CREEP-RESISTANT AND MICROSTRUCTURALLY STABLE CHROMIUM-MOLYBDENUM AND / OR CHROMIUM-TUNGSTEN STEELS WITH YTTRIUM(III) OXIDE AND MANUFACTURING PROCESSES FOR THESE STEELS

Abstract

The invention relates to chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steels with oxide compounds (Y2O3) that are creep-resistant, have stable microstructures, and contain yttrium(III) oxide (Y2O3), and to the manufacturing process for these steels. The chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steels and the manufacturing process for these steels, which are the subject of the invention, prevent problems such as coarsening / development of carbides, nitrides, and carbonitrides, grain coarsening, and degradation of the hardened martensite matrix at elevated temperatures and stresses. Working at higher temperatures increases energy efficiency, achieves lower fuel consumption, and also reduces carbon dioxide (CO2) emissions.

Description

Technical field of the invention

[0001] The invention relates to creep-resistant chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steels with yttrium(III) oxide (Y2O3), whose microstructures (or microstructures) contain stable oxidized compounds (Y2O3), and to the manufacturing process for these steels. The chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steels that are the subject of the invention and the manufacturing process for these steels prevent the problems of coarsening / development of carbides, nitrides, and carbonitrides, grain coarsening, and deterioration of the hardened martensite matrix at high temperatures and stresses. Additionally, the possibility of operating at higher temperatures is created by reducing / delaying microstructural degradation. Working at higher temperatures increases energy efficiency, lowers fuel consumption and also reduces carbon dioxide (CO2) emissions. State of the art

[0002] Chromium-molybdenum (Cr-Mo) and chromium-tungsten (Cr-W) steels are used in industries that require high temperatures, such as power plants, soda-lime glass production, and petrochemical plants. The most important properties of these steels are their high creep strength and oxidation resistance. Chromium (Cr), even used in small amounts, balances the formation of hard carbides and improves the heat treatment sensitivity (hardenability) of steels. The addition of large amounts of chromium increases the temperature and corrosion resistance of steels. Molybdenum (Mo) is a standard alloying element used to produce creep-resistant steel that can withstand temperatures up to 530°C. This is because Mo successfully reduces the creep rate of steel by producing carbide. In recent years, tungsten (W) has also been used together with or instead of Mo in high-temperature steels.Tungsten enhances the effect produced by Mo in steel. Consequently, chromium-molybdenum and tungsten steels are widely used in the oil and gas, energy, construction, and automotive industries, which require high temperatures and harsh conditions due to their high corrosion resistance, high temperature resistance, and high tensile strength.

[0003] The plastic deformation and failure that occurs in a material over time under the influence of a constant stress or strain at a constant temperature is called "creep." Plastic deformation caused by creep depends on stress, temperature, and time. Creep can be defined as time-dependent deformation at elevated temperature and constant load or stress. Failure resulting from this condition is called creep damage or sometimes creep rupture. The temperature at which creep begins depends on the composition of the alloy used. Although it occurs at high temperatures, creep can be observed in all temperature ranges [1].

[0004] In the state of the art, the operating temperature and pressure of steels currently used in industrial plants requiring high-temperature applications, such as power plants, are limited to certain values ​​[2]. The reason for this is that the microstructure of steels exposed to high temperature and pressure for long periods deteriorates, and they cannot provide the required mechanical properties under the operating conditions, thus suffering damage. Although high-temperature steels (ASTM A 335; T / P11, T / P22, T / P91, T / P92 (T: Tube, P: Pipe)), chromium-molybdenum (Cr-Mo) steels, or chromium-tungsten (Cr-W) steels) [3] have been developed for plant environments that cause these high-temperature applications, the temperature and pressure values ​​these steels can withstand are limited. The maximum operating temperature used for the best creep-resistant steels developed today (P92, P93) is 625°C.The reason for this is that, although high-temperature steels are creep-resistant, after a certain period of time, the carbides, nitrides, and carbonitrides in the microstructures of the steels that provide creep resistance undergo development and / or coarsening over time. At high temperatures and under stress, coarsening (and / or changes in morphology and composition) of carbides, nitrides, and carbonitrides, especially at grain boundaries, and deterioration of the hardened martensite (ferrite / bainite) matrix cause these steels to undergo creep damage [4].

