Summary of effects of 48 elements on steel properties

Element 1: H (hydrogen)

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Source: kaycie-kcd.blogspot.ca

Impact on steel performance:
H is the most harmful element in general steel. Hydrogen dissolved in steel can cause defects such as hydrogen embrittlement and white spots in steel. Like oxygen and nitrogen, hydrogen has very little solubility in solid steel. It dissolves in molten steel at high temperatures. When it cools, it does not reach out and accumulates in the structure to form high-pressure fine pores, which makes the steel’s plasticity, toughness and fatigue strength drop sharply. In severe cases, it will cause cracks and brittle fracture. “Hydrogen embrittlement” mainly occurs in martensitic steel, which is not very prominent in ferrite steel, and generally increases with hardness and carbon content.
On the other hand, H can increase the magnetic permeability of steel, but it also increases the coercive force and iron loss (the coercive force can be increased by 0.5 to 2 times after adding H).

Element 2: B (boron)
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Impact on steel performance:
The main role of B in steel is to increase the hardenability of the steel, thereby saving other relatively rare metals, and nickel, chromium, molybdenum and the like. For this purpose, the content is generally specified in the range of 0.001% to 0.005%. It can replace 1.6% nickel, 0.3% chromium or 0.2% molybdenum. Boron molybdenum should be noted that molybdenum can prevent or reduce temper brittleness, while boron has a slight tendency to promote temper brittleness, so it cannot be used. Boron completely replaces molybdenum.
Boron is added to the medium carbon carbon steel. Since the hardenability is improved, the properties of the steel with a thickness of 20 mm or more can be greatly improved after quenching and tempering. Therefore, 40B and 40MnB steel can be used instead of 40Cr, and 20CrMnTi carburized steel can be replaced by 20Mn2TiB steel. However, since the effect of boron decreases or even disappears with the increase of carbon content in the steel, in the selection of boron-containing carburized steel, it must be considered that after the carburization of the part, the hardenability of the carburized layer will be lower than that of the core. This feature of permeability.
Spring steel is generally required to be completely hardened, and usually the spring area is not large, and it is advantageous to use boron-containing steel. The effect of boron on high-silicon spring steel fluctuates greatly and is inconvenient to adopt.
Boron has a strong affinity for nitrogen and oxygen. The addition of 0.007% boron to the boiling steel can eliminate the aging of steel.

Element 3: C (carbon)
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Impact on steel performance:
C is the main element after iron, which directly affects the strength, ductility, toughness and weldability of steel.
When the carbon content in the steel is below 0.8%, the strength and hardness of the steel increase with the increase of carbon content, while the plasticity and toughness decrease; but when the carbon content is above 1.0%, with the carbon content When the increase, the strength of the steel decreases.
As the carbon content increases, the weldability of the steel deteriorates (steel with a carbon content greater than 0.3%, the weldability decreases significantly), the cold brittleness and ageing sensitivity increase, and the atmospheric corrosion resistance decreases.

Element 4: N (nitrogen)
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Impact on steel performance:
The effect of N on the properties of steel is similar to that of carbon and phosphorus. With the increase of nitrogen content, the strength of steel can be significantly improved, the plasticity, especially the toughness, is also significantly reduced, the weldability is deteriorated, the cold and brittleness is intensified, and the aging tendency is increased. Cold brittleness and hot brittleness, damage to the weldability and cold bending properties of steel. Therefore, the nitrogen content in the steel should be minimized and limited. Generally, the nitrogen content should not be higher than 0.018%.
Nitrogen can reduce the adverse effects of aluminum, antimony, vanadium and other elements, improve the properties of steel, and can be used as an alloying element of low alloy steel. Some grades of stainless steel, appropriate increase in the content of N, can reduce the amount of Cr used, can effectively reduce costs.

Element 5: O (oxygen)
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Impact on steel performance:
O is a harmful element in steel. It naturally enters the steel during the steelmaking process. Although manganese, silicon, iron and aluminum are added for deoxidation at the end of steelmaking, it is impossible to remove. During the solidification of molten steel, the reaction of oxygen and carbon in the solution generates carbon monoxide, which can cause bubbles. Oxygen is mainly present in the form of inclusions such as FeO, MnO, SiO2, Al2O3, etc., which reduces the strength and plasticity of the steel. In particular, it has a serious impact on fatigue strength, impact toughness and the like.
Oxygen will increase the iron loss in the silicon steel, the magnetic permeability and the magnetic induction strength are weakened, and the magnetic aging effect is intensified.

