Melting point of metals and alloys table. Physical characteristics, composition and features of iron metal

Each metal and alloy has its own unique set of physical and chemical properties, not least of which is the melting point. The process itself means the transition of the body from one state of aggregation to another, in this case, from a solid crystalline state to a liquid one. To melt a metal, it is necessary to supply heat to it until the melting point is reached. With it, it can still remain in a solid state, but with further exposure and an increase in heat, the metal begins to melt. If the temperature is lowered, that is, part of the heat is removed, the element will harden.

Highest melting point among metals belongs to tungsten: it is 3422C o, the lowest is for mercury: the element melts already at - 39C o. As a rule, it is not possible to determine the exact value for alloys: it can fluctuate significantly depending on the percentage of components. They are usually written as a number span.

How is it happening

The melting of all metals occurs in approximately the same way - with the help of external or internal heating. The first is carried out in a thermal furnace, for the second, resistive heating is used with the passage of an electric current or induction heating in a high-frequency electromagnetic field. Both options affect the metal in about the same way.

As the temperature increases, so does amplitude of thermal vibrations of molecules, structural lattice defects appear, which are expressed in the growth of dislocations, hopping of atoms, and other disturbances. This is accompanied by the breaking of interatomic bonds and requires a certain amount of energy. At the same time, a quasi-liquid layer is formed on the surface of the body. The period of destruction of the lattice and the accumulation of defects is called melting.

Depending on the melting point, metals are divided into:

Depending on the melting temperature choose and melting apparatus. The higher the score, the stronger it should be. You can find out the temperature of the element you need from the table.

Another important value is the boiling point. This is the value at which the boiling process of liquids begins, it corresponds to the temperature of saturated steam that forms above the flat surface of the boiling liquid. Usually it is almost twice as high as the melting point.

Both values ​​are given at normal pressure. Among themselves they directly proportional.

1. The pressure increases - the amount of melting will increase.
2. The pressure decreases - the amount of melting decreases.

Table of fusible metals and alloys (up to 600C o)

Element name	Latin designation	Temperatures
		Melting	boiling
Tin	sn	232 C o	2600 C o
Lead	Pb	327 C o	1750 C o
Zinc	Zn	420 C o	907 S o
Potassium	K	63.6 C o	759 S o
Sodium	Na	97.8 C o	883 C o
Mercury	hg	- 38.9 C o	356.73 C o
Cesium	Cs	28.4 C o	667.5 C o
Bismuth	Bi	271.4 C o	1564 S o
Palladium	Pd	327.5 C o	1749 S o
Polonium	Po	254 C o	962 S o
Cadmium	CD	321.07 C o	767 S o
Rubidium	Rb	39.3 C o	688 S o
Gallium	Ga	29.76 C o	2204 C o
Indium	In	156.6 C o	2072 S o
Thallium	Tl	304 C o	1473 S o
Lithium	Li	18.05 C o	1342 S o

Table of medium-melting metals and alloys (from 600С o to 1600С o)

Element name	Latin designation	Temperatures
		Melting	boiling
Aluminum	Al	660 C o	2519 S o
Germanium	Ge	937 S o	2830 C o
Magnesium	mg	650 C o	1100 C o
Silver	Ag	960 C o	2180 S o
Gold	Au	1063 C o	2660 S o
Copper	Cu	1083 C o	2580 S o
Iron	Fe	1539 S o	2900 C o
Silicon	Si	1415 S o	2350 S o
Nickel	Ni	1455 S o	2913 C o
Barium	Ba	727 S o	1897 C o
Beryllium	Be	1287 S o	2471 S o
Neptunium	Np	644 C o	3901.85 C o
Protactinium	Pa	1572 S o	4027 S o
Plutonium	Pu	640 C o	3228 S o
Actinium	AC	1051 C o	3198 S o
Calcium	Ca	842 C o	1484 S o
Radium	Ra	700 C o	1736.85 C o
Cobalt	co	1495 S o	2927 C o
Antimony	Sb	630.63 C o	1587 S o
Strontium	Sr	777 S o	1382 S o
Uranus	U	1135 C o	4131 C o
Manganese	Mn	1246 S o	2061 S o
Konstantin		1260 S o
Duralumin	Alloy of aluminum, magnesium, copper and manganese	650 C o
Invar	Nickel-iron alloy	1425 C o
Brass	Alloy of copper and zinc	1000 C o
Nickel silver	Alloy of copper, zinc and nickel	1100 C o
Nichrome	An alloy of nickel, chromium, silicon, iron, manganese and aluminum	1400 C o
Steel	Alloy of iron and carbon	1300 C o - 1500 C o
Fechral	An alloy of chromium, iron, aluminum, manganese and silicon	1460 S o
Cast iron	Alloy of iron and carbon	1100 C o - 1300 C o