[0005] Studies have begun to develop 12-chromium (12-Cr) steels to increase the operating temperature and pressure parameters on steels currently used in the state of the art. However, the problem of coarsening of carbides, nitrides, and carbon nitrides at grain boundaries (and / or changes in morphology and composition) and degradation of the hardened martensite (ferrite / bainite) matrix is ​​also evident in 12-Cr steels.

[0006] In the prior art, P11, P22, P91, P92, etc., are used in plant environments that effect the mentioned high-temperature applications. Materials used as alternatives to Cr-Mo, Cr-W, and 12-Cr steels are oxide dispersion strengthened steels or their alloys. The production of oxide dispersion strengthened steels or their alloys is carried out entirely by the mechanical alloying process [5-8]. However, this production process is quite difficult and requires expensive equipment compared to conventional casting processes. Consequently, the use of only the mechanical alloying process in steelmaking is not an economically encouraging approach and is a time-consuming process. The mechanical alloying process consists of the steps of grinding, compacting, and sintering the powders.However, in this process, determining the milling time and sintering temperature is quite difficult and time-consuming. Negative aspects such as powder agglomeration and microporosity after sintering are encountered. However, the part sizes that can be produced remain limited.

[0007] Currently, chromium-molybdenum (Cr-Mo) and chromium-tungsten (Cr-W) steels are produced by atmosphere-controlled casting. However, the production of alloys containing oxide compounds by the casting process is problematic. For example, when Y2O3 steel is used directly in the ladle, this steel remains on the liquid metal due to its density while in the ladle or before it solidifies in the mold. In other words, the desired homogeneous distribution cannot be achieved by the casting process [9].

[0008] Patent document number CN106609313A describes a process for producing high-purity steel by adding a rare earth element. More specifically, this document describes the refinement of elements such as oxygen (O) and sulfur (S), which impair purity and properties, through the use of rare elements in the production of clean steel. In the process according to the invention, Y2O3 is added directly into the molten pit (casting furnace crucible or mold), so the desired homogeneous distribution in the steel product cannot be achieved.

[0009] In the current state of the art, especially since the operating temperature and pressure of the steels used in power plant construction are limited, energy efficiency in power plants decreases and carbon dioxide (CO2) emissions increase. While the efficiency in power plants operating under subcritical conditions was 38%, it has been increased to up to 46% in power plants operating under ultra-supercritical conditions. Efficiency is higher in power plants operating at higher temperatures and pressures, and higher efficiency means lower carbon emissions for fossil fuel-fired power plants. The maximum permissible operating temperature in existing 9 Cr steels (P92, P93) is 625°C

[10] .

[0010] For reasons such as limitations and inadequacies of the state of the art, the working temperatures and pressure values ​​of steels currently used in industrial plants where high-temperature applications are required, such as power plants, are limited to certain parameters in order to avoid being subjected to creep, which is observed as a result of time-dependent deformation at high temperature and constant load. The working temperature, also applied for the best creep-resistant steels developed today (P92, P93), is limited to 625°C. Steels or alloys of these steels, reinforced by oxide dispersion, can be obtained by a mechanical alloying process that is quite difficult and requires expensive equipment compared to traditional casting processes.Where the desired homogeneous distribution in the steels cannot be achieved with the conventional casting process and, in particular, energy efficiency in power plants is decreasing and carbon dioxide (CO2) emissions are increasing, as the working temperature and pressure of the steels used in the construction of power plants are limited, it has become necessary to introduce a steel that eliminates all these problems and the manufacturing process of this steel. Brief description and objects of the invention

[0011] The invention describes chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steels with oxide compounds (Y2O3) that are creep-resistant, have stable microstructures, and contain yttrium(III) oxide (Y2O3), and the manufacturing process for these steels. The chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steels and the manufacturing process for these steels, which are the subject of the invention, prevent problems such as coarsening / development of carbides, nitrides, and carbonitrides, grain coarsening, and degradation of the hardened martensite matrix at high temperatures and stress moments. Working at higher temperatures increases energy efficiency, achieves lower fuel consumption, and also reduces carbon dioxide (CO2) emissions.