Element 6: Mg (magnesium)
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Impact on steel performance:
It can reduce the number of inclusions in the steel, reduce the size, distribute the distribution, and improve the shape. Trace magnesium can improve the carbide size and distribution of bearing steel, and the carbide particles of magnesium bearing steel are fine and uniform. When the magnesium content is 0.002% to 0.003%, the tensile strength and yield strength increase by more than 5%, and the plasticity remains substantially unchanged.

Element 7: Al (aluminum)
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Impact on steel performance:
Aluminum is added to the steel as a deoxidizer or alloying element, and the deoxidizing ability of aluminum is much stronger than that of silicon and manganese. The main role of aluminum in steel is to refine grains and fix nitrogen in steel, thereby significantly improving the impact toughness of steel and reducing the tendency of cold and brittleness and aging tendency. For example, D-grade carbon structural steel requires that the acid-soluble aluminum content in the steel is not less than 0.015%, and the cold-rolled steel sheet 08AL for deep drawing requires the acid-soluble aluminum content in the steel to be 0.015%-0.065%.
Aluminum can also improve the corrosion resistance of steel, especially when used in combination with molybdenum, copper, silicon, chromium and other elements.
The inclusion of Al in chrome molybdenum steel and chrome steel increases its wear resistance. The presence of Al in high carbon tool steels results in quench brittleness. The disadvantage of aluminum is the influence on the hot workability, weldability and machinability of the steel.

Element 8: Si (silicon)
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Impact on steel performance:
Si is an important reducing agent and deoxidizer in the steel making process: for many materials in carbon steel, it contains less than 0.5% of Si, which is generally brought into the process as a reducing agent and a deoxidizing agent in the steel making process. of.
Silicon can be dissolved in ferrite and austenite to improve the hardness and strength of steel. Its effect is second only to phosphorus, and it is stronger than elements such as manganese, nickel, chromium, tungsten, molybdenum and vanadium. However, when the silicon content exceeds 3%, the plasticity and toughness of the steel are significantly reduced. Silicon can increase the elastic limit, yield strength and yield ratio (σs/σb) of steel, as well as fatigue strength and fatigue ratio (σ-1/σb). This is because silicon or silicon manganese steel can be used as a spring steel.
Silicon can reduce the density, thermal conductivity and electrical conductivity of steel. It can promote the coarsening of ferrite grains and reduce the coercive force. There is a tendency to reduce the anisotropy of the crystal, make the magnetization easy, and the magnetoresistance is reduced, which can be used to produce electrical steel, so the magnetic resistance loss of the silicon steel sheet is low. Silicon can increase the magnetic permeability of ferrite, so that the steel sheet has a higher magnetic induction strength under a weaker magnetic field. However, silicon reduces the magnetic induction strength of steel under strong magnetic fields. Silicon has a strong deoxidizing power, which reduces the magnetic aging effect of iron.
When the silicon-containing steel is heated in an oxidizing atmosphere, a SiO2 film is formed on the surface, thereby improving the oxidation resistance of the steel at a high temperature.
Silicon promotes the growth of columnar crystals in cast steel and reduces plasticity. If the silicon steel cools faster when heated, the internal and external temperature difference of the steel is large due to the low thermal conductivity, and thus it is broken.
Silicon can reduce the weldability of steel. Because silicon is stronger than iron, it is easy to form low-melting silicate during welding, which increases the fluidity of slag and molten metal, causing splashing and affecting the quality of welding. Silicon is a good deoxidizer. When deoxidizing with aluminum, a certain amount of silicon is added as appropriate, which can significantly improve the deoxidation rate. Silicon has a certain residual in steel, which is brought into the raw material during ironmaking steelmaking. In boiling steel, silicon is limited to <0.07%. When intentionally added, a ferrosilicon alloy is added during steel making.

