High-molybdenum-content powder hastelloy, preparation method thereof and hastelloy steel ingot

Abstract

The invention relates to the technical field of powder metallurgy, in particular to a high-molybdenum-content powder hastelloy, a preparation method thereof and a hastelloy steel ingot. The powder hastelloy consists of the following chemical elements in percentage by mass: 15.0 to 17.0 percent of Mo, 14.5 to 16.5 percent of Cr, 4.0 to 7.0 percent of Fe, 3.0 to 4.5 percent of W, 0 to 0.35 percent of V, 0.3 to 0.8 percent of Mn, less than or equal to 0.01 percent of C, less than or equal to 0.08 percent of Si, less than or equal to 0.2 percent of Ce, less than or equal to 0.2 percent of Y and the balance of Ni and inevitable impurities. And the pitting corrosion resistance equivalent PREN of the hastelloy satisfies 43 < PREN < 48, wherein PREN =% Cr + 1.5 * (% Mo +% W) + 30 *% N. And the corrosion resistance is improved through a'component-corrosion resistance equivalent 'double-control principle. Finally, PREN = Cr + 1.5 (Mo + W) + 30N falls within the range of 43-48, it is guaranteed that a passivation film is stable in the Cl <-> environment, mu phase precipitation caused by too high Mo is avoided, and the pitting corrosion resistance of the high-molybdenum powder hastelloy is improved to the limit.

Description

Technical Field

[0001] This application relates to the field of powder metallurgy technology, and in particular to a high molybdenum content powder Hastelloy alloy, its preparation method, and Hastelloy alloy steel ingots. Background Technology

[0002] Hastelloy is a solid solution strengthened nickel-based corrosion-resistant alloy. - F - It exhibits excellent resistance to pitting corrosion, crevice corrosion, and stress corrosion cracking in highly corrosive media such as sulfuric acid and hydrochloric acid, and has been widely used in extreme working conditions such as flue gas desulfurization, chemical reactors, and nuclear waste treatment.

[0003] However, the traditional "vacuum induction melting + electroslag remelting + multi-fire forging" process has three major bottlenecks: ① uneven alloy element composition; ② yield rate of less than 60%; ③ difference in transverse and longitudinal mechanical properties of the microstructure >15%, and high sensitivity to intergranular corrosion. Summary of the Invention

[0004] This application provides a high-molybdenum-content powdered Hastelloy alloy, its preparation method, and a Hastelloy alloy ingot to solve the following technical problem: how to improve the corrosion resistance of high-molybdenum-content powdered Hastelloy alloy.

[0005] In a first aspect, embodiments of this application provide a high-molybdenum-content powdered Hastelloy alloy, which, by mass fraction, is composed of the following chemical elements: Mo 15.0%–17.0%, Cr 14.5%–16.5%, Fe 4.0%–7.0%, W 3.0%–4.5%, V 0–0.35%, Mn 0.3%–0.8%, C ≤0.01%, Si ≤0.08%, Ce ≤0.2%, Y ≤0.2%, with the balance being Ni and unavoidable impurities; and the pitting resistance equivalent PREN of the Hastelloy alloy satisfies 43 < PREN < 48, where PREN = %Cr + 1.5 × (%Mo + %W) + 30 × %N.

[0006] Optionally, the mass fraction of Mo is 15.5% to 16.5%, the mass fraction of Cr is 15.0% to 16.0%, and the mass fraction of W is 3.5% to 4.2%; the PREN value is 45 to 47.

[0007] Optionally, the C mass fraction is ≤0.005%, the Si mass fraction is ≤0.005%, the O mass fraction is ≤30ppm, and the N mass fraction is ≤50ppm.

[0008] Secondly, embodiments of this application provide a method for preparing high-molybdenum-content powder Hastelloy alloy, comprising: The raw materials with the specified element ratio are melted under a vacuum of ≤1Pa. The melt obtained is refined for 30-40 minutes and electromagnetically stirred for 10 minutes. When the temperature of the melt is 50-150°C higher than the melting point of the alloy, the melt is cast into an electrode rod. The surface of the electrode rod is machined to remove oxide scale and oil stains, resulting in a bright master alloy. The master alloy is continuously melted under conditions of vacuum degree ≤1Pa, temperature 1500~1580℃, and power 150~200kW. The melt obtained by continuous melting is atomized with high-purity nitrogen gas at 2.5~4.5MPa at a flow rate of 300~800Nm3 / h. The powder obtained by atomization is cooled in an argon atmosphere. The cooled powder is dried at 100°C in an inert atmosphere or vacuum, and the dried powder is classified according to the target particle size using an ultrasonic vibrating sieve to obtain alloy powder with an oxygen mass fraction ≤30ppm, sphericity ≥90%, and D50 of 25~65μm. The alloy powder is loaded into a stainless steel sleeve, and the sleeve is then evacuated to a vacuum level of ≤10 after the powder is vibrated to fill the sleeve. -3 Pa and seal the cladding, heat the sealed cladding to 1140-1160℃ at 5-10℃ / min, hold the cladding at 100-140MPa pressure for 2-4h, and then cool the cladding to room temperature at the same rate to obtain Hastelloy steel ingot with a density ≥99.5%.

[0009] Optionally, the atomizing gas pressure is 3.5–4.0 MPa, and the gas flow rate is 550–600 Nm³. 3 / h, the alloy powder D50 is 30-45μm.

[0010] Optionally, the heating rate is 7℃ / min, the holding temperature is 1150℃, the holding time is 3h, and the pressure is 140MPa.

[0011] Optionally, the vacuum degree is ≤0.1Pa, the refining time is 35-40min, and the tapping temperature is 80-120℃ higher than the alloy melting point.

[0012] Optionally, after cooling the cladding to room temperature, the cladding is machined to remove the cladding material, resulting in a Hastelloy steel ingot with no oxide scale on the surface, uniform chemical composition, tensile strength ≥800MPa, and corrosion rate ≤0.5mm / a.

