Alloy Steel is a major, high-performance steel materials, most of its production and consumption of molybdenum. With the development of China's economy, China's steel output continues to increase. In 2009, China's crude steel output has reached 57.84 million tons, accounting for 46.6% of the world's crude steel output. At present, most of the steel is consumed in the construction field dominated by ordinary steel; with the development of China's manufacturing industry, especially the promotion of localization of major equipment, the demand for the quantity and variety of alloy steel will increase.
The development of alloy steel represents the level of industrialization in a country. The ratio of the output of alloy steel in China to the total steel output, the variety and quality are much larger than those in the industrialized countries, and the production and application levels are in urgent need of development. Molybdenum is one of the main alloying elements for the production of alloy steel, which plays an important role in improving the quality of alloy steel in China.
The development of molybdenum steel is a microcosm of the development of alloy steel. In addition to the recorded fourteenth-century Japanese knives (which have been lost), molybdenum has not been industrially applied for many years since the discovery of molybdenum in the late eighteenth century. In 1894, Schneider Electric of France produced armor plates containing molybdenum for the first time. Until the First World War, most armored steel production plants were dominated by molybdenum steel. First World War, British tanks using 75mm thick steel sheet containing manganese, because of poor ballistic effect, the use of molybdenum-containing steel plate 25mm thick, good barrier properties and maneuverability. The boom in tank manufacturing in the First and Second World Wars contributed to the surge in demand for molybdenum. After the end of the First World War, people also developed low-molybdenum alloy steel for the automotive industry. In the 1930s, forging and heat treatment of molybdenum-containing high-speed steels deepened the understanding of the role of molybdenum in steel. Molybdenum is widely used as an alloying element in steel. After the Second World War, the application of molybdenum in steel was further broadened, especially for applications containing molybdenum tool steel. Since the density of molybdenum is only half that of tungsten and the price is relatively stable, molybdenum is effectively replaced by molybdenum in many steels. A typical example is the replacement of tungsten-containing T-series high-speed steel with M-series high-speed steel (M2, M4 and M42) containing molybdenum. After 1960, with the development of thermomechanical treatment technology, the demand for molybdenum in the production of high-strength low-alloy steel increased, and it continues to this day. High-strength oil and gas pipelines, high-rise buildings, large ships, pressure vessels, bridges, construction machinery, etc. all require high-strength and high-toughness steel plates. As the most effective alloying element for promoting acicular ferrite transformation, molybdenum is widely used in high-strength low-alloy steel, resulting in X70-X120 pipeline steel, 590-980MPa grade low yield ratio construction steel, refractory construction. Many steels containing molybdenum, high strength and low alloy steel, such as steel and 780-1180 MPa for construction machinery.
Molybdenum is an important alloying element and is used in all types of alloy steels. At present, the production and demand of low alloy steel, structural steel, stainless steel, tool steel and heat resistant steel in alloy steel still affect the molybdenum consumer market. Molybdenum is an alloying element widely used in steel. Because of the nature of molybdenum, molybdenum has a unique and irreplaceable role in steel.
First, the role of molybdenum in steel
The addition of molybdenum to the steel creates interactions between heterogeneous atoms, such as interactions with iron, carbon and alloying elements, which alters the stability of the phases in the steel and may result in some relatively stable new phases. Changed the original organization or formed a new organization. The difference between atomic structure, atomic size and crystal lattice between molybdenum and iron, carbon and alloying elements is the basis for the above changes.
Molybdenum, like iron (room temperature), has a body-centered cubic crystal structure (a = 3.1468) and is a ferrite forming element. Molybdenum has a certain solid solubility in steel (at room temperature, the solid solubility in α-Fe can reach 4%, and the solid solubility in γ-Fe can reach 3%), which can be related to C, N in steel. An element such as B forms a compound and forms an intermetallic compound with other alloying elements.