Element 9: P (phosphorus)
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Impact on steel performance:
P is brought into the steel by ore. Generally speaking, phosphorus is also a harmful element. Although phosphorus can increase the strength and hardness of steel, it causes a significant decrease in plasticity and impact toughness. Especially at low temperatures, it makes the steel significantly brittle, a phenomenon called “cold brittle”. The cold and brittleness causes the cold processing and weldability of the steel to deteriorate. The higher the phosphorus content, the greater the cold brittleness, so the control of the phosphorus content in the steel is stricter. High-grade steel: P<0.025%; high-quality steel: P<0.04%; ordinary steel: P<0.085%.
P solid solution strengthening and cold work hardening effect is very good, combined with copper, improve the atmospheric corrosion resistance of low alloy high strength steel, but reduce its cold stamping performance, combined with sulfur and manganese, improve machinability, increase back Fire brittleness and cold brittle sensitivity.
Phosphorus can increase the specific resistance, and the coercive force and eddy current loss can be reduced due to the easy coarse crystal. In the magnetic sense, the magnetic induction of steel with high phosphorus content in the weak medium magnetic field is improved, and the thermal processing of P-containing silicon steel is improved. It is not difficult, but it will make the silicon steel cold and brittle, with a content of ≯0.15% (for example, silicon steel for cold-rolled motors contains P=0.07~0.10%).
Phosphorus is the strongest element that strengthens ferrite. (The effect of P on the recrystallization temperature and grain growth of silicon steel will exceed 4 to 5 times the effect of the equivalent silicon content.)

Element 10: S (sulfur)
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Impact on steel performance:
Sulfur is derived from steel ore and fuel coke. It is a harmful element in steel. Sulfur is present in the steel in the form of iron sulfide (FeS), and FeS and Fe form a low melting point (985 ° C) compound. The hot working temperature of steel is generally above 1150 ~ 1200 ° C, so when the steel is hot processed, the workpiece is cracked due to premature melting of the FeS compound, this phenomenon is called “hot brittle”. Reduces the ductility and toughness of steel, causing cracks during forging and rolling. Sulfur is also detrimental to weldability and reduces corrosion resistance. High-quality steel: S<0.02%~0.03%; high-quality steel: S<0.03%~0.045%; ordinary steel: S<0.055%~0.7% or less.
Due to the brittleness of the chips, a very lustrous surface can be obtained, so it can be used to make steel parts (named fast-cut steel) with low load and high surface finish. (such as Cr14) intentionally add a small amount of sulfur (= 0.2 to 0.4%). Some high speed steel tool steels are used to vulcanize surfaces.

Element 11, 12: K/Na (potassium/sodium)

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Impact on steel performance:
Potassium/sodium can be used as a modifier to spheroidize carbides in white iron, so that white iron (and Leysite steel) can more than double the toughness while maintaining the original hardness; Refinement, the treatment of the wrought iron is stabilized; it is a strong element that promotes austenitization. For example, it can reduce the manganese/carbon ratio of austenitic manganese steel from 10:1 to 13:1 to 4:1. ~5:1.

Element 13: Ca (calcium)

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Impact on steel performance:
Calcium in steel can refine grains, partially desulfurize, and change the composition, quantity and morphology of non-metallic inclusions. It is basically similar to the effect of adding rare earth in steel.
Improve the corrosion resistance, wear resistance, high temperature and low temperature performance of steel; improve the impact toughness, fatigue strength, plasticity and welding performance of steel; increase the coldness, shock resistance, hardness and contact durability of steel.
The addition of calcium in the cast steel greatly improves the fluidity of the molten steel; the surface finish of the casting is improved, the anisotropy of the microstructure in the casting is eliminated; the casting properties, thermal crack resistance, mechanical properties and cutting performance are increased to varying degrees. .
Adding calcium to steel can improve hydrogen cracking resistance and laminating tear resistance, and can extend the use of equipment and tools.
life. Calcium is added to the master alloy as a deoxidizer and inoculant, and acts as a microalloying agent.