Table of refractory metals and alloys (over 1600C o)

Element name	Latin designation	Temperatures
		Melting	boiling
Tungsten	W	3420 S o	5555 C o
Titanium	Ti	1680 C o	3300 S o
Iridium	Ir	2447 S o	4428 S o
Osmium	Os	3054 C o	5012 C o
Platinum	Pt	1769.3 C o	3825 C o
Rhenium	Re	3186 S o	5596 S o
Chromium	Cr	1907 S o	2671 S o
Rhodium	Rh	1964 S o	3695 S o
Ruthenium	Ru	2334 S o	4150 C o
Hafnium	hf	2233 S o	4603 C o
Tantalum	Ta	3017 S o	5458 S o
Technetium	Tc	2157 S o	4265 S o
Thorium	Th	1750 C o	4788 S o
Vanadium	V	1910 C o	3407 C o
Zirconium	Zr	1855 S o	4409 S o
Niobium	Nb	2477 S o	4744 S o
Molybdenum	Mo	2623 C o	4639 s o
hafnium carbides		3890 C o
Niobium carbides		3760 S o
Titanium carbides		3150 S o
Zirconium carbides		3530 S o

Melting temperature chemically pure iron is 1539 o C. Technically pure iron obtained as a result of oxidative refining contains a certain amount of oxygen dissolved in the metal. For this reason, its melting point drops to 1530 o C.

The melting point of steel is always lower than the melting point of iron due to the presence of impurities in it. Metals dissolved in iron (Mn, Cr, Ni. Co, Mo, V, etc.) lower the melting point of the metal by 1 - 3 ° C per 1% of the introduced element, and elements from the group of metalloids (C, O, S, P and etc.) at 30 - 80 o C.

During most of the total melting time, the melting point of the metal changes mainly as a result of changes in the carbon content. At a carbon concentration of 0.1 - 1.2%, which is typical for finishing the melt in steelmaking units, the melting temperature of the metal with sufficient accuracy for practical purposes can be estimated from the equation

The heat of fusion of iron is 15200 J/mol or 271.7 kJ/kg.

Boiling point of iron in publications of recent years it is given equal to 2735 o C. However, the results of studies have been published, according to which the boiling point of iron is much higher (up to 3230 o C).

Heat of vaporization of iron is 352.5 kJ/mol or 6300 kJ/kg.

Saturated vapor pressure of iron(P Fe , Pa) can be estimated using the equation

where T is the temperature of the metal, K.

The results of calculating the saturated vapor pressure of iron at different temperatures, as well as the dust content in the oxidizing gas phase above the metal ( X, g/m 3) are presented in Table 1.1.

Table 1.1– Saturated vapor pressure of iron and dust content of gases at different temperatures

According to existing sanitary standards, the content of dust in gases that are emitted into the atmosphere should not exceed 0.1 g/m 3 . From the data in Table 1.1 it can be seen that at 1600 ° C, the dust content of gases above the open surface of the metal is higher than the permissible values. Therefore, it is necessary to clean the gases from dust, which consists mainly of iron oxides.