Molybdenum can be precipitated in various forms in steel. The atomic radius ratio of carbon to molybdenum in steel is r c ∕r Mo =0.56 (<0.59), which forms a hexagonal lattice of MC and M 2 C-type carbides, which acts as a dispersion strengthening effect. In the tungsten-molybdenum steel, a composite M 6 C-type carbide Fe 3 (W,Mo) 3 C can be formed. The atomic radius ratio of nitrogen to molybdenum is r c ∕r Mo = 0.52 (<0.59), and Mo 2 N of the face-centered cubic lattice and MoN of the hexagonal lattice can be formed in the steel. Molybdenum combines with boron in steel to form a complex structure interstitial compound Mo 2 B with a crystal lattice of CuAl 2 type structure. Molybdenum interacts with iron and other alloying elements to form various intermetallic compounds, such as δ phase in Mo-Mn, Mo-Fe, Mo-Co, etc., which are in low carbon high chromium stainless steel, chromium. Nickel austenitic stainless steel and heat-resistant steel appear to cause embrittlement of steel; in multi-alloyed heat-resistant steel, Lavas phase MoFe 2 with complex hexagonal lattice AB 2 appears, which can strengthen austenitic heat-resistant steel. 12%Cr martensitic heat-resistant steel, Cr-Mo-Co martensitic precipitation hardening stainless steel; in multi-alloyed heat-resistant steel and heat-resistant alloy, molybdenum can replace AB 3 ordered phase Ni 3 Al The aluminum forms Ni 3 Mo. Since molybdenum is a moderately forming element of various compounds, molybdenum added in different alloy steels can form a desired compound to provide a dispersion strengthening effect.
The solid solution of molybdenum can affect the iron-carbon phase diagram and change the critical point position of the steel, including temperature and carbon content. Molybdenum increases so that A 3 point temperature, A 4-point temperature decreases, reduce the austenite phase region. Molybdenum has an effect on the microstructure evolution of steel such as austenite formation, supercooled austenite transformation and martensite decomposition during tempering. Molybdenum strongly delays the pearlite phase transformation, delays the bainite transformation, increases the maximum phase transformation speed of pearlite, lowers the maximum phase transformation velocity of bainite, and obviously exhibits pearlite transformation and bainite. Two C curves of the transition. Thereby, it is easy to control the bainite in the steel. Therefore, molybdenum is the most important alloying element in bainitic steel.
In the quenching martensite tempering process, when the tempering temperature is higher than 500 ° C, the solid solution of molybdenum is enriched in the cementite, and the special carbide of molybdenum is also precipitated, accompanied by the dissolution of cementite. In steels containing 4% to 6% of molybdenum, the order of precipitation of special carbides is: Fe 3 C→M 2 C→M 6 C. In low molybdenum steel, cementite and special carbides coexist. The precipitation of special carbides in the steel increases the hardness and strength, resulting in secondary hardening. Secondary hardening is a strengthening mechanism widely used in alloy steels.
Second, the application of molybdenum in steel
Due to the above-mentioned action characteristics of molybdenum in steel, molybdenum becomes an important alloying element in steel: improving the strength and toughness of steel (especially high temperature resistance), improving the corrosion resistance of steel in acid-base solution and marine environment, and improving The hardness and wear resistance of the steel improve the hardenability and hardenability of the steel, and the grain boundary is improved to improve the delayed fracture resistance. Molybdenum is added in combination with elements such as chromium, nickel, manganese, silicon, tungsten, cobalt , ruthenium , vanadium and titanium to produce different types of low alloy steel, alloy structural steel, tool steel, stainless steel, heat resistant steel and super high. Strength steel, etc.
(1) Alloy structural steel
Alloy structural steel is a steel that is widely used in the production and application of alloy steel and is widely used in various industrial fields. In alloy structural steel, the main role of molybdenum is:
1. Improve the hardenability of steel, so that the steel with larger cross section can be hardened and increase the depth of the hardened layer;
2, in the steel containing temper brittle elements (such as Mn, Cr), can prevent or reduce the temper brittleness tendency of steel;
3. Improve the tempering stability of the steel, so that the steel can be tempered at a higher temperature to maintain high hardness, thereby more effectively eliminating or reducing the residual stress in the steel and improving the service life of the parts;
4. In carburized steel, molybdenum can also reduce the tendency of carbides to form a continuous network at the grain boundaries in the carburized layer;
5. In nitriding steel, molybdenum can avoid temper brittleness during nitriding. For example, common nitriding steel 38CrMoAl has no temper brittleness in long-term nitriding temperature and slow cooling environment, and has good heat resistance ( Up to 500 ° C) and good abrasion resistance.
Of the 77 alloy structural steel grades in the national standard GB∕T 3077-1999, 23 contain molybdenum steel. According to the alloy series, there are nine types of molybdenum-containing steels such as CrMo, CrNiMo, CrMoV, CrMoAl, SiMnMoV, MnMoB, CrMnMo, CrMnNiMo, and CrNiMoV. According to different steel types, the content of molybdenum in steel is different. Under normal circumstances, the content of molybdenum in alloy structural steel is in the range of 0.15% to 1.10%.
