Development is identified with improvement. Improving industrial and domestic capabilities is achieved through the use of materials with progressive characteristics. These are, in particular, alloyed metals. Their diversity is determined by the possibilities of correcting the quantitative and qualitative composition of alloying elements.
Natural alloy steel
The first molten iron, which in its properties differed from its relatives, was naturally alloyed. The lost prehistoric meteorite iron contained an increased amount of nickel. He was found in ancient Egyptian burials 4-5 millennia BC. e., from the same monument was built the architecture of Kutab Minar in Delhi (V century). Japanese damask swords were made of iron saturated with molybdenum, and Damascus steel contained tungsten, characteristic of modern high-speed. These were metals, for which ore was mined from certain places.
Alloys of modern production may contain natural components of metallic and nonmetallic origin, which are reflected in their characteristics and properties.
Historical path
The foundation for the development of alloying was laid by the justification of the crucible method of steel melting in Europe in the 18th century. In a more primitive version, crucibles were used in ancient times, including for the smelting of damask and damask steel. At the beginning of the 18th century, this technology was improved on an industrial scale and made it possible to adjust the composition and quality of the starting material.
- The simultaneous discovery of more and more chemical elements prompted researchers to experimental smelting experiments.
- The negative effect of copper on the quality of steel has been established.
- Open brass containing 6% iron.
Experiments were conducted in terms of the qualitative and quantitative effect of tungsten, manganese, titanium, molybdenum, cobalt, chromium, platinum, nickel, aluminum and others on the steel alloy.
The first industrial production of steel alloyed with manganese was established at the beginning of the 19th century. It has been developed since 1856 as part of the Bessemer process of smelting.
Features of alloying
Modern capabilities allow smelting alloy metals of any composition. The main principles of this technology:
- Components are considered alloying only if they are introduced purposefully and the content of each exceeds 1%.
- Sulfur, hydrogen, phosphorus are considered impurities. Boron, nitrogen, silicon, and rarely phosphorus are used as nonmetallic inclusions.
- Volumetric alloying is the introduction of components into a molten substance as part of metallurgical production. Surface is a method of diffusive saturation of the surface layer with necessary chemical elements under the influence of high temperatures.
- During the process, the additives change the crystal structure of the "daughter" material. They can create penetration or exclusion solutions, and can also be placed at the boundaries of metallic and non-metallic structures, creating a mechanical mixture of grains. An important role here is played by the degree of solubility of the elements in each other.
Alloying components
According to the general classification, all metals are divided into ferrous and non-ferrous. Blacks include iron, chromium, and manganese. Colored are divided into light (aluminum, magnesium, potassium), heavy (nickel, zinc, copper), noble (platinum, silver, gold), refractory (tungsten, molybdenum, vanadium, titanium), light, rare earth and radioactive. Alloying metals include a significant variety of light, heavy, noble and refractory non-ferrous, as well as all black.
Depending on the ratio of these elements and the bulk of the alloy, the latter are divided into low-alloyed (3%), medium-alloyed (3-10%) and highly alloyed (more than 10%).
Alloy steels
Technologically, the process is not difficult. The assortment is very wide. The main goals for steels are as follows:
- Strength increase.
- Improved heat treatment results.
- Increase in corrosion resistance, heat resistance, heat resistance, heat resistance, resistance to aggressive working conditions, service life.
The main components are ferrous alloying and refractory metals, which include Cr, Mn, W, V, Ti, Mo, as well as non-ferrous Al, Ni, Cu.
Chrome and nickel are the main components that determine stainless steel (X18H9T), as well as heat-resistant, the working conditions of which are characterized by high temperatures and shock loads (15X5). Up to 1.5% are used for bearings and friction parts (15, 15)
Manganese is a fundamental component of wear-resistant steels (110G13L). In small quantities, it promotes deoxidation and a decrease in the concentration of phosphorus and sulfur.
Silicon and vanadium are elements that increase elasticity in a certain amount and are used for the manufacture of springs and springs (552, 50).
Aluminum is applicable to iron with high electrical resistance (X13YU4).
A significant tungsten content is characteristic of high-speed resistant tool steels (P9, P18K5F2). An alloyed drill for metal from such a material is much more productive and resistant to operation than the same tool made of carbon steel.