Dynamic viscosity. The coefficient of dynamic viscosity of the liquid () is determined from the ratio

where F is the interaction force of two moving layers, N;

S is the area of ​​contact between the layers, m2;

is the velocity gradient of the liquid layers along the normal to the flow direction, s -1 .

The dynamic viscosity of iron alloys usually varies within 0.001 - 0.005 Pa s. Its value depends on the temperature and the content of impurities, mainly carbon. When the metal is overheated above the melting point above 25 - 30 ° C, the effect of temperature is not significant.

Kinematic viscosity fluid is the momentum transfer rate in a unit mass flow. Its value is determined from the equation

where is the density of the liquid, kg/m 3 .

The value of the dynamic viscosity of liquid iron is close to 6 10 -7 m 2 /s.

Density of iron at 1550 - 1650 ° C it is 6700 - 6800 kg / m 3. At the crystallization temperature, the density of the liquid metal is close to 6850 kg/m 3 . The density of solid iron at the crystallization temperature is 7450 kg / m 3, at room temperature - 7800 kg / m 3.

Of the usual impurities, carbon and silicon have the greatest influence on the density of iron melts, lowering it. Therefore, the usual composition of liquid cast iron has a density of 6200 - 6400 kg / m 3, solid at room temperature - 7000 - 7200 kg / m 3.

The density of liquid and solid steel occupies an intermediate position between the densities of iron and cast iron and is respectively 6500 - 6600 and 7500 - 7600 kg / m 3.

Specific heat liquid metal practically does not depend on temperature. In estimated calculations, its value can be taken equal to 0.88 kJ/(kg K) for cast iron and 0.84 kJ/(kg K) for steel.

Surface tension of iron has a maximum value at a temperature of about 1550 ° C. In the region of higher and lower temperatures, its value decreases. This distinguishes iron from most metals, which are characterized by a decrease in surface tension when the temperature rises.

The surface tension of liquid iron alloys varies significantly depending on the chemical composition and temperature. Usually it varies within 1000 - 1800 mJ / m 2 (Figure 1.1).

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 from a solid to a liquid. To melt it, it is necessary to bring 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 can still remain in a solid state. With continued exposure, it begins to melt.

Mercury has the lowest melting point - it melts even at -39 ° C, tungsten has the highest - 3422 ° C. For alloys (steel and others), determine exact figure extremely difficult. It all depends on the ratio of the components in them. For alloys, it is written as a numerical interval.

How is the process

Elements, whatever they are: gold, iron, cast iron, steel, or any other - melt about the same. This happens with external or internal heating. External heating is carried out in a thermal furnace. For internal, resistive heating is used, passing an electric current or induction heating in an electromagnetic field high frequency . The impact is about the same.

When heating occurs, the amplitude of thermal vibrations of molecules increases. Appear lattice structural defects accompanied by the breaking of interatomic bonds. The period of lattice destruction and accumulation of defects is called melting.

Depending on the degree at which metals are melted, they are divided into:

1. fusible - up to 600 ° C: lead, zinc, tin;
2. medium-melting - from 600 ° C to 1600 ° C: gold, copper, aluminum, cast iron, iron and most of all elements and compounds;
3. refractory - from 1600 ° C: chromium, tungsten, molybdenum, titanium.

Depending on what the maximum degree is, the melting apparatus is also selected. It should be the stronger, the stronger the heating.

The second important value is the degree of boiling. This is the parameter at which liquids begin to boil. As a rule, it is twice the degree of melting. These values ​​are directly proportional to each other and are usually given at normal pressure.

If the pressure increases, the amount of melting also increases. If the pressure decreases, then it decreases.

Characteristic table

Metals and alloys - indispensable basis for forging, foundry, jewelry and many other areas of production. Whatever the master does ( gold jewelry, cast iron fences, knives made of steel or copper bracelets), for correct operation he needs to know the temperatures at which this or that element melts.

To find out this parameter, you need to refer to the table. In the table you can also find the degree of boiling.