Among the alloy structural steels, chrome-molybdenum steel is widely used in production and application. In the national standard, chrome molybdenum steel has 7 steel grades such as 12CrMo, 15CrMo, 20CrMo, 30CrMo, 30CrMoA, 35CrMo and 42CrMo. The molybdenum content of this type of steel is between 0.15% and 0.55%, which has higher strength and better. Thermal stability and good resistance to stress corrosion, generally used for parts with complex or large cross-sections (such as shafts, bolts, gears, etc.). 35CrMo steel and 42CrMo steel have high strength, toughness and hardenability, low quenching deformation, high creep strength and long-lasting strength at high temperature, long-term work at 500 °C, and important for manufacturing under high load. Structural parts; 42CrMo steel is a steel that is produced and used more.
Among the alloy structural steels of chromium-manganese-molybdenum steel, the commonly used steel grades are 20CrMnMo and 40CrMnMo steel, and the molybdenum content of the steel is in the range of 0.20% to 0.30%. 20CrMnMo carburized steel has good processing properties, no temper brittleness, can replace carburized steel with high nickel content, and is used for important carburized parts requiring high surface strength and wear resistance. 40CrMnMo steel has good hardenability and high tempering stability. Parts with a diameter less than l00mm can be completely hardened at 850 °C. After tempering at 550-600 °C, the steel has good comprehensive mechanical properties and is mainly used to manufacture bearings and gears.
There are five steel grades such as 12CrMoV, 35CrMoV, 12Cr1MoV, 25Cr2Mo1VA and 25Cr2Mo1VA. The chromium content of this type of steel is generally between 0.20% and 0.35%, but the molybdenum content of 25Cr2Mo1VA steel is as high as 0.90%~1.10. %. The addition of a small amount of vanadium to the chrome molybdenum steel refines the grains and increases the strength, especially the yield strength. Vanadium can inhibit the diffusion of molybdenum in carbides during long-term use at high temperatures, thereby improving the structural stability and thermal strength of steel. This type of steel is used after normalizing and tempering, and has good comprehensive performance. It is mainly used for structural parts on machines such as steam turbines and blowers.
(two) stainless steel
The production of stainless steel consumes about 25% of molybdenum and is an important application area for molybdenum. Molybdenum is used in austenitic stainless steel, martensitic stainless steel, ferritic stainless steel, duplex stainless steel and corrosion resistant alloys. In recent years, the output and consumption of stainless steel in China has continued to increase year by year. In 2009, China produced 8.8 million tons of stainless steel crude steel, and apparently consumed 8.22 million tons of stainless steel, accounting for about 1∕3 of the world's stainless steel output. The main roles of molybdenum in stainless steel are:
1. Improve the corrosion resistance of steel, especially pitting resistance (pitting resistance index PREN=%Cr+3.3×%Mo+16×%N);
2. Improve the strength and secondary hardening effect of martensitic stainless steel;
3. Improve the low temperature mechanical properties of steel.
Both molybdenum and chromium are elements that form and stabilize ferrite and enlarge the ferrite phase region. As an important alloying element in austenitic stainless steel, molybdenum is added to steel to further expand its application range; its main role is to improve steel in reducing media (such as H 2 SO 4 , H 3 PO 4 and some organic acid and urea environments). ) Corrosion resistance and improved corrosion resistance and crevice corrosion resistance of steel. Commonly used molybdenum-containing austenitic stainless steels are 316, 317, 904, etc., mainly used in environments with strong corrosiveness, and the molybdenum content is generally in the range of 2% to 7%.
In recent years, ferritic stainless steel has developed rapidly due to the shortage of nickel resources. In addition to the commonly used ferritic stainless steels such as 409 and 430, in order to expand the application field of ferritic stainless steel, it is necessary to improve the corrosion resistance, thereby using ferritic stainless steel with molybdenum added. The ferritic stainless steel containing molybdenum mainly includes: 434, 444, 445, 446, etc., and the molybdenum content is generally in the range of 1% to 4%.
In martensitic chromium stainless steel, in addition to improving the corrosion resistance of steel, molybdenum can mainly improve the strength and hardness of steel and increase the secondary hardening effect. Especially in the case of low temperature quenching, this effect is widely used in stainless steel tools. In martensitic chromium-nickel stainless steel, molybdenum is added to increase tempering stability and enhance secondary hardening without reducing toughness. In this type of steel, the molybdenum content is generally in the range of 0.5% to 4.0%. In precipitation hardening stainless steel, the main role of molybdenum is to improve the corrosion resistance, low temperature mechanical properties, high temperature strength and tempering stability of steel. The 2% molybdenum in steel can make the steel cold treated under different solid solution conditions. Maintain high hardness. The martensitic stainless steel containing molybdenum mainly includes 1Cr13Mo, 9Cr18Mo, 00Cr13Ni5Mo, 0Cr15Ni7Mo2Al, 0Cr16Ni6MoCuAl and the like.