[0012] An object of the invention is to provide a steel structure that prevents the problem of carbides coarsening and deterioration of the hardened martensite matrix at high temperatures and stress moments. The problem of carbides coarsening and deterioration of the hardened martensite matrix at high temperatures and stress moments is prevented by the use of Y2O3 in the steel structure that is the subject of the invention. In existing chromium-molybdenum and / or chromium-tungsten steels, high-temperature strength (creep resistance) is provided by carbide, nitride, and carbonitride precipitation phases in the hardened microstructure. However, these phases, which provide creep resistance by preventing dislocation movement, are not thermodynamically stable for long periods at high temperatures and tend to coarsen under the influence of high temperature and high pressure.As the number of these coarsened precipitates decreases and the hardened martensite structure deteriorates, creep resistance decreases over time. When Y2O3 particles are more stable, they not only contribute to their own creep resistance but also slow the coarsening of other precipitates (carbide / carbonitride) that provide creep resistance, thus positively contributing to creep strength. In the invention, by using the casting process containing Y2O3 oxide particles homogeneously distributed throughout the structure, grain coarsening and dislocation movement are prevented and strength is increased. To delay the coarsening of carbides and carbonitrides formed during hardening, M, in particular, is used. 23C6 carbide and Laves phase, which forms after a long time under stress at high temperatures and has the effect of reducing creep resistance as it coarsens, although it is beneficial for creep resistance during its initial formation, and transformation to the Z phase, which reduces the creep resistance of MX-type carbonitrides, a cobalt (Co) element is used together with Y2O3 in the process of the invention. By using a Co element together with Y2O3 in the invention, the Curie temperature is increased, which is the temperature at which ferritic steels lose their magnetic properties

[11] . Accordingly, diffusion is delayed. Due to this effect, carbide coarsening and / or transformation to other phases that have a negative effect on creep resistance are delayed.

[0013] Another object of the invention is to provide a steel structure that allows working even at elevated temperatures. Providing a steel structure that allows working even at high temperatures is achieved by the use of Y2O3 in the steel structure that is the subject of the invention. Since the use of Y2O3 in the steel structure that is the subject of the invention increases the high-temperature resistance of the steel, the problems of carbides coarsening and deterioration of the hardened martensite matrix during periods of stress at elevated temperatures are prevented. As a result, since all negative aspects caused by high temperatures are eliminated, high temperatures no longer represent an obstacle for steel structures.Furthermore, the working temperature of the steels obtained by combining conventional casting and mechanical alloying processes (hybrid production processes) in the production of the steels subject to the invention exceeds 625°C. The most important feature that distinguishes the mechanical alloying process from other processes is the blending of metals and ceramics, which may have very different melting points. The melting temperature (2,425°C) of Y2O3, which is homogeneously distributed throughout the structure, and other intermetallic or secondary phases formed by the addition of Y2O3, impart a higher working temperature to the steel.

[0014] Another object of the invention is to provide a steel structure in which energy efficiency is increased, low fuel consumption is supported, and carbon dioxide (CO2) emissions are also reduced. Since the use of Y2O3 in the steel structure subject to the invention increases the high-temperature resistance of the steel, the problems of carbides coarsening and deterioration of the hardened martensite matrix during stress periods under high-temperature conditions are prevented. As a result, since all negative aspects caused by high temperatures are eliminated, high temperature will no longer be an obstacle for steel structures. By working at higher temperatures, energy efficiency is increased, lower fuel consumption is achieved, and carbon dioxide (CO2) emissions are also reduced.