Element 14: Ti (titanium)

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Impact on steel performance:
Titanium has strong affinity with nitrogen, oxygen and carbon. It has stronger affinity with sulfur than iron. It is a good deoxidizing deaerator and an effective element for fixing nitrogen and carbon. Although titanium is a strong carbide forming element, it does not combine with other elements to form a composite compound. Titanium carbide has strong binding force, is stable, and is not easy to decompose. It can be slowly dissolved into solid solution in steel only when heated to above 1000 °C.
The titanium carbide particles have an effect of preventing grain growth before they are dissolved. Since the affinity between titanium and carbon is much greater than the affinity between chromium and carbon, titanium is commonly used in stainless steel to fix carbon therein to eliminate the depletion of chromium at the grain boundaries, thereby eliminating or reducing intergranular corrosion of the steel.
Titanium is also one of the strong ferrite forming elements, which strongly increases the temperature of steel A1 and A3. Titanium improves plasticity and toughness in ordinary low alloy steels. Since titanium fixes nitrogen and sulfur and forms titanium carbide, the strength of the steel is increased. After normalizing to refine the grain, precipitation of carbides can significantly improve the plasticity and impact toughness of the steel. Titanium-containing alloy structural steel has good mechanical properties and process properties, and the main disadvantage is that the hardenability is slightly poor.
In high-chromium stainless steel, it is usually necessary to add about 5 times the carbon content of titanium, which not only improves the corrosion resistance of steel (mainly resistance to intergranular corrosion) and toughness; but also tends to improve the grain growth tendency of steel at high temperatures. Welding properties of steel.

Element 15: V (vanadium)

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Impact on steel performance:
Vanadium has a strong affinity with carbon, ammonia and oxygen to form a corresponding stable compound. Vanadium is mainly present in the form of carbides in steel. Its main role is to refine the structure and grain of steel and reduce the strength and toughness of steel. When dissolved in a solid solution at a high temperature, the hardenability is increased; conversely, when it exists in the form of a carbide, the hardenability is lowered. Vanadium increases the tempering stability of hardened steel and produces a secondary hardening effect. The vanadium content in steel is generally not more than 0.5% except for high speed tool steel.
Vanadium can refine grains in ordinary low carbon alloy steel, improve the strength and yield ratio and low temperature characteristics after normalizing, and improve the welding performance of steel.
Vanadium is often used in alloy structural steels in combination with elements such as manganese, chromium, molybdenum and tungsten because it reduces hardenability under general heat treatment conditions. In the quenched and tempered steel, vanadium mainly improves the strength and yield ratio of the steel, refines the grain and the superheat sensitivity of the crucible. In the carburized steel, because the grain can be refined, the steel can be directly quenched after carburizing without secondary quenching.
Vanadium improves strength and yield ratio in spring steel and bearing steel, in particular, increases the ratio limit and elastic limit, and reduces the decarburization sensitivity during heat treatment, thereby improving the surface quality. The five-chrome vanadium-containing bearing steel has high carbonization dispersion and good performance.
Vanadium refines grains in tool steel, reduces overheat sensitivity, increases tempering stability and wear resistance, and extends tool life.

Element 16: Cr (chromium)

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Impact on steel performance:
Chromium can increase the hardenability of steel and has a secondary hardening effect, which can improve the hardness and wear resistance of carbon steel without making the steel brittle. When the content exceeds 12%, the steel has good high-temperature oxidation resistance and oxidation resistance corrosion resistance, and also increases the heat strength of the steel. Chromium is the main alloying element of stainless steel acid-resistant steel and heat-resistant steel.
Chromium can increase the strength and hardness of carbon steel in rolling state, and reduce elongation and reduction of area. When the chromium content exceeds 15%, the strength and hardness will decrease, and the elongation and the area shrinkage rate will correspondingly increase. Parts with chrome steel are easily ground to achieve high surface finish quality.
The main role of chromium in the quenching and tempering structure is to improve the hardenability, so that the steel has good comprehensive mechanical properties after quenching and tempering. In the carburized steel, chromium-containing carbides can also be formed, thereby improving the surface resistance of the material. Grinding.

Chromium-containing spring steel is not easily decarburized during heat treatment. Chromium can improve the wear resistance, hardness and red hardness of tool steel, and has good tempering stability. In electrothermal alloys, chromium increases the oxidation resistance, electrical resistance and strength of the alloy.