Molybdenum acts as an element that strongly forms ferrite and shrinks the γ-region, and in the (α+γ) duplex stainless steel, favors the formation of the α phase. In addition to the oxidizing medium, the effect of molybdenum on the corrosion resistance, pitting corrosion and crevice corrosion resistance of (α+γ) duplex stainless steel is also very prominent. Therefore, (α + γ) duplex stainless steel contains 1% to 3% of molybdenum. Commonly used steel grades are 2205, 2507, 2101 and so on.
(three) mold steel
Molybdenum is the main alloying element in alloy tool steels. The main roles of molybdenum in it are:
1. Forming carbides to increase hardness and strength, and increasing wear resistance of steel, especially in large section steels;
2. During quenching and hardening, reduce quenching and bending deformation;
3. Improve the strength and toughness of steel;
4. Add molybdenum in hot forging die steel to improve hardenability and tempering stability.
Forging modules use low-alloy hot-working die steel as medium-carbon low-alloy steel. Commonly used are 4 steels such as 5CrNiMo, 5CrMnMo, 5CrNiMoV, and 5Cr2NiMoV. The carbon content is generally about 0.4%-0.6%, and the main alloying elements are Mn and Cr. Ni, Mo, etc., the molybdenum content is generally from 0.15% to 0.55% (but 1% Mo in 5Cr2NiMoV steel). Due to the proper ratio of various elements, the supercooled austenite is relatively stable, and good hardenability and mechanical properties can be obtained. Molybdenum can effectively improve the thermal strength of steel and inhibit the temper brittleness of steel. Carbides formed from molybdenum and vanadium also have an effect on the strength and wear resistance of steel. This type of steel is generally used mainly as a small forging module. In order to meet the needs of large modules, in recent years, steels for modules with higher alloy contents have been developed, such as 40CrNiMoV4, 30Cr2NiMoV, 2Cr3Mo2NiVSi and other steels.
Medium alloy chromium hot work die steel is a medium carbon alloy steel, commonly used 5Cr5MoSiV, 4Cr5MoSiV1, 4Cr5MoWVSi, SCr5MoWSiV and other five steel grades. The typical steel grade is 4Cr5MoSiV1 (equivalent to H13 steel in ASTM standard, China's annual dosage is about 50,000 tons), and steel generally contains 5% Cr, 1% Mo and a certain amount of vanadium. The steel's supercooled austenite is relatively stable and has high hardenability. Large molds made of this type of steel can achieve higher hardness after air quenching. After quenching, the tempering after 2 to 3 times has obvious secondary hardening phenomenon, good heat resistance, thermal fatigue resistance and corrosion resistance. Medium alloy chromium hot work die steel is widely used in aluminum alloy die casting, precision forging die, hot forging punch, hot extrusion die, hot shear die, hot roll and various hot work die under impact and quench conditions .
Tungsten-molybdenum hot work die steel is a hot work die steel that has been manufacturing molds earlier in history. During the Second World War, tungsten resources were strained, and a series of hot work die steels of molybdenum and tungsten molybdenum were developed. Commonly used are 6 steel grades such as 4Cr3Mo3VSi, 3Cr3Mo3W2V, SCr4W5Mo2V, SCr4Mo2W2SiV, SCr4Mo3 SiMnVAl. This type of steel generally contains about 3% molybdenum and contains 8% to 18% of tungsten. In addition, a certain amount of elements such as vanadium and cobalt are added. Due to the high content of strong carbide forming elements such as W, Mo, V, etc., when tempering is carried out at a temperature ranging from 500 ° C to 550 ° C, a large amount of alloy carbides are precipitated, resulting in a strong secondary hardening phenomenon. This type of steel can achieve a higher tempering hardness, and its hardness value can be comparable to the quenching hardness. Therefore, compared with chromium-based die steels, such steels have higher high-temperature strength, high-temperature hardness, and tempering stability. They are suitable for hot working molds with cavity working temperature exceeding 600 °C, high static load and low impact load, such as mechanical forging die and hot extrusion die, especially for manufacturing materials with large deformation resistance, such as stainless steel. , high temperature alloy, heat resistant steel, etc.