[0015] Another object of the invention is to provide a more economical and faster steelmaking process. It is a more economical and faster steelmaking process compared to manufacturing processes that use only the mechanical alloying process. The steelmaking process that is the subject of the invention, instead of the mechanical alloying process, which is not an economical process and requires a time-consuming and difficult process, is achieved by using the casting process in addition to the mechanical alloying process. The mechanical alloying process consists of the steps of grinding, compacting, and sintering the powders. However, in this process, determining the grinding time and sintering temperature is quite difficult and time-consuming. Negative aspects such as agglomeration of powders and microporosity after sintering are encountered.However, the part sizes that can be produced remain limited. Consequently, by using both the casting process and the mechanical alloying process in the steelmaking process that is the subject of the invention, instead of the mechanical alloying process, which is not an economical process and requires a time-consuming and difficult process, a more economical and faster steelmaking process is provided compared to manufacturing processes that use only the mechanical alloying process.

[0016] Another object of the invention is to ensure the homogeneous distribution of Y2O3 steels, which allow working at higher temperatures, within chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steels. A homogeneous distribution of Y2O3 in many steel materials, namely Cr-Mo and / or Cr-W in the invention, is achieved by pouring Y2O3 steel into liquid Cr-Mo and / or Cr-W steels after mechanical alloying, pressing, and sintering processes, without direct use in the casting ladle. When Y2O3 steel is used directly in the casting ladle, due to its density, this steel remains on the liquid metal (liquid Cr-Mo and / or Cr-W steel) while it is in the ladle or before it solidifies in the mold. Description of the drawings Fig. 1 Pouring yttrium(III) oxide (Y2O3) into the liquid steel in the furnace Fig.2 Yttrium(III) oxide (Y2O3) introduced into the ladle is introduced into the liquid steel a) from the pot at the bottom of the ladle, b) from under the steel scrap in the ladle pot, c) by being suspended in the liquid steel.

[0017] Definition of the elements / parts of which the invention consists 1. Yttrium(III) oxide (Y2O3) 2. Liquid metal 3. Steel scrap 4. Pot 5. Melting furnace Detailed description of the invention

[0018] The invention relates to chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steels with oxide compounds (Y2O3) that are creep-resistant, have stable microstructures, and contain yttrium(III) oxide (Y2O3), and to the manufacturing process for these steels. The chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steels and the manufacturing process for these steels, which are the subject of the invention, prevent problems such as coarsening / development of carbides, nitrides, and carbonitrides, grain coarsening, and degradation of the hardened martensite matrix at elevated temperatures and stresses. Working at higher temperatures increases energy efficiency, achieves lower fuel consumption, and also reduces carbon dioxide (CO2) emissions.

[0019] When studies in the literature are examined, it is seen that steels with different stable oxide compounds generally contain compounds such as yttrium(III) oxide (Y2O3) (1), lanthanum oxide (La2O3), cerium oxide (Ce2O3), zirconium dioxide (Zr2O), magnesium oxide (MgO), and titanium dioxide (TiO2), etc. However, steels containing Y2O3 show superior properties in environments with different temperatures.

[0020] The manufacturing process of chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steels which are creep-resistant, have stable microstructures and contain yttrium(III) oxide (Y2O3) (1), which is the subject of the invention, comprises the following process steps: i. Subjecting alloyed and unalloyed steel powders containing 0.01%-20% by mass of yttrium(III) oxide (Y2O3) (1) to a mechanical alloying process in a high-energy ball mill, ii. Hot / cold pressing of mechanically alloyed steel powders, iii. Adding steel material containing sintered or unsintered Y2O3 in tablet or powder form to liquid chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steel in the melting furnace (5) and alloyed with cobalt (Co), or adding it simultaneously with liquid chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steel at a rate of 0.25-0.35% Y2O3 compared to the final product and ensuring the formation of the Y2O3 compound in liquid chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steel, iv. Introducing the liquid metal mixture (2) in the melting furnace (5) into the ladle (4) and ensuring the homogeneous distribution of Y2O3 in the liquid by supplying it from the pot at the bottom of the ladle (4) from under the steel scrap (3) in the ladle pot (4) or by suspending it in the liquid steel or by simultaneously adding steel containing Y2O3 produced by mechanical alloying while liquid steel is poured into the mold.