Element 17: Mn (manganese)

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Impact on steel performance:
Mn can increase the strength of steel: Since the price of Mn is relatively cheap and can be infinitely solid solution with Fe, the influence on the plasticity is relatively small while increasing the strength of the steel. Therefore, manganese is widely used as a strengthening element in steel. It can be said that substantially all of the carbon steel contains Mn. Our common stamped mild steel, duplex steel (DP steel), phase change induced plastic steel (TR steel), martensitic steel (MS steel), all contain manganese. Generally, the Mn content in mild steel does not exceed 0.5%; the Mn content in high-strength steel increases with increasing strength levels, such as martensitic steel, which can be as high as 3%.
Mn improves the hardenability of steel and improves the hot workability of steel: typical examples are 40Mn and 40 gauge steel.
Mn can eliminate the influence of S (sulfur): Mn can form a high melting point MnS with S in steel smelting, thereby weakening and eliminating the adverse effects of S.
However, the content of Mn is also a double-edged sword. The Mn content is not as high as possible. An increase in the manganese content will reduce the plasticity and weldability of the steel.

Element 18: Co (cobalt)

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Impact on steel performance:
Cobalt is mostly used in special steels and alloys. Cobalt-containing high-speed steel has high high-temperature hardness. Ultra-high hardness and good comprehensive mechanical properties can be obtained by adding molybdenum to maraging steel. In addition, cobalt is also an important alloying element in heat-strength steels and magnetic materials.
Cobalt reduces the hardenability of steel. Therefore, the addition of carbon steel alone reduces the overall mechanical properties after quenching and tempering. Cobalt strengthens ferrite and is added to carbon steel. It improves the hardness, yield point and tensile strength of steel under annealing or normalizing conditions. It has an adverse effect on elongation and reduction of area. Impact toughness also follows. The cobalt content increases and decreases. Since cobalt has antioxidant properties, it is used in heat resistant steels and heat resistant alloys. The cobalt-based alloy gas turbine shows its unique role.

Element 19: Ni (nickel)

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Impact on steel performance:
The beneficial effects of nickel are: high strength, high toughness and good hardenability, high electrical resistance and high corrosion resistance.
On the one hand, the strength of the steel is strongly increased, and on the other hand, the toughness of the iron is always maintained at an extremely high level. Its brittle temperature is extremely low. (When nickel is <0.3%, its brittleness temperature is below -100 °C, when the amount of Ni is increased, about 4 to 5%, its brittle temperature can be reduced to -18 °C. Therefore, it can simultaneously improve the quenched structural steel. Strength and plasticity. Ni=3.5%, Cr-free steel can be air-quenched, and Cr steel with Ni=8% can be converted into M body at a small cooling rate.
Ni has a lattice constant close to that of γ-iron, so it can be a continuous solid solution. This is beneficial to improve the hardenability of steel. Ni can lower the critical point and increase the stability of austenite, so the quenching temperature can be lowered and the hardenability is good. Generally, heavy steel parts with large sections are made of Ni steel. When it is combined with Cr, W or Cr, Mo, the hardenability is particularly high. Nickel-molybdenum steel also has a high fatigue limit. (Ni steel has good thermal fatigue resistance, working in hot and cold times. σ, αk high)
Ni is used in stainless steel to make the steel have a uniform A-body structure to improve corrosion resistance. Ni steel is generally not easy to overheat, so it can prevent the growth of crystal grains at high temperatures and still maintain fine grain structure.

Element 20: Cu (copper)

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Impact on steel performance:
The prominent role of copper in steel is to improve the atmospheric corrosion resistance of ordinary low alloy steels. Especially when combined with phosphorus, the addition of copper can also increase the strength and yield ratio of steel without adversely affecting the weldability. The steel (U-Cu) containing 0.20% to 0.50% of copper has a corrosion-resistant life of 2-5 times that of a general carbon steel rail in addition to wear resistance.
When the copper content exceeds 0.75%, the aging strengthening effect can be produced after solution treatment and aging. When the content is low, its effect is similar to that of nickel, but it is weak. When the content is high, it is unfavorable for thermal deformation processing, and causes copper brittleness during hot deformation processing. 2% to 3% of copper can resist corrosion resistance and stress corrosion corrosion of sulfuric acid, phosphoric acid and hydrochloric acid in austenitic stainless steel.