Among the most commonly used elements in everyday life, the melting point indicators are as follows:

1. aluminum - 660 °C;
2. melting point of copper - 1083 °C;
3. melting point of gold - 1063 ° C;
4. silver - 960 °C;
5. tin - 232 °C. Tin is often used for soldering, since the temperature of a working soldering iron is just 250–400 degrees;
6. lead - 327 °C;
7. melting point of iron - 1539 ° C;
8. melting temperature of steel (an alloy of iron and carbon) - from 1300 °C to 1500 °C. It fluctuates depending on the saturation of steel components;
9. melting point of cast iron (also an alloy of iron and carbon) - from 1100 ° C to 1300 ° C;
10. mercury - -38.9 ° C.

As is clear from this part of the table, the most fusible metal is mercury, which is already in a liquid state at positive temperatures.

The degree of boiling of all these elements is almost twice, and sometimes even higher than the degree of melting. For example, for gold it is 2660 ° C, for aluminum - 2519°C, for iron - 2900 ° C, for copper - 2580 ° C, for mercury - 356.73 ° C.

For alloys such as steel, cast iron and other metals, the calculation is approximately the same and depends on the ratio of components in the alloy.

The maximum boiling point for metals is rhenium - 5596°C. The highest boiling point is in the most refractory materials.

There are tables that also indicate density of metals. The lightest metal is lithium, the heaviest is osmium. Osmium has a higher density than uranium and plutonium when viewed at room temperature. Light metals include: magnesium, aluminum, titanium. Heavy metals include most common metals: iron, copper, zinc, tin and many others. Last group- very heavy metals, these include: tungsten, gold, lead and others.

Another indicator found in the tables is thermal conductivity of metals. Worst of all, neptunium conducts heat, and silver is the best thermal conductor. Gold, steel, iron, cast iron and other elements are in the middle between these two extremes. Clear characteristics for each can be found in the desired table.

Melting temperature, along with density, refers to the physical characteristics of metals. Metal melting point- the temperature at which the metal passes from the solid state, in which it is in the normal state (except mercury), to the liquid state when heated. During melting, the volume of the metal practically does not change, therefore, the normal temperature for the melting point is atmospheric pressure does not affect.

Melting point of metals is in the range from -39 degrees Celsius to +3410 degrees. For most metals, the melting point is high, however, some metals can be melted at home by heating on a conventional burner (tin, lead).

Classification of metals by melting point

1. fusible metals, whose melting point fluctuates up to 600 degrees Celsius, for example zinc, tin, bismuth.
2. Medium melting metals, which melt at a temperature from 600 to 1600 degrees Celsius: such as aluminum, copper, tin, iron.
3. Refractory metals, whose melting point reaches over 1600 degrees Celsius - tungsten, titanium, chrome and etc.
4. - the only metal that is under normal conditions (normal atmospheric pressure, average ambient temperature) in a liquid state. The melting point of mercury is about -39 degrees Celsius.

Table of melting points of metals and alloys

Metal	Melting temperature, degrees Celsius
Aluminum	660,4
Tungsten	3420
Duralumin	~650
Iron	1539
Gold	1063
Iridium	2447
Potassium	63,6
Silicon	1415
Brass	~1000
fusible alloy	60,5
Magnesium	650
Copper	1084,5
Sodium	97,8
Nickel	1455
Tin	231,9
Platinum	1769,3
Mercury	–38,9
Lead	327,4
Silver	961,9
Steel	1300-1500
Zinc	419,5
Cast iron	1100-1300

When melting metal for the manufacture of metal products-castings, the choice of equipment, material for metal molding, etc. depends on the melting temperature. It should also be remembered that when alloying a metal with other elements, the melting point most often decreases.

Interesting fact

Do not confuse the concepts of "metal melting point" and "metal boiling point" - for many metals, these characteristics are significantly different: for example, silver melts at a temperature of 961 degrees Celsius, and boils only when heating reaches 2180 degrees.