[0013] Thirdly, embodiments of this application provide a high molybdenum content powder Hastelloy steel ingot prepared by any one of the methods described in the second aspect, characterized in that the ingot has an O mass fraction ≤30ppm, an N mass fraction ≤50ppm, a PREN value of 43~48, a density ≥99.5%, a tensile strength ≥800MPa, and a corrosion rate ≤0.5mm / a.

[0014] Optionally, the grain size of the steel ingot is not lower than ASTM grade 5, the difference between transverse and longitudinal mechanical properties is ≤5%, and no intergranular corrosion cracks are found after 120 hours of corrosion in a 50% boiling ferric sulfate solution.

[0015] The technical solutions provided in this application have the following advantages compared with the prior art: This application provides a high-molybdenum-content powder Hastelloy alloy, which improves corrosion resistance through a dual-control principle of "composition-corrosion resistance equivalent". First, the molybdenum content is increased to 15-17%, and 3-4.5% W is added. Utilizing the synergistic effect of Mo / W preferentially adsorbing Cl- in chloride solutions and reducing interfacial tension, the pitting corrosion incubation period is significantly extended. Simultaneously, 14.5-16.5% Cr ensures the formation of a dense passivation film rich in Cr2O3 on the surface. 6+ Further inhibition of Cl- by penetrating the membrane layer - Penetration. Secondly, C ≤ 0.01% and Si ≤ 0.08% are strictly controlled to eliminate Cr-Mo carbide / silicide precipitation at grain boundaries and avoid local Cr / Mo depletion. Trace amounts of Ce / Y act as active rare earth elements, forming CeO2 / Y2O3 pinning points through internal oxidation, refining grains and improving film adhesion, thus reducing the probability of pitting corrosion initiation. Ultimately, PREN = Cr + 1.5(Mo + W) + 30N is kept within the range of 43–48, ensuring the stability of the passivation film in the Cl- environment while avoiding excessive Mo leading to μ-phase precipitation, achieving the ultimate improvement in the pitting corrosion resistance of high-molybdenum powder Hastelloy alloy. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0017] Figure 1 This is a powder electron microscope image of C-276 alloy provided in Example 1 of this application; Figure 2 This is a powder electron microscope image of C-276 alloy provided in Example 2 of this application; Figure 3 This is a powder electron microscope image of C-276 alloy provided in Example 4 of this application; Figure 4The powder polishing pattern of C-276 alloy provided in Comparative Example 1 of this application; Figure 5 The powder polishing pattern of C-276 alloy provided in Comparative Example 2 of this application; Figure 6 Powder electron microscope image of C-276 alloy provided in Comparative Example 3 of this application; Figure 7 Powder electron microscope image of C-276 alloy provided for Comparative Example 4 of this application. Detailed Implementation

[0018] The present invention will be described in detail below with reference to specific embodiments and examples, thereby making the advantages and various effects of the present invention more clearly apparent. Those skilled in the art should understand that these specific embodiments and examples are for illustrative purposes only and are not intended to limit the present invention.

[0019] Throughout this specification, unless otherwise specified, the terminology used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In the event of any conflict, this specification shall prevail.

[0020] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0021] In a first aspect, embodiments of this application provide a high-molybdenum-content powdered Hastelloy alloy, which, by mass fraction, is composed of the following chemical elements: Mo 15.0%–17.0%, Cr 14.5%–16.5%, Fe 4.0%–7.0%, W 3.0%–4.5%, V 0–0.35%, Mn 0.3%–0.8%, C ≤0.01%, Si ≤0.08%, Ce ≤0.2%, Y ≤0.2%, with the balance being Ni and unavoidable impurities; and the pitting resistance equivalent PREN of the Hastelloy alloy satisfies 43 < PREN < 48, where PREN = %Cr + 1.5 × (%Mo + %W) + 30 × %N.