Element 21: Ga (gallium)

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Impact on steel performance:
Gallium is an element in the steel that blocks the gamma region. Trace amounts of gallium are easily dissolved in ferrite to form a meta-type solid solution. It is not a carbide forming element and does not form oxides, nitrides, or sulfides. In the γ+a two-phase region, trace gallium is easily diffused from austenite to ferrite, and it has a high concentration in ferrite. The effect of trace gallium on the mechanical properties of steel is mainly solid solution strengthening. Gallium has a small improvement in the corrosion resistance of steel.

Element 22: As (arsenic)

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Impact on steel performance:
The arsenic in the ore can only be removed in the sintering process, and can also be removed by chlorination roasting. The arsenic is completely reduced into the pig iron during the smelting process of the blast furnace. When the arsenic content in the steel is more than 0.1%, the steel is increased in brittleness. The welding performance deteriorates. The arsenic content in the ore should be controlled, and the arsenic content in the ore should not exceed 0.07%.
Arsenic has a tendency to increase the yield point σs, tensile strength σb and decrease the elongation δ5 of the low carbon round steel, and the effect of reducing the normal temperature impact toughness Akv of the carbon round steel is obvious.

Element 23: Se (selenium)

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Impact on steel performance:
Selenium can improve the cutting performance of carbon steel, stainless steel and copper, and the surface of the parts is smooth.
MnSe2 is often used as an inhibitor in high magnetic induction oriented silicon steel. The beneficial inclusion of MnSe2 is stronger than the beneficial inclusion of MnS, which is more effective in promoting the growth of primary recrystallized grains, and is more conducive to promoting the preferential growth of secondary recrystallized grains. A highly oriented (110) [001] texture is obtained.

Element 24: Zr (zirconium)

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Impact on steel performance:
Zirconium is a strong carbide forming element and its role in steel is similar to that of lanthanum, cerium and vanadium. The addition of a small amount of zirconium has the functions of degassing, purifying and refining grains, which is beneficial to the low temperature performance of steel and improves the punching performance. It is commonly used in the manufacture of ultra high strength steel and nickel base superalloys for gas engine and ballistic missile structures.

Element 25: Nb (niobium)

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Impact on steel performance:
The cockroaches often coexist with cockroaches, and their effects in steel are similar. Part of the cerium and lanthanum are dissolved in the solid solution to effect solid solution strengthening. When the austenite is dissolved, the hardenability of the steel is remarkably improved. However, in the form of carbides and oxide particles, the grains are refined and the hardenability of the steel is lowered. It can increase the tempering stability of steel and has secondary hardening effect. Trace bismuth can increase the strength of the steel without affecting the ductility or toughness of the steel. Due to the effect of refining the grains, the impact toughness of the steel can be improved and the brittle transition temperature can be lowered. When the content is more than 8 times that of carbon, almost all the carbon in the steel can be fixed, so that the steel has good hydrogen resistance. In the austenitic steel, intergranular corrosion of the steel by the oxidizing medium can be prevented. Due to the fixed carbon and precipitation hardening, the high temperature properties of the heat-strength steel, such as creep strength, can be improved.
铌In the ordinary low-alloy steel for construction, it can improve the yield strength and impact toughness, and reduce the brittle transition temperature and beneficial weldability. In the carburizing and quenching and tempering alloy structural steel while increasing the hardenability. Improve the toughness and low temperature properties of steel. It can reduce the air hardenability of low carbon martensitic heat-resistant stainless steel, avoid hardening and temper brittleness, and improve creep strength.

Element 26: Mo (molybdenum)

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Impact on steel performance:
Molybdenum improves hardenability and heat strength in steel, prevents temper brittleness, increases remanence and coercivity, and resists in certain media.
In quenched and tempered steel, molybdenum can deepen and harden the parts of larger sections, improve the tempering resistance or tempering stability of the steel, so that the parts can be tempered at higher temperatures, thus eliminating more effectively ( Or reduce) residual stress and improve plasticity.
In addition to the above-mentioned effects, molybdenum in carburized steel can also reduce the tendency of carbides to form a continuous network on the grain boundaries in the carburized layer, reduce the retained austenite in the carburized layer, and relatively increase the surface layer. Wear resistance.
In the forging die steel, molybdenum can also maintain the steel with a relatively stable hardness and increase the deformation. Resistance to cracking and abrasion.
In the stainless acid-resistant steel, molybdenum can further improve the corrosion resistance to organic acids (such as formic acid, acetic acid, oxalic acid, etc.) as well as hydrogen peroxide, sulfuric acid, sulfurous acid, sulfate, acid dyes, bleaching powders and the like. In particular, the addition of molybdenum prevents the tendency of pitting corrosion caused by the presence of chloride ions. W12Cr4V4Mo high speed steel containing about 1% molybdenum has wear resistance, tempering hardness and red hardness.

