is obtained in solid form and is subsequently melted in electric furnaces. Chemically pure iron is obtained by electrolysis of solutions of its salts.
At what temperature does iron melt?
The table shows the melting point of metals tmelt , their boiling point tk at atmospheric pressure, the density of metals ρ at 25°C and thermal conductivity λ at 27°C.
The melting point of metals, as well as their density and thermal conductivity are given in the table for the following metals: actinium Ac, silver Ag, aluminum Al, gold Au, barium Ba, beryllium Be, bismuth Bi, calcium Ca, cadmium Cd, cobalt Co, chromium Cr, cesium Cs, copper Cu, iron Fe, gallium Ga, hafnium Hf, mercury Hg, indium In, iridium Ir, potassium K, lithium Li, magnesium Mg, manganese Mn, molybdenum Mo, sodium Na, niobium Nb, nickel Ni, neptunium Np , osmium Os, protactinium Pa, lead Pb, palladium Pd, polonium Po, platinum Pt, plutonium Pu, radium Ra, rubidium Pb, rhenium Re, rhodium Rh, ruthenium Ru, antimony Sb, tin Sn, strontium Sr, tantalum Ta, technetium Tc, thorium Th, titanium Ti, thallium Tl, uranium U, vanadium V, tungsten W, zinc Zn, zirconium Zr.
According to the table, it can be seen that the melting point of metals varies over a wide range (from -38.83°C for mercury to 3422°C for tungsten). Metals such as lithium (18.05°C), cesium (28.44°C), rubidium (39.3°C) and other alkali metals have a low positive melting point.
The most refractory metals are the following: hafnium, iridium, molybdenum, niobium, osmium, rhenium, ruthenium, tantalum, technetium, tungsten. The melting point of these metals is above 2000°C.
Here are examples of the melting point of metals widely used in industry and everyday life:
- melting point of aluminum 660.32 °C;
- copper melting point 1084.62 °C;
- melting point of lead 327.46 °C;
- melting point of gold 1064.18 °C;
- melting point of tin 231.93 °C;
- the melting point of silver is 961.78 °C;
- The melting point of mercury is -38.83°C.
Rhenium Re has the maximum boiling point of the metals presented in the table - it is 5596°C. Also, metals belonging to the group with a high melting point have high boiling points.
The density of the metals in the table ranges from 0.534 to 22.59 g/cm 3 , that is, the lightest metal is lithium, and the heaviest metal is osmium. It should be noted that osmium has a density greater than that of uranium and even plutonium at room temperature.
The thermal conductivity of metals in the table varies from 6.3 to 427 W/(m deg), thus the worst conductor of heat is a metal such as neptunium, and the best heat-conducting metal is silver.
Melting point of steel
A table of melting temperature values for common grades of steel is presented. Steels for castings, structural, heat-resistant, carbon and other classes of steels are considered.
The melting point of steel ranges from 1350 to 1535°C. The steels in the table are arranged in order of increasing melting point.
Melting temperature of steel - tableSteeltmelt, °СStaltmelt, °C
- Volkov A.I., Zharsky I.M. Large chemical reference book. - M: Soviet School, 2005. - 608 p.
- Kazantsev E.I. Industrial furnaces. Reference manual for calculations and design.
- Physical quantities. Directory. A. P. Babichev, N. A. Babushkina, A. M. Bratkovsky and others; Ed. I. S. Grigorieva, E. Z. Meilikhova. - M.: Energoatomizdat, 1991. - 1232 p.
Each metal or alloy has unique properties, including its melting point. In this case, the object passes from one state to another, in a particular case, it becomes liquid from solid.
To melt it, you need to apply heat to it and heat it until the desired temperature is reached. At the moment when the desired temperature point of a given alloy is reached, it may still remain in a solid state.
As exposure continues, it begins to melt.
ORIGIN
Origin telluric (terrestrial) iron is rarely found in basaltic lavas (Uifak, Disko Island, off the western coast of Greenland, near Kassel, Germany). At both locations, pyrrhotite (Fe1-xS) and cohenite (Fe3C) are associated with it, which is explained by both the reduction by carbon (including from the host rocks) and the decomposition of carbonyl complexes such as Fe(CO)n. In microscopic grains, it has more than once been established in altered (serpentinized) ultrabasic rocks, also in paragenesis with pyrrhotite, sometimes with magnetite, due to which it arises during reduction reactions. Very rarely found in the oxidation zone of ore deposits, during the formation of swamp ores. Findings have been recorded in sedimentary rocks associated with the reduction of iron compounds with hydrogen and hydrocarbons.
Almost pure iron was found in lunar soil, which is associated with both meteorite falls and magmatic processes. Finally, two classes of meteorites - stony-iron and iron - contain natural iron alloys as a rock-forming component.
APPLICATION
Iron is one of the most used metals, accounting for up to 95% of global metallurgical production.
Iron is the main component of steels and cast irons - the most important structural materials.
Iron can be part of alloys based on other metals - for example, nickel. Magnetic iron oxide (magnetite) is an important material in the production of long-term computer memory devices: hard drives, floppy disks, etc.
Ultrafine magnetite powder is used in many black and white laser printers mixed with polymer granules as a toner. This uses both the black color of the magnetite and its ability to stick to the magnetized transfer roller.
The unique ferromagnetic properties of a number of iron-based alloys contribute to their widespread use in electrical engineering for magnetic cores of transformers and electric motors.
Iron(III) chloride (ferric chloride) is used in amateur radio practice for etching printed circuit boards.
Ferrous sulfate heptate (ferrous sulfate) mixed with copper sulfate is used to combat harmful fungi in gardening and construction.
Iron is used as an anode in iron-nickel batteries and iron-air batteries.
Aqueous solutions of ferrous and ferric chlorides, as well as its sulfates, are used as coagulants in the purification processes of natural and waste water in the water treatment of industrial enterprises.
At what temperature can iron be melted?
| Steels for castings Х28Л and Х34Л | 1350 | Corrosion-resistant heat-resistant 12Х18Н9Т | 1425 |
| Structural steel 12Х18Н10Т | 1400 | Heat-resistant high-alloy 20Х23Н13 | 1440 |
| Heat-resistant high-alloy 20Х20Н14С2 | 1400 | Heat-resistant high-alloy 40Х10С2М | 1480 |
| Heat-resistant high-alloy 20Х25Н20С2 | 1400 | Corrosion-resistant steel X25S3N (EI261) | 1480 |
| Structural steel 12Х18Н10 | 1410 | Heat-resistant high-alloy 40Х9С2 (ESKH8) | 1480 |
| Corrosion-resistant heat-resistant 12Х18Н9 | 1410 | Corrosion-resistant ordinary 95Х18…15Х28 | 1500 |
| Heat-resistant steel Х20Н35 | 1410 | Corrosion-resistant heat-resistant 15Х25Т (EI439) | 1500 |
| Heat-resistant high-alloy 20Х23Н18 (ЭИ417) | 1415 | Carbon steels | 1535 |