[0022] Molybdenum mass fractions of 15.0%, 15.2%, 15.4%, 15.6%, 15.8%, 16.0%, 16.2%, 16.4%, 16.6%, 16.8%, and 17.0% are incorporated into the austenitic matrix of high-molybdenum-content powder Hastelloy alloys, thereby forming a continuous MoO3 passivation film on the surface of the high-molybdenum-content powder Hastelloy alloys. This film effectively prevents pitting corrosion from initiating. - An increase of 0.05 mol / L in concentration leads to an increase of 1.5 × the increase in molybdenum mass fraction in the pitting resistance equivalent PREN of high molybdenum content powder Hastelloy. Chromium mass fractions of 14.5%, 14.7%, 14.9%, 15.1%, 15.3%, 15.5%, 15.7%, 15.9%, 16.1%, 16.3%, and 16.5% enter the austenitic matrix of high molybdenum content powder Hastelloy, thereby forming a continuous Cr2O3 passivation film on the surface of the high molybdenum content powder Hastelloy, which increases the passivation film rupture potential by 60mV, thereby increasing the pitting resistance equivalent PREN of the high molybdenum content powder Hastelloy by the increase in chromium mass fraction. Iron mass fractions of 4.0%, 4.3%, 4.6%, 4.9%, 5.2%, 5.5%, 5.8%, 6.1%, 6.4%, 6.7%, and 7.0% enter the austenitic matrix of high molybdenum content powder Hastelloy, thereby inhibiting the precipitation of μ phase and narrowing the μ phase precipitation temperature range by 30℃, thus avoiding the decrease in pitting resistance equivalent PREN of high molybdenum content powder Hastelloy caused by μ phase. Tungsten with mass fractions of 3.0%, 3.2%, 3.4%, 3.6%, 3.8%, 4.0%, 4.2%, 4.4%, and 4.5% enters the austenitic matrix of high molybdenum content powder Hastelloy, thereby producing a synergistic passivation effect with molybdenum, which reduces the defect density of the passivation film by 15%, and consequently increases the pitting resistance equivalent PREN of high molybdenum content powder Hastelloy by 1.5 × the increase in tungsten mass fraction. Vanadium mass fractions of 0, 0.05%, 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, and 0.35% enter the austenitic matrix of high molybdenum content powder Hastelloy, thereby refining the grains to ASTM grade 5 or finer, thus shortening the grain boundary corrosion channel length by 20%, and consequently reducing the corrosion rate of high molybdenum content powder Hastelloy by 0.05 mm / a. Manganese with mass fractions of 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, and 0.8% enters the austenitic matrix of high-molybdenum powder Hastelloy alloys, thereby combining with sulfur to form MnS inclusions and reducing the mass fraction of free sulfur. This reduces the probability of sulfide-induced pitting corrosion by 30%, and consequently reduces the corrosion rate of high-molybdenum powder Hastelloy alloys by 0.03 mm / a. Carbon mass fractions of 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, and 0.01% are introduced into the austenitic matrix of high molybdenum content powder Hastelloy, thereby controlling the amount of M23C6 carbide precipitation to below 0.1% by volume, thus reducing the chromium depletion around the carbides to ≥12% by chromium mass fraction, and thus avoiding carbide-induced intergranular corrosion of high molybdenum content powder Hastelloy. Silicon mass fractions of 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, and 0.08% can enter the austenitic matrix of high molybdenum content powder Hastelloy, thereby inhibiting the formation of silicate inclusions and controlling the inclusion density to ≤5 per square millimeter, thus reducing the corrosion rate of high molybdenum content powder Hastelloy by 0.02 mm / a. Cerium mass fractions of 0, 0.05%, 0.10%, 0.15%, and 0.20% enter the austenitic matrix of high molybdenum content powder Hastelloy, thereby removing oxygen mass fraction to ≤30ppm, controlling oxide inclusion size to ≤2μm, and thus reducing the corrosion rate of high molybdenum content powder Hastelloy by 0.02mm / a. Yttrium mass fractions of 0, 0.05%, 0.10%, 0.15%, and 0.20% enter the austenitic matrix of high molybdenum content powder Hastelloy, thereby removing sulfur mass fraction to ≤10ppm, controlling sulfide inclusion size to ≤1μm, and thus reducing the corrosion rate of high molybdenum content powder Hastelloy by 0.02mm / a. Nitrogen mass fractions of 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, and 0.01% enter the austenitic matrix of high molybdenum content powder Hastelloy, thereby reducing the Cr2N precipitation temperature by 50°C, reducing the probability of nitride-induced pitting corrosion by 20%, and consequently increasing the pitting corrosion resistance equivalent PREN of high molybdenum content powder Hastelloy by 30 × the increase in nitrogen mass fraction. Nickel and unavoidable impurities constitute the balance in high-molybdenum powder Hastelloy, thus maintaining a single austenitic phase and stabilizing the PREN value at 43, 44, 45, 46, 47, and 48. This ensures that the high-molybdenum powder Hastelloy exhibits a pitting weight loss of ≤1 mg / cm³ in 6% FeCl₃ solution after 72 hours. 2 .

[0023] In some embodiments, the mass fraction of Mo is 15.5% to 16.5%, the mass fraction of Cr is 15.0% to 16.0%, and the mass fraction of W is 3.5% to 4.2%; the PREN value is 45 to 47.

[0024] In these technical solutions, a "narrower elemental window that converges towards the peak" is used to advance the S-shaped curve relationship between passivation film continuity, PREN value, and critical pitting temperature (CPT) to the range of maximum slope. Molybdenum converges to 15.5%–16.5%, with single values ​​of 15.5, 15.6, 15.7, 15.8, 15.9, 16.0, 16.1, 16.2, 16.3, 16.4, and 16.5, thereby locking the MoO3 passivation film thickness at 5 nm ± 0.2 nm, and further increasing the pitting potential by 80 mV; chromium converges to 15.0%–16.0%, with single values ​​of 15.0, 15.1, 15.2, 15.3, 15.4, and 15. Values ​​of 0.5, 15.6, 15.7, 15.8, 15.9, and 16.0 increase the Cr enrichment in the Cr2O3 film from 40% to 45%, thereby raising the passivation film rupture potential by another 40mV. Tungsten content decreases to 3.5%–4.2%, with single values ​​of 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, and 4.2, thereby increasing the Mo-W synergistic passivation effect index from 1.5 to 1.8, and further reducing the passivation film defect density by 10%. The total number of defects in the three-film (MoO3 film + Cr2O3 film + WO3 film) stack is reduced by 25%, and the PREN value naturally falls into the steepest range of 45–47.

[0025] PREN45~47 corresponds to CPT85~87℃—which happens to be near the point of maximum slope on the S-curve around 85℃. This raises the CPT from "≥75℃" to "≥85℃", resulting in no pitting corrosion even under 3.5% NaCl and 85℃ conditions, thus achieving "further improvement in corrosion resistance".

[0026] The upper limits for molybdenum, chromium, and tungsten are simultaneously lowered, further shrinking the precipitation temperature range of the σ phase by 15℃; the lower limit for chromium is raised, further reducing the chromium depletion width around carbides by 0.3μm; and the lower limit for tungsten is raised, further reducing the nucleation rate of nitrides by 8%. This reduces the probability of "precipitation-induced pitting corrosion" to ≤2%, thereby further reducing the corrosion rate by 0.05mm / a.

[0027] In some embodiments, the C mass fraction is ≤0.005%, the Si mass fraction is ≤0.005%, the O mass fraction is ≤30ppm, and the N mass fraction is ≤50ppm.

[0028] By reducing impurity elements and gaseous elements to ultra-low thresholds at the ppm level, the two microscopic parameters that determine corrosion resistance, namely "passivation film defect density" and "grain boundary chromium-depleted zone width," are simultaneously reduced, further lowering the corrosion rate to the ≤0.4 mm / a level.

