There are many alloy elements in forging machinery,they are different and have different functions.Let’s see what these alloying elements are.

Carbon. This is the most important single alloy element in steel. It is necessary for the formation of cementite (and other carbides), pearlite, spherical cementite (a collection of spherical carbides in a ferrite matrix), bainite, and iron-carbon martensite. Essential. Microstructures composed of one or more of the above components can provide a wide range of mechanical and processing properties. The relative content and distribution of these elements can be controlled by heat treatment, and the microstructure and properties of specific steel workpieces can be changed by this. Most iron and steel metallurgy technologies are applied to the different structures and transformations of iron-carbon alloys. It can be said that many other elements only play a role in their iron-carbon systems to a large extent.

It is assumed that the steel types with different microstructures are compared, and their strength and hardness increase with the increase of carbon content, while toughness and plasticity decrease with the increase of carbon content (its workability, weldability And machinability should also be worsened by an increase in carbon content). Effect of carbon content on mechanical properties. As the carbon content of steel increases and reaches the maximum w (C) of about 0.6%, the hardness of iron-carbon martensite also increases due to the increase of carbon content. Increasing carbon content also improves its hardenability.

The carbon content required for the finished forgings determines the type of steel obtained. Increasing the carbon content of boiling steel will reduce its surface quality. w (C) is about 0.15% -0.30% of the surface quality of the killed steel is relatively poor, it requires special processes to obtain a surface quality similar to the steel with the highest carbon content or lower. Carbon has a medium segregation tendency, and segregation of carbon is often more significant than segregation of other elements.

Manganese. Manganese is usually found in steels supplied in all markets. Manganese is important in the smelting of steel because it is used to decarburize molten steel and is suitable for hot deformation processing of steel to reduce its sensitivity to hot brittleness. Manganese can also form fine veins of manganese sulfide with sulfur, which can improve the cutting performance of steel. It is conducive to the improvement of strength and hardness, but it is not as good as carbon, and the amount of increase depends on the carbon content. Manganese has a great effect on improving the hardenability of steel.

Manganese has less effect on macrosegregation than any of the common elements. Steels with w (Mn) exceeding 0.60% are difficult to boil. Manganese is also good for improving the surface quality of all steels of all carbon content (except for particularly low-carbon boiling steels).

Silicon. It is one of the main deoxidants used in steelmaking. Its content in steel is not necessarily specified in the specification of the chemical composition, but depends on the deoxidation process specified by the product. Boiling steel and gland steel contain a minimum silicon content, Si) is usually below 0.05%. Fully-sedated steel is deoxidized, generally u; (Si) is 0.15% ~ 0.30%. If other deoxidants are also contained, the silicon content in the steel can be reduced. There is little possibility of segregation of silicon. Silicon in low carbon steel is generally not conducive to surface quality, and this situation is even more pronounced for low carbon sulfur grade steels.

Silicon can slightly increase the strength of some ferrites, but it does not cause a large decrease in plasticity. Higher silicon content increases the steel’s resistance to oxidation in air (temperatures up to 260 ° C or 500 ° F) and reduces hysteresis losses. Such high silicon steel forgings are generally more difficult to handle.

Copper. It has a moderate tendency to segregation, and when it reaches a considerable content, it is harmful to the hot deformation process of steel. Copper has a negative impact on forging welding, but it does not seriously affect arc welding and oxyacetylene welding. As a detrimental factor to surface quality, copper will increase the original surface defects of sulfurized steel. However, when w (Cu) exceeds 0.20%, it will help to improve its corrosion resistance in the atmosphere. Steels exceeding this copper content are also called weathering steels.

Chromium. Adding chromium to steel is usually used to enhance corrosion resistance and oxidation resistance, improve hardenability, improve its high temperature strength, or enhance the wear resistance of high carbon steel. Chromium is a strong carbide former. Complex chromium-iron carbides slowly dissolve into the austenite and must have sufficient heating time before the forging is quenched.

Chromium can be used as a hardening element and is often used with toughening elements such as nickel to produce super mechanical properties. Chromium can increase the strength of thorium at higher temperatures. It can also be used with molybdenum to achieve the same purpose.