[0021] As a result of the manufacturing process subject to the invention, chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steels with yttrium(III) oxide (Y2O3) (1) are produced that are creep-resistant and have stable microstructures. The resulting steels are then formed into the desired geometries (tube, plate, etc.).

[0022] In process step (iv), depending on the milling time, Y2O3 can be found in a coherent or semi-coherent state (in precipitate form) within the matrix structure during the mechanical alloying process, or, during long milling times, it can be separated into its Y2O3 components and present as a supersaturated solid solution in the yttrium (Y)-iron crystal structure. Upon thermal activation, Y then reforms Y2O3 with oxygen (O). In both possible cases, the mechanically alloyed steel is found in the liquid Y2O3 steel, homogeneously distributed throughout the liquid, compared to the presence of Y2O3 in its pure form.

[0023] In the add-in-mold process, joint formation is achieved by placing the molds on the inlet joint during the final stage before casting. This produces alloy steel containing Y2O3 homogeneously distributed throughout the structure, without any local agglomeration or agglomeration on the ingot surface.

[0024] In the process subject of the invention, a homogeneous distribution of Y2O3 in many steel materials, namely Cr-Mo and / or Cr-W in the invention, is achieved by pouring Y2O3 steel into liquid Cr-Mo and / or Cr-W steels after mechanical alloying, pressing and sintering processes, without direct use in the casting ladle.

[0025] As can be understood from the manufacturing process of chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steels, which are creep-resistant and have oxide compounds with stable microstructures and contain Y2O3, which is the subject of the invention, the working temperature of steels obtained using the mechanical alloying process (process step number i) and conventional casting processes (ii-iv) together (hybrid manufacturing process) exceeds 625°C. In addition, since the use of Y2O3 in the steel structure subject of the invention increases the high-temperature resistance of the steel, the problems of coarsening of carbides and deterioration of the hardened martensite matrix during stress periods at elevated temperatures are prevented, and as a result, since all negative aspects caused by high temperatures are eliminated, high temperature will not be an obstacle for steel structures.Working at higher temperatures increases energy efficiency, lowers fuel consumption and also reduces carbon dioxide (CO2) emissions.

[0026] By using the mechanical alloying process (process step number i) and conventional casting processes (ii-iv) together (hybrid production process) in the production process of creep-resistant chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steels containing Y2O3 and oxide compounds with stable microstructures, which is the subject of the invention, a more economical and faster steelmaking process is provided compared to steelmaking processes that use only the mechanical alloying process. The mechanical alloying process is not economical, but it also results in a time-consuming and difficult production process.

[0027] While in a chromium-molybdenum (Cr-Mo) steel with yttrium(III) oxide (Y2O3) (1) which is the subject of the invention, the Y2O3 ratio is 0.01-5 wt%, the Cr ratio is 0.01-30 wt% and the Mo ratio is 0.01-10 wt%, the Y2O3 ratio is 0.01-5 wt% in a chromium-tungsten (Cr-W) steel with yttrium(III) oxide (Y2O3) (1), the chromium (Cr) ratio is 0.01-30 wt% and the tungsten (W) ratio is 0.01-10 wt%.