[0029] Secondly, embodiments of this application provide a method for preparing high-molybdenum-content powder Hastelloy alloy, comprising: The raw materials with the specified element ratio are melted under a vacuum of ≤1Pa. The melt obtained is refined for 30-40 minutes and electromagnetically stirred for 10 minutes. When the temperature of the melt is 50-150°C higher than the melting point of the alloy, the melt is cast into an electrode rod. The surface of the electrode rod is machined to remove oxide scale and oil stains, resulting in a bright master alloy. The master alloy is continuously melted under conditions of vacuum degree ≤1Pa, temperature 1500~1580℃, and power 150~200kW. The melt obtained by continuous melting is atomized with high-purity nitrogen gas at 2.5~4.5MPa at a flow rate of 300~800Nm3 / h. The powder obtained by atomization is cooled in an argon atmosphere. The cooled powder is dried at 100°C in an inert atmosphere or vacuum, and the dried powder is classified according to the target particle size using an ultrasonic vibrating sieve to obtain alloy powder with an oxygen mass fraction ≤30ppm, sphericity ≥90%, and D50 of 25~65μm. The alloy powder is loaded into a stainless steel sleeve, and the sleeve is then evacuated to a vacuum level of ≤10 after the powder is vibrated to fill the sleeve. -3 Pa and seal the cladding, heat the sealed cladding to 1140-1160℃ at 5-10℃ / min, hold the cladding at 100-140MPa pressure for 2-4h, and then cool the cladding to room temperature at the same rate to obtain Hastelloy steel ingot with a density ≥99.5%.

[0030] Vacuum levels of 1 Pa, 0.8 Pa, 0.6 Pa, 0.4 Pa, 0.2 Pa, 0.1 Pa, 0.08 Pa, 0.06 Pa, 0.04 Pa, 0.02 Pa, and 0.01 Pa are applied to the raw material melting furnace chamber, thereby removing the oxygen mass fraction in the melt to ≤30 ppm, controlling the oxide inclusion density to ≤5 per square millimeter, and thus reducing the corrosion rate of high molybdenum content powder Hastelloy by 0.04 mm / a. Refining times of 30 min, 32 min, 34 min, 36 min, 38 min, and 40 min are applied to the surface of the melt, thereby removing the sulfur mass fraction in the melt to ≤10 ppm, thereby controlling the size of sulfide inclusions to ≤1 μm, and thus reducing the corrosion rate of high molybdenum content powder Hastelloy by 0.03 mm / a. Electromagnetic stirring is applied inside the melt for 10 minutes, thereby controlling the melt composition uniformity deviation within ±0.1wt%, thus controlling the local PREN fluctuation caused by composition segregation within ≤1, and further ensuring that the overall corrosion rate uniformity deviation of high molybdenum content powder Hastelloy is ≤0.02mm / a. The melt temperature is 50℃, 70℃, 90℃, 110℃, 130℃, 150℃, etc., higher than the alloy melting point. It is applied inside the melt, thereby increasing the melt fluidity by 20%, thereby controlling the shrinkage volume fraction of the electrode rod to ≤0.1%, and thus ensuring that the proportion of hollow powder in the subsequent atomization powder of high molybdenum content Hastelloy powder is ≤0.5%. Turning removes oxide scale and oil stains from the surface of the electrode rod, thereby reducing the surface oxygen mass fraction to ≤10ppm, thus preventing the oxide scale from introducing inclusions in the subsequent melting stage, and thus ensuring that the oxygen mass fraction of high molybdenum content Hastelloy powder is ≤30ppm. Vacuum degree ≤1Pa, temperature 1500℃, 1520℃, 1540℃, 1560℃, 1580℃, etc., power 150kW, 160kW, 170kW, 180kW, 190kW, 200kW, etc., are applied in the continuous melting furnace cavity of the master alloy, thereby completely melting the master alloy and maintaining the superheat at 100℃, thereby reducing the melt viscosity by 15%, and thus making the sphericity of the high molybdenum content powder Hastelloy atomized powder ≥90%; Atomizing gas pressures of 2.5 MPa, 3.0 MPa, 3.5 MPa, 4.0 MPa, and 4.5 MPa, and high-purity nitrogen flow rates of 300 Nm³ / h, 400 Nm³ / h, 500 Nm³ / h, 600 Nm³ / h, 700 Nm³ / h, and 800 Nm³ / h, are applied to the outside of the melt flow, thereby breaking the melt into powders with D50 values ​​of 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, and 65 μm, thus controlling the powder specific surface area to 0.1 m². 2 / g, thereby shortening the diffusion distance of high molybdenum content powder Hastelloy to ≤15μm during subsequent hot isostatic pressing; Argon atmosphere cooling is applied inside the atomization tower to control the powder cooling rate at 10. 4 K / s, thereby refining the powder grain size to ≤5μm, and thus enabling the subsequent steel ingot grain size of high molybdenum content powder Hastelloy to reach ASTM grade 5 or finer; 100℃ drying is applied to the cooled powder surface to remove the adsorbed moisture to ≤10ppm, thereby preventing water vapor from forming oxides during subsequent hot isostatic pressing, and thus ensuring that the oxygen mass fraction of high molybdenum content powder Hastelloy steel ingot is ≤30ppm. An ultrasonic vibrating screen is applied to the dried powder particles to classify the powder according to the target particle size, thereby controlling the D50 fluctuation within ±2μm, and thus achieving a density of ≥99.5% after hot isostatic pressing of high molybdenum content powder Hastelloy. Powder vibration packing within a stainless steel sheath is applied to the alloy powder particle group, thereby increasing the packing density to 65%, reducing the deformation required for hot isostatic pressing to 35%, and ultimately achieving a density of ≥99.5% for high-molybdenum content powder Hastelloy steel ingots. Vacuum inside the casing ≤10 -3 Pa is applied between alloy powder particles to remove interstitial oxygen mass fraction to ≤1ppm, thereby preventing oxide film from hindering diffusion and resulting in a difference of ≤5% in the transverse and longitudinal mechanical properties of high molybdenum content powder Hastelloy steel ingots. Heating rates of 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, and 10℃ / min are applied to the outer surface of the cladding to control the temperature difference between the inside and outside of the cladding to ≤10℃, thereby avoiding cracking of the cladding due to thermal stress and ensuring that the surface of the high molybdenum content powder Hastelloy steel ingot is free of oxide scale. Insulation temperatures of 1140℃, 1145℃, 1150℃, 1155℃, and 1160℃, insulation pressures of 100MPa, 110MPa, 120MPa, 130MPa, and 140MPa, and insulation times of 2h, 2.5h, 3h, 3.5h, and 4h are applied to the outer surface of the casing, thereby increasing the diffusion coefficient between powder particles to 10. -11 m 2 / s, thereby reducing the porosity to ≤0.5%, and thus achieving a density of ≥99.5% for high molybdenum content powder Hastelloy steel ingots; The cladding is cooled to room temperature at the same rate, thereby controlling the cooling stress to ≤50MPa, thus avoiding cooling cracks, and thereby ensuring that the tensile strength of the high molybdenum content powder Hastelloy steel ingot is ≥800MPa.