Nickel. When used as an alloying element in structural steel, it is a ferrite strengthening agent. Because nickel does not form any carbide compounds in the steel, it remains dissolved in the ferrite, thereby increasing the strength and toughness of the ferrite phase. Nickel steel is easier to heat treat because it reduces its critical cooling rate. The combined use of nickel and chromium results in higher hardenability, impact strength and fatigue resistance than can be achieved with carbon steel. Nickel alloys also have superior low temperature strength and toughness.

Molybdenum. Molybdenum can increase the hardenability of steel, and it is particularly useful when it is necessary to maintain this hardenability within specified limits. This element can reduce the tempering brittleness of steel to a minimum when its content (mass fraction) is 0.15% to 0.30%. Hardened steels containing molybdenum must be hardened at higher temperatures in order to obtain the same softening effect. Molybdenum is unique in that it can increase the high temperature tensile strength and creep limit of steel. Its ability to delay the transformation of bainite to ferrite far exceeds its ability to delay the transformation of austenite to bainite, so bainite can be formed during continuous cooling of molybdenum-containing steel.

Vanadium. It is one of the strong carbide-forming elements. Its degree of dissolution in ferrite can give strength and toughness. Vanadium steels exhibit a finer structure than steels of similar composition without vanadium. Vanadium dissolved in austenite before quenching can also improve its greenness, secondary quenching effect on tempering, and improve hot hardness.

Niobium. A small amount of niobium can increase the yield strength of carbon steel and its tensile strength to a lesser extent. Adding niobium with w (Nb) of 0.20% can increase the yield strength of medium carbon steel by 70-100MPa (10-15ksi). With this increase in strength, the notched impact toughness will be greatly reduced, unless special methods are adopted to refine its grains during hot rolling. Grain refinement during hot rolling includes special deformation heat treatment technologies, such as controlled rolling process, low-temperature finishing as the final pressing process, and accelerated cooling after rolling is completed.

Aluminum. It is widely used as a deoxidizer for controlling grain size. When added to the steel in a specified amount, it controls the austenite growth during reheating. Of all the elements, aluminum is most effective in controlling grain size before quenching. Titanium, zirconium, and vanadium are all effective grain growth inhibitors, but for structural grade steels that require heat treatment (quenching and tempering), these three elements have a negative impact on hardenability because of their carbides It is very stable, so it is difficult to dissolve into austenite before quenching.

Boron. Add it to fully calm the steel to improve hardenability. Boron-treated steel is produced in a content range of w (B) of 0.0005% -0.003%. Wherever boron is used to replace other alloying elements, consideration should be given to doing so only for hardenability, as reducing the alloy content may be disadvantageous for some applications. Boron is most effective for carbon steels with low carbon readings.

Titanium. It is mainly used as a deoxidizer and inhibits the growth of grains in fully-sedated steel. Titanium can be added to boron steel because it is easy to firmly combine oxygen and nitrogen in the steel, thereby improving the effectiveness of boron in terms of increasing the hardenability of the steel.

Tungsten. It is used to increase the hardness and promote the refinement of the grain structure, and has excellent heat resistance. At high temperatures, tungsten forms very hard and stable tungsten carbide. Tungsten carbide helps prevent the steel from softening during tempering. Tungsten is widely used in high-speed tool steels.

Zirconium. It inhibits the growth of grains and is used as a deoxidizer in sedated steel. Its main purpose is to improve its hot-rollability in high-strength low-alloy steel (HSLA). The dissolved zirconium can also slightly improve its hardenability.

Calcium. Sometimes used to deoxidize steel. In HSLA, it helps to control the shape of non-metallic inclusions to improve toughness. Steel deoxidized with calcium generally has better cutting performance than steel deoxidized with silicon or aluminum.

Lead. It is sometimes added to carbon steel and alloy steel by mechanical dispersion during the casting process to achieve the purpose of improving the cutting characteristics of steel. For this reason, its added amount (mass fraction) is generally 0.15% -0.35%.

Lead cannot be dissolved in the steel during the casting process, but it can maintain a very small spherical shape to improve toughness and strength. At temperatures close to the melting point of lead, it can cause embrittlement of liquid metals.

Nitrogen. It can increase the strength, hardness and machinability of steel, but it will reduce plasticity and toughness. Nitrogen forms aluminum nitride particles in the aluminum-killed steel to control the grain size of the steel to improve toughness and strength. Nitrogen can also reduce the effect of boron on the hardenability of steel.

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