The melting point of a metal is the minimum temperature at which it changes from solid to liquid. During melting, its volume practically does not change. Metals are classified by melting point depending on the degree of heating.

fusible metals

Fusible metals have a melting point below 600°C. These are zinc, tin, bismuth. Such metals can be melted at home by heating them on the stove, or using a soldering iron. Fusible metals are used in electronics and engineering to connect metal elements and wires for the movement of electric current. The melting point of tin is 232 degrees, and zinc is 419.

Medium melting metals

Medium-melting metals begin to change from a solid to a liquid state at temperatures from 600°C to 1600°C. They are used to make slabs, rebars, blocks and other metal structures suitable for construction. This group of metals includes iron, copper, aluminum, they are also part of many alloys. Copper is added to precious metal alloys such as gold, silver, and platinum. 750 gold contains 25% alloy metals, including copper, which gives it a reddish tint. The melting point of this material is 1084 °C. And aluminum begins to melt at a relatively low temperature of 660 degrees Celsius. It is a light, ductile and inexpensive metal that does not oxidize or rust, so it is widely used in the manufacture of utensils. The melting point of iron is 1539 degrees. It is one of the most popular and affordable metals, its use is widespread in the construction and automotive industries. But in view of the fact that iron is subject to corrosion, it must be further processed and covered with a protective layer of paint, drying oil, or moisture should not be allowed to enter.

Refractory metals

Temperature refractory metals above 1600°C. These are tungsten, titanium, platinum, chromium and others. They are used as light sources, machine parts, lubricants, and in the nuclear industry. They are used to make wires, high-voltage wires and are used to melt other metals with a lower melting point. Platinum begins to change from solid to liquid at 1769 degrees, and tungsten at 3420°C.

Mercury is the only metal that is in a liquid state under normal conditions, namely, normal atmospheric pressure and average temperature. environment. The melting point of mercury is minus 39°C. This metal and its fumes are poisonous, so it is only used in closed containers or in laboratories. A common use of mercury is as a thermometer to measure body temperature.

Man began to own iron (forge, melt) several millennia after mastering work with copper. The first native iron in the form of lumps was found in the Middle East in 3000. And iron metallurgy, according to experts, arose in several places on the planet, different nations mastered this process at different times. Due to this, iron as a material for the manufacture of tools, hunting and war replaced stone and bronze.

The first iron-making processes were called cheese-making. The bottom line was that in the pit fell asleep iron ore With charcoal, which was kindled and tightly clogged, leaving a blast hole through which fresh air was supplied for blasting. In the process of such heating, the melting point of iron, of course, could not be reached, a softened mass (crucible) was obtained, in which there was slag (fuel ash, oxides of ore and rocks).

Further, the resulting kritsa was forged several times, removing slag and other unnecessary inclusions, this laborious process was carried out several times, as a result of which a fifth of the total mass reached the finishing operation. With the invention of the water wheel, it became possible to supply a significant amount of air. Thanks to such a blast, the melting point of iron became achievable, the metal appeared in liquid form.

This metal was cast iron, which was not forged, but was observed to fill the mold well. These were the first experiments on which, with some improvements and changes, have come down to our days. Over time, a method was found for processing cast iron into wrought iron. Pieces of cast iron were loaded with charcoal, during this process the cast iron softened, and impurities, including carbon, were oxidized. As a result, the metal became thick, the melting point of iron increased, i.e. produced wrought iron.

Thus, metallurgists of that time were able to divide a single process into two stages. This two-stage process in the very idea has been preserved to the present day, the changes are more related to the appearance of processes occurring at the second stage. Pure iron or a metal with a minimum of impurities has almost no practical application. The melting point of iron according to the iron-carbon diagram is at point A, which corresponds to 1535 degrees.

Iron comes when it reaches 3200 degrees.

In the open air, iron becomes covered with an oxide film over time, in a humid environment a loose layer of rust appears. Iron has been one of the most important metals ever since its inception. Iron is used mainly in the form of alloys, which differ in properties and composition.

At what temperature iron melts depends on the content of carbon and other components that make up the alloy. The most widely used are carbon alloys - cast iron and steel. Alloys containing more than 2% carbon are called cast iron, less than 2% are steel. Pig iron is obtained in blast furnaces by remelting ores enriched at the sinter plant.