[0031] In some embodiments, the atomizing gas pressure is 3.5–4.0 MPa, and the gas flow rate is 550–600 Nm³. 3 / h, the alloy powder D50 is 30-45μm.

[0032] Atomizing gas pressures of 3.5 MPa, 3.6 MPa, 3.7 MPa, 3.8 MPa, 3.9 MPa, and 4.0 MPa are applied to the outside of the melt flow, thereby stabilizing the powder D50 at 30 μm, 32 μm, 34 μm, 36 μm, 38 μm, 40 μm, 42 μm, 44 μm, and 45 μm, thereby improving the powder sphericity to ≥92%, and consequently achieving a density of ≥99.7% after hot isostatic pressing of high molybdenum content powder Hastelloy. Gas flow rate 550 Nm 3560 Nm³ / h, 570 Nm³ / h, 580 Nm³ / h, 590 Nm³ / h, 600 Nm³ / h, etc., are applied to the outside of the melt flow, thereby increasing the powder cooling rate to 1.2 × 10⁻⁶ Nm³ / h. 4 K / s, thereby refining the powder grain size to ≤4μm, and thus enabling the high molybdenum content powder Hastelloy steel ingot to achieve ASTM grade 6 or finer grain size.

[0033] In some embodiments, the heating rate is 7°C / min, the holding temperature is 1150°C, the holding time is 3 hours, and the pressure is 140 MPa.

[0034] A heating rate of 7℃ / min is applied to the outer surface of the cladding, thereby controlling the temperature difference between the inside and outside of the cladding to ≤8℃, thereby reducing the thermal stress to ≤40MPa, and thus ensuring that the surface of the high molybdenum content powder Hastelloy steel ingot is free of cracks. An insulation temperature of 1150℃ was applied to the outer surface of the casing, thereby locking the peak diffusion coefficient at 10. -11 m 2 / s, thereby reducing the porosity to ≤0.3%, and thus achieving a density of ≥99.7% for high molybdenum content powder Hastelloy steel ingots; A heat treatment time of 3 hours is applied to the outer surface of the casing, thereby increasing the diffusion distance to ≥50μm, completely eliminating the interparticle interface, and thus ensuring that the difference in mechanical properties between the transverse and longitudinal directions of the high molybdenum content powder Hastelloy steel ingot is ≤3%. A pressure of 140 MPa is applied to the outer surface of the cladding, thereby increasing the densification driving force to 140 MPa, thereby reducing the residual porosity to ≤0.2%, and thus enabling the high molybdenum content powder Hastelloy steel ingot to have a tensile strength of ≥820 MPa.

[0035] In some embodiments, the vacuum degree is ≤0.1Pa, the refining time is 35-40min, and the tapping temperature is 80-120℃ higher than the alloy melting point.

[0036] Vacuum levels of 0.1 Pa, 0.08 Pa, 0.06 Pa, 0.04 Pa, 0.02 Pa, and 0.01 Pa are applied inside the melting furnace to remove the oxygen mass fraction of the melt to ≤20 ppm, thereby reducing the number of oxide inclusions to ≤2 per square millimeter, and consequently reducing the corrosion rate of high molybdenum content powder Hastelloy by 0.05 mm / a. Refining times of 35 min, 36 min, 37 min, 38 min, 39 min, and 40 min are applied to the surface of the melt to remove sulfur mass fraction to ≤5 ppm, thereby controlling the size of sulfide inclusions to ≤0.5 μm, and thus reducing the corrosion rate of high molybdenum content powder Hastelloy by 0.04 mm / a. The tapping temperature is 80℃, 90℃, 100℃, 110℃, 120℃, etc., higher than the alloy melting point. It is applied inside the melt, thereby increasing the superheat of the melt to 100℃, thereby controlling the volume fraction of the shrinkage cavity of the electrode rod to ≤0.05%, and thus making the proportion of hollow powder of high molybdenum content powder Hastelloy atomized powder ≤0.3%.

[0037] In some embodiments, after the cladding is cooled to room temperature, the cladding is machined to remove the cladding material, resulting in a Hastelloy steel ingot with no oxide scale on the surface, uniform chemical composition, tensile strength ≥800MPa, and corrosion rate ≤0.5mm / a.

[0038] Machining removes the cladding material, thereby reducing the thickness of the cladding contamination layer by ≥1mm, reducing surface iron contamination to ≤0.1wt%, and thus ensuring that the surface of high molybdenum content powder Hastelloy steel ingots is free of oxide scale. The surface is free of oxide scale, thereby reducing the surface oxygen mass fraction to ≤10ppm, thus avoiding oxide scale as a corrosion source, and making the corrosion rate of high molybdenum content powder Hastelloy ≤0.5mm / a; The chemical composition uniformity deviation is ≤±0.1wt%, thereby controlling the PREN fluctuation to ≤1, thus controlling the local corrosion rate difference to ≤0.05mm / a, and thus making the overall corrosion rate of high molybdenum content powder Hastelloy steel ingot ≤0.5mm / a; Tensile strengths of 800MPa, 810MPa, 820MPa, 830MPa, 840MPa, and 850MPa (a total of 6 individual values) were locked, thereby increasing the critical stress intensity factor for stress corrosion cracking (KISCC) to 80MPa√m (megapascals multiplied by the square root of meters). This resulted in high-molybdenum powder Hastelloy being free from stress corrosion cracking after 1000 hours under 80% yield stress applied by 3.5% NaCl+.

[0039] Thirdly, embodiments of this application provide a high molybdenum content powder Hastelloy steel ingot prepared by any one of the methods described in the second aspect, characterized in that the ingot has an O mass fraction ≤30ppm, an N mass fraction ≤50ppm, a PREN value of 43~48, a density ≥99.5%, a tensile strength ≥800MPa, and a corrosion rate ≤0.5mm / a.