Element 27: Sn (tin)

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Impact on steel performance:
Tin has always been used as a harmful impurity element in steel. It affects the quality of steel, especially the quality of continuous casting. It causes hot brittleness, temper brittleness, cracks and fractures, and affects the welding performance of steel. It is the “five evils” of steel. one. However, tin plays an important role in electrical steel, cast iron, and free-cutting steel.
The size of the silicon steel grains is related to the segregation of tin, and the segregation of tin hinders the growth of the grains. The higher the tin content, the larger the amount of crystal grains precipitated, which effectively hinders the growth of crystal grains. The higher the tin content, the larger the amount of crystal grains precipitated, the stronger the ability to inhibit grain growth, the smaller the crystal grains, and the less iron loss. Tin can change the magnetic properties of silicon steel, improve the favorable texture {100} strength in the finished silicon steel product, and the magnetic induction intensity increases significantly.
When the cast iron contains a small amount of tin, it can improve its wear resistance and affect the fluidity of molten iron. Pearlite ball-milled cast iron has high strength and high wear resistance. In order to obtain as-cast pearlite, tin is added to the alloy liquid during smelting. Since tin is an element that hinders the spheroidization of graphite, it is necessary to control the amount of addition. Generally controlled at ≤0.1%.
Free cutting steel can be divided into sulfur, calcium, lead and composite free cutting steel. Tin has a clear tendency to segregate near inclusions and defects. Tin does not change the shape of sulfide inclusions in steel. Instead, it improves the brittleness by segregation of grain boundaries and phase boundaries, and improves the machinability of steel. When the tin content is >0.05%, the steel has good machinability.

Element 28: Sb (antimony)

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Impact on steel performance:
After adding Sb to the high magnetic induction oriented silicon steel, the primary recrystallization and secondary recrystallization grain size are refined, the secondary recrystallization structure is more perfect, and the magnetic properties are improved. After the cold rolling and decarburization annealing of Sb-containing steel, in the texture component, it is beneficial to develop the secondary recrystallization component {110}<115> or {110}<001> enhancement, secondary crystal school The number has increased.
In Sb-containing welded steel, at the austenitic temperature, Sb in the steel precipitates at the Mn S inclusions and along the prior austenite grain boundaries, increasing the precipitation of Mn S inclusions, which can make the steel structure. Refined and improved toughness.

Element 29: W (tungsten)

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Impact on steel performance:
In addition to carbide formation, tungsten is partially dissolved in iron to form a solid solution. Its effect is similar to that of molybdenum. The general effect is not as significant as molybdenum by mass fraction. The main sample of tungsten in steel is to increase tempering stability, red hardness, heat strength and increased wear resistance due to the formation of carbides. Therefore, it is mainly used for tool steel, such as high speed steel, steel for hot forging die, and the like.
Tungsten forms refractory carbides in high-quality spring steel, which can alleviate the aggregation process of carbides and maintain high high-temperature strength when tempered at higher temperatures. Tungsten also reduces the heat sensitivity of steel, increases hardenability and increases hardness. 65SiMnWA spring steel has high hardness after air-cooling, and the spring steel with 50mm2 cross-section can be hardened in oil, which can be used as an important spring to withstand heavy load, heat resistance (not more than 350 °C) and impact. 30W4Cr2VA high-strength heat-resistant high-quality spring steel with large hardenability, quenching at 1050~1100°C, tensile strength after tempering at 550~650°C reaches 1470~1666Pa. It is mainly used to manufacture springs that are used at high temperatures (not more than 500 ° C).
Since the addition of tungsten can significantly improve the wear resistance and machinability of steel, tungsten is the main element of alloy tool steel.