[0028] In the structure of a steel in the state of the art, there are 0.001-2.0 wt% carbon (C), 0.01-2 wt% silicon (Si), 0.1-20 wt% manganese (Mn), maximum 0.2 wt% phosphorus (P), maximum 0.2 wt% sulfur (S), 0.01-30.0 wt% nickel (Ni), 0.01-10.0 wt% vanadium (V) and 0.01-25.0 wt% tungsten (W) and iron (Fe) in the remaining ratio (balance). By using chromium (Cr), molybdenum (Mo), cobalt (Co) and yttrium(III) oxide (Y2O3) (1) in the specified proportions in the process which is the subject of the invention, in addition to all these elements in steel, the problems of coarsening / development of carbides, nitrides and carbonitrides, grain coarsening and deterioration of the hardened martensite matrix in steels at high temperatures and stresses are prevented, and in addition, microstructure degradation in steels is reduced / delayed, thus creating the possibility of working at higher temperatures.The same effect applies to chromium-tungsten (Cr-W) steel. Working at higher temperatures increases energy efficiency, lowers fuel consumption, and also reduces carbon dioxide (CO2) emissions. REFERENCES [1] Serdar Korkut. (2021, December 30). Malt Melde Sürünme Davranışı. Serdar Korkut, accessed on September 7, 2022 at https: / / www.serdar-korkut.com / 2017 / 06 / 01 / malzemelerde-surunme-davranisi / [2] J. Hilkes, V. Gross, Welding CrMo steels for power generation and petrochemical applications-past, present and future, Biuletyn Instytutu Spawalnictwa 2 (2013) 12-22. [3] A. Standard, Standard Specification for Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service, A335 / A335M - 19a, 2020, pp. 1-12. [4] K. Sawada, M. Takeda, K. Maruyama, R. Ishii, M. Yamada, Y. Nagae, R. Komine, Effect of W on recovery of lath structure during creep of high chromium martensitic steels, Materials Science and Engineering: A 267(1) (1999) 19-25. [5] N. Oono, S. Ukai, K. Tominaga, N. Ebisawa, K. Tomura, Precipitation of various oxides in ODS ferritic steels, Journal of materials science 54(11) (2019) 8786-8799. [6] L. Zhang, S. Ukai, T. Hoshino, S. Hayashi, X. Qu, Y2O3 evolution and dispersion refinement in Co-base ODS alloys, Acta Materialia 57(12) (2009) 3671-3682. [7] CA Williams, P. Unifantowicz, N. Baluc, GDW Smith, EA Marquis, Acta Materialia 61(6) (2013) 2219-2235. [8] M. Gong, Z. Zhou, H. Hu, G. Zhang, S. Li, M. Wang, Effects of aluminum on microstructure and mechanical behavior of 14Cr-ODS steels, Journal of Nuclear Materials 462 (2015) 502-507. [9] Y. Zhuang, X. Zhang, T. Peng, H. Fan, X. Zhang, Q. Yan, A.A. Volinsky, Effects of yttrium oxides on the microstructure and mechanical properties of 15-15Ti ODS alloy fabricated by casting, Materials Characterization 162 (2020) 110228.

[10] W. Xue, P. Qian-gang, L. Zhi-jun, Z. Hui-qiang, T. Yong-shun, Creep rupture behaviour of P92 steel weldment, Engineering Failure Analysis 18(1) (2011) 186-191.

[11] F. Kabakcı, M. Acarer, M. Baydoğan, A.S. Keskinkılıç, F.K. Acar, H. Çimenoğlu, Effect of Co Addition on the Creep Rupture Properties of 9Cr-1.8 W-x Co Weld Metals, Metallurgical and Materials Transactions A 52(1) (2021) 129-142. ZITATE ENTHALTEN IN DER BESCHREIBUNG

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] CN 106609313A

[0008] Cited non-patent literature

[0000] Serdar Korkut. (2021, December 30). Malt Melde Sürünme Davranışı. Serdar Korkut, accessed on September 7, 2022 at https: / / www.serdar-korkut.com / 2017 / 06 / 01 / malzemelerde-surunme-davranisi

[0028] J. Hilkes, V. Gross, Welding CrMo steels for power generation and petrochemical applications-past, present and future, Biuletyn Instytutu Spawalnictwa 2 (2013) 12-22

[0028] A. Standard, Standard Specification for Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service, A335 / A335M - 19a, 2020, S. 1-12