[0040] The oxygen mass fraction of steel ingots is locked at 5ppm, 10ppm, 15ppm, 20ppm, 25ppm, and 30ppm, thereby controlling the number density of oxide inclusions to ≤2 per square millimeter, thus reducing the probability of pitting corrosion induced by inclusions by 80%, and consequently making the corrosion rate of high molybdenum content powder Hastelloy steel ingots ≤0.5mm / a. The nitrogen mass fractions of steel ingots of 5ppm, 10ppm, 15ppm, 20ppm, 25ppm, 30ppm, 35ppm, 40ppm, 45ppm, and 50ppm are locked, thereby reducing the driving force for Cr2N precipitation by 40%, thereby reducing the probability of nitride-induced pitting corrosion by 60%, and thus making the corrosion rate of high molybdenum content powder Hastelloy steel ingots ≤0.5mm / a. PREN values ​​of 43, 44, 45, 46, 47, and 48 are locked, thus locking the critical pitting temperature (CPT) at 80–90℃. Consequently, the pitting weight loss of high-molybdenum content powdered Hastelloy steel ingots in 6% FeCl3 solution after 72 hours is ≤1 mg / cm³. 2 ; Densities of 99.5%, 99.6%, 99.7%, 99.8%, and 99.9% are locked, thereby controlling the porosity to ≤0.5%, which reduces the probability of pores acting as a corrosion source by 90%, and thus makes the corrosion rate of high molybdenum content powder Hastelloy steel ingots ≤0.5mm / a. Tensile strengths of 800MPa, 810MPa, 820MPa, 830MPa, 840MPa, and 850MPa were locked, thereby increasing KISCC to 80MPa√m, and further enabling high-molybdenum content powder Hastelloy steel ingots to achieve high molybdenum content in Cl-containing... - No stress corrosion cracking occurs in the environment; The corrosion rates of 0.1 mm / a, 0.2 mm / a, 0.3 mm / a, 0.4 mm / a, and 0.5 mm / a are locked, thereby controlling the annual corrosion depth to ≤0.5 mm, which in turn ensures that the design life of high molybdenum content powder Hastelloy steel ingots is ≥20 years.

[0041] In some embodiments, the steel ingot has a grain size not lower than ASTM grade 5, a difference of ≤5% between transverse and longitudinal mechanical properties, and no intergranular corrosion cracks after 120 hours of corrosion in a 50% boiling ferric sulfate solution.

[0042] The grain size of the steel ingot is locked according to ASTM grades 5, 6, 7, and 8, thereby increasing the grain boundary area to ≥500 mm / square millimeter. 2 This shortens the grain boundary corrosion channel length by 30%, thereby reducing the corrosion rate of high molybdenum content powder Hastelloy steel ingots by 0.1 mm / a. The differences in mechanical properties between the transverse and longitudinal directions, such as 0%, 1%, 2%, 3%, 4%, and 5%, are locked, thereby reducing the anisotropic stress corrosion sensitivity to ≤5%. As a result, high molybdenum content powder Hastelloy steel ingots do not crack in either the transverse or longitudinal directions for 1000 hours under an environment of 80% yield stress applied by 3.5% NaCl. No intergranular corrosion cracks were observed after 120 hours of corrosion with 50% boiling ferric sulfate solution, thus controlling the grain boundary corrosion depth to ≤10μm and the intergranular corrosion rate to ≤0.05mm / a. Consequently, the design life of high molybdenum content powder Hastelloy steel ingots in sulfuric acid environment is ≥15 years.

[0043] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If no corresponding national standard exists, then generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0044] Example 1 A high-molybdenum content powder Hastelloy alloy, by mass fraction, is composed of the following chemical elements: The alloy is composed of 16.0% Mo, 15.5% Cr, 5.5% Fe, 3.8% W, 0.2% V, 0.5% Mn, 0.005% C, 0.005% Si, 0.01% Ce, 0.01% Y, and ≤0.005% N, with the balance being Ni and unavoidable impurities. The pitting resistance equivalent PREN = %Cr + 1.5 × (%Mo + %W) + 30 × %N = 45.35, satisfying 43 < PREN < 48.

[0045] The preparation method is as follows: (1) Smelting of master alloy Under vacuum conditions of ≤0.1Pa, pure nickel plates are first melted and the residue on the inner wall of the crucible is washed away; then the remaining elements are added, refined for 38 minutes, and electromagnetically stirred for 10 minutes; when the melt temperature is 100℃ higher than the alloy melting point, it is cast into an electrode rod; the surface oxide scale and oil stains are removed by turning to obtain a bright master alloy.

[0046] (2) Powdering of master alloy The master alloy was continuously melted under vacuum conditions ≤0.1 Pa, temperature 1530℃, and power 180 kW; the melt was atomized with 3.5 MPa high-purity nitrogen gas at a flow rate of 550 Nm³ / h; the resulting powder was cooled to room temperature in an Ar atmosphere, dried at 100℃ in an inert atmosphere, and then classified by an ultrasonic vibrating sieve to obtain normal spherical alloy powder with an oxygen content of 20 ppm, sphericity of 92%, and D50=62 μm.

[0047] (3) Powder hot isostatic pressing The alloy powder was loaded into a stainless steel sleeve, vibrated during loading, and then evacuated to a vacuum level of ≤1×10⁻⁶. - The pressure was increased to 1150℃ at 7℃ / min and sealed; then heated to 140MPa for 3 hours and cooled to room temperature at the same rate; the cladding was removed by machining to obtain Hastelloy steel ingot.

[0048] Example 2 A high-molybdenum content powder Hastelloy alloy, by mass fraction, is composed of the following chemical elements: Mo 16.9%, Cr 16.0%, Fe 3.9%, W 4.1%, V 0.1%, Mn 0.3%, C 0.002%, Si 0.04%, Ce 0.015%, Y 0.015%, N ≤ 0.005%, balance Ni and unavoidable impurities; PREN = 47.64.

[0049] The preparation steps are the same as in Example 1, except that the hot isostatic pressing temperature is adjusted to 1140°C, while the other process parameters remain unchanged.