Alloy steels have come into everyday use. At the same time, the so-called alloys with amazing properties are known, obtained also by alloying methods. So βwooden steelβ contains 1% chromium and 35% nickel, which determines its high thermal conductivity, which is typical for wood. Diamond includes 1.5% carbon, 0.5% chromium and 5% tungsten, which characterizes it as particularly hard, akin to diamond.
Cast Iron Alloying
Cast irons differ from steels in their significant carbon content (from 2.14 to 6.67%), high hardness and corrosion resistance, but low strength. In order to expand the range of indicative properties and applications, it is alloyed with chromium, manganese, aluminum, silicon, nickel, copper, tungsten, vanadium.
Due to the special characteristics of this iron-carbon material, its alloying is a more complex process than for steel. Each of the components affects the conversion of carbon forms in it. So manganese contributes to the formation of the "right" graphite, which increases strength. The introduction of others results in the transition of carbon to a free state, bleaching of cast iron and a decrease in its mechanical properties.
The technology is complicated by a low melting point (on average, up to 1000 Λ), while for most alloying elements it significantly exceeds this level.
Complex alloying is most effective for cast irons. At the same time, one should take into account the increased likelihood of segregation of such castings, the risk of cracking, and casting defects. Carry out the process more rationally in electromagnetic and induction furnaces. An obligatory sequential step is high-quality heat treatment.
Chromium cast irons are characterized by high wear resistance, strength, heat resistance, resistance to aging and corrosion (3, 16). They are used in chemical engineering and in the production of metallurgical equipment.
Silicon-alloyed cast iron is characterized by high corrosion resistance and resistance to aggressive chemical compounds, although it has satisfactory mechanical properties (ChS13, ChS17). Form parts of chemical equipment, pipelines and pumps.
An example of highly productive complex alloying are heat-resistant cast irons. They contain ferrous and alloying metals such as chromium, manganese, nickel. They are characterized by high resistance to corrosion, wear resistance and resistance to high loads under high temperature conditions - parts of turbines, pumps, engines, equipment of the chemical industry (ChN15D3Sh, ChN19Kh3Sh).
An important component is copper, which is involved in combination with other metals, while increasing the casting characteristics of the alloy.
Alloyed copper
It is used in its pure form and as part of copper alloys, which have a wide variety depending on the ratio of the main and alloying elements: brass, bronze, nickel silver, nelsiber and others.
Pure brass - an alloy with zinc - is not alloyed. If it includes alloying non-ferrous metals in a certain amount - it is considered multicomponent. Bronzes are alloys with other metal components, can be tin and not containing tin, alloy in all cases. Improving their quality is carried out using Mn, Fe, Zn, Ni, Sn, Pb, Be, Al, P, Si.
The silicon content in copper compounds increases their corrosion resistance, strength and elasticity; tin and lead - determine antifriction qualities and positive characteristics regarding machinability; nickel and manganese - components of the so-called wrought alloys, which also positively affect corrosion resistance; iron improves mechanical properties, and zinc - technological.
They are used in electrical engineering, as the main raw material for the manufacture of various wires, material for the manufacture of critical parts for chemical equipment, in mechanical engineering and instrumentation, in pipelines and heat exchangers.
Alloying aluminum
Used in the form of wrought or cast alloys. Its alloyed metals are compounds with copper, manganese or magnesium (duralumin and others), the latter are compounds with silicon, the so-called silumins, while all their possible variants are alloyed with Cr, Mg, Zn, Co, Cu, Si.
Copper increases its ductility; silicon - fluidity and quality casting properties; chromium, manganese, magnesium - improve strength, technological properties of processability by pressure and corrosion resistance. Also, B, Pb, Zr, Ti, Bi can be taken as alloying components that contribute to aging resistance and aggressive working conditions.
Iron is an undesirable component, but is used in small quantities for the production of aluminum foil. Silumins are used for casting critical parts and housings in mechanical engineering. Duralumin and aluminum-based stamping alloys are an important raw material for the manufacture of hull elements, including power structures, in the aircraft industry, shipbuilding and mechanical engineering.
Alloyed metals are involved in all areas of industry as those that have improved mechanical and technological characteristics, in comparison with the starting material. The assortment of alloying elements and the capabilities of modern technology allow for a variety of modifications that expand the possibilities in science and technology.