Element 30: Pb (lead)

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Impact on steel performance:
Lead can improve machinability. Lead-based free-cutting steels have good mechanical properties and heat treatment properties. Lead has been gradually replaced due to environmental pollution and harmful effects in scrap recovery and smelting.
It is difficult for lead and iron to form a solid solution or a compound, and it is easy to be spherically segregated at the grain boundary, which is one of the root causes of brittleness and cracking of the weld at 200 to 480 °C.

Element 31: Bi (Bismuth)

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Impact on steel performance:
Adding 0.1~0.4 bismuth to free-cutting steel can improve the cutting performance of steel. When the crucible is uniformly dispersed in the steel, the crucible is melted in contact with the cutting tool, acts as a lubricant, and breaks the cutting to avoid overheating, thereby increasing the cutting speed. Recently, a large amount of niobium has been added to stainless steel to improve the cutting performance of stainless steel.
Bi exists in free-formed steel in three forms: it is present alone in the steel matrix, surrounded by sulfide and interposed between the steel matrix and the sulfide. In S-Bi free-cutting steel ingots, the deformation rate of MnS inclusions decreases as the Bi content increases. The Bi metal in the steel can inhibit the deformation of the sulfide during the forging process of the steel ingot.
Adding 0.002-0.005% bismuth to cast iron can improve the casting properties of malleable cast iron, increase the tendency of white mouth and shorten the annealing time, and the extension performance of parts is improved. Adding 0.005% niobium to ductile iron improves its shock resistance and tensile resistance. It is difficult to add antimony to steel because the crucible has been volatilized in a large amount at 1500 ° C, and it is difficult to uniformly permeate the crucible into the steel. At present, Bi-Mn combined with a melting point of 1050 ° C is used as an additive in foreign countries, but the utilization rate of niobium is still only about 20%.
Nippon Steel, Posco Steel, and Kawasaki Steel have proposed that adding Bi can significantly increase the B8 value of oriented silicon steel. According to statistics, the total number of inventions for the production of high magnetic induction oriented silicon steel by Nippon Steel, JFE and Bi has exceeded 100. After adding Bi, the magnetic induction reaches 1.90T and above, and the highest reaches 1.99T.

Other elements: Re rare earth

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Impact on steel performance:
Generally speaking, the rare earth element refers to the lanthanides plus, a total of 17 elements. They are close in nature and difficult to separate. Unseparated is called mixed rare earth, which is relatively cheap. The rare earth can be deoxidized, desulfurized and microalloyed in steel can also change the deformability of rare earth inclusions. In particular, it denatures the brittle Al2O3 to a certain extent, which can improve the fatigue properties of most steel grades.
Like rare earth elements such as Ca, Ti, Zr, Mg, and Be, it is the most effective deforming agent for sulfides. Adding an appropriate amount of RE to the steel can cause the oxide and sulfide inclusions to become finely dispersed spherical inclusions, thereby eliminating the hazard of inclusions such as MnS. In production practice, sulfur exists in the form of FeS and MnS in steel. When Mn is high in steel, the formation tendency of MnS is high. Although its higher melting point can avoid the occurrence of hot brittleness, MnS can extend into a strip shape along the processing direction during processing deformation, and the steel’s plasticity, toughness, and fatigue strength are significantly reduced. Therefore, it is necessary to add RE to the steel for deformation treatment. .
Rare earth elements can also improve the oxidation resistance and corrosion resistance of steel. The effect of oxidation resistance exceeds that of elements such as silicon, aluminum, and titanium. It can improve the fluidity of steel, reduce non-metallic inclusions, and make steel structure dense and pure.
The role of rare earths in steel is mainly purification, deterioration and alloying. With the gradual control of oxygen and sulfur content, the traditional purification of molten steel and metamorphism has been weakened, and a more complete clean-up technology and alloying effect have been replaced.
The rare earth element increases the oxygen resistance of the alloy in the iron-chromium-aluminum alloy, maintains the fine grain of the steel at a high temperature, and increases the high-temperature strength, thereby significantly increasing the life of the electrothermal alloy.

Source: China Flanges Manufacturer – Yaang Pipe Industry Co., Limited (www.metallicsteel.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

If you want to have more information about the article or you want to share your opinion with us, contact us at sales@metallicsteel.com

References:

  • kaycie-kcd.blogspot.ca
  • https://www.yaang.com

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