[0050] Example 3 A high-molybdenum content powder Hastelloy alloy, by mass fraction, is composed of the following chemical elements: Mo 15.5%, Cr 15.0%, Fe 6.5%, W 3.5%, V 0.3%, Mn 0.7%, C 0.007%, Si 0.03%, Ce 0.005%, Y 0.005%, N ≤ 0.005%, balance Ni and unavoidable impurities; PREN = 43.65.

[0051] The preparation method is the same as in Example 1, except that the pressure of the atomizing gas is increased to 4.0 MPa and the gas flow rate is 600 Nm³ / h, and the resulting powder has a D50 of 28 μm.

[0052] Example 4 A high-molybdenum content powder Hastelloy alloy, by mass fraction, is composed of the following chemical elements: Mo 16.5%, Cr 15.6%, Fe 3.9%, W 4.2%, V 0.1%, Mn 0.3%, C 0.002%, Si 0.04%, Ce 0.015%, Y 0.015%, N ≤ 0.005%, balance Ni and unavoidable impurities; PREN = 46.79.

[0053] The preparation method is the same as in Example 1, except that the pressure of the atomizing gas is increased to 4.0 MPa and the gas flow rate is 560 Nm³ / h; and the hot isostatic pressing temperature is adjusted to 1145 °C.

[0054] Comparative Example 1 A Hastelloy alloy with the same chemical element mass fraction as in Example 1, PREN=45.46, but with a vacuum degree of only 0.9 Pa and a refining time of 28 min during the smelting stage; the hot isostatic pressing temperature is still 1150℃.

[0055] Comparative Example 2 A Hastelloy alloy, by mass fraction, is composed of the following chemical elements: Mo 16.3%, Cr 15.8%, Fe 5.2%, W 3.6%, V 0.25%, Mn 0.5%, C 0.006%, Si 0.004%, Ce 0.013%, Y 0.013%, N ≤ 0.005%, balance Ni and unavoidable impurities; PREN = 46.29.

[0056] The preparation method is basically the same as in Example 1, but the melting temperature is increased to 1580℃ and the melting time is shortened to 26min in the atomization powder preparation stage of the master alloy, resulting in a decrease in melt viscosity and a decrease in the sphericity of atomized powder to 88%.

[0057] Comparative Example 3 A Hastelloy alloy with the following chemical element mass fractions: Mo 16.8%, Cr 15.4%, Fe 5.3%, W 3.1%, V 0.25%, Mn 0.5%, C 0.005%, Si 0.004%, Ce 0.015%, Y 0.015%, N ≤ 0.005%, PREN = 45.38.

[0058] The preparation method is the same as in Example 1, except that the atomization melting temperature is reduced to 1500℃ and the power is 170kW, the melt superheat is insufficient, and the proportion of atomized hollow powder is 1.2%.

[0059] Comparative Example 4 A Hastelloy alloy with the following chemical element mass fractions: Mo 16.6%, Cr 16.1%, Fe 5.3%, W 3.6%, V 0.32%, Mn 0.41%, C 0.003%, Si 0.004%, Ce 0.018%, Y 0.018%, N ≤ 0.005%, PREN = 46.06.

[0060] The preparation method is the same as in Example 1, except that the hot isostatic pressing temperature is lowered to 1100℃, resulting in insufficient diffusion coefficient.

[0061] Experimental methods for evaluating results: 1. PREN (Pit Equivalent) The formula PREN is calculated according to the instruction manual: PREN = %Cr + 1.5 × (%Mo + %W) + 30 × %N. %Cr, %Mo, %W, and %N are the measured values ​​of the master alloy drill chips by ICP-OES and inert gas melting-thermal conductivity method. The average value of the top, middle, and bottom samples of the three electrode rods is taken.

[0062] 2. Oxygen / Nitrogen Content of Master Alloy Drill cuttings were sampled at R / 2 of the electrode rod and analyzed using a LECOTC-436 inert gas melting-infrared / thermal conductivity method with 99.999% He as the carrier gas. The analytical precision was ≤±1ppm, and the reported value was the average of three parallel samples.

[0063] 3. Powder D50 The laser diffraction method was performed according to GB / T19077-2016 on a Mastersizer 3000. The dispersion medium was anhydrous ethanol. The instrument was sonicated for 60 seconds with an opacity of 8%–12%. The median value of three measurements was taken.

[0064] 4. Types of powder defects 200 powder particles were randomly observed using a scanning electron microscope (ZEISS Sigma 300) and classified and recorded according to the following definitions: Normal spherical powder: aspect ratio ≤ 1.2 and no obvious satellites / hollows; satellite powder: ≥ 1 ≥ 5 μm adhering particle is visible; hollow powder: closed pores ≥ 10 μm exist after the cross section is polished; inclusions: oxides / sulfides other than Cr, Mo, W confirmed by energy dispersive spectroscopy ≥ 2 μm.

[0065] Report the typical morphology and the proportion of major defects.

[0066] 5. Corrosion rate: GB / T4334-2020E method 30mm×20mm×2mm; Ra≤0.4µm; 50% boiling H2SO4+Fe2(SO4)3, 120h; Equipment model: self-made glass reflux device + constant temperature water bath; 3 parallel samples, if the range is >0.1mm / a, 2 more samples are added for retesting, and the average value is taken.

[0067] 6. Tensile strength: GB / T228.1-2021 A standard specimen with a diameter of φ5mm × M12 was taken from a steel ingot at a height of 1 / 2 R / 2, with the strain direction parallel to the HIP compression axis; the strain rate was 0.00025s. -1 Equipment model: Zwick Z600 electronic universal testing machine; average value of 3 valid samples.

[0068] 7. Pitting corrosion weight loss: Corrosion rate conversion using GB / T4334-2020E method. Same corrosion sample as above, weighed with an accuracy of 0.01 mg before and after 120 h test; Equipment model: Sartorius CPA225D analytical balance; Corrosion rate → weight loss formula: 1 mm / a = 14.4 mg / 120 h (8.6 g / cm³ density, area 1.52 × 10⁻⁶) -3 m 2 ).

[0069] Table 1. Results data for examples and comparative examples.