High-strength and high-tough cold-working die steel generally contains high carbon, contains 12% chromium, and has a molybdenum content of about 1%. It is a Leysite steel with strong versatility. A typical steel grade for cold work die steel is Cr12Mo1V1 (corresponding to D2 steel in the ASTM standard), which has high wear resistance due to the presence of a large amount of carbides in the steel and has a small deformation property. Cold work die steel is widely used in die and punch for punching and cold forming, including cold forming dies such as blanking die, punch, stamping die and wire drawing die.
The air-quenched micro-deformation cold-working die steel is generally high-carbon medium-chromium steel, and the molybdenum content is in the range of 1% to 3%. Commonly used are five steel grades such as Cr5Mo1V and Cr4W2MoV. The steel has good air-cooling hardenability and hardenability, and has good shape stability characteristics and good comprehensive performance. It is widely used in cold forming dies such as blanking die, punch, pressure die and wire drawing die.
The base steel has a carbon content of 0.55% to 0.70%, a chromium content of about 4%, a molybdenum content of 2% to 5%, and an alloying element such as W, V, Nb, and Ti. Representative steel grades are 6W6Mo5Cr4V and 6Cr4W3Mo2VNb. Its chemical composition is equivalent to the matrix structure of the high-speed steel after quenching, so the number of eutectic carbides in the base steel is small and uniform, and the toughness is relatively high. Mainly used for cold extrusion die, cold die, forming die, trimming die, cold die, punch and so on.
In plastic mold steel, molybdenum is mainly used in pre-hardened plastic mold steel, and its typical steel grade is 3Cr2Mo (corresponding to P20 steel in ASTM standard). The molybdenum content of 3Cr2NiMnMo steel is generally between 0.30% and 0.50%. The steel is generally hardened in a special steel plant, and the hardness is controlled at about 28-34HRC, which has good cutting performance and polishing performance. Pre-hardened plastic mold steel is widely used in plastics, home appliances, rubber and other industries.
(4) High speed steel
China's high-speed steel production ranks first in the world. Tungsten and molybdenum are the most important alloying elements in high-speed steel. The production of high-speed steel consumes a lot of molybdenum. The main role of molybdenum in it is:
1. Forming a certain amount of primary carbides that are difficult to dissolve, so that the steel can be quenched at a high temperature near the melting point, and the wear resistance of the steel is improved;
2. Forming a sufficient amount of secondary carbide to obtain high Mo(W) martensite by high temperature solution hardening, and precipitation of M2C and MC during tempering is the main factor for secondary hardening and red hardness;
3. Improve the toughness of high speed steel;
4. Due to the addition of molybdenum, the microstructure of the primary carbide in the pure tungsten-containing high-speed steel is improved, thereby improving the thermoplasticity of the steel.
The universal high-speed steel is the basic steel in high-speed steel, and it is also the grade, specification and quantity of high-speed steel cutters, accounting for more than 80% of the total amount of high-speed steel; mainly M2, T1, W9, M7, M10 For other steel grades, except for T1 (W18Cr4V steel, which is rarely used, it is gradually replaced by M2), the rest are W-Mo high-speed steel, and the general molybdenum content is in the range of 3% to 9%. The molybdenum content of the largest amount of M2 steel is about 6%. It is suitable for cutting speed of 25~40m∕min for general steel materials. When the cutting edge temperature is between 5 50 °C and 600 °C, it can maintain the hardness of 55-60HRC. Used in the manufacture of turning tools, milling cutters, hobs, planers, broaches, drills, etc., also used in the manufacture of cold and hot molds, rolls and high temperature bearings that require high wear resistance.
The super-hard high-speed steel has a carbon content of about 1.10%, a molybdenum content of about 3.25% to 10%, and a certain amount of alloying elements such as W, V, and Co (5% to 13%), and the representative steel has M41. And M42. This type of steel is quenched by high temperature. After 2 to 3 times of tempering, the hardness is as high as 68-69HRC, which can be used as ordinary car, milling and cobalt cutting tools. When the workpiece is medium hard hardened steel and general austenitic stainless steel which are difficult to cut, the cutting life of the M42 steel tool is twice as high as that of the M2.