[0028] K. Sawada, M. Takeda, K. Maruyama, R. Ishii, M. Yamada, Y. Nagae, R. Komine, Effect of W on recovery of lath structure during creep of high chromium martensitic steels, Materials Science and Engineering: A 267(1) (1999) 19-25

[0028] N. Oono, S. Ukai, K. Tominaga, N. Ebisawa, K. Tomura, Precipitation of various oxides in ODS ferritic steels, Journal of materials science 54(11) (2019) 8786-8799

[0028] L. Zhang, S. Ukai, T. Hoshino, S. Hayashi, X. Qu, Y2O3 evolution and dispersion refinement in Co-base ODS alloys, Acta Materialia 57(12) (2009) 3671-3682

[0028] C.A. Williams, P. Unifantowicz, N. Baluc, G.D.W. Smith, E.A. Marquis, The formation and evolution of oxide particles in oxide-dispersion-strengthened ferritic steels during processing, Acta Materialia 61(6) (2013) 2219-2235

[0028] M. Gong, Z. Zhou, H. Hu, G. Zhang, S. Li, M. Wang, Effects of aluminum on microstructure and mechanical behavior of 14Cr-ODS steels, Journal of Nuclear Materials 462 (2015) 502-507

[0028] Y. Zhuang, X. Zhang, T. Peng, H. Fan, X. Zhang, Q. Yan, A.A. Volinsky, Effects of yttrium oxides on the microstructure and mechanical properties of 15-15Ti ODS alloy fabricated by casting, Materials Characterization 162 (2020) 110228

[0028] W. Xue, P. Qian-gang, L. Zhi-jun, Z. Hui-qiang, T. Yong-shun, Creep rupture behaviour of P92 steel weldment, Engineering Failure Analysis 18(1) (2011) 186-191

[0028] F. Kabakcı, M. Acarer, M. Baydoğan, A.S. Keskinkılıç, F.K. Acar, H. Çimenoğlu, Effect of Co Addition on the Creep Rupture Properties of 9Cr-1.8 W-x Co Weld Metals, Metallurgical and Materials Transactions A 52(1) (2021) 129-142

[0028]

Claims

[1] Manufacturing process of chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steels with yttrium(III) oxide (Y2O3), comprising the following process steps: i. Subjecting alloyed and unalloyed steel powders containing 0.01%-20% by mass of yttrium(III) oxide (Y2O3) (1) to a mechanical alloying process in a high-energy ball mill, ii. Hot / cold pressing of mechanically alloyed steel powders, iii. Adding steel material containing sintered or unsintered Y2O3 in tablet or powder form to liquid chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steel in the melting furnace (5) and alloyed with cobalt (Co), or adding it simultaneously with liquid chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steel at a rate of 0.25-0.35% Y2O3 compared to the final product and ensuring the formation of the Y2O3 compound in liquid chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steel, iv. Introducing the liquid metal mixture (2) in the melting furnace (5) into the ladle (4) and ensuring the homogeneous distribution of Y2O3 in the liquid by supplying it from the pot at the bottom of the ladle (4) from under the steel scrap (3) in the ladle pot (4) or by suspending it in the liquid steel or by simultaneously adding steel containing Y2O3 produced by mechanical alloying while liquid steel is poured into the mold. [2] Chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steel containing yttrium(III) oxide (Y2O3) (1) and produced by a process according to claim 1. [3] Chromium-molybdenum (Cr-Mo) and / or chromium-tungsten (Cr-W) steel with yttrium(III) oxide (Y2O3) (1), where in the case of Cr-Mo steel the Y2O3 ratio is 0.01-5 wt%, the Cr ratio is 0.01-30 wt% and the Mo ratio is 0.01-10 wt%, and in the case of Cr-W steel the Y2O3 ratio is 0.01-5 wt%, the chromium (Cr) ratio is 0.01-30 wt% and the tungsten (W) ratio is 0.01-10 wt%.

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