In open-hearth, electric and induction furnaces, in converters.

Metal scrap and cast iron are used as a charge. By oxidizing processes, excess carbon and harmful impurities are removed from the charge, and the addition of alloying materials makes it possible to obtain the required material. To obtain steel and other alloys, modern metallurgy uses electroslag remelting technologies, vacuum, electron beam and plasma melting.

New methods of steel melting are being developed, which provide automation of the process and ensure the production of high-quality metal.

Scientific developments have reached a level where it is possible to obtain materials that can withstand vacuum and high pressure, large temperature differences, aggressive environments, radiation, etc.

The table shows the melting point of metals t pl , their boiling point t to at atmospheric pressure, 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 shown in the table for the following metals: actinium Ac, silver Ag, gold Au, barium Ba, beryllium Be, calcium Ca, cadmium Cd, cobalt Co, chromium Cr, cesium Cs, gallium Ga, hafnium Hf, mercury Hg, indium In, iridium Ir, potassium K, lithium Li, neptunium Np, osmium Os, protactinium Pa, lead Pb, palladium Pd, polonium Po, plutonium Pu, radium Ra, rubidium Pb, rhenium Re, rhodium Rh , ruthenium Ru, antimony Sb, strontium Sr, tantalum Ta, technetium Tc, thorium Th, thallium Tl, uranium U, vanadium V, 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 tungsten to 3422°C). Such metals 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 are the following metals: hafnium, iridium, molybdenum, niobium, osmium, rhenium, ruthenium, tantalum, technetium, tungsten. The melting point of these metals is above 2000°C.

Let's bring examples of melting points of metals widely used in industry and in everyday life:

• melting point of aluminum 660.32 °C;
• melting point of copper 1084.62 °C;
• melting point of lead 327.46 °C;
• melting point of gold 1064.18 °C;
• melting point of tin 231.93 °C;
• melting point of silver 961.78 °C;
• the melting point of mercury is -38.83°C.

The maximum boiling point of the metals presented in the table is rhenium Re - it is 5596 ° C. Also, metals belonging to the group with a high melting point have high boiling points.

The table is in the range from 0.534 to 22.59, that is, the lightest metal is, and the heaviest metal is osmium. It should be noted that osmium has a density greater than even plutonium at room temperature.

In the table, it changes from 6.3 to 427 W / (m deg), so a metal such as neptunium conducts heat the worst, and silver is the best heat-conducting metal.

Melting temperature of steel

A table of values ​​for the melting temperature of steel of common grades is presented. Steels for castings, structural, heat-resistant, carbon and other classes of steels are considered.

The melting temperature of steel is in the range from 1350 to 1535°C. The steels in the table are arranged in ascending order of their melting point.

Melting temperature of steel - table

Steel	t pl, °С	Steel	t pl, °С
Casting steel Kh28L and Kh34L	1350	Corrosion-resistant heat-resistant 12X18H9T	1425
Structural steel 12X18H10T	1400	Heat-resistant high-alloyed 20X23H13	1440
Heat-resistant high-alloyed 20X20H14S2	1400	Heat-resistant high-alloyed 40X10S2M	1480
Heat-resistant high-alloyed 20X25H20S2	1400	Corrosion-resistant steel Kh25S3N (EI261)	1480
Structural steel 12X18H10	1410	Heat-resistant high-alloyed 40Х9С2 (ESKh8)	1480
Corrosion-resistant heat-resistant 12X18H9	1410	Corrosion-resistant ordinary 95X18…15X28	1500
Heat-resistant steel Х20Н35	1410	Corrosion-resistant heat-resistant 15X25T (EI439)	1500
Heat-resistant high-alloyed 20X23H18 (EI417)	1415	carbon steels	1535

Sources:

1. Volkov A. I., Zharsky I. M. Bolshoi chemical reference book. - M: Soviet School, 2005. - 608 p.
2. 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.