[0070] As can be seen from Table 1, the inventiveness of this application includes: 1. Within the same window of 43 < PREN < 48, by locking D50 to 30–48 μm and ensuring ≥90% normal spherical powder, the corrosion rate was reduced from 1.8–2.5 mm / a in the control sample to 0.41–0.45 mm / a, and the pitting weight loss was reduced by more than 75%. For the first time, the ultimate corrosion resistance performance was quantitatively "extruded" using both particle size and defect indicators within the same PREN range.

[0071] 2. When [O]≤35ppm, [N]≤51ppm and the ratio of the two is 0.4–0.7, the tensile strength is stable at 825–842MPa; once [O]≥60ppm or [N]≥85ppm (Comparative Example 1), the strength drops sharply by more than 50MPa, revealing the "embrittlement inflection point" of interstitial elements in the low PREN alloy system.

[0072] 3. In Examples 1-4, refining the D50 from 62μm to 30μm resulted in a continuous increase in strength to 842MPa; refining the grains increased the strength of the steel ingot and reduced pitting weight loss. In contrast, in Comparative Examples 1-4, the powder D50 was in different ranges, and the atomization pressure and gas flow rate were not well matched, resulting in a decrease in tensile strength and an increase in pitting weight loss after the hollow powder was pressed and formed.

[0073] 4. HIP temperature-particle size coupling window Under the combination of 1140–1150℃ and D5030–48μm, the relative density is ≥99.5% and the porosity is ≤0.5%. When deviating from this window (Comparative Example 4, 1100℃), the porosity increases to 0.8% and the corrosion rate doubles. The coupling boundary of "fine powder needs to be matched with 1140℃ level HIP temperature" is proposed to avoid the traditional single temperature increase approach.

[0074] It should be understood that the endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0075] It should be noted that in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Additionally, the term "and / or" as used herein is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone.

[0076] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A high-molybdenum-content powder Hastelloy alloy, characterized in that, The alloy is composed of the following chemical elements by mass fraction: Mo 15.0%–17.0%, Cr 14.5%–16.5%, Fe 4.0%–7.0%, W 3.0%–4.5%, V 0–0.35%, Mn 0.3%–0.8%, C ≤0.01%, Si ≤0.08%, Ce ≤0.2%, Y ≤0.2%, with the balance being Ni and unavoidable impurities; and the pitting resistance equivalent PREN of the Hastelloy alloy satisfies 43 < PREN < 48, where PREN = %Cr + 1.5 × (%Mo + %W) + 30 × %N.

2. The high molybdenum content powder Hastelloy according to claim 1, characterized in that, The mass fraction of Mo is 15.5%–16.5%, the mass fraction of Cr is 15.0%–16.0%, and the mass fraction of W is 3.5%–4.2%; the PREN value is 45–47.

3. The high molybdenum content powder Hastelloy according to claim 1 or 2, characterized in that, The C mass fraction is ≤0.005%, the Si mass fraction is ≤0.005%, the O mass fraction is ≤30ppm, and the N mass fraction is ≤50ppm.

4. A method for preparing high-molybdenum-content powder Hastelloy alloy, characterized in that, include: The raw materials with the element ratio described in claim 1 are melted under a vacuum of ≤1 Pa. The melt obtained by melting is refined for 30 to 40 minutes and the melt is electromagnetically stirred for 10 minutes. When the temperature of the melt is 50 to 150°C higher than the melting point of the alloy, the melt is cast into an electrode rod. The surface of the electrode rod is machined to remove oxide scale and oil stains, resulting in a bright master alloy. The master alloy is continuously melted under conditions of vacuum degree ≤1Pa, temperature 1500~1580℃, and power 150~200kW. The melt obtained by continuous melting is atomized with high-purity nitrogen gas at 2.5~4.5MPa at a flow rate of 300~800Nm3 / h. The powder obtained by atomization is cooled in an argon atmosphere. The cooled powder is dried at 100°C in an inert atmosphere or vacuum, and the dried powder is classified according to the target particle size using an ultrasonic vibrating sieve to obtain alloy powder with an oxygen mass fraction ≤30ppm, sphericity ≥90%, and D50 of 25~65μm. The alloy powder is loaded into a stainless steel sleeve, and the sleeve is then evacuated to a vacuum level of ≤10 after the powder is vibrated to fill the sleeve. -3 Pa and seal the cladding, heat the sealed cladding to 1140-1160℃ at 5-10℃ / min, hold the cladding at 100-140MPa pressure for 2-4h, and then cool the cladding to room temperature at the same rate to obtain Hastelloy steel ingot with a density ≥99.5%.

5. The preparation method according to claim 4, characterized in that, The atomizing gas pressure is 3.5–4.0 MPa, and the gas flow rate is 550–600 Nm³. 3 / h, the alloy powder D50 is 30-45μm.

6. The preparation method according to claim 4, characterized in that, The heating rate is 7℃ / min, the holding temperature is 1150℃, the holding time is 3h, and the pressure is 140MPa.

7. The preparation method according to claim 4, characterized in that, The vacuum degree is ≤0.1Pa, the refining time is 35-40min, and the tapping temperature is 80-120℃ higher than the alloy melting point.

8. The preparation method according to claim 4, characterized in that, After the cladding is cooled to room temperature, the cladding is machined to remove the cladding material, resulting in a Hastelloy steel ingot with no oxide scale on the surface, uniform chemical composition, tensile strength ≥800MPa, and corrosion rate ≤0.5mm / a.

9. A high-molybdenum-content powdered Hastelloy steel ingot prepared by the method according to any one of claims 4 to 8, characterized in that, The steel ingot has an O mass fraction ≤30ppm, an N mass fraction ≤50ppm, a PREN value of 43~48, a density ≥99.5%, a tensile strength ≥800MPa, and a corrosion rate ≤0.5mm / a.

10. The high molybdenum content powdered Hastelloy steel ingot according to claim 9, characterized in that, The steel ingot has a grain size of not less than ASTM grade 5, a difference of ≤5% between transverse and longitudinal mechanical properties, and no intergranular corrosion cracks after 120 hours of corrosion in a 50% boiling ferric sulfate solution.

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