Low-alloy high-speed steel is a high-speed steel with a tungsten equivalent of no more than 12%, which can save precious alloying elements and reduce the cost of steel. Representative steel grades are M50, D950 (Sweden), W4Mo3Cr4VSi, W3Mo2Cr4VSi, and the like. The steel generally has a molybdenum content of 2% to 5%, and also contains alloying elements such as Cr, W, V, and Si. Improve the performance of high speed steel by chemical composition optimization. In recent years, China's low-alloy high-speed steel has developed rapidly, mainly rolling drill bits, machine saw blades, woodworking planers, and some for end mills, taps, etc.; China's annual output of nearly 10,000 tons of low-alloy high-speed steel, mainly making tools such as twist drills Products are exported abroad.
(5) Heat resistant steel
It has long been known that the addition of molybdenum can increase the high temperature strength of steel. As early as 1909, Robin pointed out that adding 0.5% to 2% Mo can increase the high temperature hardness of steel. In ferrite-pearlite heat-resistant steel, martensitic heat-resistant steel, austenitic heat-resistant steel, solid solution molybdenum acts as a strengthening matrix; molybdenum in the form of a compound acts as a dispersion strengthening effect. In ferritic-pearlite heat-resistant steel, molybdenum may form M2C and M6C-type carbides with poor stability, which reduces the content of molybdenum in the matrix α phase and weakens the solid solution strengthening effect of molybdenum in the matrix. Solid solution molybdenum is the most effective element for increasing the high temperature strength of the alpha phase. Typical ferrite-pearlite heat-resistant steels 12Cr1MoV, 2.25Cr1Mo, 15CrMo, 12Cr2MoWVSiTiB, etc. all contain molybdenum. It can be said that molybdenum is already the basic alloying element of heat-resistant steel.
The main strengthening phase in 9% to 12% Cr-type martensitic heat-resistant steel is MC, M23C6 and M6C type carbides. Due to the presence of vanadium and niobium in the steel, some molybdenum and tungsten form M23C6 and M6C, and most of the molybdenum and tungsten dissolve in the matrix to form a solid solution strengthening effect. The proportion of molybdenum and tungsten in the steel affects the long-term strength of the steel. Studies have shown that the addition of molybdenum can increase the creep rupture strength. Typical martensitic heat resistant steels are 2Cr12MoV, 1Cr10Mo2VNb, 1Cr10Mo2VNb, 1Cr9W2MoVNbNB (T∕P91, T∕P92) and the like.
For Cr18Ni9 austenitic heat-resistant steel, the addition of molybdenum and tungsten mainly plays a role of solid solution strengthening. Generally, adding 2% to 3% of molybdenum can significantly increase the permanent strength of 650 °C, such as 1Cr18Ni12Mo2Ti steel. In carbide precipitation-enhanced austenitic heat-resistant steel GH36 and intermetallic compound precipitation-reinforced austenitic heat-resistant steel GH132 (A-286), molybdenum is mainly dissolved in the matrix, which acts as a solid solution strengthening agent to improve the permanent strength of the steel. Improve gap sensitivity.
Molybdenum is used as a solid solution strengthening element (about 90% or more) in high-temperature alloys, such as GH4169 (nickel-based alloy, molybdenum content is about 3.25%), GH4141 (molybdenum content is about 10%), GH4049 (molybdenum content). Steel grades such as around 5%). Superalloys are widely used in aerospace engine blades, turbine disks and aerospace rocket engine parts.
Third, the conclusion
Due to the unique role of molybdenum in steel, it has become an important alloying element in steel. Molybdenum is widely used in alloy steels such as low alloy steel, alloy structural steel, stainless steel, tool steel and heat resistant steel. China has the strategic advantage of molybdenum resources, but the consumption of molybdenum per ton of steel lags behind that of industrialized countries. We should strengthen the application technology research of molybdenum in the field of alloy steel, improve the application technology level of molybdenum in the steel field, and produce higher quality alloy steel to meet the needs of the development of China's equipment manufacturing industry. At the same time, we need to strengthen basic research and develop a new high-performance molybdenum-containing alloy steel based on the understanding of the characteristics of molybdenum. Molybdenum mainly acts in solid solution and precipitation in steel. It needs to pay more attention to the effect of solid solution, to obtain effective phase change structure control ability and improve steel performance.
We also need to find out more advantages of solid solution (or segregation) of molybdenum in steel, such as grain boundary purification, to further improve the various service properties of steel. Using the properties of molybdenum, we can improve the properties of steels related to stress, temperature, medium, time and other factors to obtain higher performance steel. We believe that through the research and development of molybdenum-containing steel, we can improve the innovation capability of steel production and application, and promote the continuous upgrading of China's steel products.
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